WHAT: Chorea. Chorea (Sydenham's): a neurological disorder characterized by purposeless, rapid, involuntary movements, emotional lability, and muscular weakness. WHY: Sydenham's chorea is seen in rheumatic fever. The chorea may be associated with other rheumatic manifestations or it may present as the sole expression of rheumatic fever. HOW: Typically, the onset of chorea is gradual, with irritability, uncooperativeness, fits of anger, crying, and inappropriate behavior present before the choreiform movements are noted. The movements are rapid and jerky, unlike the slower, rhythmic motion seen in athetosis. Characteristically, on raising his arms above the head, the patient turns the arms so as to oppose the backs of the hands. The patient is unable to sustain a tetanic muscular contraction. On squeezing an examiner's hand the patient can only provide a repetitive, spasmodic grip which is overly pronated and is similar to the motion of milking a cow (milk-maid's grip). The patient's facial expression alternates between frowning, grinning and grimacing. His tongue darts in and out of his mouth. His speech is slurred and vacillates between a halting and an explosive rhythm. The deep tendon reflexes tend to be pendular, i.e., when the knee jerk is elicited with the patient sitting, the leg swings back and forth four or five times like a pendulum, rather than one or two times as in a normal person. Chorea is most common prior to puberty, and in females. It is occasionally seen in adult women but never in adult men. REFS: 1) Jones criteria (revised) for guidance in the diagnosis of rheumatic fever. Circulation 32:664, 1965. 2) Cooper, IS: Involuntary Movement Disorders. New York: Hoeber, 1969.