Limbic evoked potentials predict site of epileptic focus

Limbic evoked potentials (LEPs) were recorded from intracerebral electrodes in the hippocampi of seven preoperative epilepsy surgery patients. LEPs were evaluated using amplitude, form, and asymmetry by raters blinded as to the side of electrographically proven seizure onset. Raters correctly predicted the side of focus in all four patients with proven unilateral temporal lobe seizure onset. Further, LEP amplitudes in two patients with bilateral independent temporal lobe seizure onset were markedly diminished compared with one patient with a nontemporal lobe seizure onset. LEP recordings may assist in determination of the site of epileptogenic pathology.