P19-T Neurophysiological evaluation in multiple hippocampal transections for intractable temporal epilepsy

Abstract

The purpose of this study was to evaluate the neurophysiological tactic in 9 patients during the multiple hippocampal transections (MHT). 9 patients with temporal lobe epilepsy underwent MHT, lesionectomy in uncus and nearby hippocampus, with additional resections in pole in 4 patients. Follow up was more than 6 months. The left dominant hemisphere was affected in all cases. They had normal or nearly normal memory function. Intraoperatively ECoG was performed on basal and lateral temporal cortex and leaded resection of possible lesion. ECoG was then recorded from strip of 4-6 electrodes over hippocampus and amygdala region. Transections were performed and then added to posterior part when epileptiform discharges persisted. After multiple transections were made control ECoG was repeated. 7 patients are seizure free, one has IIIA outcome and one has IVA. Memory worsening occured in 1 patient with intraoperative vascular damage in hippocampus. The epileptiform activity completely disappeared in hippocampus in 7 cases. Local epileptiform patterns were observed limited under 1 electrode in hippocampus in 2 patients. Basal epileptiform discharges persisted after MHT in 6 patients. It was significantly reduced in 4 cases, in 2 with local predominance. Residual cortical epileptiform activity was presented in the form of high-amplitude spikes. Spread of discharges from the basal or lateral cortex to hippocampus was suspected when small spikes persisted and were observed over a wide area of the hippocampus simultaneously with high amplitude cortical spikes, noted in 2 cases. Precise neurophysiologic evaluation is crucial for epilepsy surgery using MHT.