Chorea (disease)

Chorea sancti viti (Latin for "St. Vitus' dance") is an abnormal voluntary movement disorder, one of a group of neurological disorders called dyskinesias. The term chorea is derived from a Greek word khoreia (a kind of dance, see chorea), as the quick movements of the feet or hands are vaguely comparable to dancing or piano playing.

Description and cause
These disorders are caused by overactivity 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 it may also occur in a variety of other conditions. Sydenham's chorea occurs in a small percentage (20 percent) of children and adolescents as a complication of rheumatic fever. Chorea can also be induced by drugs (levodopa, anti-convulsants, and anti-psychotics) metabolic and endocrine disorders and vascular incidents.

Ballism
When chorea is serious, slight movements will become thrashing motions, this form of severe chorea is referred to as "ballism". Walking may become peculiar, and include odd postures and leg movements. Unlike ataxia and dystonia, which affect the quality of voluntary movements or parkinsonism, which is a hindrance of voluntary movements, the movements of chorea and ballism occur on their own, without conscious effort.

Treatment
There is no standard course of treatment for chorea. Treatment depends on the type of chorea and the associated disease. Treatment for Huntington's disease is supportive, while treatment for Syndenham's chorea usually involves antibiotic drugs to treat the infection, followed by drug therapy to prevent recurrence. Adjusting medication dosages can treat drug-induced chorea. Metabolic and endocrine-related choreas are treated according to the cause(s) of symptoms.