List of Neurological Disorders and Their Descriptions

Introduction

There are many recognized neurological disorders, some relatively common, but many rare. They may be assessed by neurological examination, studied, and treated within neurology and clinical neuropsychology specialties. On the other hand, mental disorders are "psychiatric illnesses" or diseases that appear primarily as abnormalities of thought, feeling, or behavior, producing either distress or impairment of function.

Main Digest

Neurological disorders affect the brain and the nerves found throughout the human body and the spinal cord. These three body parts work together and are referred to as the central nervous system that controls everything in the body. Neurology is a medical science that deals with the nervous system and the disorders that affect it. Conditions that are classed as mental disorders, or learning disabilities and forms of Intellectual disability, are not themselves usually dealt with as neurological disorders.

Neurological disorders can be categorized according to the primary location affected, type of dysfunction involved, or cause. The broadest division is between central and peripheral nervous system disorders. Neurological disorders can affect an entire neurological pathway or a single neuron. Even a small disturbance to a neuron's structural pathway can result in dysfunction.

The University of California, San Francisco states that more than 600 neurological disorders strike millions yearly. These diseases and disorders inflict great pain and suffering on millions of patients and their families, costing the U.S. economy billions of dollars annually. Social Security approves disability benefits for serious cases of epilepsy, cerebral palsy, Parkinson's disease, multiple sclerosis, ALS, and other nerve-based diseases.

Diagram of the human brain showing the four lobes - frontal lobe, parietal lobe, occipital lobe, and temporal lobe - of the cerebral cortex. The cerebrum or cortex is the largest part of the human brain, associated with the higher brain function such as thought and action.

Currently Known Human Neurological Conditions

A

Absence of the Septum Pellucidum

The septum pellucidum (SP) is a thin membrane located at the mid-line of the brain. Children born without this membrane and with other abnormalities, pituitary deficiencies, and abnormal optic disk development have a septo-optic dysplasia disorder.

Acid Lipase Disease

A name used to describe two related disorders of fatty acid metabolism. Acid lipase disease occurs when the enzyme needed to break down certain fats normally digested by the body is lacking or missing, resulting in the toxic buildup of these fats in the body's cells and tissues. These fatty substances, called lipids, include waxes, oils, and cholesterol.

Acid Maltase Deficiency

Glycogen storage disease type II (also called Pompe disease or acid maltase deficiency) is a rare genetic disorder caused by a deficiency in the enzyme acid alpha-glucosidase (GAA) (EC 3.2.1.20), which is needed to break down glycogen, a stored form of sugar used for energy.

Acquired Epileptiform Aphasia

Landau-Kleffner syndrome (LKS) is a rare, childhood neurological disorder characterized by the sudden or gradual development of aphasia (the inability to understand or express language) and an abnormal electro-encephalogram (EEG). LKS affects the parts of the brain that control comprehension and speech. The disorder usually occurs in children between the ages of 5 and 7.

Acute Disseminated Encephalomyelitis

An immune-mediated disease of the brain. It usually occurs following a viral infection or vaccination but may also appear spontaneously. It is similar in some ways to multiple sclerosis and is considered part of the Multiple sclerosis borderline.

ADHD

Attention-Deficit Hyperactivity Disorder (ADHD), or Hyper-kinetic Disorder as officially known in the UK (though ADHD is more commonly used), is generally considered to be a developmental disorder, largely neurological, affecting about 5% of the world's population.

Adie's Pupil

A neurological condition of unknown origin with an unusual, asymmetric presentation known as anisocoria, an inequality in the size of the pupils of the eyes. It is believed to result from damage to the nerve innervating a muscle of the eye known as the ciliary body. The problem may be located at the ciliary ganglion, a nerve junction structure from which the nerve to the ciliary body runs.

Adie's Syndrome

Also Adie's syndrome, Adie's Tonic Pupil or Holmes-Adie's syndrome, is caused by damage to the postganglionic fibers of the parasympathetic innervation of the eye and characterized by a tonically dilated pupil. It most commonly affects younger women and is unilateral in 80% of cases. The pupil is characteristically poorly reactive to light but slowly reactive to accommodation. Signs and symptoms may/can include blurry vision due to accommodative paresis, photophobia, and difficulty reading.

Adrenoleukodystrophy

One of a group of genetic disorders called the leukodystrophies that cause damage to the myelin sheath. This insulating membrane surrounds nerve cells in the brain. People with ALD accumulate high levels of saturated, very long-chain fatty acids (VLCFA) in the brain and adrenal cortex because they do not produce the enzyme that breaks down these fatty acids in a normal manner. The loss of myelin and the progressive dysfunction of the adrenal gland are the primary characteristics of ALD.

Agenesis of the Corpus Callosum

(ACC) is a rare congenital disability (congenital disorder) in which there is a complete or partial absence of the corpus callosum. Agenesis of the corpus callosum occurs when the corpus callosum, the band of tissue connecting the brain's two hemispheres, does not typically develop in utero. In addition to agenesis of the corpus callosum, other callosal disorders include hypogenesis (partial formation), dysgenesis (malformation) of the corpus callosum, and hypoplasia (underdevelopment) of the corpus callosum.

Agnosia

A loss of ability to recognize objects, persons, sounds, shapes, or smells while the specific sense is not defective, nor is there any significant memory loss. It is usually associated with brain injury or neurological illness, particularly after damage to the right parietal lobe.

Aicardi Syndrome

A rare genetic disorder. Aicardi syndrome is characterized by the following: Absence of the corpus callosum, either partial or complete (the corpus callosum is part of the brain which sits between the right and left sides of the brain and allows the right side to communicate with the left.) Infantile spasms (a form of seizure) Lesions or "lacunae" of the eye's retina are particular to this disorder. Other types of defects of the brain such as microcephaly (small brain); enlarged ventricles; or porencephalic cysts (a gap in the brain where there should be healthy brain tissue). Aicardi syndrome only affects females, and in sporadic cases, males with Klinefelter syndrome (XXY).

AIDS

Neurological complications are common in HIV disease. The spectrum of neurological disorders is broad and involves the central nervous system, or CNS (brain and spinal cord), and the peripheral nervous system, or PNS (nerves outside the brain and spinal cord, and related muscle).

Alexander Disease

A slowly progressing and fatal neurodegenerative disease. It is a sporadic disorder that results from a genetic mutation and mostly affects infants and children, causing developmental delay and changes in physical characteristics.

Alpers' Disease

A rare degenerative disease of the brain involving the grey matter. It is characterized by the acute onset of severe convulsions leading to a rapid intellectual and bodily breakdown. Other traits are blindness, deafness, myoclonus, spasticity, choreoathetosis, cerebellar ataxia, growth retardation, plus terminal decortication. It manifests in early childhood and usually causes death within months.

Alternating Hemiplegia

Alternating hemiplegia is a rare neurological disorder that develops in childhood, usually before the first four years. The disorder is characterized by recurrent but temporary episodes of paralysis on one side of the body.

Alzheimer's Disease

(AD) is a slowly progressive disease of the brain that is characterized by impairment of memory and eventually by disturbances in reasoning, planning, language, and perception.

Amyotrophic Lateral Sclerosis

(ALS) is a disease of unknown cause characterized by slowly progressive degeneration of upper (UMN) and lower motor neurons (LMN). The UMN findings include hyperreflexia and spasticity. They result from degeneration of the lateral corticospinal tracts in the spinal cord. The LMN findings include weakness, atrophy, and fasciculations. ALS is eventually fatal because of respiratory muscle weakness.

Anencephaly

A condition present at birth that affects the formation of the brain and skull bones surrounding the head. Often, the brain lacks part or all of the cerebrum. There is no bony covering over the back of the head, and there may also be missing bones around the front and sides of the head.

Aneurysm

An aneurysm (or aneurism) is a localized, blood-filled dilation of a blood vessel caused by disease or weakening of the vessel wall. Aneurysms most commonly occur in arteries at the base of the brain and in the aorta (the main artery coming out of the heart). The bulge in a blood vessel can burst and lead to death at any time. The larger an aneurysm becomes, the more likely it is to burst. Aneurysms can usually be treated.

Angelman Syndrome

Symptoms of Angelman syndrome are a learning disability, jerky movements, a tendency to seizures, and a happy, friendly personality. Children with Angelman syndrome often do not learn to sit until around one year of age. Most children will learn to walk but with a stiff-legged gait. Many children with Angelman syndrome have a facial appearance with a wide, smiling mouth, deep-set eyes, and a prominent chin. These features become more prominent as children get older.

Angiomatosis

Refers to little knots of capillaries in various organs. These tend to be cavernous hemangiomas, which are sharply defined, sponge-like tumors composed of large, dilated, cavernous vascular spaces.

Anoxia

Hypoxia is a pathological condition in which the body as a whole (generalized hypoxia) or region of the body (tissue hypoxia) is deprived of adequate oxygen supply. Hypoxia, in which there is complete deprivation of oxygen supply, is referred to as anoxia. In the case of altitude sickness, where hypoxia develops gradually, the symptoms include headaches, fatigue, shortness of breath, a feeling of euphoria, and nausea. In severe hypoxia or hypoxia of very rapid onset, changes in levels of consciousness, seizures, coma, and death occur.

Antiphospholipid Syndrome

(APS) is a disorder characterized by recurrent venous or arterial thrombosis and fetal losses associated with characteristic laboratory abnormalities, such as persistently elevated levels of antibodies directed against membrane anionic phospholipids (i.e., anticardiolipin [aCL] antibody, anti phosphatidylserine) or their associated plasma proteins, predominantly beta-2 glycoprotein I (apolipoprotein H), or evidence of a circulating anticoagulant.

Aphasia

Or aphemia, is a loss of the ability to produce and comprehend language, due to injury to brain areas specialized for these functions. It is not a result of deficits in sensory, intellect, or psychiatric functioning. Depending on the area and extent of the damage, someone suffering from aphasia may be able to speak but not write, or vice versa, or display a variety of other deficiencies in language comprehension and production, such as being able to sing but not speak. Aphasia may co-occur with speech disorders such as dysarthria or apraxia of speech.

Apraxia

A neurological disorder characterized by loss of the ability to execute or carry out learned purposeful movements, despite having the desire to and the physical ability to perform the movements. It is a disorder of motor planning which may be acquired or developmental but may not be caused by in-coordination, sensory loss, or failure to comprehend simple commands.

Arachnoid Cysts

Represent benign cysts that occur in the cerebrospinal axis about the arachnoid membrane and do not communicate with the ventricular system. They usually contain clear, colorless fluid that is most likely normal cerebrospinal fluid, but they rarely contain xanthochromic fluid. Arachnoid cysts also occur within the spinal canal, in which arachnoid cysts or arachnoid diverticula may be located subdurally or in the epidural space. Spinal arachnoid cysts are commonly located dorsal to the cord in the thoracic region.

Arachnoiditis

A neuropathic disease caused by the inflammation of the arachnoid, one of the membranes that surround and protect the nerves of the central nervous system, including the brain and spinal cord. The arachnoid can become inflamed because of an irritation from chemicals, infection from bacteria or viruses, as the result of direct injury to the spine, chronic compression of spinal nerves, or complications from spinal surgery or other invasive spinal procedures.

Arnold-Chiari Malformation

Sometimes referred to as Chiari II malformation or ACM, is a congenital malformation of the brain. It occurs in almost all children born with both spina bifida and hydrocephalus. The cerebellar tonsils are elongated and pushed down through the opening of the base of the skull blocking the flow of cerebrospinal fluid (CSF). The brainstem, cranial nerves, and the lower portion of the cerebellum may be stretched or compressed.

Arteriovenous Malformation

(AVMs) are defects of the circulatory system that are generally believed to arise during embryonic or fetal development or soon after birth. Although AVMs can develop in many different sites, those located in the brain or spinal cord can have pervasive effects on the body. Most people with neurological AVMs experience few, if any, significant symptoms. The malformations tend to be discovered only incidentally, usually either at autopsy or during treatment for an unrelated disorder.

Asperger Syndrome

Also called Asperger's syndrome, Asperger's disorder, Asperger's or AS) is one of several autism spectrum disorders (ASD) characterized by difficulties in social interaction and by restricted, stereotyped interests and activities. AS is distinguished from the other ASDs' lack of general language or cognitive development delay.

Ataxia

Friedreich's ataxia is an inherited disease that causes progressive damage to the nervous system resulting in symptoms ranging from gait disturbance and speech problems to heart disease. Coordination problems, such as clumsy or awkward movements and unsteadiness, occur in many diseases and conditions. Friedreich's ataxia results from the degeneration of nerve tissue in the spinal cord and nerves that control muscle movement in the arms and legs. The spinal cord becomes thinner, and nerve cells lose some myelin sheath, the insular covering on all nerve cells that helps conduct nerve impulses.

Ataxia Telangiectasia

A rare childhood neurological disorder that causes degeneration in the part of the brain that controls motor movements and speech. Its most unusual symptom is an acute sensitivity to ionizing radiation, such as X-rays or gamma-rays. The first signs of the disease, which include delayed development of motor skills, poor balance, and slurred speech, usually occur during the first decade of life.

Ataxias and Cerebellar or Spinocerebellar Degeneration

(SCA) is a genetic disease with multiple types, each of which could be considered a disease in its own right. Spinocerebellar ataxia (SCA) is one of a group of genetic disorders characterized by slowly progressive in-coordination of gait and often associated with poor coordination of hands, speech, and eye movements. Frequently, atrophy of the cerebellum occurs.

Atrial Fibrillation and Stroke

Atrial fibrillation is a rapid, uncoordinated generation of electrical impulses by the atria of the heart. The most serious side effect of atrial fibrillation is stroke. Half of all strokes associated with atrial fibrillation are major and disabling.

Autism

A brain development disorder that impairs social interaction and communication, and causes restricted and repetitive behavior, all starting before a child is three years old. This set of signs distinguishes autism from milder autism spectrum disorders (ASD), such as Asperger syndrome. Autism is highly heritable, although the genetics of autism are complex, and it is generally unclear which genes are responsible.

Autonomic Dysfunction

Refers to a disorder of autonomic nervous system (ANS) function. Most physicians view dysautonomia as the failure of the sympathetic or parasympathetic components of the ANS, but dysautonomia involving excessive ANS activities can also occur. Dysautonomia can be local, as in reflex sympathetic dystrophy, or generalized, as in pure autonomic failure. It can be acute and reversible, as in Guillain-Barre syndrome, or chronic and progressive. Several common conditions, such as diabetes and alcoholism, can include dysautonomia.

B

Back Pain

Also known as "dorsalgia," is pain felt in the back that may originate from the muscles, nerves, bones, joints or other structures in the spine.

Barth Syndrome

A rare congenital metabolic and neuromuscular disorder that affects boys. It is passed from mother to son through the sex-linked, or X, chromosome. Symptoms affect multiple body systems and may include changes to metabolism, motor delays, hypotonia, delayed growth, cardiomyopathy, weakened immune system, chronic fatigue, lack of stamina, hypoglycemia, mouth ulcers, diarrhea, and varying degrees of physical and learning disability.

Batten Disease

A rare, fatal, autosomal recessive neurodegenerative disorder that begins in childhood. Also known as Spielmeyer-Vogt-Sjogren-Batten disease is the most common form of a group of disorders called neuronal ceroid lipofuscinosis (or NCLs). Although Batten disease is usually regarded as the juvenile form of NCL, some physicians use the term Batten disease to describe all forms of NCL.

Becker's Myotonia

Myotonia congenita is an inherited neuromuscular disorder characterized by the inability of muscles to relax after a voluntary contraction quickly. The condition has been present since early childhood, but symptoms can be mild. Most children will be 2 or 3 years old when parents first notice muscle stiffness, particularly in the legs, often provoked by sudden activity after rest.

Behcet's Disease

A chronic condition due to disturbances in the body's immune system. This system, which normally protects the body against infections through controlled inflammation, becomes over-active and produces unpredictable outbreaks of exaggerated inflammation. This extra inflammation affects blood vessels, usually the small ones. As a result, symptoms occur wherever there is a patch of inflammation and can be anywhere with a blood supply.

Bell's Palsy

A weakness or paralysis of the muscles that control expression on one side of your face. The disorder results from damage to one of a pair of facial nerves that runs beneath each ear to the muscles in your face.

Benign Essential Blepharospasm

(BEB) is a progressive neurological disorder characterized by involuntary muscle contractions and spasms of the eyelid muscles. It is a form of dystonia, a movement disorder in which muscle contractions cause sustained eyelid closure, twitching, or repetitive movements.

Benign Focal Amyotrophy

Monomelic amyotrophy (MMA) is a rare disease of the nerves that control voluntary movements of the limbs. Monomeric amyotrophy may also be known as benign focal amyotrophy, single limb atrophy, Hirayama syndrome, or Sobue disease. Descriptive terms such as brachial monomeric amyotrophy (MMA confined to an arm) or monomeric amyotrophy of the lower limb (MMMA of a leg) may be used to specify the type of limb affected.

Benign Intracranial Hypertension

Sometimes called benign intracranial hypertension (BIH), or pseudotumor cerebri (PTC) is a neurological disorder that is characterized by increased intracranial pressure (ICP), in the absence of a tumor or other diseases affecting the brain or its lining. The main symptoms are headache and visual problems. Diagnosis requires brain scans and lumbar puncture. There are various medical and surgical treatments.

Bernhardt-Roth Syndrome

A disorder characterized by tingling, numbness, and burning pain in the outer side of the thigh. The disorder is caused by compression of the lateral femoral cutaneous nerve as it exits the pelvis. It more commonly occurs in men than women and is generally found in middle-aged or overweight individuals. People with the disorder frequently report that it appears or worsens after walking or standing. The skin is often sensitive to the touch. Meralgia paresthetica is associated with clothing that is too tight, pregnancy, diabetes, and obesity.

Binswanger's Disease

Or Subcortical Leukoencephalopathy, a rare form of multi-infarct dementia caused by damage to deep white brain matter. It is characterized by loss of memory and intellectual function and by changes in mood.

Blepharospasm

Eye twitching is any strange tic or twitch of the eyelid. However, it is normally distinguished from less serious disorders. It refers to Benign Essential Blepharospasm, focal dystonia (a neurological movement disorder involving involuntary and sustained muscle contractions) of the muscles around the eyes. The cause is often undetermined, but fatigue or irritants are possible contributing factors.

Bloch-Sulzberger Syndrome

Incontinentia pigmenti (IP) is one of a group of gene-linked diseases known as neurocutaneous disorders. These disorders cause characteristic discolored skin patterns and involve the brain, eyes, nails, and hair. In most cases, IP is caused by mutations in a gene called NEMO (NF-kappaB essential modulator). Males are more severely affected than females.

Brachial Plexus Injuries

The brachial plexus is a network of nerves that conducts signals from the spine to the shoulder, arm, and hand. Brachial plexus injuries are caused by damage to those nerves. Erb-Duchenne (Erb's) palsy refers to paralysis of the upper brachial plexus. Dejerine-Klumpke (Klumpke's) palsy refers to paralysis of the lower brachial plexus. Symptoms of brachial plexus injury may include a limp or paralyzed arm, lack of muscle control in the arm, hand, or wrist, and lack of feeling or sensation in the arm or hand.

Bradbury-Eggleston Syndrome

Orthostatic hypotension is a sudden fall in blood pressure that occurs when a person assumes a standing position. It may be caused by hypovolemia (a decreased amount of blood in the body), resulting from the excessive use of diuretics, vasodilators, other drugs, dehydration, or prolonged bed rest. The disorder may be associated with Addison's disease, atherosclerosis (build-up of fatty deposits in the arteries), diabetes, and certain neurological disorders.

Brain and Spinal Tumors

Abnormal growths of tissue found inside the skull or the bony spinal column, which are the primary components of the central nervous system (CNS). Benign tumors are noncancerous, and malignant tumors are cancerous. The CNS is housed within rigid, bony quarters (i.e., the skull and spinal column), so any abnormal growth, whether benign or malignant, can place pressure on sensitive tissues and impair function. Tumors that originate in the brain or spinal cord are called primary tumors.

Brain Aneurysm

A cerebral aneurysm or brain aneurysm is a cerebrovascular disorder in which weakness in the wall of a cerebral artery or vein causes a localized dilation or ballooning of the blood vessel.

Brain Injury

(TBI), traumatic injuries to the brain, also called intracranial injury, or simply head injury, occurs when a sudden trauma causes brain damage. TBI can result from a closed head injury or a penetrating head injury and is one of two subsets of acquired brain injury (ABI). The other subset is non-traumatic brain injury (e.g., stroke, meningitis, anoxia). Parts of the brain that can be damaged include the cerebral hemispheres, cerebellum, and brain stem. TBI can cause various physical, cognitive, emotional, and social effects.

Brown-Sequard Syndrome

An incomplete spinal cord lesion characterized by a clinical picture reflecting hemisection of the spinal cord, often in the cervical cord region. It is a rare syndrome consisting of ipsilateral hemiplegia with contralateral pain and temperature sensation deficits because of the crossing of the fibers of the spinothalamic tract.

Bulbospinal Muscular Atrophy

Or Kennedy's disease is an inherited motor neuron disease that affects males. It is one of a group of disorders called spinal muscular atrophy (SMA). The onset of the disease is usually between the ages of 20 and 40, although it has been diagnosed in men from their teens to 70s. Early symptoms include tremors in the outstretched hands, muscle cramps with exertion, and fasciculations (fleeting muscle twitches visible under the skin).

C

Cadasil

(Cerebral Autosomal Dominant Arteriopathy with Sub-cortical Infarcts and Leukoencephalopathy) is an inherited form of cerebrovascular disease that occurs when the thickening of blood vessel walls blocks the flow of blood to the brain. The disease primarily affects small blood vessels in the brain's white matter. A mutation in the Notch3 gene alters the muscular walls in these small arteries. CADASIL is characterized by migraine headaches and multiple strokes progressing to dementia. Other symptoms include white matter lesions throughout the brain, cognitive deterioration, seizures, vision problems, and psychiatric problems such as severe depression and changes in behavior and personality. Individuals may also be at higher risk of a heart attack.

Canavan Disease

One of the most common cerebral degenerative diseases of infancy, is a gene-linked, neurological birth disorder in which the white matter of the brain degenerates into spongy tissue riddled with microscopic fluid-filled spaces. Canavan disease is one of a group of genetic disorders known as leukodystrophies. These diseases cause imperfect growth or development of the myelin sheath, the fatty covering that acts as an insulator around nerve fibers in the brain. Myelin, which lends its color to the "white matter" of the brain, is a complex substance of at least ten different chemicals. Each of the leukodystrophies affects one (and only one) of these substances. Mutations cause Canavan disease in the gene for an enzyme called aspartoacylase. Symptoms of Canavan disease, which appear in early infancy and progress rapidly, may include mental retardation, loss of previously acquired motor skills, feeding difficulties, abnormal muscle tone (floppiness or stiffness), and an abnormally large, poorly controlled head.

Carpal Tunnel Syndrome

Occurs when the median nerve, which runs from the forearm into the hand, becomes pressed or squeezed at the wrist. The median nerve controls sensations to the palm side of the thumb and fingers (although not the little finger) and impulses to some small muscles in the hand that allow the fingers and thumb to move. The carpal tunnel, a narrow, rigid passageway of ligament and bones at the base of the hand, houses the median nerve and tendons. Sometimes, thickening from irritated tendons or other swelling narrows the tunnel and causes the median nerve to be compressed. The result may be pain, weakness, or numbness in the hand and wrist, radiating up the arm.

