Motor programming is more affected in progressive supranuclear palsy than in Parkinson's disease: a spatiotemporal study of event-related desynchronization.

To determine the benefit of motor programming analysis for distinguishing patients with parkinsonism, we compared the spatiotemporal pattern of event-related desynchronization (ERD) preceding a self-paced voluntary wrist flexion between two groups of 10 patients with progressive supranuclear palsy (PSP) and Parkinson's disease (PD) and 10 control subjects. ERD of the mu rhythm was computed from 11 source derivations covering the medial frontocentral, central, and parietocentral areas during two successive left and right experimental conditions (80 self-paced wrist flexions). ERD began in the control group 1750 ms before movement onset over the contralateral central area and then appeared bilaterally on movement execution. In both patient groups, spatiotemporal distribution differed from that in the control group. In the PSP group, ERD had a shorter latency over the contralateral primary sensorimotor area compared with the PD group (PSP: 375 ms before movement onset for both conditions; PD: right flexion 1125 ms before movement onset, left flexion 1000 ms). ERD was observed over the parietocentral area in both groups but also with a clear reduction of latency before movement onset in the PSP group. In both groups, a bilateral central pattern appeared 250 ms before movement execution. In conclusion, our study indicates that ERD analysis is a useful method for observing the changes in cortical activation and for measuring motor programming impairment in parkinsonism, which was more affected in PSP than in PD.