TAILORED ANTERIOR TEMPORAL LOBECTOMY - RELATION BETWEEN EXTENT OF RESECTION OF MESIAL STRUCTURES AND POSTSURGICAL SEIZURE OUTCOME

Objective: The purpose of this study was to assess the relationship be tween the extent of resection of mesial temporal structures and postsu rgical seizure outcome in a group of patients who had undergone a tail ored anterior temporal lobectomy. Methods: Twenty-four patients with u nilateral interictal and ictal foci restricted to anterior/mesial temp oral regions underwent resection of mesial and temporal lateral struct ures, the extent of which was tailored by intraoperative electrocortic ographic findings and functional mapping of eloquent cortex. The exten t of resection was determined with postoperative magnetic resonance im aging scans, using a semiquantitative method, based on a 20-compartmen t model of the temporal lobe. The magnetic resonance imaging scans wer e rated by three investigators blinded to seizure outcome. Follow-up p eriod ranged between 18 months and 5 years. Results: Amygdala and hipp ocampus were spared in six patients; nine patients had a partial to to tal resection of amygdala, eight patients had a resection of amygdala and the anterior third of the hippocampus, and one patient underwent r esection of amygdala and anterior two thirds of hippocampus. Twenty-on e of the 24 patients were seizure free (Engel's class I) and three had rare seizures (Engel's class II). Among these three patients, one had a resection of amygdala; one had resection of amygdala and anterior t hird of hippocampus; while in the third patient, mesial structures wer e spared. Conclusion: These data suggest that in patients with an ante rotemporal seizure focus, the sparing or limited resection of amygdala and/or hippocampus is not necessarily associated with a poor seizure outcome, as had been previously suggested, provided that the decision not to resect is based on the absence of epileptiform activity during intraoperative electrocorticography or during recordings with depth el ectrodes.