Improved resection in lesional temporal lobe epilepsy surgery using neuronavigation and intraoperative MR imaging: Favourable long term surgical and seizure outcome in 88 consecutive cases

Purpose: To investigate the value of intraoperative MR imaging (iopMRI) combined with neuronavigation to avoid intraoperative underestimation of the resection amount during surgery of lesional temporal lobe epilepsy (LTLE) patients. Methods: We retrospectively investigated 88 patients (40 female, 48 male, mean age 37.2 yrs, from 12 to 69 yrs, 41 left sided lesions) with LTLE operated at our department, including 40.9% gangliogliomas (GG), 26.1% cavernomas (CM), 10.2% dysembryoplastic neuroepithelial tumours (DNT) and 11.4% focal cortical dysplasias (FCD), excluding hippocampal sclerosis. Results: Complete resection was achieved in 85 of 88 patients (96.6%), as proven by postoperative MRI 6 months after surgery. In contrast, the routine first iopMR imaging before closure revealed radical resection in only 66 of these 88 patients (75%). After re-intervention, the second iopMR imaging demonstrated complete resection in 19 more patients. Thus, as a direct effect of iopMRI and neuronavigation, overall resection rate was increased by 21.6%. An excellent seizure outcome Engel Class I was found in 76.1% of patients during a mean follow-up of 26.4 months, irrespective of histological entity (74% in CM, 75% in GG, 78% in DNT and 60% in FCD). No severe postoperative complications occurred; permanent superior visual field defects were detected in 10.2% and permanent dysphasia/ dyscalculia in 1.1%. Conclusion: Refined surgery using neuronavigation combined with iopMR imaging in LTLE surgery led to radical resection in 96.6% of the patients, due to immediate correction of underestimated resection in 21.6% of patients. This protocol resulted in a favourable seizure outcome and a low complication rate. (C) 2013 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.