Chorea sancti viti (Latin for "St. Vitus' dance") is an abnormal involuntary movement disorder, one of a group of neurological disorders called dyskinesias. The term chorea is derived from a Greek word χορεία (a kind of dance, see chorea), as the quick movements of the feet or hands are vaguely comparable to dancing or piano playing.
Twenty percent of children and adolescents with rheumatic fever develop Sydenham's chorea as a complication.
Chorea may also be caused by drugs (levodopa, anti-convulsants, anti-psychotics), metabolic disorders, endocrine disorders, and vascular incidents.
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.
There is no standard course of treatment for chorea. Treatment depends on the type of chorea and the associated disease.