[Late auditory evoked potentials in subcortical cognitive deterioration]

Late auditory evoked potentials (AEPs) were recorded by the odd-ball method in 55 non-deteriorated parkinsonians (NP) and in 27 parkinsonians with cognitive deterioration (CDP), compared with 20 controls (C) and 24 patients with Alzheimer-type senile dementia (ATSD). The latency of P 300 was prolonged in the CDP and ATSD groups (410.72 +/- 24.45 and 433.62 +/- 38.30 respectively; P less than 0.001. The latency of N 100 was prolonged only in the CDP group (106.6 +/- 4.82; P less than 0.001). Late AEPs were also studied in 63 subjects with possible or confirmed disseminated sclerosis (DS) compared with 33 controls of similar mean age. The ERFC test divided these patients into 38 with non-deteriorated DS (NDS) and 25 with deteriorated DS (DDS). The latency of P 300 was prolonged in both groups: NDS 331.14 +/- 25.89; DDS 376.64 +/- 29.51 (P less than 0.001). The latency of N 100 was prolonged in the NDS group (100.25 +/- 9.20) and the DDS group (104.43 +/- 9.01). Following a study of correlations between the degree of mental deterioration and the electrophysiological parameters in these populations, the significance of the N 100 latency as electrophysiological marker of subcortical dementia is discussed.