Neurological Conditions

Definitions - Neurological Conditions - P

Definitions of Neurological Conditions. These definitions begin with the letter 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 - are 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 a period of days to weeks and usually occur prior to tumor detection, which can complicate diagnosis. These symptoms may include difficulty in walking and/or 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/or 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 slowness of 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, which affects the majority of PD patients may begin to interfere with daily activities. Other symptoms may include depression and other emotional changes; difficulty in 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 - is a movement disorder characterized by episodes or attacks of involuntary movements of the limbs, trunk, and facial muscles. The disorder may occur in several members of a family, or in only a single family member. Prior to 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 - is a rare form of headache that usually begins in adulthood. Patients experience severe throbbing, claw-like, or boring pain usually on one side of the face; in, around, or behind the eye; and occasionally reaching to the back of the neck. This pain may be accompanied by red and tearing eyes, a drooping or swollen eyelid on the affected side of the face, and nasal congestion. 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 on a daily basis 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 the leukodystrophies, which affect growth of the myelin sheath -- the fatty covering that wraps around and protects nerve fibers in the brain. The disease is caused by a mutation in the gene that controls 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. Severity and onset of the disease ranges widely, depending on the type of PLP mutation, and extends from the 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/or 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 are men.

Periodic Paralyses - Familial periodic paralyses 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 paralyses 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 by 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 3 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 other conditions such as 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. Pinched nerve is a common cause of on-the-job injury.

Piriformis Syndrome - is 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 causes pain-frequently described as tingling or numbness-in the buttocks and along the nerve, often down to the leg. The pain may worsen as a result of sitting for a long period of time, climbing stairs, walking, or running.

Polymyositis - is 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 making movement) on both sides of the body. It is rarely seen in persons under age 18; most cases are in adults between the ages of 31 and 60. Slow, but progressive muscle weakness starts in the proximal muscles (muscles closest to the trunk of the body) which eventually leads 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 - is 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 form of sugar used for energy. But in Pompe disease, mutations in the GAA gene reduce or completely eliminate this essential enzyme. Excessive amounts of glycogen accumulate everywhere in the body, but the cells of the heart and skeletal muscles 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 - is 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), but it can also be caused by abnormal development before birth (which is inherited and less common). Diagnosis is usually made before an infant reaches his or her 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 vesicles 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 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 symptoms of 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 that were previously affected by the polio infection and in muscles that seemingly were 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, or other types of 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, which generally occur after sudden standing, include dizziness, lightheadedness, blurred vision, and syncope (temporary loss of consciousness).

Postural Orthostatic Tachycardia Syndrome - POTS) is 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. Onset of PLS usually occurs after age 50. Symptoms may include difficulty with balance, weakness and stiffness in the legs, and clumsiness. Other symptoms may include spasticity (sudden, involuntary muscle spasms) in the hands, feet, or legs; foot dragging, and speech problems due to involvement of the facial muscles. The disorder usually begins in the legs, but it 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 a majority of people and is harmless except among those with lowered immune defenses. The disease occurs, rarely, 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 prior to 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 Alpers' disease is caused by an underlying metabolic defect. 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. The term 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 still others may not even be able to distinguish a face as being different from an object. Some people with the disorder are unable to recognize their own face. 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 the ages of 20 and 50. Symptoms of pseudotumor cerebri, which include headache, nausea, vomiting, and pulsating intracranial noises, closely mimic symptoms of brain tumors.

Alphabetical list of Neurological Disorder Definitions.

A - B - C - D - E - F - G - H - I - J - K - L - M - N - O - P - R - S - T - V - W - X - Z

Email article    Print