Causalgia

Complex regional pain syndrome (CRPS) is a chronic pain condition. The key symptom of CRPS is continuous, intense pain out of proportion to the severity of the injury, which gets worse rather than better over time. CRPS most often affects one of the arms, legs, hands, or feet. Often the pain spreads to include the entire arm or leg. Typical features include dramatic changes in the color and temperature of the skin over the affected limb or body part, accompanied by intense burning pain, skin sensitivity, sweating, and swelling.

Cavernomas

A cavernous cerebral malformation (CCM) is a collection of small blood vessels (capillaries) in the central nervous system (CNS) that is enlarged and irregular in structure and takes the shape of a characteristic honeycomb-like pattern. In CCM, the walls of the capillaries are thinner than normal, less elastic, and prone to leaking. Cavernous malformations can occur anywhere in the body but usually only produce symptoms when they are found in the brain and spinal cord. Some people with CCM experts estimate 25 percent will never experience any related medical problems.

Cavernous Angioma

Also known as cavernous cerebral malformation (CCM), cavernous haemangioma and cavernoma, is a vascular disorder of the central nervous system that may appear either sporadically or exhibit autosomal dominant inheritance.

Central Cord Syndrome

A form of incomplete spinal cord injury characterized by impairment in the arms and hands and, to a lesser extent, in the legs. The brain's ability to send and receive signals to and from parts of the body below the injury site is reduced but not entirely blocked. This syndrome is associated with damage to the large nerve fibers that carry information directly from the cerebral cortex to the spinal cord. These nerves are vital for hand and arm function. Symptoms may include paralysis or loss of fine control of arm and hand movements, with relatively less impairment of leg movements. Sensory loss below the injury site and loss of bladder control may also occur.

Central Pain Syndrome

A neurological condition caused by damage to or dysfunction of the central nervous system (CNS), which includes the brain, brainstem, and spinal cord. This syndrome can be caused by stroke, multiple sclerosis, tumors, epilepsy, brain or spinal cord trauma, or Parkinson's disease. The character of the pain associated with this syndrome differs widely among individuals partly because of the variety of potential causes. Central pain syndrome may affect a large portion of the body or be more restricted to specific areas, such as hands or feet. The extent of pain is usually related to the cause of the CNS injury or damage. Pain is typically constant, may be moderate to severe in intensity, and is often made worse by touch, movement, emotions, and temperature changes, usually cold temperatures.

Central Pontine Myelinolysis

(CPM) is a neurological disorder that most frequently occurs after too rapid medical correction of sodium deficiency (hyponatremia). The rapid rise in sodium concentration is accompanied by the movement of small molecules and pulls water from brain cells. Through a mechanism that is only partly understood, the shift in water and brain molecules leads to the destruction of myelin, which surrounds and protects nerve fibers. Nerve cells (neurons) can also be damaged. Certain areas of the brain are particularly susceptible to myelinolysis, especially the part of the brainstem called the pons. Some individuals will also have damage in other areas of the brain, which is called extrapontine myelinolysis (EPM). Experts estimate that 10 percent of those with CPM will also have areas of EPM.

Cephalic Disorders

Congenital conditions that stem from damage to, or abnormal development of, the budding nervous system. Cephalic is a term that means "head" or "head end of the body." Congenital means the disorder is present at, and usually before, birth. Although there are many congenital developmental disorders, this fact sheet briefly describes only cephalic conditions. Cephalic disorders are not necessarily caused by a single factor but may be influenced by hereditary or genetic conditions or environmental exposures during pregnancy, such as medication taken by the mother, maternal infection, or radiation exposure. Some cephalic disorders occur prematurely when the cranial sutures (the fibrous joints that connect the skull bones) join. Most cephalic disorders are caused by a disturbance that occurs very early in the fetal nervous system development.

Ceramidase Deficiency

Farber's disease describes a group of inherited metabolic disorders called lipid storage diseases, in which excess amounts of lipids (oils, fatty acids, and related compounds) build up to harmful levels in the joints, tissues, and central nervous system. The liver, heart, and kidneys may also be affected. Symptoms typically appear in the first few weeks of life, including impaired motor and mental ability and difficulty swallowing. Other symptoms may include arthritis, swollen lymph nodes and joints, hoarseness, nodules under the skin (and sometimes in the lungs and other body parts), chronic shortening of muscles or tendons around joints, and vomiting. Affected persons may require the insertion of a breathing tube. In severe cases, the liver and spleen are enlarged.

Cerebellar Degeneration

A disease process in which neurons in the cerebellum, the area of the brain that controls muscle coordination and balance, deteriorate and die. Diseases that cause cerebellar degeneration can also involve areas of the brain that connect the cerebellum to the spinal cord, such as the medulla oblongata, the cerebral cortex, and the brain stem. Cerebellar degeneration is often the result of inherited genetic mutations that alter the normal production of specific proteins necessary for the survival of neurons.

Cerebellar Hypoplasia

A neurological condition in which the cerebellum is smaller than usual or not completely developed. Cerebellar hypoplasia is a feature of several congenital (present at birth) malformation syndromes, such as Walker-Warburg syndrome. It is also associated with several inherited metabolic disorders, such as Williams syndrome, and some neurodegenerative disorders that begin in early childhood, such as ataxia telangiectasia. In an infant or young child, symptoms of a disorder that features cerebellar hypoplasia might include floppy muscle tone, developmental or speech delay, problems with walking and balance, seizures, mental retardation, and involuntary side-to-side movements of the eyes. An older child's symptoms might include headache, dizzy spells, clumsiness, and hearing impairment.

Cerebral Aneurysm

Also known as an intracranial or intracerebral aneurysm, a weak or thin spot on a blood vessel in the brain that balloons out and fills with blood. The bulging aneurysm can put pressure on a nerve or surrounding brain tissue. It may also leak or rupture, spilling blood into the surrounding tissue (called a hemorrhage). Some cerebral aneurysms, particularly very small ones, do not bleed or cause other problems. Cerebral aneurysms can occur anywhere in the brain, but most are located along a loop of arteries that run between the brain's underside and the skull's base.

Cerebral Arteriosclerosis

Cerebral arteriosclerosis is the result of the thickening and hardening of the walls of the arteries in the brain. Symptoms of cerebral arteriosclerosis include headache, facial pain, and impaired vision. Cerebral arteriosclerosis can cause serious health problems. If the walls of an artery are too thick, or a blood clot becomes caught in the narrow passage, blood flow to the brain can become blocked and cause an ischemic stroke. When the thickening and hardening are uneven, arterial walls can develop bulges (called aneurysms). If a bulge ruptures, bleeding in the brain can cause a hemorrhagic stroke. Both types of stroke can be fatal.

Cerebral Atrophy

A common feature of many of the diseases that affect the brain. Atrophy of any tissue means loss of cells. In brain tissue, atrophy describes a loss of neurons and their connections. Atrophy can be generalized, which means that all of the brain has shrunk, or it can be focal, affecting only a limited area of the brain and resulting in a decrease of the functions that area of the brain controls. If the cerebral hemispheres (the two lobes of the brain that form the cerebrum) are affected, conscious thought and voluntary processes may be impaired.

Cerebral Beriberi

Wernicke's encephalopathy is a degenerative brain disorder caused by the lack of thiamine (vitamin B1). It may result from alcohol abuse, dietary deficiencies, prolonged vomiting, eating disorders, or the effects of chemotherapy. Symptoms include mental confusion, vision impairment, stupor, coma, hypothermia, hypotension, and ataxia. Korsakoff's amnesic syndrome- a memory disorder- also results from a deficiency of thiamine and is associated with alcoholism. The heart, vascular, and nervous systems are involved. Symptoms include amnesia, confabulation, attention deficit, disorientation, and vision impairment. The main features of Korsakoff's amnesic syndrome are the impairments in acquiring new information or establishing new memories and retrieving previous memories.

Cerebral Gigantism

Sotos syndrome is a rare genetic disorder characterized by excessive physical growth during the first 2 to 3 years of life. The disorder may accompany mild mental retardation, delayed motor, cognitive, and social development, hypotonia (low muscle tone), and speech impairments. Children with Sotos syndrome tend to be large at birth and are often taller, heavier, and have larger heads (macro crania) than are normal for their age. Symptoms of the disorder, which vary among individuals, include a disproportionately large and long head with a slightly protrusive forehead, large hands and feet, hypertelorism (an abnormally increased distance between the eyes), and down-slanting eyes. Clumsiness, an awkward gait, and unusual aggressiveness or irritability may also occur.

Cerebral Hypoxia

A condition in which there is a decrease of oxygen supply to the brain even though there is adequate blood flow. Drowning, strangling, choking, suffocation, cardiac arrest, head trauma, carbon monoxide poisoning, and complications of general anesthesia can create conditions that can lead to cerebral hypoxia. Symptoms of mild cerebral hypoxia include inattentiveness, poor judgment, memory loss, and decreased motor coordination. Brain cells are susceptible to oxygen deprivation and can begin to die within five minutes after the oxygen supply has been cut off. Hypoxia can cause coma, seizures, and even brain death when it lasts longer. There is no measurable activity in brain death, although cardiovascular function is preserved. Life support is required for respiration.

Cerebral Palsy

The term cerebral palsy refers to any one of several neurological disorders that appear in infancy or early childhood and permanently affect body movement and muscle coordination but don't worsen over time. Even though cerebral palsy affects muscle movement, it isn't caused by muscle or nerve problems. Abnormalities cause it in parts of the brain that control muscle movements. Most children with cerebral palsy are born with it, although it may not be detected until months or years later. The early signs of cerebral palsy usually appear before a child ages three. The most common is a lack of muscle coordination when performing voluntary movements (ataxia); stiff or tight muscles and exaggerated reflexes (spasticity); walking with one foot or leg dragging; walking on the toes, a crouched gait, or a "scissored" gait; and muscle tone that is either too stiff or too floppy.

Cerebro-Oculo-Facio-Skeletal Syndrome

(COFS) is a pediatric, genetic, degenerative disorder that involves the brain and the spinal cord. Craniofacial and skeletal abnormalities characterize it, with severely reduced muscle tone and impaired reflexes. Symptoms may include large, low-set ears, small eyes, microcephaly (abnormal smallness of the head), micrognathia (abnormal smallness of the jaws), clenched fists, wide-set nipples, vision impairments, involuntary eye movements, and mental retardation, which can be moderate or severe. Respiratory infections are frequent. COFS is diagnosed at birth.

Charcot-Marie-Tooth Disease

(CMT) is one of the most common inherited neurological disorders, affecting approximately 1 in 2,500 people in the United States. The disease is named for the three physicians who first identified it in 1886 - Jean-Martin Charcot and Pierre Marie in Paris, France, and Howard Henry Tooth in Cambridge, England. CMT, also known as hereditary motor and sensory neuropathy (HMSN) or peroneal muscular atrophy, comprises a group of disorders that affect peripheral nerves. The peripheral nerves lie outside the brain and spinal cord and supply the muscles and sensory organs in the limbs. Disorders that affect the peripheral nerves are called peripheral neuropathies.

Chiari Malformation

(CMs) are structural defects in the cerebellum, the part of the brain that controls balance. When the indented bony space at the lower rear of the skull is smaller than normal, the cerebellum and brainstem can be pushed downward. The resulting pressure on the cerebellum can block the flow of cerebrospinal fluid (the liquid that surrounds and protects the brain and spinal cord). It can cause a range of symptoms, including dizziness, muscle weakness, numbness, vision problems, headache, and problems with balance and coordination. There are three primary types of CM. The most common is Type I, which may not cause symptoms and is often found by accident during an examination for another condition. Type II (also called Arnold-Chiari malformation) is usually accompanied by a myelomeningocele-a form of spina bifida that occurs when the spinal canal and backbone do not close before birth, causing the spinal cord to protrude through an opening in the back. This can cause partial or complete paralysis below the spinal opening. Type III is the most serious form of CM and causes severe neurological defects. Other conditions sometimes associated with CM include hydrocephalus, syringomyelia, and spinal curvature.

Chorea

An abnormal voluntary movement disorder, one of a group of neurological disorders called dyskinesias, which are caused by over-activity of the neurotransmitter dopamine in the areas of the brain that control movement. Chorea is characterized by brief, irregular contractions that are not repetitive or rhythmic but appear to flow from one muscle to the next. Chorea often occurs with athetosis, which adds twisting and writhing movements. Chorea is a primary feature of Huntington's disease, a progressive, hereditary movement disorder that appears in adults but may also occur in various conditions. Syndenham's chorea occurs in a small percentage (20 percent) of children and adolescents as a complication of rheumatic fever.

Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)

A neurological disorder characterized by progressive weakness and impaired sensory function in the legs and arms. The disorder, sometimes called chronic relapsing polyneuropathy, is caused by damage to the myelin sheath (the fatty covering that wraps around and protects nerve fibers) of the peripheral nerves. Although it can occur at any age and in both genders, CIDP is more common in young adults and men than in women. It often presents symptoms that include tingling or numbness (beginning in the toes and fingers), weakness of the arms and legs, loss of deep tendon reflexes (areflexia), fatigue, and abnormal sensations. CIDP is closely related to Guillain-Barre syndrome and is considered the chronic counterpart of that acute disease.

Chronic Pain

While acute pain is a normal sensation triggered in the nervous system to alert you to possible injury and the need to take care of yourself, chronic pain is different. Chronic pain persists. Pain signals keep firing in the nervous system for weeks, months, and even years. There may have been an initial mishap, sprained back, serious infection, or an ongoing cause of pain, arthritis, cancer, or ear infection. Still, some people suffer chronic pain without any past injury or evidence of body damage. Many chronic pain conditions affect older adults. Common chronic pain complaints include headache, low back pain, cancer pain, arthritis pain, neurogenic pain (pain resulting from damage to the peripheral nerves or to the central nervous system itself), psychogenic pain (pain not due to past disease or injury or any visible sign of damage inside or outside the nervous system).

Coffin Lowry Syndrome

A rare genetic disorder characterized by craniofacial (head and facial) and skeletal abnormalities, mental retardation, short stature, and hypotonia. Characteristic facial features may include an underdeveloped upper jaw bone (maxillary hypoplasia), a broad nose, protruding nostrils (nares), an abnormally prominent brow, down-slanting eyelid folds (palpebral fissures), widely spaced eyes (hypertelorism), large ears, and unusually thick eyebrows. Skeletal abnormalities may include abnormal front-to-back and side-to-side curvature of the spine (kyphoscoliosis), unusual prominence of the breastbone (pectus carinatum), and short, hyper-extensible, tapered fingers. Additional abnormalities may also be present. Other features may include feeding and respiratory problems, developmental delay, mental retardation, hearing impairment, awkward gait, flat feet, and heart and kidney involvement.

Colpocephaly

A congenital brain abnormality in which the occipital horns of the posterior or rear portion of the lateral ventricles (cavities) of the brain are larger than normal because the white matter in the posterior cerebrum has failed to develop or thicken. Colpocephaly, one of a group of structural brain disorders known as cephalic disorders, is characterized by microcephaly (an abnormally small head) and mental retardation. Other features may include movement abnormalities, muscle spasms, and seizures. Although the cause of colpocephaly is unknown, researchers believe that the disorder results from some fetal environment disturbance between the second and sixth months of pregnancy. Colpocephaly may be diagnosed late in pregnancy, although it is often misdiagnosed as hydrocephalus (excessive accumulation of cerebrospinal fluid in the brain).

Coma and Persistent Vegetative State

A coma is a profound state of unconsciousness. An individual in a coma is alive but unable to move or respond to their environment. Coma may occur as a complication of an underlying illness or as a result of injuries, such as head trauma. A persistent vegetative state (commonly, but incorrectly, referred to as "brain death") sometimes follows a coma. Individuals in such a state have lost their thinking abilities and awareness of their surroundings but retain non-cognitive function and normal sleep patterns. Even though those in a persistent vegetative state lose their higher brain functions, other key functions, such as breathing and circulation, remain relatively intact. Spontaneous movements may occur, and the eyes may open in response to external stimuli.

Congenital Facial Diplegia

Mobius syndrome is a rare congenital disability caused by the absence or underdevelopment of the 6th and 7th cranial nerves, which control eye movements and facial expression. The first symptom, present at birth, is an inability to suck. Other symptoms can include feeding, swallowing, and choking problems; excessive drooling; crossed eyes; lack of facial expression; inability to smile; eye sensitivity; motor delays; high or cleft palate; hearing problems; and speech difficulties. Small or absent brain stem nuclei that control the cranial nerves and decreased numbers of muscle fibers have been reported. Deformities of the tongue, jaw, and limbs, such as clubfoot and missing or webbed fingers, may also occur. As children age, lack of facial expression and inability to smile become the dominant visible symptoms. The prognosis for otherwise normal development is excellent in most cases.

Congenital Myasthenia

An inherited disorder that affects the transmission of signals to the muscles. It results from various genetic defects in the molecules associated with neuromuscular transmission. Congenital myasthenia is not the same as myasthenia gravis, an autoimmune disorder. More than a dozen congenital myasthenic syndromes have been classified. Symptoms are usually noticed in early childhood and include drooping eyelids, facial weakness, and limb weakness. Parents of children with congenital myasthenia frequently show no symptoms of the disorder.

Congenital Myopathy

A term for any muscle disorder present at birth. By this definition, congenital myopathy could include hundreds of distinct neuromuscular syndromes and disorders. In general, congenital myopathies cause loss of muscle tone and muscle weakness in infancy and delayed motor milestones, such as walking, later in childhood. Three distinct disorders are definitively classified as congenital myopathies: central core disease, nemaline rod myopathy, and centronuclear (myotubular) myopathy. The central core disease is a dominantly inherited genetic disease characterized by mild leg weakness in infancy. This weakness does not progress with age but leads to delays in walking. Nemaline rod myopathy is a dominantly or recessively inherited genetic disease characterized by infantile muscle weakness and loss of muscle tone, accompanied by problems in suckling or feeding, delay in walking, and occasionally respiratory problems.

Corticobasal Degeneration

A progressive neurological disorder characterized by nerve cell loss and atrophy (shrinkage) of multiple areas of the brain, including the cerebral cortex and the basal ganglia. Corticobasal degeneration progresses gradually. Initial symptoms, which typically begin at or around age 60, may first appear on one side of the body (unilateral) but eventually affect both sides as the disease progresses. Symptoms are similar to those found in Parkinson's disease, such as poor coordination, akinesia (an absence of movements), rigidity (a resistance to imposed movement), disequilibrium (impaired balance), and limb dystonia (abnormal muscle postures). Other symptoms such as cognitive and visual-spatial impairments, apraxia (loss of the ability to make familiar, purposeful movements), hesitant and halting speech, myoclonus (muscular jerks), and dysphagia (difficulty swallowing) may also occur. An individual with corticobasal degeneration eventually becomes unable to walk.

Cranial Arteritis

Vasculitis is an inflammation of the vascular system, which includes the veins, arteries, and capillaries. Dysfunction may occur due to the inflammation or over time as the blood vessel walls swell, harden, thicken, and develop scar tissue. This narrows the passage through which blood can flow. As the condition progresses, it can slow or completely stop the normal flow of blood. Vasculitis can cause problems in any organ system, including the central (CNS) and peripheral (PNS) nervous systems. A vasculitis syndrome may begin suddenly or develop over time. Symptoms include headaches, fever, malaise (feeling out-of-sorts), rapid weight loss, confusion or forgetfulness, aches and pains in the joints and muscles, pain while chewing or swallowing, paralysis or numbness in the arms or legs, double vision, blurred vision, or blindness.

Craniosynostosis

A congenital disability of the brain characterized by the premature closure of one or more of the fibrous joints between the bones of the skull (called the cranial sutures) before brain growth is complete. Closure of a single suture is most common. The abnormally shaped skull results from the brain's inability to grow in its natural shape because of the closure. Instead, it compensates with growth in areas of the skull where the cranial sutures have not yet closed. The condition can be gene-linked or caused by metabolic diseases, such as rickets or over-active thyroid. Some cases are associated with other disorders, such as microcephaly (abnormally small head) and hydrocephalus (excessive accumulation of cerebrospinal fluid in the brain). The first sign of craniosynostosis is an abnormally shaped skull. Other features can include increased intracranial pressure, developmental delays, or mental retardation caused by constriction of the growing brain. Seizures and blindness may also occur.

Creutzfeldt-Jakob Disease

(CJD) is a rare, degenerative, invariably fatal brain disorder. It affects about one person in every one million people per year worldwide; in the United States, there are about 200 cases per year. CJD usually appears in later life and runs a rapid course. Typically, the onset of symptoms occurs at about age 60, and about 90 percent of patients die within one year. In the early stages of the disease, patients may have failing memory, behavioral changes, lack of coordination, and visual disturbances. As the illness progresses, mental deterioration becomes pronounced, and involuntary movements, blindness, weakness of extremities, and coma may occur.

Cumulative Trauma Disorders

Repetitive motion disorders (RMDs) are a family of muscular conditions that result from repeated motions performed in the course of normal work or daily activities. RMDs include carpal tunnel syndrome, bursitis, tendonitis, epicondylitis, ganglion cyst, tenosynovitis, and trigger finger. RMDs are caused by too many uninterrupted repetitions of an activity or motion, unnatural or awkward motions such as twisting the arm or wrist, overexertion, incorrect posture, or muscle fatigue. RMDs occur most commonly in the hands, wrists, elbows, and shoulders but can also happen in the neck, back, hips, knees, feet, legs, and ankles. The disorders are characterized by pain, tingling, numbness, visible swelling or redness of the affected area, and loss of flexibility and strength. Some individuals may have no visible sign of injury, although they may find it hard to perform easy tasks. Over time, RMDs can cause temporary or permanent damage to the soft tissues in the body, such as the muscles, nerves, tendons, and ligaments, and compression of nerves or tissue.

Cushing's Syndrome

Also called hypercortisolism, is a rare endocrine disorder caused by chronic exposure of the body's tissues to excess levels of cortisol, a hormone naturally produced by the adrenal gland. Exposure to too much cortisol can occur from the long-term use of synthetic glucocorticoid hormones to treat inflammatory illnesses. Pituitary adenomas (benign pituitary gland tumors) that secrete increased amounts of ACTH (adrenocorticotropic hormone, a substance that controls the release of cortisol) can also spur the overproduction of cortisol. Tumors of the adrenal gland and ectopic ACTH syndrome (a condition in which ACTH is produced by various types of potentially malignant tumors that occur in different parts of the body) can cause similar problems with cortisol balance. Common symptoms of Cushing's syndrome include upper body obesity, severe fatigue, muscle weakness, high blood pressure, backache, elevated blood sugar, easy bruising, and bluish-red stretch marks on the skin. In women, facial and body hair growth may increase, and menstrual periods may become irregular or stop completely. Neurological symptoms include difficulties with memory and neuromuscular disorders.

Cytomegalic Inclusion Body Disease

The cytomegalovirus (CMV) is a virus found universally throughout the world that infects between 50 to 80 percent of all adults in the United States by the age of 40. CMV is in the same family of viruses that includes herpes simplex types 1 and 2 and the viruses that cause infectious mononucleosis (EBV), chickenpox, and shingles. A hallmark of CMV is the reappearance of symptoms throughout life, as the virus cycles through periods of dormancy and active infection. Most people who acquire the virus as children or adults display no signs or have mild symptoms and no long-term health consequences. Those with symptoms experience mononucleosis-like indications, such as prolonged fever, fatigue, mild hepatitis, and tender lymph nodes.

