LONG-LATENCY AUDITORY-EVOKED POTENTIALS IN NONLESIONAL PARTIAL EPILEPSY

Event-related potentials have been occasionally investigated in epilep sy. We recorded slow vertex responses or long-latency auditory evoked potentials (LLAEPs) to auditory stimuli in patients with complex parti al and secondarily generalized seizures. Fifty consecutive neurologica lly-normal patients with normal imaging studies and 50 controls were c ompared. Slow vertex response (SVR) recordings utilized monaural conde nsation clicks presented at 0.5 Hz and 100 dB sound pressure level (SP L) with 40 dB contralateral masking; filter bandpass was 1-50 Hz, anal ysis time was 500 mseconds, and 200 averages were recorded and replica ted. Long-latency auditory evoked potentials were recorded from Fz and Ct to linked-ear and ipsilateral-ear reference. Long-latency auditory evoked potential latencies of N100 potentials were significantly prol onged in patients as compared to controls, while P180 and N200 were lo nger in latency among patients but did not achieve statistical signifi cance. N100 and P180 were significantly prolonged in latency on the si de of the electroencephalogram (EEG)-documented epileptogenic focus in the seizure patients. These findings support previous suggestions of frontal or temporal cortical origin for SVRs, and suggest that LLAEP c omponents may be prolonged in latency on the side of an irritative foc us. Long-latency auditory evoked potential latency prolongation or asy mmetry may therefore assist in the noninvasive neurophysiologic assess ment of epilepsy patients.