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 with atypical parkinsonian disorder (APD). While no patient with PD developed a HY-III stage within 1 year of onset of motor symptoms, 72% of those with APDs did. In fact, development of a HY-III within 1 year of motor onset accurately predicted an APD. However, the progression to each HY stage was unhelpful in distinguishing the APDs from each other. Once patients with PD and APD became wheelchair-bound, both had equally short survival times.