D

Dancing Eyes-Dancing Feet Syndrome

Opsoclonus myoclonus is a rare neurological disorder characterized by an unsteady, trembling gait, myoclonus (brief, shock-like muscle spasms), and opsoclonus (irregular, rapid eye movements). Other symptoms may include difficulty speaking, poorly articulated speech, or an inability to speak. A decrease in muscle tone, lethargy, irritability, and malaise (a vague feeling of bodily discomfort) may also be present.

Dandy-Walker Syndrome

(DWS), or Dandy-Walker complex, is a congenital brain-malformation involving the cerebellum and the fluid-filled spaces around it. The Dandy-Walker complex is a genetically sporadic disorder that occurs one in every 25,000 live births, mostly in females.

Dawson Disease

Subacute sclerosing panencephalitis (SSPE) is a chronic persistent infection of the central nervous system caused by an altered form of the measles virus. It affects primarily children and young adults and usually has a progressive downhill course, resulting in death within a few years in most patients with a 5% chance of spontaneous remission. It can occur anywhere from 2 to 10 years after the original measles illness and generally results in progressive neurological deterioration due to brain inflammation and nerve cell death. Since the widespread use of the measles vaccine, SSPE has become very rare.function due to damage or disease in the brain beyond what might be expected from normal aging.

Dementia

The progressive decline in cognitive function due to damage or disease in the brain beyond what might be expected from normal aging. Although dementia is far more common in the geriatric population, it may occur in any stage of adulthood.

Dementia

Multi-Infarct (MID) is a common cause of memory loss in the elderly. MID is caused by multiple strokes (disruption of blood flow to the brain). Disruption of blood flow leads to damaged brain tissue. Some of these strokes may occur without noticeable clinical symptoms. Doctors refer to these as "silent strokes." An individual having a silent stroke may not even know it is happening, but over time, as more areas of the brain are damaged, and more small blood vessels are blocked, the symptoms of MID begin to appear. An MRI or CT of the brain and a neurological examination can diagnose MID. Symptoms include confusion or problems with short-term memory; wandering or getting lost in familiar places; walking with rapid, shuffling steps; losing bladder or bowel control; laughing or crying inappropriately.

Dementia

Semantic Frontotemporal dementia (FTD) describes a clinical syndrome associated with the shrinking of the frontal and temporal anterior lobes of the brain. Originally known as Pick's disease, the name and classification of FTD have been a topic of discussion for over a century. The current designation of the syndrome groups together Pick's disease, primary progressive aphasia, and semantic dementia as FTD. Some doctors propose adding corticobasal degeneration and progressive supranuclear palsy to FTD and calling the group Pick Complex.

Dementia

Subcortical Binswanger's disease (BD), also called subcortical vascular dementia, is a type of dementia caused by widespread, microscopic areas of damage to the deep layers of white matter in the brain. The damage results from the thickening and narrowing (atherosclerosis) of arteries that feed the subcortical areas of the brain. Atherosclerosis (commonly known as "hardening of the arteries") is a systemic process that affects blood vessels throughout the body. It begins late in the fourth decade of life and increases in severity with age. As the arteries become more and more narrowed, the blood supplied by those arteries decreases, and brain tissue dies.

Dementia With Lewy Bodies

(DLB) is one of the most common types of progressive dementia. The central feature of DLB is progressive cognitive decline, combined with three additional defining features: pronounced "fluctuations" in alertness and attention, such as frequent drowsiness, lethargy, lengthy periods spent staring into space, or disorganized speech; recurrent visual hallucinations, and parkinsonian motor symptoms, such as rigidity and the loss of spontaneous movement.

Dentate Cerebellar Ataxia

Dyssynergia Cerebellaris Myoclonica refers to a collection of rare, degenerative, neurological disorders characterized by epilepsy, cognitive impairment, myoclonus, and progressive ataxia. Symptoms include seizures, tremors, and reduced muscle coordination. The onset of the disorder generally occurs in early adulthood. Tremors may begin in one extremity and involve the entire voluntary muscular system. Arms are usually more affected than legs. Some of the cases are due to mitochondrial abnormalities.

Dentatorubral Atrophy

Dentatorubral pallidoluysian atrophy is a rare neurodegenerative disorder characterized by cerebellar ataxia, myoclonic epilepsy, choreoathetosis, and dementia. The disorder is related to the expansion of a trinucleotide repeat within this gene. The encoded protein includes a serine repeat, alternating acidic and basic amino acid regions, and the variable glutamine repeat. Alternative splicing results in two transcripts variants that encode the same protein.

Dermatomyositis

A connective-tissue disease that is characterized by inflammation of the muscles and the skin. Its cause is unknown but may result from a viral infection or an autoimmune reaction. Up to 50% of the cases may be a paraneoplastic phenomenon, indicating the presence of cancer.

Developmental Dyspraxia

One or all of a heterogeneous range of psychological development disorders affecting the initiation, organization, and performance of action. It entails the partial loss of the ability to coordinate and perform certain purposeful movements and gestures without motor or sensory impairments.

Devic's Syndrome

Neuromyelitis optica (NMO) is an uncommon disease syndrome of the central nervous system (CNS) that affects the optic nerves and spinal cord. Individuals with NMO develop optic neuritis, which causes pain in the eye and vision loss, and transverse myelitis, which causes weakness, numbness, and sometimes paralysis of the arms and legs, along with sensory disturbances and loss of bladder and bowel control. NMO leads to the loss of myelin, a fatty substance that surrounds nerve fibers and helps nerve signals move from cell to cell. The syndrome can also damage nerve fibers and leave areas of broken-down tissue. In the disease process of NMO, immune system cells and antibodies attack and destroy myelin cells in the optic nerves and the spinal cord for reasons that aren't clear.

Diabetic Neuropathy

A peripheral nerve disorder caused by diabetes. The symptoms of diabetic neuropathy are often slight at first. Some mild cases may go unnoticed for a long time. Numbness, pain, or tingling in the feet or legs may, after several years, lead to weakness in the muscles of the feet. Occasionally, diabetic neuropathy can flare up suddenly and affect specific nerves so that an affected individual will develop double vision, drooping eyelids, or weakness and atrophy of the thigh muscles. Nerve damage caused by diabetes generally occurs over the years. It may lead to problems with the digestive tract and sexual organs, which can cause indigestion, diarrhea or constipation, dizziness, bladder infections, and impotence.

Diffuse Sclerosis

Schilder's disease is not the same as Addison-Schilder disease (adrenoleukodystrophy). Schilder's disease is a rare progressive demyelinating disorder that usually begins in childhood. Symptoms may include dementia, aphasia, seizures, personality changes, poor attention, tremors, balance instability, incontinence, muscle weakness, headache, vomiting, and vision and speech impairment. The disorder is a variant of multiple sclerosis.

Dravet Syndrome

Also called severe myoclonic epilepsy of infancy (SMEI), it is a severe form of epilepsy. It appears during the first year of life with frequent febrile seizures - fever-related seizures that, by definition, are rare beyond age 5. Later, other types of seizures typically arise, including myoclonus (involuntary muscle spasms). Status epilepticus - a state of continuous seizure requiring emergency medical care - also may occur. Children with Dravet syndrome typically experience poor language and motor skills development, hyperactivity, and difficulty relating to others.

Dysautonomia

A disorder of autonomic nervous system (ANS) function. Most physicians view dysautonomia as the failure of the sympathetic or parasympathetic components of the ANS, but dysautonomia involving excessive ANS activities can also occur. Dysautonomia can be local, as in reflex sympathetic dystrophy, or generalized, as in pure autonomic failure. It can be acute and reversible, as in Guillain-Barre syndrome, or chronic and progressive. Several common conditions, such as diabetes and alcoholism, can include dysautonomia. Dysautonomia also can occur as a primary condition or in association with degenerative neurological diseases such as Parkinson's disease.

Dysgraphia

A neurological disorder characterized by writing disabilities. Specifically, the disorder causes a person's writing to be distorted or incorrect. In children, the disorder generally emerges when they are first introduced to writing. Despite thorough instruction, they make inappropriately sized and spaced letters or write wrong or misspelled words. Children with the disorder may have other learning disabilities. However, they usually have no social or academic problems. Cases of dysgraphia in adults generally occur after some trauma. In addition to poor handwriting, dysgraphia is characterized by wrong or odd spelling and the production of words that are not correct (i.e., using "boy" for "child"). The cause of the disorder is unknown.

Dyslexia

A specific learning disability that manifests primarily as a difficulty with written language, particularly with reading and spelling. It is separate and distinct from reading difficulties resulting from other causes, such as a non-neurological deficiency with vision or hearing or poor or inadequate reading instruction.Evidence suggests that dyslexia results from differences in how the brain processes written and verbal language. Although dyslexia results from a neurological difference, it is not an intellectual disability. Dyslexia occurs at all levels of intelligence, average, above average, and highly gifted.

Dysphagia

Swallowing disorders - defined as difficulty in passing food or liquid from the mouth to the stomach - occur in all age groups, but especially in the elderly. The disorders can occur at any stage of the normal swallowing process, in which food and liquid move from the mouth, through the pharynx, into the esophagus, and finally, into the stomach. The disorders are common in individuals with degenerative neurological disorders such as amyotrophic lateral sclerosis (ALS), post-polio syndrome, myasthenia gravis, multiple sclerosis, and Parkinson's disease. They may be the first symptom of the disease.

Dyssynergia Cerebellaris Myoclonica

A collection of rare, degenerative, neurological disorders characterized by epilepsy, cognitive impairment, myoclonus, and progressive ataxia. Symptoms include seizures, tremors, and reduced muscle coordination. The onset of the disorder generally occurs in early adulthood. Tremors may begin in one extremity and involve the entire voluntary muscular system. Arms are usually more affected than legs. Some of the cases are due to mitochondrial abnormalities.

Dystonias

The dystonias are movement disorders in which sustained muscle contractions cause twisting and repetitive movements or abnormal postures. The movements, which are involuntary and sometimes painful, may affect a single muscle; a group of muscles such as those in the arms, legs, or neck; or the entire body. Early symptoms may include a deterioration in handwriting, foot cramps, or a dragging foot after running or walking some distance. Other possible symptoms are tremors and voice or speech difficulties.

E

Early Infantile Epileptic Encephalopathy

Or Ohtahara syndrome is a neurological disorder characterized by seizures. The disorder affects newborns, usually within the first three months of life (most often within the first ten days), in the form of epileptic seizures. Infants primarily have tonic seizures but may also experience partial and rarely myoclonic seizures. Most infants with the disorder show significant underdevelopment of part or all of the cerebral hemispheres.

Empty Sella Syndrome

Abbreviated ESS, is a disorder that involves the sella turcica, a bony structure at the base of the brain that surrounds and protects the pituitary gland. ESS is a condition often discovered during tests for pituitary disorders when radiological imaging of the pituitary gland reveals a sella turcica that appears empty. There are two types of ESS: primary and secondary.

Encephalitis

An acute inflammation of the brain, commonly caused by a viral infection. It can be caused by a bacterial infection such as bacterial meningitis or a complication of other infectious diseases like rabies (viral) or syphilis (bacterial). Certain parasitic or protozoal infestations, such as toxoplasmosis, malaria, or primary amoebic meningoencephalitis, can also cause encephalitis in people with compromised immune systems. Brain damage occurs as the inflamed brain pushes against the skull and can lead to death.

Encephalitis Lethargica

(EL) or von Economo disease is an atypical form of encephalitis. Also known as sleeping sickness (though different from the sleeping sickness transmitted by the tsetse fly), EL is a devastating illness that swept the world in the 1920s and then vanished as quickly as it had appeared.

Encephaloceles

Rare neural tube defects characterized by sac-like protrusions of the brain and the membranes that cover it through openings in the skull. These defects are caused by the failure of the neural tube to close completely during fetal development. The result is a groove down the mid-line of the upper part of the skull, the area between the forehead and nose, or the back of the skull. When located in the back of the skull, encephaloceles are often associated with neurological problems.

Encephalopathy

A syndrome observed in patients with cirrhosis. Hepatic encephalopathy is a spectrum of neuropsychiatric abnormalities in patients with liver dysfunction after excluding other known brain diseases. It is characterized by personality changes, intellectual impairment, and a depressed level of consciousness.

Encephalotrigeminal Angiomatosis

A rare genetic disorder characterized by excessive blood vessel growth, calcium accumulation inside the brain, and seizures.

Epilepsy

A general term that includes various types of seizures. People with diagnosed epilepsy have had more than one seizure and may have had more than one kind of seizure. A seizure happens when abnormal electrical activity in the brain causes an involuntary change in body movement or function, sensation, awareness, or behavior.

Erb-Duchenne and Dejerine-Klumpke Palsies

The brachial plexus is a network of nerves that conducts signals from the spine to the shoulder, arm, and hand. Brachial plexus injuries are caused by damage to those nerves. Erb-Duchenne (Erb's) palsy refers to paralysis of the upper brachial plexus. Dejerine-Klumpke (Klumpke's) palsy refers to paralysis of the lower brachial plexus. Although injuries can occur anytime, many brachial plexus injuries happen when a baby's shoulders become impacted during delivery, and the brachial plexus nerves stretch or tear.

Erb's Palsy

Leads to a weakness of a newborn baby's arm. A stretch injury causes it to the brachial plexus (BRAY-key-el PLEK-sis). The brachial plexus is a network of nerves near the neck that give rise to all arm nerves. These nerves provide movement and feeling to the arm, hand, and fingers.

Essential Tremor

A nerve disorder in which tremors (shakes) occur in a person who is moving or trying to move and no cause can be identified. Essential tremor is a relatively benign condition affecting movement or voice quality but without other effects.

Extrapontine Myelinolysis

(CPM) is a neurological disorder that most frequently occurs after too rapid medical correction of sodium deficiency (hyponatremia). The rapid rise in sodium concentration is accompanied by the movement of small molecules and pulls water from brain cells. Through a mechanism that is only partly understood, the shift in water and brain molecules leads to the destruction of myelin, which surrounds and protects nerve fibers.

F

Fabry Disease

Caused by the lack of or faulty enzyme needed to metabolize lipids, fat-like substances that include oils, waxes, and fatty acids. The enzyme is known as ceramide trihexosidase, also called alpha-galactosidase-A. A mutation in the gene that controls this enzyme causes the insufficient breakdown of lipids, which build up to harmful levels in the eyes, kidneys, autonomic nervous system, and cardiovascular system.

Fahr's Syndrome

Also known as Idiopathic Basal Ganglia Calcification or Fahr's Syndrome, is a rare, genetically dominant, inherited neurological disorder characterized by abnormal deposits of calcium in areas of the brain that control movement, including the basal ganglia and the cerebral cortex. Symptoms of the disorder may include deterioration of motor function, psychosis, dementia, seizures, headache, dysarthria (poorly articulated speech), spasticity (stiffness of the limbs) and spastic paralysis, eye impairments, and athetosis (involuntary, writhing movements).

Fainting

Also called Syncope, is a sudden and generally momentary loss of consciousness or blacking out caused by the Central Ischaemic Response because of a lack of sufficient blood and oxygen in the brain. Factors influencing fainting are taking in too little food and fluids, low blood pressure, hypoglycemia, growth spurts, physical exercise over the body's energy reserve, emotional distress, and lack of sleep. Fainting can also occur if pressure on the carotid artery in the neck triggers a vagal signal to the Vaso-Motor Center, reflexly causing a vagal response to slow the heart.

Familial Dysautonomia

FD, sometimes called Riley-Day syndrome, is a disorder of the autonomic nervous system, which affects the development and survival of sensory, sympathetic, and some parasympathetic neurons in the autonomic and sensory nervous system resulting in variable symptoms including insensitivity to pain, inability to produce tears, poor growth, and labile blood pressure (episodic hypertension and postural hypotension). There currently is no cure for FD, and death occurs in 50% of affected individuals by age 30. There are only two treatment centers, one at New York University Hospital and one at the Hadassah Hospital in Israel. One is being planned for the San Francisco area.

Familial Hemangioma

Or Cavernous malformation, is a rare disorder of the capillaries and smallest veins in one part of the brain. The disorder occurs when a blood-filled mass resembling a tumor, called a hemangioma, forms. Symptoms include headaches and seizures. A cavernous malformation is frequently inherited.

Familial Idiopathic Basal Ganglia Calcification

See Fahr's Syndrome above.

Familial Periodic Paralyzes

A group of inherited neurological disorders caused by mutations in genes that regulate sodium and calcium channels in nerve cells. They are characterized by episodes in which the affected muscles become slack, weak, and unable to contract. Between attacks, the affected muscles usually work as normal. Treatment of periodic paralyzes focuses on preventing further attacks and relieving acute symptoms. Avoiding carbohydrate-rich meals, strenuous exercise, and taking acetazolamide daily may prevent hypokalemic attacks.

Familial Spastic Paralysis

Also known as Hereditary spastic paraplegia (HSP), refers to a group of inherited disorders that are characterized by progressive weakness and stiffness of the legs. Though the primary feature of HSP is severe, progressive, lower extremity spasticity in more complicated forms, it can be accompanied by other neurological symptoms. These include optic neuropathy, retinopathy (diseases of the retina), dementia, ataxia (lack of muscle control), ichthyosis (a skin disorder resulting in dry, rough, scaly skin), mental retardation, peripheral neuropathy, and deafness.

Farber's Disease

Also known as Farber's lipogranulomatosis or ceramidase deficiency, describes a group of rare autosomal recessive disorders that cause an accumulation of lipids in the joints, tissues, and central nervous system. Most children with the disease die by age 2, usually from lung disease. In one of the most severe forms of the disease, an enlarged liver and spleen (hepatosplenomegaly) can be diagnosed soon after birth.

Febrile Seizures

A convulsion in young children caused by a sudden spike in body temperature, often from an infection. During a febrile seizure, a child often loses consciousness and shakes, moving limbs on both sides of the body. Less commonly, the child becomes rigid or twitches in only a portion of the body, such as an arm or a leg, or on the right or left side.

Fibromuscular Dysplasia

(FMD) is an arterial disease of unknown etiology typically affecting the medium and large arteries of young to middle-aged women. In individuals with FMD, the walls of one or more arteries undergo dysplasia. Due to this abnormal cellular development, the vessels may become stenosed. A sufficient decrease in blood flow through the artery can cause symptoms. However, FMD is often diagnosed incidentally without any signs or symptoms during an imaging study.

Fisher Syndrome

A rare, acquired nerve disease that is considered to be a variant of Guillain-Barre syndrome. It is characterized by abnormal muscle coordination, paralysis of the eye muscles, and the absence of tendon reflexes. Like Guillain- Barre syndrome, symptoms may be preceded by a viral illness.

Floppy Infant Syndrome

Also known as hypotonia or infantile hypotonia, a condition of abnormally low muscle tone (the amount of tension or resistance to movement in a muscle), often involving reduced muscle strength. Hypotonia is not a specific medical disorder but a potential manifestation of many different diseases and disorders that affect motor nerve control by the brain or muscle strength. Motor skills delay is often observed, along with hypermobile or hyperflexible joints, drooling, speech difficulties, poor reflexes, decreased strength, decreased activity tolerance, rounded shoulder posture, leaning onto supports, and poor attention and motivation.

Foot Drop

A deficit in turning the ankle and toes upward. Conditions leading to foot drop may be neurologic, muscular, or anatomic, often with significant overlap. Foot drop is characterized by steppage gait. When the person with foot drop walks, the foot slaps down onto the floor. The underlying disorder must be treated. For example, if a spinal disc herniation in the low back is impinging on the nerve that goes to the leg and causing symptoms of foot drop, then the herniated disc should be treated.

Friedreich's Ataxia

An inherited disease that causes progressive damage to the nervous system resulting in symptoms ranging from gait disturbance and speech problems to heart disease. Symptoms usually begin between the ages of 5 and 15 but can, on rare occasions, appear as early as 18 months or as late as 50 years of age. The first symptom to appear is usually difficulty walking or gait ataxia. The ataxia gradually worsens and slowly spreads to the arms and trunk. Foot deformities such as clubfoot, flexion (involuntary bending) of the toes, hammer toes, or foot inversion (turning inward) may be early signs.

Frontotemporal Dementia

(Frontotemporal lobar degeneration), an umbrella term for a diverse group of rare disorders that primarily affect the frontal and temporal lobes of the brain - the areas generally associated with personality and behavior. It differs from other causes of dementia, such as Alzheimer's, Pick's, and Creutzfeldt Jakob's diseases. Behavioral symptoms include apathy and aspontaneity or oppositely disinhibition. Apathetic patients may become socially withdrawn and stay in bed all day or no longer take care of themselves. Disinhibited patients can make inappropriate (sometimes sexual) comments or perform inappropriate acts.

G

Gangliosidoses

The GM1 gangliosidoses are caused by a deficiency of beta-galactosidase, with resulting abnormal storage of acidic lipid materials in cells of the central and peripheral nervous systems, but particularly in the nerve cells. Excess lipid materials build up to harmful levels in the central and peripheral nervous systems, particularly in nerve cells. These genetically different disorders occur when both parents pass along the same mutated gene that regulates these proteins. Symptoms of early infantile GM1 (the most severe subtype, with onset shortly after birth) may include neurodegeneration, seizures, liver and spleen enlargement, coarsening of facial features, skeletal irregularities, joint stiffness, distended abdomen, muscle weakness, exaggerated startle response to sound, and problems with gait. No specific treatment exists for gangliosidoses. Anticonvulsants may initially control seizures. Other supportive treatment includes proper nutrition and hydration and keeping the airway open.

Gaucher's Disease

The most common of the lysosomal storage diseases. It is caused by a deficiency of the enzyme glucocerebrosidase, leading to an accumulation of its substrate, the fatty substance glucocerebroside (also known as glucosylceramide). Fatty material can collect in the spleen, liver, kidneys, lungs, brain, and bone marrow. Symptoms may include enlarged spleen and liver, liver malfunction, skeletal disorders, and bone lesions that may cause pain, severe neurologic complications, swelling of lymph nodes and (occasionally) adjacent joints, distended abdomen, a brownish tint to the skin, anemia, low blood platelets and yellow fatty deposits on the sclera.

Gerstmann's Syndrome

A neurological disorder characterized by four primary symptoms: a writing disability (agraphia or dysgraphia), a lack of understanding of the rules for calculation or arithmetic (acalculia or dyscalculia), an inability to distinguish right from left, and an inability to identify fingers (finger agnosia).

Gerstmann-Straussler-Scheinker Disease

In adults, the syndrome may occur after a stroke or in association with damage to the parietal lobe. In addition to exhibiting the above symptoms, many adults also experience aphasia (difficulty expressing oneself when speaking, understanding speech, or reading and writing).

Giant Cell Arteritis

(GCA) is an inflammation of the lining of your arteries - the blood vessels that carry oxygen-rich blood from your heart to the rest of your body. Adults older than 50 are at the greatest risk of giant cell arteritis. Although there's no cure for giant cell arteritis, immediate treatment with corticosteroid medications usually relieves symptoms and prevents loss of vision.

