SEIZURE CONTROL AND EXTENT OF MESIAL TEMPORAL RESECTION

Controversy exists about the extent of mesial temporal lobe resection that improves seizure control in patients with temporal lobe epilepsy. In this retrospective study, 70 patients with mesial temporal seizure activity (without evidence of tumor or vascular malformation) were su rgically treated and followed for at least 2 years. The extent of mesi al temporal resection was based on the findings of interictal and icta l discharges using depth electrodes, which were inserted preoperativel y or intraoperatively by the orthogonal approach to the amygdaloid and hippocampal regions. Only the amygdala was resected along with the li mited lateral neocortex if no epileptiform activity involved the hippo campus. The amount of hippocampal excision was determined by the exten t of interictal seizure activity. The following groups became seizure free: all 8 patients with only amygdalar resection; 6 of 10 patients w ith amygdalar and less than or equal to 1 cm hippocampal resection; 23 of 38 with 1-2 cm hippocampal removal, and 11 of 14 with > 2 cm hippo campal excision. In cases where there was no hippocampal resection, ne uropsychological outcome compared favorably with controls. Our results suggest that although most patients with temporal lobe epilepsy requi re hippocampal resection of varying degrees, there is a subset in whom the amygdala may be the crucial element of a mesial temporal epilepto genic network. These patients can undergo a surgical resection sparing the hippocampus without compromising seizure outcome.