Visual and somatosensory evoked potentials in Parkinson's and Binswanger's disease

To compare subcortical involvement of Parkinson's disease (PD) with that of Binswanger's disease (ED), we examined visual evoked potentials (VEPs) and somatosensory evoked potentials (SEPs) in 29 patients with PD and 7 patients with ED and 11 control subjects. The patients with PD were divided into two groups: PD without dementia (nD-PD: n = 18) and PD with dementia (D-PD: n = 11). The D-PD patients showed significantly longer P100 latencies in VEPs compared with the nD-PD patients or controls. The P100 latencies were negatively correlated with Mini-Mental State Examination (MMSE) score in the PD patients. The ED patients showed significantly longer central conduction time (CCT) in SEPs (interpeak latency between N13 and N20 responses) compared with the nD-PD patients or controls. There was no correlation between CCT and MMSE score in the ED patients. These results suggest that PD has a predilection for sensory system involvement distinct from that of ED. In D-PD, the visual system seems more vulnerable than the somatosensory system, but almost the reverse is true of ED.