Giant Cell Inclusion Disease

The cytomegalovirus (CMV) is a virus found universally throughout the world that infects between 50 to 80 percent of all adults in the United States by the age of 40. CMV is in the same family of viruses that includes herpes simplex types 1 and 2 and the viruses that cause infectious mononucleosis (EBV), chickenpox, and shingles. There is no cure for CMV infection. Good hygiene, including proper hand washing, is recommended to avoid transmission from one person to the next. Individuals who work with young children should avoid sharing drinking glasses and utensils and carefully throw-away diapers, tissues, and other items contaminated with body fluids. For most people, CMV infection is not a problem.

Globoid Cell Leukodystrophy

Or Krabbe disease - a rare, inherited degenerative disorder of the central and peripheral nervous systems. It is characterized by the presence of globoid cells (cells with more than one nucleus), the breakdown of the nerve's protective myelin coating, and the destruction of brain cells. Krabbe disease is one of a group of genetic disorders called leukodystrophies. There is no cure for Krabbe disease. A tiny clinical trial of patients with infantile Krabbe disease showed that children who received umbilical cord blood stem cells from unrelated donors before symptom onset developed little neurological impairment.

Glossopharyngeal Neuralgia

A chronic pain syndrome that causes intense, shooting pains in the back of the tongue and throat, tonsillar areas, and middle ear. The cause of glossopharyngeal neuralgia is not completely understood. However, conditions (tumors, infections, injuries, or blood vessels close to the glossopharyngeal nerve) that pressure the glossopharyngeal nerve may sometimes be responsible for its development. Individuals with diabetes or multiple sclerosis may also develop glossopharyngeal neuralgia.

Glycogen Storage Disease

(Glycogenosis, dextrinosis) is any one of several inborn errors of metabolism that result from enzyme defects that affect the processing of glycogen synthesis or breakdown within muscles, liver, and other cell types. Nine diseases are commonly considered to be glycogen storage diseases.

Guillain-Barre Syndrome

(GBS) is an acute, autoimmune, polyradiculoneuropathy affecting the peripheral nervous system, usually triggered by an acute infectious process. There are several types of GBS, but unless otherwise stated, GBS refers to the most common form, acute inflammatory demyelinating polyneuropathy (AIDP). It is frequently severe and usually exhibits an ascending paralysis noted by weakness in the legs that spreads to the upper limbs and the face, along with complete loss of deep tendon reflexes. With prompt treatment of plasmapheresis followed by immunoglobulins and supportive care, most patients will regain full functional capacity. However, death may occur if severe pulmonary complications and dysautonomia are present.

H

Hallervorden-Spatz Disease

Neurodegeneration with brain iron accumulation (NBIA) is a rare, inherited, neurological movement disorder characterized by progressive degeneration of the nervous system. Symptoms, which vary greatly among patients and usually develop during childhood, may include slow writhing, distorting muscle contractions of the limbs, face, or trunk, choreoathetosis (involuntary, purposeless jerky muscle movements), muscle rigidity (uncontrolled tightness of the muscles), spasticity (sudden, involuntary muscle spasms), ataxia (inability to coordinate movements), confusion, disorientation, seizures, stupor, and dementia.

Head Injury

Head injuries include both injuries to the brain and those to other parts of the head, such as the scalp and skull. Head injuries may be closed or open. A closed (non-missile) head injury is one in which the skull is not broken. A penetrating head injury occurs when an object pierces the skull and breaches the dura mater. Brain injuries may be diffuse, occurring over a wide area, or focal, located in a small, specific area.

Headache

There are four types of headache:

• Vascular
• Muscle contraction (tension)
• Traction
• Inflammatory

The most common type of vascular headache is migraine. Migraine headaches are usually characterized by severe pain on one or both sides of the head, an upset stomach, and, at times, disturbed vision. Women are more likely than men to have migraine headaches. After migraine, the most common type of vascular headache is the toxic headache produced by fever. Other vascular headaches include "cluster" headaches, which cause repeated episodes of intense pain, and headaches resulting from high blood pressure. Muscle contraction headaches appear to involve the tightening or tensing facial and neck muscles. Traction and inflammatory headaches are symptoms of other disorders, ranging from stroke to sinus infection. Like other types of pain, headaches can serve as warning signals of more serious disorders.

Hemicrania Continua

Hemicrania continua is a rare form of chronic headache marked by continuous pain on one side of the face that varies in severity. Superimposed on the continuous but fluctuating pain are occasional attacks of more severe pain. Symptoms fall into two main categories: autonomic, including runny nose, tearing, eye redness, eye discomfort, sweating, and swollen and drooping eyelids, and migraine-like, including nausea, vomiting, and sensitivity to light and sound.

Hemifacial Spasm

Hemifacial spasm is a neuromuscular disorder characterized by frequent involuntary contractions of the muscles on one side of the face. The disorder occurs in men and women, although it affects middle-aged or older women more frequently. The first symptom is usually an intermittent twitching of the eyelid muscle that can lead to the forced closure of the eye.

Hemiplegia Alterans

Alternating hemiplegia is a rare neurological disorder that develops in childhood, usually before the first four years. The disorder is characterized by recurrent but temporary episodes of paralysis on one side of the body. Paralysis can affect eye movements, limbs, or facial muscles.

Hereditary Neuropathies

Hereditary neuropathies are a group of inherited disorders of the peripheral nervous system. Within the group, there are four subcategories of disorders: hereditary motor and sensory neuropathy, hereditary sensory neuropathy, hereditary motor neuropathy, and hereditary sensory and autonomic neuropathy. Symptoms of these disorders vary and may include numbness and tingling in the feet and hands, muscle weakness (especially in the distal muscles), scoliosis, thin lower legs, foot deformities, insensitivity to pain, and autonomic symptoms such as impaired sweating, postural hypotension, and skin blotching.

Hereditary Spastic Paraplegia

Hereditary spastic paraplegia (HSP), also called familial spastic paraparesis (FSP), refers to a group of inherited disorders that are characterized by progressive weakness and stiffness of the legs.

Heredopathia Atactica Polyneuritiformis

Adult Refsum disease (ARD) is one of a group of genetic diseases called leukodystrophies, which damage the white matter of the brain and affect motor movements. Due to a genetic abnormality, people with ARD disease lack the enzyme that breaks down phytanic acid, a substance commonly found in foods. As a result, toxic levels of phytanic acid build up in the brain, blood, and other tissues.

Herpes Zoster

Shingles (herpes zoster) is an outbreak of rash or blisters on the skin that is caused by the same virus that causes chickenpox - the varicella-zoster virus. The first sign of shingles is often burning or tingling pain, or sometimes numbness or itch, in one particular location on only one side of the body. After several days or weeks, a rash of fluid-filled blisters, similar to chickenpox, appears in one area on one side of the body. Shingles pain can be mild or intense.

Herpes Zoster Oticus

Also called Ramsay Hunt Syndrome or Ramsay Hunt Syndrome type II, it is a common complication of shingles. Shingles is an infection caused by the varicella-zoster virus, which is the virus that causes chickenpox. Shingles occur in people who have had chickenpox and represent a reactivation of the dormant varicella-zoster virus. Herpes zoster oticus, which is caused by the spread of the varicella-zoster virus to facial nerves, is characterized by intense ear pain, a rash around the ear, mouth, face, neck, and scalp, and paralysis of facial nerves.

Hirayama Syndrome

Monomelic amyotrophy (MMA) is characterized by progressive degeneration and loss of motor neurons, the nerve cells in the brain and spinal cord that are responsible for controlling voluntary muscles. It is characterized by weakness and wasting in a single limb, usually an arm and hand, rather than a foot and leg. There is no pain associated with MMA. While some physicians contend that mild sensory loss may be associated with this disease, many experts suggest that such symptoms indicate a cause other than MMA. MMA occurs in males between the ages of 15 and 25.

Holmes-Adie syndrome

(HAS) is a neurological disorder affecting the pupil of the eye and the autonomic nervous system. It is characterized by one eye with a pupil larger than normal. It constricts slowly in bright light (tonic pupil), along with the absence of deep tendon reflexes, usually in the Achilles tendon. HAS is thought to result from a viral or bacterial infection that causes inflammation and damage to neurons in the ciliary ganglion, an area of the brain that controls eye movements, and the spinal ganglion, an area of the brain involved in the response of the autonomic nervous system. HAS begins gradually in one eye and often progresses to involve the other eye. At first, it may only cause the loss of deep tendon reflexes on one side of the body but then progress to the other. The eye and reflex symptoms may not appear at the same time. People with HAS may also sweat excessively, sometimes only on one side of the body.

Holoprosencephaly

A type of cephalic disorder. This disorder is characterized by the failure of the prosencephalon (the embryo's forebrain) to develop. During normal development, the forebrain is formed. The face begins to develop in the fifth and sixth weeks of human pregnancy.

HTLV-1 Associated Myelopathy

For several decades, the term "tropical spastic paraparesis" (TSP) has been used to describe a chronic and progressive disease of the nervous system that affects adults living in equatorial areas of the world and causes progressive weakness, stiff muscles, muscle spasms, sensory disturbance, and sphincter dysfunction. The cause of TSP was obscure until the mid-1980s when an important association was established between the human retrovirus - human T-cell lymphotropic virus type 1 (also known as HTLV-1) - and TSP. TSP is now called HTLV-1-associated myelopathy/ tropical spastic paraparesis or HAM/TSP. The HTLV-1 retrovirus is thought to cause at least 80 percent of the cases of HAM/TSP by impairing the immune system.

Hughes Syndrome

Antiphospholipid syndrome (APS or APLS) or antiphospholipid antibody syndrome is a disorder of coagulation, which causes blood clots (thrombosis) in both arteries and veins, as well as pregnancy-related complications such as miscarriage, preterm delivery, or severe preeclampsia.

Huntington's Disease

Caused by a trinucleotide repeat expansion in the gene coding for Huntingtin protein (Htt) and is one of several polyglutamine diseases. This expansion produces an altered form of the Htt protein, mutant Huntingtin (mHtt), which results in neuronal cell death in select brain areas. Huntington's disease isn't a terminal illness, but complications caused by it reduce life expectancy.

Hydranencephaly

Hydranencephaly is a rare condition in which the brain's cerebral hemispheres are absent and replaced by sacs filled with cerebrospinal fluid. An infant with hydranencephaly may appear normal at birth. The infant's head size and spontaneous reflexes such as sucking, swallowing, crying, and moving the arms and legs may all seem normal. However, after a few weeks, the infant usually becomes irritable and has increased muscle tone. After a few months of life, seizures, and hydrocephalus (excessive accumulation of cerebrospinal fluid in the brain) may develop. Other symptoms may include visual impairment, lack of growth, deafness, blindness, spastic quadriparesis (paralysis), and intellectual deficits.

Hydrocephalus

A term derived from the Greek words "hydro," meaning water, and "cephalus," meaning head, and this condition is sometimes known as "water in the brain." People with this condition have an abnormal cerebrospinal fluid (CSF) accumulation in the ventricles, or cavities, of the brain. This may cause increased intracranial pressure inside the skull and progressive enlargement of the head, convulsion, and mental disability.

Hydromyelia

Refers to an abnormal widening of the central canal of the spinal cord that creates a cavity in which cerebrospinal fluid (commonly known as spinal fluid) can accumulate. As the spinal fluid builds up, it may put abnormal pressure on the spinal cord and damage nerve cells and their connections. Hydromyelia is sometimes used interchangeably with syringomyelia, the name for a condition that also involves cavitation in the spinal cord. In hydromyelia, the cavity that forms is connected to the fourth ventricle in the brain and is almost always associated with infants and children with hydrocephalus or congenital disabilities such as Chiari Malformation II and Dandy-Walker Malformation. Syringomyelia, however, features a closed cavity and occurs primarily in adults, most of whom have Chiari Malformation II or have experienced spinal cord trauma. Symptoms, which may occur over time, include weakness of the hands, arms, and legs; and sensory loss in the neck and arms.

Hypernychthemeral Syndrome

(Non 24 Sleep Wake Disorder) - A neurological sleep disorder in which a person's sleep/wake cycle is longer than 24 hours. While Non-24 is believed to affect over half of all blind individuals, it also affects some sighted people. However, the underlying causes are different, and these should be seen as two distinct disorders: Blind Non-24 and Sighted Non-24 - (www.circadiansleepdisorders.org/docs/N24-QandA.php). The disorder in its extreme form is an invisible disability that can be extremely debilitating.

Hypersomnia

Characterized by recurrent episodes of excessive daytime sleepiness or prolonged nighttime sleep. Unlike feeling tired due to lack of or interrupted sleep at night, persons with hypersomnia are compelled to nap repeatedly during the day, often at inappropriate times such as at work, during a meal, or in conversation. These daytime naps usually provide no relief from symptoms. Patients often have difficulty waking from a long sleep and may feel disoriented. Other symptoms may include anxiety, increased irritation, decreased energy, restlessness, slow thinking, slow speech, loss of appetite, hallucinations, and memory difficulty.

Hypertonia

A condition marked by an abnormal increase in the tightness of muscle tone and a reduced ability of a muscle to stretch (i.e., an increased stiffness). It is generally accompanied by (increased) spasticity of the particular muscles.

Hypotonia

A medical term used to describe decreased muscle tone (the amount of resistance to movement in a muscle). It is not the same as muscle weakness, although the two conditions can co-exist. Hypotonia may be caused by trauma, environmental factors, genetic, muscle, or central nervous system disorders, such as Down syndrome, muscular dystrophy, cerebral palsy, Prader-Willi syndrome, myotonic dystrophy, and Tay-Sachs disease. Sometimes it may not be possible to find what causes hypotonia. Infants with hypotonia have a floppy quality or "rag doll" appearance because their arms and legs hang by their sides, and they have little or no head control. Other hypotonia symptoms include mobility and posture problems, breathing and speech difficulties, lethargy, ligament and joint laxity, and poor reflexes.

Hypoxia

A restriction in blood supply (and therefore oxygen supply) to an organ or section of the body, generally due to constriction or blocking of blood vessels.

I

Immune-Mediated Encephalomyelitis

Acute disseminated encephalomyelitis (ADE) is a neurological disorder involving inflammation of the brain and spinal cord. A hallmark of the disorder is damage to the myelin sheath that surrounds the nerve fibers in the brain, which results in inflammation. ADE can occur in children and adults, although it occurs more commonly in children. ADE is not rare, accounting for approximately 30% of all cases of encephalitis.

Inclusion Body Myositis

Sporadic inclusion body myositis (IBM) is an inflammatory muscle disease characterized by slowly progressive weakness and wasting of the distal and proximal muscles, most apparent in the muscles of the arms and legs. Because sIBM affects different people in different ways and at different rates, there is no "textbook case." During the illness, the patient's mobility is progressively restricted as it becomes hard for them to bend down, reach for things, walk quickly, and so on. Many patients say they have balance problems and fall easily.

Incontinentia Pigmenti

(IP) is one of a group of gene-linked diseases known as neurocutaneous disorders. These disorders cause characteristic discolored skin patterns and involve the brain, eyes, nails, and hair. In most cases, IP is caused by mutations in a gene called NEMO (NF-kappaB essential modulator). Males are more severely affected than females. Excessive deposits of melanin cause discolored skin. Most newborns with IP will develop discolored skin within the first two weeks.

Infantile Hypotonia

Or severely reduced muscle tone (the amount of tension or resistance to movement in a muscle), is seen primarily in children. It is not the same as muscle weakness but can co-exist with it. Hypotonia may be caused by trauma, environmental factors, or genetic, muscle, or central nervous system disorders. Physical therapy can improve fine motor control and overall body strength. Occupational and speech-language therapy can help breathing, speech, and swallowing difficulties.

Infantile Neuroaxonal Dystrophy

INAD is caused by an abnormal build-up of substances in the nerves throughout the brain and body, which prevents them working properly. These deposits (sometimes called spheroid bodies because of their appearance under the microscope) are found particularly in the nerve endings going to muscles, skin, and conjunctiva. A child's development will start to slow down between the ages of six months and two years. Over the following years, they will lose skills previously learned, and their vision will become increasingly impaired and eventually lost. Nystagmus (rapid, wobbly eye movements) and squints may be the first signs of this. They will become hypotonic (floppy), especially in the legs and body (more than in the arms).

Infantile Phytanic Acid Storage Disease

(IRD) is one of a small group of genetic diseases called peroxisome biogenesis disorders (PBD), which are part of a larger group of diseases called the leukodystrophies. These inherited conditions damage the brain's white matter and affect motor movements. The primary treatment for IRD is to avoid foods that contain phytanic acid, including dairy products; beef and lamb; and fatty fish such as tuna, cod, and haddock. Some infants and children may also require plasma exchange (plasmapheresis) in which blood is drawn, filtered, and re-infused back into the body to control the buildup of phytanic acid.

Infantile Refsum Disease

A disorder characterized by the reduction or absence of peroxisomes in the body and by the accumulation of phytanic acid in blood plasma and tissue. Infantile Refsum disease is a group of genetic disorders called the leukodystrophies that affect the growth of the myelin sheath, the fatty covering - which acts as an insulator - on nerve fibers in the brain.

Infantile Spasms

(IS) is a specific type of seizure seen in an epilepsy syndrome of infancy and early childhood known as West Syndrome. The onset is predominantly in the first year of life, typically between 3-6 months. The typical pattern of IS is a sudden bending forward and stiffening of the body, arms, and legs, although there can also be arching of the torso. The prognosis for children with IS depends on the seizures' underlying causes. The intellectual prognosis for children with IS is generally poor because many babies with IS have neurological impairment before the onset of spasms.

Inflammatory Myopathies

A term that defines a group of muscle diseases involving inflammation and degeneration of skeletal muscle tissues. Inclusion body myositis (IBM) mainly affects individuals over 50. The onset is insidious, with symptoms often present for more than five years before diagnosis. The cause of IBM remains unknown but is thought to be a form of autoimmune disease where the immune system responds in a harmful manner to the rest of the body.

Iniencephaly

A rare congenital disability caused by improper closure of the neural tube during fetal development. Iniencephaly is in the same family of neural tube defects as spina bifida but is more severe. Diagnosis is made immediately after birth because an infant's head is so severely bent backward that the face looks upward. There is no standard treatment for iniencephaly since most infants rarely live longer than a few hours.

Intestinal Lipodystrophy

Also called Whipple's disease, a rare bacterial infection that most often affects your gastrointestinal system. It interferes with normal digestion, impairing the breakdown of foods such as fats and carbohydrates and hampering your body's ability to absorb nutrients.

Intracranial Cysts

Cerebrospinal fluid-filled sacs that are located between the brain or spinal cord and the arachnoid membrane, one of the three membranes that cover the brain and spinal cord. Primary arachnoid cysts are present at birth and result from developmental abnormalities in the brain and spinal cord that arise during the early weeks of gestation. Secondary arachnoid cysts are not as common as primary cysts and develop due to head injury, meningitis, or tumors or as a complication of brain surgery.

Intracranial Hypertension

Idiopathic intracranial hypertension (IIH), sometimes called benign intracranial hypertension (BIH) or pseudotumor cerebri (PTC) is a neurological disorder that is characterized by increased intracranial pressure (ICP), in the absence of a tumor or other diseases affecting the brain or its lining. The main symptoms are headache and visual problems. Diagnosis requires brain scans and lumbar puncture.

Isaac's Syndrome

Also known as neuromyotonia, Isaac-Mertens syndrome, continuous muscle fiber activity syndrome, and quantal squander syndrome, is a rare neuromuscular disorder caused by continuous signaling of the end regions of peripheral nerve fibers that activate muscle fibers (motor neurons). Symptoms, which include progressive muscle stiffness, continuous vibrating or twitching muscles, cramping, increased sweating, and delayed muscle relaxation, occur even during sleep. Anticonvulsants, including phenytoin and carbamazepine, usually relieve the stiffness, muscle spasms, and pain associated with Isaac's syndrome. Plasma exchange may provide short-term relief for patients with some forms of the acquired disorder.

J

Joubert syndrome

Synonyms: Joubert-Boltshauser syndrome, cerebelloparenchymal disorder IV, familial cerebellar vermis agenesis, cerebello-oculo-renal syndrome. Joubert syndrome is a rare genetic disorder that affects the cerebellum, an area of the brain that controls balance and coordination. The disorder is characterized by the absence or underdevelopment of the cerebellar vermis and a malformed brain stem (molar tooth sign).

K

Kearns-Sayre Syndrome

(KSS) is a disease caused by a 5,000 base deletion in the mitochondrial DNA. Kearnes-Sayre syndrome starts before the age of 20. It is a rare genetic disease that can be heteroplasmic; more than one genome can be in a cell at any given time. Unlike most mitochondrial diseases, it is not maternally inherited. Rather, it occurs sporadically.

Kennedy's Disease

(KD) or X-linked spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disease associated with mutations of the androgen receptor (AR). Because of its endocrine manifestations related to the impairment of the AR, it can be viewed as a variation of the disorders of androgen insensitivity syndrome (AIS). It is named after WR Kennedy, a neurologist who was among the first to describe this disease.

Kinsbourne syndrome

Or Opsoclonus myoclonus syndrome (OMS), a rare neurological disorder of unknown causes which appears to be the result of an autoimmune process involving the nervous system. It is a rare condition, affecting as few as 1 in 10,000,000 people annually. It affects 2 to 3% of children with neuroblastoma.

Kleine-Levin Syndrome

KLS is a rare disorder characterized by the need for excessive amounts of sleep (hypersomnia) (e.g., up to 20 hours a day); excessive food intake (compulsive hyperphagia); and an abnormally uninhibited sexual drive. Adolescent males are the predominant victims of the disorder. Individual sufferers may often become irritable, lethargic, and apathetic. KLS patients may appear disoriented and report hallucinations. Symptoms are cyclical, with days to weeks (even up to months) of suffering interspersed by weeks or months (even up to years) symptom-free.

Klippel-Feil Syndrome

A rare disorder characterized by the congenital fusion of any 2 of the seven cervical vertebrae. It is caused by a failure in the normal segmentation or division of the cervical vertebrae during the early weeks of fetal development. Most individuals with KFS have a good prognosis if the disorder is treated early and appropriately. Activities that can injure the neck should be avoided. Anomalies associated with the syndrome can be fatal if not treated or found too late to be treatable.

Klippel-Trenaunay Syndrome (KTS)

(KTS) is a congenital circulatory disorder characterized by hemangiomas (abnormal benign growths on the skin consisting of masses of blood vessels), arteriovenous abscesses, and varicose veins, usually on the limbs. The affected limbs may be enlarged and warmer than normal. Fused toes or fingers, or extra toes or fingers, may be present. Bleeding may occur, often due to a rectal or vaginal tumor. KTS is a progressive disorder, and complications may be life-threatening.

Kluver-Bucy Syndrome

A behavioral disorder that occurs when both the right and left medial temporal lobes of the brain malfunction. The amygdala has been a particularly implicated brain region in the pathogenesis of this syndrome. Kluver- Bucy Syndrome causes individuals to put objects in their mouths and engage in inappropriate sexual behavior. Other symptoms may include visual agnosia (inability to recognize objects visually), loss of normal fear and anger responses, memory loss, distractibility, seizures, and dementia. The disorder may be associated with herpes encephalitis and trauma, which can result in brain damage.

