Neurological Conditions

Definitions - Neurological Conditions - X - X-Linked Spinal Bulbar Muscular Atrophy

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.

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.

Homozygous females, both of whose X chromosomes have a mutation leading to CAG expansion of the AR gene, have been reported to show only mild symptoms of muscle cramps and twitching. No endocrinopathy has been described.

Kennedy's disease patients have muscle cramps and progressive weakness due to degeneration of motor neurons in the brainstem and spinal cord. It occurs only in men. Age at onset is usually in the third to fifth decade of life, but earlier involvement has been reported. The disorder is characterized by slowly progressive limb and bulbar muscle weakness with fasciculations, muscle atrophy, and gynecomastia.

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.

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).

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