Progression of Hoehn and Yahr stages in parkinsonian disorders: A clinicopathologic study

The progression to different Hoehn and Yahr (HY) stages was evaluated in 81 pathologically confirmed patients with parkinsonism. Patients with PD (n = 18) showed significantly longer latencies to each HY stage than patients w ith atypical parkinsonian disorder (APD). While no patient with PD develope d a MY-III stage within 1 year of onset of motor symptoms, 72% of those wit h APDs did. In fact, development of a MY-III within 1 year of motor onset a ccurately predicted an APD. However, the progression to each HY stage was u nhelpful in distinguishing the APDs from each other. Once patients with PD and APD became wheelchair-bound, both had equally short survival times.