MULTIPLE SYSTEM ATROPHY PRESENTING AS PARKINSONISM - CLINICAL-FEATURES AND DIAGNOSTIC-CRITERIA

To evaluate the possibility that parkinsonian signs may be the only pr esenting feature of multiple system atrophy (MSA), parkinsonian patien ts were studied who had no atypical clinical signs and had no symptoms of autonomic dysfunction, but who reported that they had not experien ced the anticipated good response to dopaminergic treatment. These str ingent criteria identified 20 patients from a series of 298 consecutiv e parkinsonian outpatients. The following clinical pointers were analy sed: (ca) rate of disease progression; (b) symmetry of parkinsonian sy mptoms and signs; (c) occurrence of resting tremor during the first th ree years from onset. In addition, all patients underwent (d) acute an d chronic challenge with dopaminergic drugs; (e) cardiovascular reflex autonomic function tests; (f) high field MRI. Rapid progression of di sease was seen in 45% of patients, onset was symmetric in 25%, tremor was absent at onset in 70%, response to dopaminergic drug challenges w as inadequate in 40%, abnormal cardiovascular reflexes occurred in 50% , and some abnormal MRI finding occurred in 35% of cases. Each of thes e features was equally weighted by giving to each patient a 0 to 6 poi nt score corresponding to the number of abnormal findings. Fifteen pat ients scoring higher than 1 were considered at risk for having MSA: fi ve of them were classified as clinically possible (score 2), six as cl inically probable (score 3-4), and four patients were classified as cl inically definite multiple system atrophy (score 5). The six pointers considered were variably combined in each patient, none of them being universally abnormal in patients with high scores. The patients were f ollowed up for a mean 2 1 (SEM 0.65) years. Ah but one of the 10 patie nts prospectively classified as probable or definite MSA developed une quivocal clinical signs of fully symptomatic MSA. A receiver operator characteristic curve was plotted for the prospective score, based on f ollow up diagnosis. The best compromise for trade off between sensitiv ity and specificity was a cut off value at a score of 3. The sensitivi ty and specificity of the individual pointers considered to predict fu lly symptomatic MSA varied considerably, and no single item could pred ict whether patients presenting with just parkinsonian signs went on d uring the two year follow up period to develop fully symptomatic MSA. Instead, the number of abnormalities offered a predictive value for th e clinical prognosis of these parkinsonian patients.