Korsakoff's Amnesic Syndrome

(Korsakoff's psychosis, amnesic-confabulatory syndrome) is a degenerative brain disorder caused by the lack of thiamine (vitamin B1) in the brain. There are six major symptoms of Korsakoff's syndrome: anterograde and retrograde amnesia, or severe memory loss; confabulation, that is, invented memories which are then taken as true due to gaps in memory sometimes associated with blackouts; meager content in conversation; lack of insight, and apathy (the patients lose interest in things quickly and generally appear indifferent to change).

Krabbe Disease

Also known as globoid cell leukodystrophy or galactosylceramide lipidosis, is a rare, often fatal degenerative disorder that affects the myelin sheath of the nervous system. This condition is inherited in an autosomal recessive pattern. Infants with Krabbe disease are normal at birth. Symptoms begin between 3 and 6 months with irritability, fevers, limb stiffness, seizures, feeding difficulties, vomiting, and slowing mental and motor development. In the first stages of the disease, doctors often mistake the symptoms for those of cerebral palsy.

Kugelberg-Welander Disease

Spinal Muscular Atrophy (SMA) Types I, II, and III belong to a group of hereditary diseases that cause weakness and wasting of the voluntary muscles in the arms and legs of infants and children. The disorders are caused by an abnormal or missing gene known as the survival motor neuron gene (SMN1), which is responsible for producing a protein essential to motor neurons. Without this protein, lower motor neurons in the spinal cord degenerate and die. The age of onset and the severity of symptoms determines the type of SMA (I, II, or III).

Kuru

A disease which affects the brain. It is endemic among the Fore tribe of Papua New Guinea and is universally fatal. It is characterized by headaches, joint pains, and limb shaking. It is believed to be caused by prions and is related to Creutzfeldt-Jakob disease. It is best known for the epidemic in Papua New Guinea in the middle of the twentieth century. Kuru belongs to a class of infectious diseases called transmissible spongiform encephalopathies (TSEs), also known as prion diseases. The hallmark of a TSE disease is misshapen protein molecules that clump together and accumulate in brain tissue. There were no treatments that could control or cure kuru other than discouraging the practice of cannibalism. Currently, there are no cures or treatments for any of the other TSE diseases.

L

Lambert-Eaton Myasthenic Syndrome

(LEMS) is a rare disorder of neuromuscular transmission. It is a presynaptic disorder of neuromuscular transmission in which quantal release of acetylcholine (ACh) is impaired, causing a unique set of clinical characteristics, which include proximal muscle weakness, depressed tendon reflexes, post-tetanic potentiation, and autonomic changes. The initial presentation can be similar to that of myasthenia gravis, but the progressions of the two diseases have some important differences.

Landau-Kleffner Syndrome

(LKS) is a rare, childhood neurological disorder characterized by the sudden or gradual development of aphasia (the inability to understand or express language) and an abnormal electro-encephalogram (EEG). LKS affects the parts of the brain that control comprehension and speech. The disorder usually occurs in children between the ages of 5 and 7. Typically, children with LKS develop normally but then lose their language skills for no apparent reason.

Lateral Medullary Syndrome

Also called Wallenberg's syndrome and posterior inferior cerebellar artery syndrome, is a disease in which the patient has difficulty with swallowing or speaking or both owing to one or more patches of dead tissue (known as an infarct) caused by interrupted blood supply to parts of the brain.

Learning Disabilities

Disorders that affect the ability to understand or use spoken or written language, do mathematical calculations, coordinate movements, or direct attention. Although learning disabilities occur in very young children, the disorders are usually not recognized until the child reaches school age.

Leigh's Disease

A form of Leigh syndrome, also known as Subacute Necrotizing Encephalomyelopathy (SNEM), an inherited disorder that usually affects infants, but in rare cases, teenagers and adults, as well. In the case of the disease, mutations in mitochondrial DNA or nuclear DNA (gene SURF1 and some COX assembly factors) cause degradation of motor skills and eventually death.

Lennox-Gastaut Syndrome

A severe form of epilepsy. Seizures usually begin before four years of age. Seizure types, which vary among patients, include tonic (stiffening of the body, upward deviation of the eyes, dilation of the pupils, and altered respiratory patterns), atonic (brief loss of muscle tone and consciousness, causing abrupt falls), atypical absence (staring spells), and myoclonic (sudden muscle jerks).

Lesch-Nyhan Syndrome

Also known as Nyhan's syndrome, is a rare, inherited disorder caused by a deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT). LNS is an X-linked recessive disease: the mother carries the gene and passes it on to her son. LNS is present at birth in baby boys. Patients have severe mental and physical problems throughout life.

Leukodystrophy

A progressive degeneration of the white matter of the brain due to imperfect growth or development of the myelin sheath, the fatty covering that acts as an insulator around nerve fiber. Myelin, which lends its color to the brain's white matter, is a complex substance of at least ten different chemicals. Leukodystrophies are a group of disorders caused by genetic defects in how myelin produces or metabolizes these chemicals.

Levine-Critchley Syndrome

Very rare inherited disorder mainly involving progressive muscle weakness and wasting, abnormal limb movement, progressive cognitive loss, and red blood cell abnormalities.

Lewy Body Dementia

One of the most common types of progressive dementia. The central feature of DLB is progressive cognitive decline, combined with three additional defining features: (1) pronounced "fluctuations" in alertness and attention, such as frequent drowsiness, lethargy, lengthy periods spent staring into space, or disorganized speech; (2) recurrent visual hallucinations, and (3) parkinsonian motor symptoms, such as rigidity and the loss of spontaneous movement.

Lipid Storage Diseases

Or the lipidoses, are a group of inherited metabolic disorders in which harmful amounts of fatty materials called lipids accumulate in some of the body's cells and tissues. People with these disorders either do not produce enough of one of the enzymes needed to metabolize lipids or produce enzymes that do not work properly. Over time, this excessive storage of fats can cause permanent cellular and tissue damage, particularly in the brain, peripheral nervous system, liver, spleen, and bone marrow.

Lipoid Proteinosis

Rare autosomal recessive genodermatosis characterized by the deposition of amorphous hyaline material in the skin, mucosa, and viscera. The classic manifestation is onset in infancy with a hoarse cry due to laryngeal infiltration. Skin and mucous membrane changes become apparent clinically, and the disease typically follows a slowly progressive, yet often benign, course.

Lissencephaly

A rare brain formation disorder characterized by the lack of normal convolutions (folds) in the brain. It is caused by defective neuronal migration, the process in which nerve cells move from their place of origin to their permanent location. It is a form of cephalic disorder.

Locked-In Syndrome

A condition in which a patient is aware and awake but cannot move or communicate due to complete paralysis of nearly all voluntary muscles in the body. It results from a brain stem lesion in which the ventral part of the pons is damaged.

Lou Gehrig's Disease

Or Amyotrophic lateral sclerosis (ALS), a rapidly progressive, invariably fatal neurological disease that attacks the nerve cells (neurons) responsible for controlling voluntary muscles. In ALS, the upper and lower motor neurons degenerate or die, ceasing to send messages to muscles. Unable to function, the muscles gradually weaken, waste away, and twitch. Eventually, the ability of the brain to start and control voluntary movement is lost. Lou Gehrig's Disease Symptoms - Individuals with ALS lose their strength and the ability to move their arms, legs, and body. When muscles in the diaphragm and chest wall fail, individuals lose the ability to breathe without ventilatory support.

Lupus

Neurological Sequelae - (also called systemic lupus erythematosus) is a disorder of the immune system. Normally, the immune system protects the body against invading infections and cancers. In lupus, the immune system is over-active and produces increased amounts of abnormal antibodies that attack the body's tissues and organs. Lupus can affect many body parts, including the joints, skin, kidneys, lungs, heart, nervous system, and blood vessels. The signs and symptoms of lupus differ from person to person; the disease can range from mild to life-threatening.

Lyme Disease

Lyme disease is caused by a bacterial organism that is transmitted to humans via the bite of an infected tick. Most people bitten by an infected tick develop a characteristic skin rash around the bite area. The rash may feel hot to the touch and vary in size, shape, and color, but it will often have a "bull's eye" appearance (a red ring with a clear center). However, some will not develop the rash, which makes Lyme disease hard to diagnose because its symptoms and signs mimic those of many other diseases.

M

Machado-Joseph Disease

(MJD)-also called spinocerebellar ataxia type 3-is a rare hereditary ataxia. (Ataxia is a general term meaning lack of muscle control.) The disease is characterized by clumsiness and weakness in the arms and legs, spasticity, a staggering lurching gait easily mistaken for drunkenness, difficulty with speech and swallowing, involuntary eye movements, double vision, and frequent urination. Some patients have dystonia (sustained muscle contractions that cause twisting of the body and limbs, repetitive movements, abnormal postures, and rigidity) or symptoms similar to those of Parkinson's disease. Others have twitching of the face or tongue or peculiar bulging eyes.

Macrencephaly

Also called macrencephaly, is a condition in which an infant or child has an abnormally large, heavy, and usually malfunctioning brain. By definition, the brain weight is greater than average for the age and gender of the child. Head enlargement may be evident at birth, or the head may become abnormally large in the early years of life. Megalencephaly is thought to be related to a disturbance in regulating cell production in the brain. In normal development, neuron proliferation - the process in which nerve cells divide to form new generations of cells - is regulated so that the correct number of cells is produced in the proper place at the appropriate time. In a megalencephalic brain, too many cells are produced either during development or progressively as part of another disorder, such as one of the neurofibromatoses or leukodystrophies. Symptoms of megalencephaly include delayed development, seizures, and corticospinal (brain cortex and spinal cord) dysfunction. Megalencephaly affects males more often than females. Unilateral megalencephaly or hemimegalencephaly is a rare condition characterized by the enlargement of one side of the brain. Children with this disorder may have a large, asymmetrical head accompanied by seizures, partial paralysis, and mental retardation.

Melkersson-Rosenthal Syndrome

A rare neurological disorder characterized by recurring facial paralysis, swelling of the face and lips (usually the upper lip), and the development of folds and furrows in the tongue. Onset is in childhood or early adolescence. After recurrent attacks (ranging from days to years in between), swelling may persist and increase, eventually becoming permanent. The lip may become hard, cracked, and fissured with a reddish-brown discoloration. The cause of Melkersson-Rosenthal syndrome is unknown, but there may be a genetic predisposition. It can be symptomatic of Crohn's disease or sarcoidosis.

Meningitis

The inflammation of the protective membranes covering the central nervous system, known collectively as the meninges. Meningitis may develop in response to several causes, most prominently bacteria, viruses, other infectious agents, physical injury, cancer, or certain drugs. While some forms of meningitis are mild and resolve independently, meningitis is a potentially serious condition owing to the inflammation's proximity to the brain and spinal cord. The potential for serious neurological damage or death necessitates prompt medical attention and evaluation.

Menkes Disease

Caused by a defective gene that regulates the metabolism of copper in the body. Because it is an X-linked gene, the disease primarily affects male infants. Copper accumulates at abnormally low levels in the liver and brain but at higher than normal levels in the kidney and intestinal lining. Affected infants may be born prematurely. Symptoms appear during infancy. Normal or slightly slowed development may proceed for 2 to 3 months, and then there will be a severe developmental delay and a loss of early developmental skills. Menkes Disease is also characterized by seizures, failure to thrive, subnormal body temperature, and strikingly peculiar hair, which is kinky, colorless, or steel-colored and easily broken. There can be extensive neurodegeneration in the gray matter of the brain. Arteries in the brain can also be twisted with frayed and split inner walls. This can lead to rupture or blockage of the arteries. Weakened bones (osteoporosis) may result in fractures.

Meralgia Paresthetica

A disorder characterized by tingling, numbness, and burning pain in the outer side of the thigh. The disorder is caused by compression of the lateral femoral cutaneous nerve as it exits the pelvis. It more commonly occurs in men than women and is generally found in middle-aged or overweight individuals. People with the disorder frequently report that it appears or worsens after walking or standing. The skin is often sensitive to the touch. Meralgia paresthetica is associated with clothing that is too tight, pregnancy, diabetes, and obesity.

Metachromatic Leukodystrophy

(MLD, also called Arylsulfatase A deficiency) is the most common form of a family of genetic diseases known as the leukodystrophies, diseases which affect the growth and development of myelin, the fatty covering which acts as an insulator around nerve fibers throughout the central and peripheral nervous systems.

Microcephaly

A medical condition in which the circumference of the head is smaller than normal because the brain has not developed properly or has stopped growing. Microcephaly can be present at birth or may develop in the first few years of life. It is most often caused by genetic abnormalities that interfere with the growth of the cerebral cortex during the early months of fetal development. It is associated with Down's syndrome, chromosomal syndromes, and neurometabolic syndromes. Babies may also be born with microcephaly if, during pregnancy, their mother abused drugs or alcohol, became infected with a cytomegalovirus, rubella (German measles), or varicella (chicken pox) virus, was exposed to certain toxic chemicals or had untreated phenylketonuria (PKU). Babies born with microcephaly will have a smaller-than-normal head that will fail to grow as they progress through infancy. Depending on the severity of the accompanying syndrome, children with microcephaly may have mental retardation, delayed motor functions and speech, facial distortions, dwarfism or short stature, hyperactivity, seizures, difficulties with coordination and balance, and other brain or neurological abnormalities.

Migraine

The pain of a migraine headache is often described as an intense pulsing or throbbing pain in one area of the head. It is often accompanied by extreme sensitivity to light and sound, nausea, and vomiting. Migraine is three times more common in women than in men. Some individuals can predict the onset of a migraine because it is preceded by an "aura," visual disturbances that appear as flashing lights, zig-zag lines, or a temporary loss of vision. People with migraine tend to have recurring attacks triggered by a lack of food or sleep, exposure to light, or hormonal irregularities (only in women). Anxiety, stress, or relaxation after stress can also be triggered. For many years, scientists believed that migraines were linked to the dilation and constriction of blood vessels in the head. Investigators now believe that inherited abnormalities cause migraine in genes that control the activities of certain cell populations in the brain.

Miller Fisher Syndrome

A rare, acquired nerve disease that is considered to be a variant of Guillain-Barre syndrome. It is characterized by abnormal muscle coordination, paralysis of the eye muscles, and the absence of tendon reflexes. Like Guillain-Barre syndrome, symptoms may be preceded by a viral illness. Additional symptoms include generalized muscle weakness and respiratory failure. Most individuals with Miller-Fisher syndrome have a unique antibody that characterizes the disorder.

Mini-Strokes

A transient ischemic attack (TIA) is a transient stroke that lasts only a few minutes. It occurs when the blood supply to part of the brain is briefly interrupted. TIA symptoms, which usually occur suddenly, are similar to those of stroke but do not last as long. Most symptoms of a TIA disappear within an hour, although they may persist for up to 24 hours. Symptoms can include numbness or weakness in the face, arm, or leg, especially on one side of the body; confusion or difficulty in talking or understanding speech; trouble seeing in one or both eyes; difficulty walking; dizziness or loss of balance and coordination.

Mitochondrial Myopathies

A group of neuromuscular diseases caused by damage to the mitochondria-small, energy-producing structures that serve as the cells' "power plants." Nerve cells in the brain and muscles require a great deal of energy and thus appear to be particularly damaged when mitochondrial dysfunction occurs. Some common mitochondrial myopathies include Kearns-Sayre syndrome, myoclonus epilepsy with ragged-red fibers, and mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes. The symptoms of mitochondrial myopathies include muscle weakness or exercise intolerance, heart failure or rhythm disturbances, dementia, movement disorders, stroke-like episodes, deafness, blindness, droopy eyelids, limited mobility of the eyes, vomiting, and seizures. The prognosis for these disorders ranges in severity from progressive weakness to death. Most mitochondrial myopathies occur before age 20 and often begin with exercise intolerance or muscle weakness.

Motor Neuron Diseases

(MNDs) are a group of progressive neurological disorders that destroy motor neurons, the cells that control essential voluntary muscle activity such as speaking, walking, breathing, and swallowing. Normally, messages from nerve cells in the brain (called upper motor neurons) are transmitted to nerve cells in the brainstem and spinal cord (called lower motor neurons ) and from them to particular muscles. Upper motor neurons direct the lower motor neurons to produce movements such as walking or chewing. Lower motor neurons control movement in the arms, legs, chest, face, throat, and tongue.

Moyamoya Disease

A rare, progressive cerebrovascular disorder caused by blocked arteries at the base of the brain in an area called the basal ganglia. The name "moyamoya" means "puff of smoke" in Japanese and describes the look of the tangle of tiny vessels formed to compensate for the blockage. Moyamoya disease was first described in Japan in the 1960s, and it has since been found in individuals in the United States, Europe, Australia, and Africa. The disease primarily affects children, but it can also occur in adults. In children, the first symptom of Moyamoya disease is often stroke or recurrent transient ischemic attacks (TIA, commonly referred to as "mini-strokes"), frequently accompanied by muscular weakness or paralysis affecting one side of the body or seizures. Adults often experience a hemorrhagic stroke due to recurring blood clots in the affected brain vessels. Individuals with this disorder may have disturbed consciousness, speech deficits (usually aphasia), sensory and cognitive impairments, involuntary movements, and vision problems.

Mucolipidoses

The mucolipidoses (ML) are a group of inherited metabolic diseases that affect the body's ability to carry out the normal turnover of various materials within cells. In ML, abnormal amounts of carbohydrates or fatty materials (lipids) accumulate in cells. Because our cells cannot handle such large amounts of these substances, damage occurs, causing symptoms ranging from mild learning disabilities to severe mental retardation and skeletal deformities.

Mucopolysaccharidoses

The mucopolysaccharidoses are a group of inherited metabolic diseases caused by the absence or malfunctioning of certain enzymes needed to break down molecules called glycosaminoglycans - long chains of sugar carbohydrates in each of our cells that help build bone, cartilage, tendons, corneas, skin, and connective tissue. Glycosaminoglycans (formerly called mucopolysaccharides) are also found in the fluid that lubricates our joints. People with mucopolysaccharidosis either do not produce enough of one of the 11 enzymes required to break down these sugar chains into proteins and simpler molecules, or they produce enzymes that do not work properly. Over time, these glycosaminoglycans collect in the cells, blood, and connective tissues. The result is permanent, progressive cellular damage that affects the individual's appearance, physical abilities, organ and system functioning, and, in most cases, mental development.

Multiple sclerosis (MS)

Also known as disseminated sclerosis or encephalomyelitis disseminate, is an inflammatory disease in which the insulating covers of nerve cells in the brain and spinal cord are damaged. MS is a disease in which your immune system attacks the protective sheath (myelin) that covers your nerves. Myelin damage disrupts communication between your brain and the rest of your body. Ultimately, the nerves themselves may deteriorate, a process that's currently irreversible. An estimated 400,000 Americans have MS. It generally occurs in people between the ages of 20 and 50. The disease is twice as common in women as in men. The illness is probably an autoimmune disease, which means your immune system responds as if part of your body is a foreign substance.

Multiple System Atrophy

With orthostatic hypotension is the current classification for a neurological disorder that was once called Shy-Drager syndrome. A progressive disorder of the central and autonomic nervous systems is characterized by orthostatic hypotension (an excessive drop in blood pressure when standing up), which causes dizziness or fainting. Multiple system atrophy can occur without orthostatic hypotension, but it is rare. Doctors classify the disorder into three types: the Parkinsonian type includes symptoms of Parkinson's disease such as slow movement, stiff muscles, and tremors; the cerebellar type, which causes problems with coordination and speech; and the combined type, which includes symptoms of both parkinsonism and cerebellar failure. Problems with urinary incontinence, constipation, and sexual impotence in men happen early in the course of the disease. Other symptoms include generalized weakness, double vision or other vision disturbances, difficulty breathing and swallowing, sleep disturbances, and decreased sweating. Because the disease resembles others, a correct diagnosis may take years.

Muscular Dystrophy

The muscular dystrophies (MD) are a group of more than 30 genetic diseases characterized by progressive weakness and degeneration of the skeletal muscles that control movement. Some forms of MD are seen in infancy or childhood, while others may not appear until middle age or later. The disorders differ in terms of the distribution and extent of muscle weakness (some forms of MD also affect cardiac muscle), age of onset, rate of progression, and inheritance pattern.Duchenne MD is the most common form of MD and primarily affects boys. It is caused by the absence of dystrophin, a protein that maintains muscle integrity. Onset is between 3 and 5 years, and the disorder progresses rapidly. Most boys cannot walk by age 12 and need breathing respirators. Girls in these families have a 50 percent chance of inheriting and passing the defective gene to their children. Boys with Becker MD (similar to but less severe than Duchenne MD) have faulty or insufficient dystrophin.Facioscapulohumeral MD usually begins in the teenage years. It causes progressive weakness in the muscles of the face, arms, legs, and around the shoulders and chest. It progresses slowly and can vary in symptoms from mild to disabling.Myotonic MD is the disorder's most common adult form and is typified by prolonged muscle spasms, cataracts, cardiac abnormalities, and endocrine disturbances. Individuals with myotonic MD have long, thin faces, drooping eyelids, and swan-like necks.

Myasthenia Gravis

A chronic autoimmune neuromuscular disease characterized by varying degrees of weakness of the skeletal (voluntary) muscles of the body. The name myasthenia gravis, which is Latin and Greek in origin, literally means "grave muscle weakness." With current therapies, however, most cases of myasthenia gravis are not as "grave," as the name implies. In fact, for most individuals with myasthenia gravis, life expectancy is not lessened by the disorder. The hallmark of myasthenia gravis is muscle weakness that increases during periods of activity and improves after periods of rest. Certain muscles, such as those that control eye and eyelid movement, facial expression, chewing, talking, and swallowing, are often, but not always, involved in the disorder. The muscles that control breathing and neck and limb movements may also be affected.

Myoclonus

Describes a symptom and generally is not a diagnosis of a disease. It refers to the sudden, involuntary jerking of a muscle or group of muscles. Myoclonic twitches or jerks usually are caused by sudden muscle contractions, called positive myoclonus, or by muscle relaxation, called negative myoclonus. Myoclonic jerks may occur alone or in sequence, in a pattern or without a pattern. They may occur infrequently or many times each minute. Myoclonus sometimes occurs in response to an external event or when someone attempts to move. The twitching cannot be controlled by the person experiencing it.

Myopathy

The myopathies are neuromuscular disorders in which the primary symptom is muscle weakness due to dysfunction of muscle fiber. Other myopathy symptoms include muscle cramps, stiffness, and spasm. Myopathies can be inherited (such as muscular dystrophies) or acquired (such as common muscle cramps). Myopathies are grouped as follows:

• congenital myopathies: characterized by developmental delays in motor skills; skeletal and facial abnormalities are occasionally evident at birth. Muscular dystrophies: characterized by progressive weakness in voluntary muscles; sometimes evident at birth.
• mitochondrial myopathies: caused by genetic abnormalities in mitochondria, cellular structures that control energy; include Kearns-Sayre syndrome, MELAS, and MERRF.
• glycogen storage diseases of muscle: caused by mutations in genes controlling enzymes that metabolize glycogen and glucose (blood sugar); include Pompe's, Andersen's, and Cori's diseases.
• myoglobinurias: caused by disorders in the metabolism of a fuel (myoglobin) necessary for muscle work; include McArdle, Tarui, and DiMauro diseases.
• dermatomyositis: an inflammatory myopathy of skin and muscle myositis ossificans: characterized by bone growing in muscle tissue.
• familial periodic paralysis: characterized by episodes of weakness in the arms and legs.
• polymyositis, inclusion body myositis, and related myopathies: inflammatory myopathies of skeletal muscle.
• neuromyotonia: characterized by alternating episodes of twitching and stiffness.
• stiff-man syndrome: characterized by episodes of rigidity and reflex spasms, common muscle cramps and stiffness, and tetany: characterized by prolonged spasms of the arms and legs.

