Pattern evoked potentials (PEPs) in Parkinson's disease.

Controversy exists in the literature concerning whether Parkinson's disease (PD) results in prolongation of pattern evoked potential (PEP) responses. PEPs were obtained in 20 patients with PD. The latencies of the first major positive potential (P2) in response to independent left and right eye stimulation were evaluated. There was no statistically significant difference (group or individual) when patients with PD were compared with age-corrected controls. There was no difference in results in comparing patients with mild, moderate, and severe PD. These results contradict previous reports of markedly abnormal PEPs.