LANGUAGE FUNCTION IN PATIENTS WITH LEFT DOMINANT MESIAL VERSUS REGIONAL LATERAL TEMPORAL SEIZURE ONSET DETERMINED BY CHRONIC CORTICOGRAPHY/

Language function is impaired in patients with left, speech-dominant t emporal ictal onset compared to those with non-speech-dominant onset, Even though the pathology in most cases is mesial temporal. in patient s with intractable epilepsy undergoing chronic invasive electroencepha lograph (EEG) with subdural electrodes, ictal onset was classified as mesial temporal (MT) when only the mesial contacts of the subtemporal electrode were initially involved, lateral temporal (LT) when only the contacts of the lateral temporal electrode were involved, and regiona l temporal (RT) when the contacts of all temporal electrodes were invo lved. We hypothesized that preoperative language function assessed by neuropsychological parameters would be worse in the patients with RT o r LT onset compared with patients in whom ictal onset was MT. Fifty-tw o patients were studied. Thirty-nine patients had MT onset, 10 had RT onset, and 3 had LT onset. Language function was assessed by a standar d aphasia battery and no significant differences were found between th e two groups. All patients underwent anterior temporal lobectomy. All LT patients and 40% RT patients had evidence of lateral temporal lobe pathology. None of the MT patients had lateral temporal pathology, 29 had hippocampal sclerosis (HS) and 10 had normal hippocampus. LT or RT ictal onset do not appear to confer additional language deficits comp ared with patients with MT onset. (C) 1997 by Elsevier Science Inc.