Myotonia

An inherited neuromuscular disorder characterized by the inability of muscles to relax quickly after a voluntary contraction. The condition has been present since early childhood, but symptoms can be mild. Most children will be 2 or 3 years old when parents first notice muscle stiffness, particularly in the legs, often provoked by sudden activity after rest. The disease doesn't cause muscle wasting; it may cause muscle enlargement. Muscle strength is increased. The disorder has two forms: Becker-type, the most common form, and Thomsen's disease, a rare and milder form. The disorder is caused by mutations in a gene responsible for shutting off electrical excitation in the muscles.

N

Narcolepsy

A neurological condition most characterized by Excessive Daytime Sleepiness (EDS). A narcoleptic will most likely experience disturbed nocturnal sleep, often confused with insomnia and disorder of REM or rapid eye movement sleep. It is one of the dyssomnias. A narcoleptic may also sleep at any random time.

Neuroacanthocytosis

A rare movement disorder marked by progressive muscle weakness and atrophy, progressive cognitive loss, chorea (involuntary twisting movements of the body), and acanthocytosis (spiked red blood cells associated with several inherited neurological disorders). Other symptoms include facial tics, uncontrolled muscle movement, instability when walking, seizures, biting of the tongue and lips, and changes in personality, comprehension, and judgment.

Neurodegeneration with Brain Iron Accumulation

(NBIA) is a rare, inherited, neurological movement disorder characterized by progressive degeneration of the nervous system. Symptoms, which vary greatly among patients and usually develop during childhood, may include slow writhing, distorting muscle contractions of the limbs, face, or trunk, choreoathetosis (involuntary, purposeless jerky muscle movements), muscle rigidity (uncontrolled tightness of the muscles), spasticity (sudden, involuntary muscle spasms), ataxia (inability to coordinate movements), confusion, disorientation, seizures, stupor, and dementia.

Neurofibromatosis

An autosomal dominant genetic disorder. It encompasses a set of distinct genetic disorders that cause tumors to grow along types of nerves and, in addition, can affect the development of non-nervous tissues such as bones and skin. The tumors can grow anywhere on or in the body.

Neuroleptic Malignant Syndrome

(NMS) is a life-threatening neurological disorder most often caused by an adverse reaction to neuroleptic or antipsychotic drugs. It generally presents with muscle rigidity, fever, autonomic instability, and cognitive changes such as delirium and is proven on a raised creatine phosphokinase (CPK). Treatment is generally supportive.

Neurological Complications of AIDS

AIDS is primarily an immune system disorder caused by the human immunodeficiency virus (HIV), but it can also affect the nervous system. HIV does not appear to invade nerve cells directly. Still, it jeopardizes their health and function, causing symptoms such as confusion, forgetfulness, behavioral changes, severe headaches, progressive weakness, loss of sensation in the arms and legs, stroke, cognitive motor impairment, or damage to the peripheral nerves. Other complications that can occur as a result of HIV infection or the drugs used to treat it include pain, seizures, shingles, spinal cord problems, lack of coordination, difficult or painful swallowing, anxiety disorder, depression, fever, vision loss, gait disorders, destruction of brain tissue, and coma.

Neurological Complications Of Lyme Disease

Lyme disease is caused by a bacterial organism that is transmitted to humans via the bite of an infected tick. Most people bitten by an infected tick develop a characteristic skin rash around the bite area. The rash may feel hot to the touch and vary in size, shape, and color, but it will often have a "bull's eye" appearance (a red ring with a clear center). However, some will not develop the rash, making Lyme disease hard to diagnose because its symptoms and signs mimic many other diseases.

Neurological Consequences of Cytomegalovirus Infection

CMV is in the same family of viruses that includes herpes simplex types 1 and 2, and the viruses that cause infectious mononucleosis (EBV), chickenpox, and shingles. A hallmark of CMV is the reappearance of symptoms throughout life, as the virus cycles through periods of dormancy and active infection.

Neurological Manifestations of Pompe Disease

Pompe disease is a rare inherited and often fatal disorder that disables the heart and muscles. It is caused by mutations in a gene that makes an enzyme called alpha-glucosidase (GAA). Normally, the body uses GAA to break down glycogen, a stored sugar used for energy. But in Pompe disease, mutations in the GAA gene reduce or eliminate this essential enzyme. Excessive amounts of glycogen accumulate everywhere in the body, but the heart and skeletal muscle cells are the most seriously affected.

Neurological Sequelae Of Lupus

A disorder of the immune system. Normally, the immune system protects the body against invading infections and cancers. In lupus, the immune system is over-active and produces increased amounts of abnormal antibodies that attack the body's tissues and organs. Lupus can affect many body parts, including the joints, skin, kidneys, lungs, heart, nervous system, and blood vessels.

Neuromyelitis Optica or Devic's disease

An autoimmune, inflammatory disorder in which a person's immune system attacks the optic nerves and spinal cord. This produces an inflammation of the optic nerve (optic neuritis) and the spinal cord (myelitis). Although inflammation may also affect the brain, the lesions differ from those observed in the related condition, multiple sclerosis. Spinal cord lesions lead to varying degrees of weakness or paralysis in the legs or arms, loss of sensation, and bladder and bowel dysfunction. Devic's disease is a rare disorder that resembles multiple sclerosis (MS) in several ways.

Neuromyotonia

Also known as Isaacs' Syndrome, it is spontaneous muscular activity resulting from repetitive motor unit action potentials of peripheral origin.

Neuronal Ceroid Lipofuscinosis

(NCL, also known as Batten Disease) is the general name for a family of at least eight genetically separate neurodegenerative disorders that result from excessive accumulation of lipopigments (lipofuscin) in the body's tissues. These lipopigments are made up of fats and proteins. Their name comes from the technical word lipo, which is short for "lipid" or fat, and from the term pigment, used because they take on a greenish-yellow color when viewed under an ultraviolet light microscope. The lipopigments build up in brain and eye cells, skin, muscle, and many other tissues.

Neuronal Migration Disorders

(NMDs) are a group of congenital disabilities caused by the abnormal migration of neurons in the developing brain and nervous system.

Neuropathy

Hereditary - a group of inherited disorders of the peripheral nervous system. Within the group, there are four subcategories of disorders: hereditary motor and sensory neuropathy, hereditary sensory neuropathy, hereditary motor neuropathy, and hereditary sensory and autonomic neuropathy. Symptoms of these disorders vary and may include numbness and tingling in the feet and hands, muscle weakness (especially in the distal muscles), scoliosis, thin lower legs, foot deformities, insensitivity to pain, and autonomic symptoms such as impaired sweating, postural hypotension, and skin blotching.

Neurosarcoidosis

Refers to sarcoidosis, a condition of unknown cause featuring granulomas in various tissues, involving the central nervous system (brain and spinal cord). It can have many manifestations, but abnormalities of the cranial nerves (a group of twelve nerves supplying the head and neck area) are the most common. It may develop acutely, subacutely, and chronically.

Neurotoxicity

Occurs when the exposure to natural or artificial toxic substances, which are called neurotoxins, alters the normal activity of the nervous system. This can eventually disrupt or even kill neurons, key cells that transmit and process signals in the brain and other parts of the nervous system. Neurotoxicity can result from exposure to substances used in chemotherapy, radiation treatment, drug therapies, and organ transplants, as well as exposure to heavy metals such as lead and mercury, certain foods and food additives, pesticides, industrial and cleaning solvents, cosmetics, and some naturally occurring substances.

Nevus Cavernosus

Or cavernous angioma, vascular malformation composed of sinusoidal vessels without a large feeding artery; can be multiple, especially if inherited as an autosomal-dominant trait.

Niemann-Pick Disease

An autosomal recessive disorder affecting lipid metabolism (the breakdown and use of fats and cholesterol in the body) in a way that causes harmful amounts of lipids to accumulate in the spleen, liver, lungs, bone marrow, and brain.

Non 24 Sleep Wake Disorder

(See Hypernychthemeral Disorder)

Normal Pressure Hydrocephalus

(NPH) is an abnormal increase of cerebrospinal fluid (CSF) in the brain's ventricles or cavities. It occurs if the normal flow of CSF throughout the brain and spinal cord is blocked somehow. This causes the ventricles to enlarge, putting pressure on the brain.

O

Occipital Neuralgia

A distinct type of headache characterized by piercing, throbbing, or electric-shock-like chronic pain in the upper neck, back of the head, and behind the ears, usually on one side of the head. Typically, the pain of occipital neuralgia begins in the neck and then spreads upwards. Some individuals will also experience pain in the scalp, forehead, and behind the eyes. Their scalp may also be tender to the touch, and their eyes are susceptible to light.

Occult Spinal Dysraphism Sequence

Or Tethered spinal cord syndrome, is a neurological disorder caused by tissue attachments that limit the movement of the spinal cord within the spinal column. These attachments cause an abnormal stretching of the spinal cord. The course of the disorder is progressive. In children, symptoms may include lesions, hairy patches, dimples, or fatty tumors on the lower back; foot and spinal deformities; weakness in the legs; low back pain; scoliosis; and incontinence.

Ohtahara Syndrome

A neurological disorder characterized by seizures. The disorder affects newborns, usually within the first three months of life (most often within the first ten days), in the form of epileptic seizures. Infants have primarily tonic seizures but may also experience partial and, rarely, myoclonic seizures Individuals with Ohtahara syndrome often have mental retardation or other developmental impairments. The cause of the disorder is unknown.

Olivopontocerebellar Atrophy

(OPCA) is a term used to define neuronal degeneration in the cerebellum, pontine nuclei, and inferior olive. OPCA may also be found in the brains of individuals with prion disorders and inherited metabolic diseases. The distinct areas of brain damage that indicate OPCA can be seen by imaging the brain using CT scans or MRI studies.

Opsoclonus Myoclonus

(OMS) is a rare neurological disorder of unknown causes that appears to be the result of an autoimmune process involving the nervous system. It is an extremely rare condition, affecting as few as 1 in 10,000,000 people annually. It affects 2 to 3% of children with neuroblastoma. In most cases, OMS starts with an acute flare-up of physical symptoms within days or weeks. Still, some less obvious symptoms such as irritability and malaise may begin weeks or months earlier

Orthostatic Hypotension

Also known as postural hypotension, orthostatic reflect, orthostatic intolerance and, colloquially, as head rush or a dizzy spell - is a sudden fall in blood pressure, typically greater than 20/10 mm Hg, that occurs when a person assumes a standing position, usually after a prolonged period of rest. Symptoms, which occur after standing, include dizziness, lightheadedness, headache, blurred or dimmed vision (possibly to the point of momentary blindness), generalized (or extremity) numbness/tingling, and fainting. They are consequences of insufficient blood pressure and cerebral perfusion (blood supply).

O'Sullivan-McLeod Syndrome

Or Monomelic amyotrophy (MMA), is characterized by progressive degeneration and loss of motor neurons, the nerve cells in the brain and spinal cord that are responsible for controlling voluntary muscles. It is characterized by weakness and wasting in a single limb, usually an arm and hand, rather than a foot and leg. There is no pain associated with MMA. While some physicians contend that mild sensory loss may be associated with this disease, many experts suggest that such symptoms indicate a cause other than MMA. MMA occurs in males between the ages of 15 and 25.

Overuse Syndrome

Can also be known as Carpal Tunnel Syndrome (CTS) is a condition where a part of the body is injured by repeatedly overusing or exerting to much strain on that body part. A strain occurs when the body part is called on to work harder, stretch farther, impact more directly, or otherwise function at a greater level than it is prepared for. The immediate impact may be minute, but the constant straining causes damage when it repeatedly occurs.

P

Pantothenate Kinase-Associated Neurodegeneration

(PKAN), also known as Hallervorden-Spatz syndrome, is a degenerative disease of the brain, which can lead to parkinsonism. Neurodegeneration in PKAN is accompanied by an excess of iron that progressively builds in the brain.

Paraneoplastic Syndromes

A group of rare degenerative disorders that are triggered by a person's immune system response to a neoplasm, or cancerous tumor. Neurologic paraneoplastic syndromes are believed to occur when cancer-fighting antibodies or white blood cells, known as T cells, mistakenly attack normal cells in the nervous system. These disorders typically affect middle-aged to older persons and are most common in persons with lung, ovarian, lymphatic, or breast cancer. Neurologic symptoms generally develop over days to weeks and usually occur before tumor detection, which can complicate diagnosis. These symptoms may include difficulty walking and swallowing, loss of muscle tone, loss of fine motor coordination, slurred speech, memory loss, vision problems, sleep disturbances, dementia, seizures, sensory loss in the limbs, and vertigo. Neurologic paraneoplastic syndromes include Lambert-Eaton myasthenic syndrome, stiff-person syndrome, encephalomyelitis (inflammation of the brain and spinal cord), myasthenia gravis, cerebellar degeneration, limbic and brainstem encephalitis, neuromyotonia, and opsoclonus (involving eye movement) and sensory neuropathy.

Paresthesia

Refers to a burning or prickling sensation that is usually felt in the hands, arms, legs, or feet, but can also occur in other parts of the body. The sensation, which happens without warning, is usually painless and described as tingling or numbness, skin crawling, or itching.Most people have experienced temporary paresthesia - a feeling of "pins and needles" - at some time in their lives when they have sat with legs crossed for too long or fallen asleep with an arm crooked under their head. It happens when sustained pressure is placed on a nerve. The feeling quickly goes away once the pressure is relieved.

Parkinson's Disease

(PD) belongs to a group of conditions called motor system disorders, which are the result of the loss of dopamine-producing brain cells. The four primary symptoms of PD are tremor or trembling in hands, arms, legs, jaw, and face; rigidity, or stiffness of the limbs and trunk; bradykinesia, or slow movement; and postural instability, or impaired balance and coordination. As these symptoms become more pronounced, patients may have difficulty walking, talking, or completing other simple tasks. PD usually affects people over the age of 50. Early symptoms of PD are subtle and occur gradually. In some people, the disease progresses more quickly than in others. As the disease progresses, the shaking or tremor affecting most PD patients may begin to interfere with daily activities. Other symptoms may include depression and other emotional changes; difficulty swallowing, chewing, and speaking; urinary problems or constipation; skin problems; and sleep disruptions. There are currently no blood or laboratory tests that have been proven to help in diagnosing sporadic PD.

Paroxysmal Choreoathetosis

A movement disorder characterized by episodes or attacks of involuntary movements of the limbs, trunk, and facial muscles. The disorder may occur in several or only a single family member. Before an attack, some individuals experience tightening of muscles or other physical symptoms. Involuntary movements precipitate some attacks, and other attacks occur when the individual has consumed alcohol or caffeine or is tired or stressed. Attacks can last from 10 seconds to over an hour. Some individuals have lingering muscle tightness after an attack. Paroxysmal choreoathetosis frequently begins in early adolescence. A gene associated with the disorder has been discovered. The same gene is also associated with epilepsy.

Paroxysmal Hemicrania

A rare form of headache that usually begins in adulthood. Patients experience severe throbbing, claw-like, or dull pain, usually on one side of the face; in, around, or behind the eye; and occasionally reaching to the back of the neck. Red and tearing eyes, a drooping or swollen eyelid on the affected side of the face, and nasal congestion may accompany this pain. Patients may also feel dull pain, soreness, or tenderness between attacks. Attacks of paroxysmal hemicrania typically occur from 5 to 40 times per day and last 2 to 45 minutes. The disorder has two forms: chronic, in which patients experience attacks daily for a year or more, and episodic, in which the headaches may remit for months or years.

Parry-Romberg

Parry-Romberg syndrome is a rare disorder characterized by slowly progressive deterioration (atrophy) of the skin and soft tissues of half of the face (hemifacial atrophy), usually the left side. It is more common in females than in males. Initial facial changes usually involve the tissues above the upper jaw (maxilla) or between the nose and the upper corner of the lip (nasolabial fold) and subsequently progress to the angle of the mouth, areas around the eye, the brow, the ear, and the neck. The deterioration may also affect the tongue, the soft and fleshy part of the roof of the mouth, and the gums. The eye and cheek of the affected side may become sunken and facial hair may turn white and fall out (alopecia). In addition, the skin overlying affected areas may become darkly pigmented (hyperpigmentation) with, in some cases, areas of hyperpigmentation and patches of unpigmented skin (vitiligo).

Pelizaeus-Merzbacher Disease

PMD) is a rare, progressive, degenerative central nervous system disorder in which coordination, motor abilities, and intellectual function deteriorate. The disease is one of a group of gene-linked disorders known as leukodystrophies, which affect the growth of the myelin sheath - the fatty covering that wraps around and protects nerve fibers in the brain. The disease is caused by a gene mutation controlling the production of a myelin protein called proteolipid protein (PLP). PMD is inherited as an X-linked recessive trait in that the affected individuals are male, and the mothers are carriers of the PLP mutation. The severity and onset of the disease range widely, depending on the type of PLP mutation and extends from mild, adult-onset spastic paraplegia (SPG2) to the severe form with onset at infancy and death in early childhood. The characteristic set of neurological symptoms includes nystagmus (rapid, involuntary, rhythmic jerking of the eyes and the head), spastic paraparesis (paralysis of the legs with hyperactive tendon reflexes), and limb ataxia (lack of coordination in the arms and legs).

Perineural Cysts

Tarlov cysts are fluid-filled sacs that most often affect nerve roots in the sacrum, the group of bones at the base of the spine. These cysts can compress nerve roots, causing lower back pain, sciatica (shock-like or burning pain in the lower back, buttocks, and down one leg to below the knee), urinary incontinence, sexual dysfunction, and some loss of feeling or control of movement in the leg and foot. Pressure on the nerves next to the cysts can also cause pain. Tarlov cysts may become symptomatic following shock, trauma, or exertion that causes the buildup of cerebrospinal fluid. Women are at much higher risk of developing these cysts than men.

Periodic Paralyzes

Familial periodic paralyzes are a group of inherited neurological disorders caused by mutations in genes that regulate sodium and calcium channels in nerve cells. They are characterized by episodes in which the affected muscles become slack, weak, and unable to contract. Between attacks, the affected muscles usually work as normal. The two most common types of periodic paralyzes are:

• Hypokalemic periodic paralysis is characterized by a fall in potassium levels in the blood. In individuals with this mutation, attacks often begin in adolescence and are triggered by strenuous exercise or high-carbohydrate meals. Weakness may be mild and limited to certain muscle groups or more severe and affect the arms and legs. Attacks may last for a few hours or persist for several days. Some patients may develop chronic muscle weakness later in life.
• Hyperkalemic periodic paralysis is characterized by a rise in potassium levels in the blood. Attacks often begin in infancy or early childhood and are precipitated by rest after exercise or fasting. Attacks are usually shorter, more frequent, and less severe than the hypokalemic form. Muscle spasms are common.

Peripheral Neuropathy

Describes damage to the peripheral nervous system, the vast communications network that transmits information from the brain and spinal cord (the central nervous system) to every other part of the body. Peripheral nerves also send sensory information back to the brain and spinal cord, such as a message that the feet are cold or a finger is burned. Damage to the peripheral nervous system interferes with these vital connections. Like static on a telephone line, peripheral neuropathy distorts and sometimes interrupts messages between the brain and the rest of the body.

Periventricular Leukomalacia

(PVL) is characterized by the death of the white matter of the brain due to softening of the brain tissue. It can affect fetuses or newborns; premature babies are at the greatest risk of the disorder. PVL is caused by a lack of oxygen or blood flow to the periventricular area of the brain, which results in the death or loss of brain tissue. The periventricular area-the area around the spaces in the brain called ventricles contains nerve fibers that carry messages from the brain to the body's muscles. Although babies with PVL generally have no outward signs or symptoms of the disorder, they are at risk for motor disorders, delayed mental development, coordination problems, and vision and hearing impairments. PVL may be accompanied by a hemorrhage or bleeding in the periventricular-intraventricular area (the area around and inside the ventricles) and can lead to cerebral palsy. The disorder is diagnosed by ultrasound of the head.

Pervasive Developmental Disorders

The diagnostic category of pervasive developmental disorders (PDD) refers to a group of disorders characterized by delays in the development of socialization and communication skills. Parents may note symptoms as early as infancy, although the typical age of onset is before three years of age. Symptoms may include problems with using and understanding language; difficulty relating to people, objects, and events; unusual play with toys and other objects; difficulty with changes in routine or familiar surroundings; and repetitive body movements or behavior patterns. Autism (a developmental brain disorder characterized by impaired social interaction and communication skills and a limited range of activities and interests) is the most characteristic and best-studied PDD. Other types of PDD include Asperger's Syndrome, Childhood Disintegrative Disorder, and Rett's Syndrome. Children with PDD vary widely in abilities, intelligence, and behaviors.

Pinched Nerve

The term pinched nerve describes one type of damage or injury to a nerve or set of nerves. The injury may result from compression, constriction, or stretching. Symptoms include numbness, "pins and needles" or burning sensations, and pain radiating outward from the injured area. One of the most common examples of a single compressed nerve is the feeling of having a foot or hand "fall asleep." Pinched nerves can sometimes lead to peripheral neuropathy, carpal tunnel syndrome, and tennis elbow. The extent of such injuries may vary from minor, temporary damage to a more permanent condition. Early diagnosis is important to prevent further damage or complications. A pinched nerve is a common cause of on-the-job injury.

Piriformis Syndrome

A rare neuromuscular disorder that occurs when the piriformis muscle compresses or irritates the sciatic nerve-the largest nerve in the body. The piriformis muscle is a narrow muscle located in the buttocks. Compression of the sciatic nerve is pain-frequently described as tingling or numbness in the buttocks and along the nerve, often down to the leg. The pain may worsen due to sitting for a long time, climbing stairs, walking, or running.

Plexopathy

A disorder affecting a network of nerves, blood vessels, or lymph vessels. The region of nerves it affects is at the brachial or lumbosacral plexus. Symptoms include pain, loss of motor control, and sensory deficits. There are two main types of plexopathy: brachial plexopathy and lumbosacral plexopathy. They are usually caused by localized trauma, such as a dislocated shoulder. The disorder can also be caused secondary to compression, co-morbid vascular disease, infection, or maybe idiopathic with an unknown cause. Both plexopathies can also occur as a consequence of radiation therapy, sometimes after 30 or more years have passed, in conditions known as Radiation-induced Brachial Plexopathy (RIBP) and Radiation-induced Lumbosacral Plexopathy (RILP).

Polymyositis

One of a group of muscle diseases known as the inflammatory myopathies, which are characterized by chronic muscle inflammation accompanied by muscle weakness. Polymyositis affects skeletal muscles (those involved with moving) on both sides of the body. It is rarely seen in persons under 18; most cases are in adults between 31 and 60. Slow but progressive muscle weakness starts in the proximal muscles (muscles closest to the body's trunk), eventually leading to difficulties climbing stairs, rising from a sitting position, lifting objects, or reaching overhead. People with polymyositis may also experience arthritis, shortness of breath, difficulty swallowing and speaking, and heart arrhythmias.

