Abnormal occurrence of the ulnar nerve-hypothenar muscle H-reflex in Sydenham's chorea

Six patients, 8 to 14 years of age, were examined for abnormal H-reflex activity by means of an electrophysiological technique, and the findings were compared with the clinical examination, in Sydenham's chorea. Four of the patients were examined at the stage of the disease in which purposeless, involuntary movements were present in the upper extremity. In all four patients an aberrant H-reflex was elicited from the hypothenar muscles by weak, painless, percutaneous, electrical stimulation of the ulnar nerve. The H-reflex declined pari passu with the reduction of movements noted clinically. Two of the patients, studied electrophysiologically when abnormal movements were present, were re-examined long after disappearance of choreiform activity. At this time H-reflexes were either minimal or absent. Two patients who presented unilateral choreiform movements showed H-reflexes only on the affected side. Two patients who were studied only once, after the choreiform movements had disappeared, showed minimal H-reflexes, or complete absence of the abnormal response. The locus of disturbance in the central nervous system in this disease is discussed and the need for further investigation noted.