THE DOPAMINERGIC RESPONSE IN MULTIPLE SYSTEM ATROPHY

Fifteen of 23 pathologically confirmed cases of Multiple system atrophy (MSA) showed some initial response to levodopa and eight of these remained at least partially responsive at the time of death. Eleven developed motor oscillations, and drug-induced dyskinesias, often involving the face and jaw, were also seen in 11 cases. Acute levodopa and apomorphine challenges were administered to 11 patients with clinical MSA who were considered levodopa responsive. A short duration relatively small amplitude response with associated dyskinesias occurred in six and a further three developed dyskinesias without any motor response. Following levodopa withdrawal, a delayed deterioration occurred after three to six days in six patients, five of whom had shown no short duration motor response to the acute challenges. The occurrence of levodopa-induced dyskinesias without a concomitant motor response and delayed deterioration several days after levodopa withdrawal may be more typical of patients with MSA than Parkinson's disease.