Pompe Disease

A rare (estimated at 1 in every 40,000 births), inherited and often fatal disorder that disables the heart and muscles. It is caused by mutations in a gene that makes an enzyme called alpha-glucosidase (GAA). Normally, the body uses GAA to break down glycogen, a stored sugar used for energy. But in Pompe disease, mutations in the GAA gene reduce or eliminate this essential enzyme. Excessive amounts of glycogen accumulate everywhere in the body, but the heart and skeletal muscle cells are the most seriously affected. Researchers have identified up to 70 different mutations in the GAA gene that cause the symptoms of Pompe disease, which can vary widely in terms of age of onset and severity. The severity of the disease and the age of onset are related to the degree of enzyme deficiency.

Porencephaly

An extremely rare disorder of the central nervous system in which a cyst or cavity filled with cerebrospinal fluid develops in the brain. It is usually the result of damage from stroke or infection after birth (the more common type). Still, it can also be caused by abnormal development before birth (which is inherited and less common). Diagnosis is usually made before an infant reaches their first birthday. Symptoms of porencephaly include delayed growth and development, spastic hemiplegia (slight or incomplete paralysis), hypotonia (low muscle tone), seizures (often infantile spasms), and macrocephaly (large head) or microcephaly (small head).

Postherpetic Neuralgia

(PHN) is a painful condition caused by the varicella-zoster virus in a dermatomal distribution (the area governed by a particular sensory nerve) after an attack of herpes zoster (HZ) (commonly known as shingles), usually manifesting after the blisters have crusted over and begun to heal.

Postinfectious Encephalomyelitis

Acute disseminated encephalomyelitis (ADEM) is characterized by a brief but intense attack of inflammation in the brain and spinal cord that damages myelin - the protective covering of nerve fibers. It often follows a viral infection or, less often, vaccination for measles, mumps, or rubella. The symptoms of ADEM come on quickly, beginning with encephalitis-like symptoms such as fever, fatigue, headache, nausea and vomiting, and in severe cases, seizures, and coma. It may also damage white matter (brain tissue that takes its name from the white color of myelin), leading to neurological symptoms such as visual loss (due to inflammation of the optic nerve) in one or both eyes, weakness even to the point of paralysis, and difficulty coordinating voluntary muscle movements (such as those used in walking). ADEM is sometimes misdiagnosed as a severe first attack of multiple sclerosis (MS) since some of the symptoms of the two disorders, particularly those caused by white matter injury, may be similar. However, ADEM usually has symptoms of encephalitis (such as fever or coma), as well as myelin damage (visual loss, paralysis), as opposed to MS, which doesn't have encephalitis symptoms.

Post-Polio Syndrome

(PPS) is a condition that affects polio survivors years after recovery from an initial acute attack of the poliomyelitis virus. PPS is mainly characterized by new weakening in muscles previously affected by the polio infection and in muscles seemingly unaffected. Symptoms include slowly progressive muscle weakness, unaccustomed fatigue (both generalized and muscular), and, at times, muscle atrophy. Pain from joint degeneration and increasing skeletal deformities such as scoliosis are common. Some patients experience only minor symptoms. While less common, others may develop visible muscle atrophy or wasting.

Postural Hypotension

Orthostatic hypotension is a sudden fall in blood pressure that occurs when a person assumes a standing position. It may be caused by hypovolemia (a decreased amount of blood in the body), resulting from the excessive use of diuretics, vasodilators, other drugs, dehydration, or prolonged bed rest. The disorder may be associated with Addison's disease, atherosclerosis (build-up of fatty deposits in the arteries), diabetes, and certain neurological disorders, including Shy-Drager syndrome and other dysautonomias. Symptoms generally occur after sudden standing include dizziness, lightheadedness, blurred vision, and syncope (temporary loss of consciousness).

Postural Orthostatic Tachycardia Syndrome (POTS)

A disorder characterized by a pulse rate that is too fast when the patient stands. Symptoms include rapid heartbeat, lightheadedness with prolonged standing, headache, chronic fatigue, chest pain, and other nonspecific complaints. Causes of POTS usually are not identified in individual patients. Reversible causes, such as low blood volume, should be ruled out.

Primary Lateral Sclerosis

(PLS) is a rare neuromuscular disease characterized by progressive muscle weakness in the voluntary muscles. PLS belongs to a group of disorders known as motor neuron diseases. Motor neuron diseases develop when the nerve cells that control voluntary muscle movement degenerate and die, causing weakness in the muscles they control. The onset of PLS usually occurs after age 50. Symptoms may include balance, weakness, leg stiffness, and clumsiness. Other symptoms may include spasticity (sudden, involuntary muscle spasms) in the hands, feet, or legs; foot-dragging; and speech problems due to the involvement of the facial muscles. The disorder usually begins in the legs but may also start in the tongue or the hands.

Prion Diseases

Transmissible spongiform encephalopathies (TSEs), also known as prion diseases, are a group of rare degenerative brain disorders characterized by tiny holes that give the brain a "spongy" appearance. These holes can be seen when brain tissue is viewed under a microscope.

Progressive Multifocal Leukoencephalopathy

(PML) is caused by the reactivation of a common virus in the central nervous system of immune-compromised individuals. Polyomavirus JC (often called JC virus) is carried by most people and is harmless except among those with lowered immune defenses. The disease rarely occurs in organ transplant patients; people undergoing chronic corticosteroid or immunosuppressive therapy; and individuals with cancer, such as Hodgkin's disease, lymphoma, and sarcoidosis. PML is most common among individuals with acquired immune deficiency syndrome (AIDS). Studies estimate that before effective antiretroviral therapy, as many as 5 percent of people with AIDS eventually developed PML. For them, the disease was most often rapidly fatal.

Progressive Sclerosing Poliodystrophy

Alpers' disease is a rare, genetically determined disease of the brain that causes progressive degeneration of grey matter in the cerebrum. The first sign of the disease usually begins early in life with convulsions. Other symptoms are developmental delay, progressive mental retardation, hypotonia (low muscle tone), spasticity (stiffness of the limbs), dementia, and liver conditions such as jaundice and cirrhosis that can lead to liver failure. Optic atrophy may also occur, often causing blindness. Researchers believe that an underlying metabolic defect causes Alpers' disease. Some patients have mutations in mitochondrial DNA. Researchers suspect that Alpers' disease is sometimes misdiagnosed as childhood jaundice or liver failure since the only method of making a definitive diagnosis is by autopsy or brain biopsy after death.

Progressive Supranuclear Palsy

(PSP) is a rare brain disorder that causes serious and permanent problems with control of gait and balance. The most obvious sign of the disease is an inability to aim the eyes properly, which occurs because of lesions in the area of the brain that coordinates eye movements. Some patients describe this effect as a blurring. PSP patients often show alterations of mood and behavior, including depression and apathy as well as progressive mild dementia.

Prosopagnosia

Prosopagnosia is a neurological disorder characterized by the inability to recognize faces. Prosopagnosia is also known as face blindness or facial agnosia. Prosopagnosia comes from the Greek words for "face" and "lack of knowledge." Depending upon the degree of impairment, some people with prosopagnosia may only have difficulty recognizing a familiar face; others will be unable to discriminate between unknown faces, while others may not even be able to distinguish a face as different from an object. Some people with the disorder are unable to recognize their faces. Prosopagnosia is not related to memory dysfunction, memory loss, impaired vision, or learning disabilities. Prosopagnosia is thought to be the result of abnormalities, damage, or impairment in the right fusiform gyrus, a fold in the brain that appears to coordinate the neural systems that control facial perception and memory.

Pseudotumor Cerebri

Pseudotumor cerebri literally means "false brain tumor." It is likely due to high pressure caused by the buildup or poor absorption of cerebrospinal fluid in the subarachnoid space surrounding the brain. The disorder is most common in women between 20 and 50. Symptoms of pseudotumor cerebri, which include headache, nausea, vomiting, and pulsating intracranial noises, closely mimic symptoms of brain tumors.

R

Ramsay Hunt Syndrome I

A rare and nebulous entity that has alternatively been called dyssynergia cerebellaris myoclonica, dyssynergia cerebellaris progressiva, dentatorubral degeneration, or Ramsay Hunt cerebellar syndrome. Characterized by seizures, cognitive impairment, action myoclonus, and progressive ataxia. Symptoms include seizures, tremors, and reduced muscle coordination. Myoclonus and seizures may be treated with drugs like valproate. RHS type 1 is caused by the impairment of a regulatory mechanism between cerebellar and brainstem nuclei and has been associated with a wide range of diseases, including Lafora disease and celiac disease.

Ramsay Hunt Syndrome II

A disorder that is caused by the reactivation of pre-existing herpes zoster virus in a nerve cell bundle (the geniculate ganglion). The neurons in this ganglion are responsible for the movements of facial muscles, the touch sensation of a part of the ear and ear canal, the taste function of the frontal two-thirds of the tongue, and the moisturization of the eyes the mouth. The syndrome specifically refers to the combination of this entity with weakness of the muscles activated by the facial nerve. In isolation, the latter entity would be called Bell's Palsy. Symptoms and signs include acute facial nerve paralysis, pain in the ear, taste loss in the front two-thirds of the tongue, dry mouth and eyes, and eruption of vesicles in the ear canal, tongue, and hard palate.

Rasmussen's Encephalitis

A rare, chronic inflammatory disease that usually affects only one hemisphere of the brain. It occurs in children under 10 (and more rarely in adolescents and adults). It is characterized by frequent and severe seizures, loss of motor skills and speech, paralysis on one side of the body (hemiparesis), inflammation of the brain (encephalitis), and mental deterioration.

Reflex Sympathetic Dystrophy Syndrome

RSDS, also called: Causalgia, CRPS, Reflex sympathetic dystrophy, involves a disturbance in the sympathetic nervous system, which is the network of nerves located alongside the spinal cord and controls certain bodily functions, such as opening and closing blood vessels or sweat glands. It primarily affects the hands and feet. The cause is unknown, and there is no cure. It can get worse over time and spread to other body parts. Occasionally it goes away, either temporarily or for good. Treatment focuses on relieving the pain and can include medicines, physical therapy, and nerve blocks.

Refsum Disease

Adult Refsum disease (ARD) is one of a group of genetic diseases called leukodystrophies, which damage the white matter of the brain and affect motor movements. Due to a genetic abnormality, people with ARD disease lack the enzyme that breaks down phytanic acid, a substance commonly found in foods. As a result, toxic levels of phytanic acid build up in the brain, blood, and other tissues. The disease usually begins in late childhood with increasing night blindness due to retina degeneration (retinitis pigmentosa) and loss of the sense of smell (anosmia). The primary treatment for ARD is to restrict or avoid foods that contain phytanic acid, including dairy products; beef and lamb; and fatty fish such as tuna, cod, and haddock.

Refsum Disease

Infantile

(IRD) is one of a small group of genetic diseases called peroxisome biogenesis disorders (PBD), which are part of a larger group of diseases called the leukodystrophies. These inherited conditions damage the brain's white matter and affect motor movements. IRD is the mildest PBDs; Zellweger syndrome, neonatal adrenoleukodystrophy, and rhizomelic chondrodysplasia have similar but more severe symptoms.

Repetitive Motion Disorders

Any of various injuries caused by repetitive motion, which may include Carpal tunnel syndrome, Bursitis, Tendonitis, Epicondylitis, Ganglion cyst, Tenosynovitis, Trigger finger, Writer's cramp, Repetitive Strain Injury, Hand-Arm Vibration Syndrome, Tennis elbow, golfer's elbow.

Repetitive Stress Injuries

(RSI), also called cumulative trauma disorder (CTD), occupational overuse syndrome, or work-related upper limb disorder (WRULD), is any of a loose group of conditions resulting from overuse of a tool, e.g., computer, guitar, knife, etc. or other activity that requires repeated movements. It is a syndrome that affects muscles, tendons, and nerves in the hands, arms, and upper back.

Restless Legs Syndrome

(RLS, Wittmaack-Ekbom's syndrome, or sometimes referred to as Nocturnal myoclonus) is a condition that is characterized by an irresistible urge to move one's legs. It is described as uncontrollable urges to move the limbs to stop uncomfortable or odd sensations in the body, most commonly in the legs, but it can also be in the arms and torso. Moving the affected body part modulates the sensations, providing temporary relief.

Retrovirus-Associated Myelopathy

Or Tropical Spastic Paraparesis, For several decades, the term "tropical spastic paraparesis" (TSP) was used to describe a chronic and progressive clinical syndrome that affected adults living in equatorial areas of the world. Treatments for Retrovirus-Associated Myelopathy (Tropical Spastic Paraparesis) include Treatments for spasticity, Lioresal, and Tizanidine.

Rett Syndrome

A childhood neuro-developmental disorder characterized by normal early development followed by loss of purposeful use of the hands, distinctive hand movements, slowed brain and head growth, gait abnormalities, seizures, and mental retardation. It affects females almost exclusively. Rett syndrome is caused by mutations (structural alterations or defects) in the MECP2 (pronounced meck-pea-two) gene found on the X chromosome.

Reye's Syndrome

A potentially fatal disease that causes numerous detrimental effects to many organs, especially the brain, and liver. It is associated with aspirin consumption by children with viral diseases such as chicken pox. The Centers for Disease Control and Prevention (CDC), the U.S. Surgeon General, the American Academy of Pediatrics (AAP), and the Food and Drug Administration (FDA) recommend that aspirin and combination products containing aspirin not be given to children under 19 years of age during episodes of fever-causing illnesses.

Rheumatic Encephalitis

Sydenham chorea (SD) is a neurological disorder of childhood resulting from infection via Group A beta-hemolytic streptococcus (GABHS), the bacterium that causes rheumatic fever. Rapid, irregular, and aimless involuntary movements of the arms, legs, trunk, and facial muscles characterize SD. It affects girls more often than boys and typically occurs between 5 and 15 years of age.

Riley-Day Syndrome

A very rare congenital disorder of the autonomic nervous system, occurring almost exclusively in Ashkenazi Jewish children. Symptoms include lack of tears, emotional instability, relative indifference to pain and lack of a flare response to skin scratches, corneal ulcers, hypertension, stress, taste deficiency, decreased fungiform and circumvalate papillae, unexplained bouts of fever, urinary frequency, absent deep tendon reflexes.

S

Saint Vitus Dance

Sydenham chorea (SD) is a neurological disorder of childhood resulting from infection via Group A beta-hemolytic streptococcus (GABHS), the bacterium that causes rheumatic fever. Rapid, irregular, and aimless involuntary movements of the arms, legs, trunk, and facial muscles characterize SD. It affects girls more often than boys and typically occurs between 5 and 15 years of age. Some children will have a sore throat several weeks before the symptoms begin, but the disorder can also strike up to 6 months after the fever or infection has cleared. Symptoms can appear gradually or all at once, including uncoordinated movements, muscular weakness, stumbling and falling, slurred speech, difficulty concentrating and writing, and emotional instability. The symptoms of SD can vary from a halting gait and slight grimacing to involuntary movements that are frequent and severe enough to be incapacitating. The random, writhing movements of chorea are caused by an auto-immune reaction to the bacterium that interferes with the normal function of a part of the brain (the basal ganglia) that controls motor movements.

Sandhoff Disease

A rare, genetic, lipid storage disorder resulting in the progressive deterioration of the central nervous system. It is caused by a deficiency of the enzyme beta-hexosaminidase, which results in the accumulation of certain fats (lipids) in the brain and other organs of the body. Sandhoff disease is a severe form of Tay-Sachs disease - which is prevalent primarily in people of Eastern European and Ashkenazi Jewish descent - but is not limited to any ethnic group. The onset of the disorder usually occurs at six months of age. Neurological symptoms may include motor weakness, startle reaction to sound, early blindness, progressive mental and motor deterioration, macrocephaly (an abnormally enlarged head), cherry-red spots in the eyes, seizures, and myoclonus (shock-like contractions of a muscle).

Schizencephaly

An extremely rare developmental congenital disability characterized by abnormal slits, or clefts, in the cerebral hemispheres of the brain. Babies with clefts in both hemispheres (called bilateral clefts) commonly have developmental delays, speech and language skills delays, and brain-spinal cord communication problems. Individuals with clefts in only one hemisphere (called unilateral clefts) are often paralyzed on one side of the body but may have average to near-average intelligence. Individuals with schizencephaly may also have an abnormally small head, mental retardation, partial or complete paralysis, or poor muscle tone.

Septo-Optic Dysplasia

(SOD) (de Morsier syndrome) is a congenital malformation syndrome manifested by hypoplasia (underdevelopment) of the optic nerve, hypopituitarism, and absence of the septum pellucidum (a midline part of the brain). In severe cases, this results in pituitary hormone deficiencies, blindness, and mental retardation. However, there are milder degrees of each of the three problems, and some children only have one or two of the three.

Shaken Baby Syndrome

A inflicted traumatic brain injury that happens when a baby is violently shaken. A baby has weak neck muscles and a large, heavy head. Shaking makes the fragile brain bounce back and forth inside the skull and causes bruising swelling, and bleeding, which can lead to permanent, severe brain damage or death. The characteristic injuries of the shaken baby syndrome are subdural hemorrhages (bleeding in the brain), retinal hemorrhages (bleeding in the retina), damage to the spinal cord and neck, and fractures of the ribs and bones. These injuries may not be immediately noticeable. Symptoms of the shaken baby syndrome include extreme irritability, lethargy, poor feeding, breathing problems, convulsions, vomiting, and pale or bluish skin. Shaken baby injuries usually occur in children younger than two years old. Still, they may be seen in children up to the age of 5.

Shingles

Or Herpes Zoster, an outbreak of rash or blisters on the skin that is caused by the same virus that causes chickenpox - the varicella-zoster virus. The first sign of shingles is often burning or tingling pain, or sometimes numbness or itch, in one particular location on only one side of the body. After several days or weeks, a rash of fluid-filled blisters, similar to chickenpox, appears in one area on one side of the body. Shingles pain can be mild or intense. Some people are mostly itching; some feel pain from the gentle touch or breeze. The most common location for shingles is a band called a dermatome, spanning one side of the trunk around the waistline. Anyone who has had chickenpox is at risk for shingles. Scientists think that in the original battle with the varicella-zoster virus, some virus particles leave the skin blisters and moved into the nervous system. When the varicella-zoster virus reactivates, the virus moves back down the long nerve fibers that extend from the sensory cell bodies to the skin.

Shy-Drager Syndrome

Multiple system atrophy with orthostatic hypotension is the current classification for a neurological disorder that was once called Shy-Drager syndrome. A progressive disorder of the central and autonomic nervous systems is characterized by orthostatic hypotension (an excessive drop in blood pressure when standing up), which causes dizziness or fainting. Multiple system atrophy can occur without orthostatic hypotension, but it is rare. Doctors classify the disorder into three types: the Parkinsonian type includes symptoms of Parkinson's disease such as slow movement, stiff muscles, and tremors; the cerebellar type, which causes problems with coordination and speech; and the combined-type, which includes symptoms of both parkinsonism and cerebellar failure. Problems with urinary incontinence, constipation, and sexual impotence in men happen early in the course of the disease. Other symptoms include generalized weakness, double vision or other vision disturbances, difficulty breathing and swallowing, sleep disturbances, and decreased sweating. Because the disease resembles others, a correct diagnosis may take years.

Sjogren's Syndrome

An autoimmune disorder in which immune cells attack and destroy the glands that produce tears and saliva. Sjogren's syndrome is also associated with rheumatic disorders such as rheumatoid arthritis. The hallmark symptoms of the disorder are dry mouth and dry eyes. In addition, Sjogren's syndrome may cause skin, nose, and vaginal dryness and affect other body organs, including the kidneys, blood vessels, lungs, liver, pancreas, and brain.

Sleep Apnea

A common sleep disorder characterized by brief interruptions of breathing during sleep. These episodes usually last 10 seconds or more and repeatedly occur throughout the night. People with sleep apnea will partially awaken as they struggle to breathe, but in the morning, they will not be aware of the disturbances in their sleep. The most common type of sleep apnea is obstructive sleep apnea (OSA), caused by the relaxation of soft tissue in the back of the throat that blocks the air passage. Central sleep apnea (CSA) is caused by irregularities in the brain's normal signals to breathe. Most people with sleep apnea will have a combination of both types. The hallmark symptom of the disorder is excessive daytime sleepiness. Additional sleep apnea symptoms include restless sleep, loud snoring (with periods of silence followed by gasps), falling asleep during the day, morning headaches, trouble concentrating, irritability, forgetfulness, mood or behavior changes, anxiety, and depression.

Sleeping Sickness

Or African trypanosomiasis, a parasitic disease in people and animals, caused by protozoa of genus Trypanosoma and transmitted by the tsetse fly. The disease is endemic in certain regions of Sub-Saharan Africa, covering about 36 countries and 60 million people. It is estimated that 50,000 to 70,000 people are currently infected, which has declined somewhat in recent years.

Sotos Syndrome

A rare genetic disorder characterized by excessive physical growth during the first 2 to 3 years of life. The disorder may accompany mild mental retardation, delayed motor, cognitive, and social development, hypotonia (low muscle tone), and speech impairments. Children with Sotos syndrome tend to be large at birth and are often taller, heavier, and have larger heads (macro crania) than are normal for their age. Symptoms of the disorder, which vary among individuals, include a disproportionately large and long head with a slightly protrusive forehead, large hands and feet, hypertelorism (an abnormally increased distance between the eyes), and down-slanting eyes. Clumsiness, an awkward gait, and unusual aggressiveness or irritability may also occur. Although most cases of Sotos syndrome occur sporadically, familial cases have also been reported.

Spasticity

A condition in which certain muscles are continuously contracted. This contraction causes stiffness or tightness of the muscles and may interfere with movement, speech, and walking. Spasticity is usually caused by damage to the portion of the brain or spinal cord that controls voluntary movement. It may occur in association with spinal cord injury, multiple sclerosis, cerebral palsy, damage to the brain because of lack of oxygen, brain trauma, severe head injury, and metabolic diseases such as adrenoleukodystrophy, amyotrophic lateral sclerosis (Lou Gehrig's disease), and phenylketonuria. Symptoms may include hypertonicity (increased muscle tone), clonus (a series of rapid muscle contractions), exaggerated deep tendon reflexes, muscle spasms, scissoring (involuntary crossing of the legs), and fixed joints. The degree of spasticity varies from mild muscle stiffness to severe, painful, and uncontrollable muscle spasms.

Spinal Cord Infarction

A stroke either within the spinal cord or the arteries that supply it. It is caused by arteriosclerosis or a thickening or closing of the major arteries to the spinal cord. Frequently spinal cord infarction is caused by a specific form of arteriosclerosis called atheromatosis, in which a deposit or accumulation of lipid-containing matter forms within the arteries. Symptoms, which generally appear within minutes or a few hours of the infarction, may include intermittent sharp or burning back pain, aching pain down through the legs, weakness in the legs, paralysis, loss of deep tendon reflexes, loss of pain and temperature sensation, and incontinence.

Spinal Cord Injury

Usually begins with a sudden, traumatic blow to the spine that fractures or dislocates vertebrae. The damage begins at the moment of injury when displaced bone fragments, disc material, or ligaments bruise or tear into spinal cord tissue. Most injuries to the spinal cord don't completely sever it. Instead, an injury is more likely to cause fractures and compression of the vertebrae, which then crush and destroy the axons, extensions of nerve cells that carry signals up and down the spinal cord between the brain and the rest of the body. An injury to the spinal cord can damage a few or almost all of these axons. Some injuries will allow almost complete recovery. Others will result in complete paralysis.

