Also called Huntington’s chorea, hereditary chorea, chronic progressive chorea, and adult chorea, Huntington’s disease is a hereditary disease in which degeneration in the cerebral cortex and basal ganglia causes chronic progressive chorea (involuntary and irregular movements) and cognitive deterioration, ending in dementia.
Huntington’s disease usually strikes people between ages 25 and 55 (the average age is 35); however, 2% of cases occur in children, and 5%, as late as age 60. Males and females are equally affected. Death usually results 10 to 15 years after onset from suicide, heart failure, or pneumonia.
Huntington’s disease is transmitted as an autosomal dominant trait, and either sex can transmit and inherit it. Each child of a parent with this disease has a 50% chance of inheriting it; the child who inherits it can pass it on to his own children.
Because of hereditary transmission, Huntington’s disease is prevalent in areas in which affected families have lived for several generations. Genetic testing is offered to those with a known family history of the disease.
Signs and symptoms
The onset of this disease is insidious. The patient eventually becomes totally dependent—emotionally and physically—through loss of musculoskeletal control.
Gradually, the patient develops progressively severe choreic movements. Such movements are rapid, usually violent, and purposeless. Initially, they’re unilateral and more prominent in the face and arms than in the legs, progressing from mild fidgeting to grimacing, tongue smacking, dysarthria (indistinct speech), athetoid movements (slow, twisting muscle contractions, especially of the hands) related to emotional state, and torticollis (neck muscle contractions).
Bradykinesia (slow movements) is commonly accompanied by rigidity. Muscle strength is generally maintained. The combination of chorea, bradykinesia, and normal muscle strength results in