Electroencephalographic correlations of extracranial and epidural electrodes in temporal lobe epilepsy

Thirty patients with medically intractable complex partial seizures of temporal lobe origin, but no structural abnormalities on neuroradiologic investigations, had both extracranial (scalp) and epidural EEG recordings. Fifteen patients (50%) had localized, unilateral, ictal, scalp EEGs, but one of these had bilateral independent temporal seizure onset according to epidural recordings. Of the 15 patients in whom scalp EEGs were non-localizing, 12 had well-localized epidural ictal EEGs, and 3 had multifocal or bilateral independent temporal ictal recordings. Epidural recordings provide information for determination of site of onset of temporal lobe seizures in selected patients.