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. It is noteworthy that chorea may often be the only manifestation of acute rheumatic fever. Patients with Sydenham's Chorea not infrequently will not fulfill the Jones criteria. Other signs of rheumatic fever may be present and should be sought for carefully.
Active carditis is found in a significant number of children whose initial complaint is chorea.
Active arthritis however rarely occurs concurrently with chorea. The diagnosis of Sydenham's Chorea largely lies on clinical grounds. Often there is minimal evidence of preceding streptococcal infection. In fact it is not infrequent for routine streptococcal serology including ASO titers, streptozyme, and anti- DNAase levels to all be normal. The differential diagnosis must include entities such as familial chorea, CNS mass lesion, drugs or other toxins, and collagen vascular diseases.