n.
Neurological disorder causing irregular, involuntary, purposeless movements.
It is believed to be caused by degeneration of the basal ganglia in the cerebral cortex. Sydenham chorea (St. Vitus dance) is usually associated with rheumatic fever . It usually occurs between ages 5 and 15, more often in girls. Typical jerking movements, mostly in the extremities and face, may affect speech and swallowing and range from mild to incapacitating; attacks last several weeks and recur frequently. Senile chorea, a progressive disease resembling Sydenham chorea, usually occurs late in life. Huntington chorea is rare, hereditary, and fatal. It usually begins between ages 35 and 50 and progresses to random, often violent, and eventually totally incapacitating spasms, absent only during sleep. Mental deterioration begins later, and death occurs in 1020 years. There is no effective therapy. Children of those afflicted have a 50% chance of developing the illness.