P50 AUDITORY-EVOKED POTENTIALS IN EPILEPSY

Event-related potentials have occasionally been investigated in epilep sy. The P50 auditory evoked potential (AEP), which may have a temporal cortical origin, has not yet been studied in seizure patients. We rec orded P50 responses in patients with complex partial seizures (CPS) an d secondarily generalized seizures. Fifty patients and 50 controls wer e compared. The P50 was elicited by paired rarefaction clicks presente d first every 10 s and then at five per second, binaurally at 76 dB SL , with 100-ms analysis time, 0.1- to 200-Hz filter bandpass; 100 avera ges were replicated. P50 was recorded from Fz and Cz with linked ear r eference. P50 was reduced in amplitude and prolonged in latency in sei zure patients as compared with controls. P50 attenuation with more rap id stimulation as measured by condition-test ratio was greater among c ontrols than in the epilepsy patients. P50 abnormality in partial epil epsy may support suggestions of a frontal or temporal cortical origin for this potential. P50 attenuation differences may be related to inte rictal behavioral or cognitive effects or could reflect the effects of medications.