Spinal Cord Tumors

Brain and spinal cord tumors are abnormal growths of tissue found inside the skull or the bony spinal column, which are the primary components of the central nervous system (CNS). Benign tumors are noncancerous, and malignant tumors are cancerous. The CNS is housed within rigid, bony quarters (i.e., the skull and spinal column), so any abnormal growth, whether benign or malignant, can place pressure on sensitive tissues and impair function. Tumors that originate in the brain or spinal cord are called primary tumors. Most primary tumors are caused by out-of-control growth among cells that surround and support neurons. In a small number of individuals, primary tumors may result from a specific genetic disease (e.g., neurofibromatosis, tuberous sclerosis) or exposure to radiation or cancer-causing chemicals. The cause of most primary tumors remains a mystery. They are not contagious and, at this time, not preventable. Symptoms of brain tumors include headaches, seizures, nausea and vomiting, vision or hearing problems, behavioral and cognitive problems, motor problems, and balance problems.

Spinocerebellar Atrophy

(SCA) is one of a group of genetic disorders characterized by slowly progressive in-coordination of gait and often associated with poor coordination of hands, speech, and eye movements. Frequently, atrophy of the cerebellum occurs.

Spinocerebellar Degeneration

Ataxia often occurs when parts of the nervous system that control movement are damaged. People with ataxia experience a failure of muscle control in their arms and legs, resulting in a lack of balance and coordination or a disturbance of gait. While the term ataxia is primarily used to describe this set of symptoms, it is sometimes also used to refer to a family of disorders. It is not, however, a specific diagnosis.

Stiff-Person Syndrome

(SPS) is a rare neurological disorder with features of an autoimmune disease. SPS is characterized by fluctuating muscle rigidity in the trunk and limbs and a heightened sensitivity to stimuli such as noise, touch, and emotional distress, which can set off muscle spasms. Abnormal postures, often hunched over and stiffened, are characteristic of the disorder. People with SPS can be too disabled to walk or move or afraid to leave the house because street noises, such as the sound of a horn, can trigger spasms and falls. SPS affects twice as many women as men. It is frequently associated with other autoimmune diseases such as diabetes, thyroiditis, vitiligo, and pernicious anemia. Scientists don't yet understand what causes SPS, but research indicates that it results from an autoimmune response in the brain and spinal cord. The disorder is often misdiagnosed as Parkinson's, multiple sclerosis, fibromyalgia, psychosomatic illness, or anxiety and phobia.

Striatonigral Degeneration

A neurological disorder caused by a disruption in the connection between two areas of the brain-the striatum and the substantia nigra. These two areas work together to enable balance and movement. Striatonigral degeneration is a type of multiple system atrophy (MSA). Symptoms of the disorder resemble some of those seen in Parkinson's disease, including rigidity, instability, impaired speech, and slow movements.

Stroke

(CVA) is the rapidly developing loss of brain functions due to a disturbance in the blood vessels supplying blood to the brain. This can be due to ischemia (lack of blood supply) caused by thrombosis, embolism, or a hemorrhage. [1] In medicine, a stroke, fit, or faint is sometimes referred to as an ictus [cerebri], from the Latin icere ("to strike"), especially before a definitive diagnosis.

Sturge-Weber Syndrome

A neurological disorder indicated at birth by seizures accompanied by a large port-wine stain birthmark on the forehead and upper eyelid of one side of the face. The birthmark can vary in color from light pink to deep purple and is caused by an overabundance of capillaries around the trigeminal nerve just beneath the face's surface. Sturge-Weber syndrome is also accompanied by the loss of nerve cells and tissue calcification in the brain's cerebral cortex on the same side of the body as the birthmark. Neurological symptoms include seizures that begin in infancy and may worsen with age. Convulsions usually happen on the side of the body opposite the birthmark and vary in severity. There may be muscle weakness on the same side. Some children will have developmental delays and mental retardation; most will have glaucoma (increased pressure within the eye) at birth or develop later. The increased pressure within the eye can cause the eyeball to enlarge and bulge out of its socket (buphthalmos). Sturge-Weber syndrome rarely affects other body organs.

SUNCT Headache

SUNCT-Short-lasting, Unilateral, Neuralgiform headache attacks with Conjunctival injection and Tearing-is a rare form of headache that is most common in men after age 50. The disorder is marked by bursts of moderate to severe burning, stabbing, or throbbing pain, usually on one side of the head and around the eye or temple. Attacks typically occur in daytime hours and last from 5 seconds to 4 minutes per episode. Patients generally have five to six attacks per hour.

Syncope

The temporary loss of consciousness due to a sudden decline in blood flow to the brain. An irregular cardiac rate, rhythm, blood volume changes, or distribution may cause it. Syncope can occur in otherwise healthy people. The patient feels faint, dizzy, lightheaded (presyncope), or loses consciousness (syncope).

Syphilitic Spinal Sclerosis

Tabes dorsalis is a slow degeneration of the nerve cells and nerve fibers that carry sensory information to the brain. The degenerating nerves are in the dorsal columns of the spinal cord (the portion closest to the back of the body) and carry information that helps maintain a person's sense of position. Tabes dorsalis is the result of an untreated syphilis infection. Symptoms may not appear for decades after the initial infection and include weakness, diminished reflexes, unsteady gait, progressive degeneration of the joints, loss of coordination, episodes of intense pain and disturbed sensation, personality changes, dementia, deafness, visual impairment, and impaired response to light.

Syringomyelia

Pronounced "Sear-IN-go-my-EEL-ya," is a disorder in which a cyst forms within the spinal cord. This cyst, called a syrinx, expands and elongates over time, destroying a portion of the spinal cord from its center and expanding outward. When a syrinx widens enough to affect nerve fibers that carry information from the brain to the extremities, this damage results in pain, weakness, and stiffness in the back, shoulders, arms, or legs. Other symptoms may include headaches and a loss of the ability to feel extremes of hot or cold, especially in the hands. Each patient experiences a different combination of symptoms depending on where in the spinal cord the syrinx forms and how far it expands.

T

Tabes Dorsalis

A slow degeneration of the nerve cells and nerve fibers that carry sensory information to the brain. The degenerating nerves are in the dorsal columns of the spinal cord (the portion closest to the back of the body) and carry information that helps maintain a person's sense of position.

Tardive Dyskinesia

A symptom caused by the long-term or high-dose use of dopamine antagonists, usually antipsychotics, but also, e.g., antiemetic metoclopramide. These neuroleptic drugs are generally prescribed for psychiatric disorders. Other dopamine antagonists that can cause tardive dyskinesia are drugs for gastrointestinal disorders (for example, metoclopramide) and neurological disorders.

Tarlov Cysts

Fluid-filled sacs that most often affect nerve roots in the sacrum, the group of bones at the base of the spine. These cysts can compress nerve roots, causing lower back pain, sciatica (shock-like or burning pain in the lower back, buttocks, and down one leg to below the knee), urinary incontinence, sexual dysfunction, and some loss of feeling or control of movement in the leg and foot.

Tay-Sachs Disease

(TSD, also known as GM2 gangliosidosis, Hexosaminidase A deficiency or Sphingolipidosis) is a genetic disorder, fatal in its most common variant known as Infantile Tay-Sachs disease. TSD is inherited in an autosomal recessive pattern. The disease occurs when harmful quantities of a fatty acid derivative called a ganglioside to accumulate in the brain's nerve cells.

Temporal Arteritis

Also called giant cell arteritis (GCA), is an inflammatory disease of blood vessels (most commonly large and medium arteries of the head). It is, therefore, a form of vasculitis. The name comes from the most frequently involved vessel (the temporal artery, which branches from the external carotid artery of the neck). The alternative name (giant cell arteritis) reflects the type of inflammatory cell involved (as seen on biopsy).

Tethered Spinal Cord Syndrome

A neurological disorder caused by tissue attachments that limit the movement of the spinal cord within the spinal column. These attachments cause an abnormal stretching of the spinal cord. The course of the disorder is progressive. In children, symptoms may include lesions, hairy patches, dimples, or fatty tumors on the lower back; foot and spinal deformities; weakness in the legs; low back pain; scoliosis; and incontinence.

Thomsen's Myotonia

An inherited neuromuscular disorder characterized by the inability of muscles to relax after a voluntary contraction quickly. The condition has been present since early childhood, but symptoms can be mild. Most children will be 2 or 3 years old when parents first notice muscle stiffness, particularly in the legs, often provoked by sudden activity after rest.

Thoracic Outlet Syndrome

(TOS) consists of a group of distinct disorders that affect the nerves in the brachial plexus (nerves that pass into the arms from the neck) and the subclavian artery and vein blood vessels between the base of the neck and axilla (armpit).

Thyrotoxic Myopathy

A neuromuscular disorder that may accompany hyperthyroidism (Graves' disease, caused by overproduction of the thyroid hormone thyroxine). Symptoms may include muscle weakness, wasting of the pelvic girdle and shoulder muscles, fatigue, and heat intolerance. Muscle breakdown may occur in acute cases. Physical acts such as climbing stairs may be difficult. Patients may develop muscle damage to the eyes and eyelids, which may affect the mobility of the eye muscles, and temporary but severe attacks of muscle weakness known as periodic paralysis.

Tinnitus

The high incidence of neurologic disease in association with tinnitus indicates tinnitus is often an early sign of Central Nervous System Disease CNS). Tinnitus can be perceived in one or both ears or in the head. Tinnitus is usually described as a ringing noise, high-pitched whining, buzzing, hissing, humming, or whistling sound, or as ticking, clicking, roaring, "crickets" or "tree frogs" or "locusts," tunes, songs, or beeping.

Todd's Paralysis

(or postictal paresis/paralysis, "after seizure") is focal weakness in a part of the body after a seizure. This weakness typically affects appendages and is localized to either the left or right side of the body. It usually subsides completely within 48 hours. Todd's paresis may also affect speech, eye position (gaze), or vision.

Tourette Syndrome

(TS) is a neurological disorder characterized by repetitive, stereotyped, involuntary movements and vocalizations called tics. The early symptoms of TS are almost always noticed first in childhood, with the average onset between 7 and 10 years. TS occurs in people from all ethnic groups; males are affected about three to four times more often than females. Tics are classified as either simple or complex. Simple motor tics are sudden, brief, repetitive movements that involve a limited number of muscle groups. Some common simple tics include eye blinking and other vision irregularities, facial grimacing, shoulder shrugging, and head or shoulder jerking. Simple vocalizations might include repetitive throat-clearing, sniffing, or grunting sounds.

Transient Ischemic Attack

(TIA) is a transient stroke that lasts only a few minutes. It occurs when the blood supply to part of the brain is briefly interrupted. TIA symptoms, which usually occur suddenly, are similar to those of stroke but do not last as long. Most symptoms of a TIA disappear within an hour, although they may persist for up to 24 hours. Symptoms can include numbness or weakness in the face, arm, or leg, especially on one side of the body; confusion or difficulty in talking or understanding speech; trouble seeing in one or both eyes; difficulty with walking; dizziness or loss of balance and coordination.

Transmissible Spongiform Encephalopathies

(TSEs, also known as prion diseases) are a group of progressive conditions that affect the brain and nervous system of humans and animals and are transmitted by prions. Mental and physical abilities deteriorate, and myriad tiny holes appear in the cortex, causing it to appear like a sponge (hence 'spongiform') when brain tissue obtained at autopsy is examined under a microscope. The disorders cause impairment of brain function, including memory changes, personality changes, and problems with movement that worsen over time.

Transverse Myelitis

A neurological disorder caused by inflammation across both sides of one level, or segment, of the spinal cord. The term myelitis refers to inflammation of the spinal cord; transverse describes the position of the inflammation, that is, across the width of the spinal cord.

Traumatic Brain Injury

(TBI), traumatic injuries to the brain, also called intracranial injury, or simply head injury, occurs when a sudden trauma causes brain damage. TBI can result from a closed head injury or a penetrating head injury and is one of two subsets of acquired brain injury (ABI). The other subset is non-traumatic brain injury (e.g., stroke, meningitis, anoxia). Parts of the brain that can be damaged include the cerebral hemispheres, cerebellum, and brain stem. TBI can cause various physical, cognitive, emotional, and social effects. Anyone with signs of moderate or severe TBI should receive medical attention as soon as possible. Because little can be done to reverse the initial brain damage caused by trauma, medical personnel try to stabilize an individual with TBI and focus on preventing further injury. Primary concerns include ensuring proper oxygen supply to the brain and the rest of the body, maintaining adequate blood flow, and controlling blood pressure. Imaging tests help in determining the diagnosis and prognosis of a TBI patient.

Tremor

An unintentional, somewhat rhythmic muscle movement involving to-and-fro movements (oscillations) of one or more parts of the body. It is the most common of all involuntary movements and can affect the hands, arms, head, face, vocal cords, trunk, and legs. Most tremors occur in the hands. In some people, tremor is a symptom of another neurological disorder. There is no cure for most tremors. The appropriate treatment depends on an accurate diagnosis of the cause. Drug treatment for parkinsonian tremors involves levodopa or dopamine-like drugs such as pergolide mesylate, bromocriptine mesylate, and ropinirole. Essential tremors may be treated with propranolol or other beta-blockers (such as nadolol) and primidone, an anticonvulsant drug.

Trigeminal Neuralgia

(TN), or Tic Douloureux, ( also known as prosopalgia ) is a neuropathic disorder of the trigeminal nerve that causes episodes of intense pain in the eyes, lips, nose, scalp, forehead, and jaw. Trigeminal neuralgia is considered by many to be among the most painful of conditions. It is often labeled the "suicide disease" because of the significant number of people taking their own lives when they cannot find effective treatments.

Tropical Spastic Paraparesis

(TSP) has been used to describe a chronic and progressive disease of the nervous system that affects adults living in equatorial areas of the world and causes progressive weakness, stiff muscles, muscle spasms, sensory disturbance, and sphincter dysfunction.

Troyer Syndrome

One of about 30 neurological disorders known as hereditary spastic paraplegia. It is characterized by progressive muscle weakness and spasticity in the legs. Additional symptoms include leg contractures, difficulty walking, speech disorders, drooling, atrophy of the hand muscles, mild developmental delays, fluctuating emotions, and short stature. Onset is in early childhood

Tuberous Sclerosis

Or tuberous sclerosis complex (TSC), is a rare, multi-system genetic disease that causes benign tumors to grow in the brain and on other vital organs such as the kidneys, heart, eyes, lungs, and skin. A combination of symptoms may include seizures, developmental delay, behavioral problems, skin abnormalities, and lung and kidney disease. Mutations cause TSC on either of two genes, TSC1 and TSC2, which encode for the proteins hamartin and tuberin, respectively.

V

Vasculitis including Temporal Arteritis

Vasculitis is an inflammation of the vascular system, which includes the veins, arteries, and capillaries. Dysfunction may occur due to the inflammation or over time as the blood vessel walls swell, harden, thicken, and develop scar tissue. This narrows the passage through which blood can flow. As the condition progresses, it can slow or completely stop the normal flow of blood. Vasculitis can cause problems in any organ system, including the central (CNS) and peripheral (PNS) nervous systems.

Von Economo's Disease

Encephalitis lethargica (EL) is a form of encephalitis. Also known as sleeping sickness (different from the sleeping sickness transmitted by the tsetse fly), EL is a devastating illness that swept the world in the 1920s and then vanished as quickly as it had appeared. EL attacks the brain, leaving some victims in a statue-like condition, speechless and motionless. Between 1917 and 1928, an epidemic of encephalitis lethargica spread throughout the world, but no recurrence of the epidemic has since been reported, though isolated cases continue to occur.

Von Hippel-Lindau Disease (VHL)

(VHL) is a rare, genetic multi-system disorder characterized by the abnormal growth of tumors in certain parts of the body (angiomatosis). The tumors of the central nervous system (CNS) are benign and are comprised of a nest of blood vessels called hemangioblastomas (or angiomas in the eye). Hemangioblastomas may develop in the brain, the eye's retina, and other nervous system areas. Other types of tumors develop in the adrenal glands, the kidneys, or the pancreas.

Von Recklinghausen's Disease

Or Neurofibromatosis 1 (NF1), is characterized by spots of increased skin pigmentation combined with peripheral nerve tumors and a variety of others dysplastic abnormalities of the skin, nervous system, bones, endocrine organs, and blood vessels. The peripheral nerve tumors of two types, schwannomas, and neurofibromas. Both types of tumors occasionally become malignant.

W

Wallenberg's Syndrome

Also called Lateral medullary syndrome and posterior inferior cerebellar artery syndrome, is a disease in which the patient has difficulty with swallowing or speaking or both owing to one or more patches of dead tissue caused by interrupted blood supply to parts of the brain. This syndrome is characterized by sensory deficits affecting the trunk and extremities on the opposite side of the infarct and sensory and motor deficits affecting the face and cranial nerves on the same side with the infarct. Other clinical symptoms and findings are ataxia, facial pain, vertigo, nystagmus, Horner's syndrome, diplopia, and dysphagia.

Werdnig-Hoffman Disease

Also known as "Infantile spinal muscular atrophy," "spinal muscular atrophy type 1", or "spinal muscular atrophy type I," is an autosomal recessive muscular disease. It is the most severe form of spinal muscular atrophy. Werdnig-Hoffman affects the lower motor neurons only. It has been linked to an abnormal survival motor neuron (SMN) gene. It is evident before birth or within the first few months of life. There may be a reduction in fetal movement in the final months of pregnancy. Symptoms include floppiness of the limbs and trunk, feeble movements of the arms and legs, swallowing and feeding difficulties, and impaired breathing. Affected children never sit or stand unassisted and will require respiratory support to survive before the age of 2.

Wernicke-Korsakoff Syndrome

Wernicke's encephalopathy is a degenerative brain disorder caused by the lack of thiamine (vitamin B1). It may result from alcohol abuse, dietary deficiencies, prolonged vomiting, eating disorders, or the effects of chemotherapy. Symptoms include mental confusion, vision impairment, stupor, coma, hypothermia, hypotension, and ataxia. Korsakoff's amnesic syndrome-a memory disorder-also results from a deficiency of thiamine and is associated with alcoholism.

West Syndrome

Otherwise known as infantile spasms, it is uncommon to a rare and serious form of epilepsy in infants. The syndrome is age-related, generally occurring between the third and the twelfth month, manifesting around the fifth month. There are various causes ("polyetiology"). The syndrome is often caused by an organic brain dysfunction whose origins may be prenatal, perinatal (caused during birth), or postnatal. Lots of different brain disorders create the same symptom of West Syndrome.

Whiplash

The common name for neck sprains, such as those caused by hyperextension/flexion injury to the cervical, thoracic or lumbar spines. The injury is called "whiplash" due to the neck or back being thrown forwards and backward rapidly. This may cause the fibers of the neck muscles to tear, resulting in pain and often a decreased range of movement.

Whipple's Disease

A rare infectious disease that typically infects the bowel. It causes malabsorption primarily but may affect any part of the body, including the heart, lungs, brain, joints, and eyes. It interferes with the body's ability to absorb certain nutrients. Whipple's disease causes weight loss, incomplete breakdown of carbohydrates or fats, and immune system malfunctions. When recognized and treated, Whipple's disease can usually be cured. Untreated, the disease may be fatal.

Williams Syndrome

(Williams-Beuren syndrome) is a rare genetic disorder characterized by a distinctive, "elfin" facial appearance, along with a low nasal bridge; an unusually cheerful demeanor and ease with strangers, coupled with unpredictably occurring negative outbursts, mental retardation coupled with exceptional language skills, a love for music, and cardiovascular problems, such as supravalvular aortic stenosis and transient hypercalcemia.

Wilson's Disease

(WD) is a rare inherited disorder in which excessive amounts of copper accumulate in the body. The buildup of copper leads to damage in the kidneys, brain, and eyes. Although copper accumulation begins at birth, symptoms of the disorder appear later in life. The most characteristic symptom of WD is the Kayser-Fleisher ring - a rusty brown ring around the eye's cornea. WD requires lifelong treatment, generally using drugs to remove excess copper from the body and to prevent it from re-accumulating.

Wolman's Disease

Also known as Wolman's syndrome and acid lipase deficiency, is a rare lipid storage disease that is usually fatal at a very young age. Infants may be normal and active at birth but quickly develop progressive mental deterioration, hepatosplenomegaly, distended abdomen, and gastrointestinal problems, including steatorrhea, jaundice, anemia, vomiting, and calcium deposits in the adrenal glands, causing them to harden.

X

X-Linked Spinal and Bulbar Muscular Atrophy

Also known as Kennedy disease, named after WR Kennedy, a neurologist who was among the first to describe this disease. Spinal and bulbar muscular atrophy is a disorder of specialized nerve cells that control muscle movement (motor neurons) that usually begins in adulthood and worsens slowly over time. This condition is inherited in an X-linked recessive pattern. A condition is considered X-linked if the mutated gene that causes the disorder is located on the X chromosome, one of the two sex chromosomes. Early signs often include weakness of tongue and mouth muscles, fasciculations, and gradually increasing weakness of limb muscles with muscle wasting. In some cases, premature muscle fatigue begins in adolescence. Neuromuscular management is supportive, and the disease progresses very slowly and often does not lead to extreme disability. The ages of onset and severity of manifestations in affected males vary from adolescence to old age but most commonly develop in middle adult life. The latest onset was described in a male of 84 years of age. KD does not usually compromise longevity. The syndrome has neuromuscular and endocrine manifestations. It has been suggested that some men with KD may be misdiagnosed to have amyotrophic lateral sclerosis (ALS, also Lou Gehrig's disease).

Z

Zellweger Syndrome

(Named after Hans Zellweger, a former professor of Pediatrics and Genetics at the University of Iowa who did research into the disease.) is one of a group of four related diseases called peroxisome biogenesis disorders (PBD), which are part of a larger group of diseases known as the leukodystrophies. These inherited conditions damage the brain's white matter and affect how the body metabolizes particular substances in the blood and organ tissues. Zellweger syndrome is the most severe of the PBDs. Infantile Refsum disease (IRD) is the mildest, and neonatal adrenoleukodystrophy and rhizomelic chondrodysplasia have similar but less severe symptoms. There is no cure for Zellweger syndrome nor a standard course of treatment. Infections should be guarded against to prevent such complications as pneumonia and respiratory distress. Another treatment is symptomatic and supportive. The prognosis for individuals with Zellweger syndrome is poor. Death usually occurs within six months after onset and may be caused by respiratory distress, gastrointestinal bleeding, or liver failure.

Also See:

• Human Brain Facts
• Definitions of Human Brain Components
• Definitions of medical terms and health conditions

Related Publications


Share This Information To:
𝕏.com Facebook Reddit

Page Information, Citing and Disclaimer

Disabled World is an independent disability community founded in 2004 to provide news and information to people with disabilities, seniors, their family and carers. You can connect with us on social media such as X.com and Facebook.

Cite This Page (APA): Langtree, I. C. (2015, April 8). List of Neurological Disorders and Their Descriptions. Disabled World. Retrieved May 14, 2024 from www.disabled-world.com/health/neurology/disorders-list.php

Permalink: <a href="https://www.disabled-world.com/health/neurology/disorders-list.php">List of Neurological Disorders and Their Descriptions</a>: Alphabetical list of currently known Human Neurological Conditions, including short definitions for each type of disorder.

Disabled World provides general information only. Materials presented are never meant to substitute for qualified medical care. Any 3rd party offering or advertising does not constitute an endorsement.