Electroclinical features of auras persisting after temporal lobectomy and their prognosis

Abstract

Some patients with temporal lobe epilepsy (TLE) continue to have simple partial seizures or auras postoperatively. To scrutinize factors which may correlate with persistence of auras and to characterize their natural history, we studied 56 TLE patients who underwent anterior temporal lobectomy after a precise focus determination by long-term intracranial EEG monitoring using bitemporal depth/subdural electrodes. They were followed for a minimum of 2 years postoperatively. Thirty-one patients had no postoperative seizures (group 1), 14 patients had auras but no complex partial seizures (CPSs) (group 2), and 11 patients both auras and CPSs (group 3). In group 2 and 3, history of early brain injury, such as convulsive status, encephalitis and head trauma was found more frequently; duration of epilepsy was longer and auras occurred more frequently than in group 1, preoperatively. Analysis of ictal intracranial EEGs during auras recorded in 18 patients in group 1, 12 in group 2 and 10 in group 3 disclosed that ictal discharges, when arising from amygdalo-hippocampal region, were prone to spread toward the posteromedial structures in group 2 and 3, while in group 1 toward anterior basal-temporal area. Auras recurred mostly within a half postoperative year in those patients having medial temporal seizure origin and mesial temporal sclerosis, regardless of whether or not CPSs recurred afterwards. Those patients having seizures of lateral temporal origin had CPSs as well when they experienced auras postoperatively. Auras decreased in frequency as years passed. Postoperative persistence of isolated auras was considered to correlate with a temporomedial epileptogenic zone that extends over posteromedial structures. Nonetheless, the vast majority of postoperative auras run down.