It is more common in girls than in boys. It is rare after puberty and exceedingly uncommon after the age of 20 years. Chorea may appear several weeks after an attack of acute rheumatic fever or it may be the initial symptom of a rheumatic episode. The onset is usually gradual. Typically the patient first becomes increasingly nervous and tends to have difficulty writing and may have reports of grimacing.
Speech becomes indistinct and characteristic purposeless movements of the arms and legs develop.
The movements are increased by effort, excitement, and fatigue but cease when the patient is asleep. Muscular weakness is common and the child may be unable to walk or even sit up. In mild cases the movements can be exaggerated after periods of direct questioning or enforced quiet. Characteristically if the patient is asked to extend the arms, hands, and fingers, flexion of the wrists and hyperextension of the metacarpophalangeal joints are observed. Other signs consist of an inability to hold the tongue still when it is protruded and spasmodic contractions of the hands when the patient intentionally grabs objects.