Abstracts

Rationale: Surgical failure of non-lesional TLE might be due to a seizure focus in contralateral temporal lobe, extratemporal or in complete resection of epileptogenic zone. Few studies have evaluated the relative frequency of these proposed mechanisms. The purpose of this study was to analyze the surgical failure of temporal lobe epilepsy with nMRI at the Calgary Epilepsy Program. Methods: We retrospectively evaluated the surgical outcome of all patients who underwent temporal lobe surgery with nMRI between 2000 and 2010. All patients underwent comprehensive presurgical evaluation. Failed patient had re-evaluation and repeat surgery in selected cases Results: A total of 43 patients underwent TLE surgery with nMRI. They were 18 women and 25 men. The mean age at surgery was 29.0 years (with 7 patients younger than 18 years). Patients underwent anteromesial temporal lobe resection and (n=30 trans cortical selective amygdalo-hippocampectomy (n=8) or neocortiectomy (n=5). Of the 43 patients, 15 underwent intracranial electrodes implantation prior to the resection. At the final follow-up (average 51 months), 27 out of the 43 patients (62 %) were seizure free. Out of the 16 patients who failed surgery 15 patients (94%) had re-evaluation. The focus of recurrence was identified as follows: Posterior neocortical (n=5), contralateral temporal lobe (n=4), extra temporal (n=3), and residual mesial structures (n=3). Out of the 6 patients who had repeat surgery only 1 patient (14%) had a favorable outcome. Conclusions: Temporal lobe resection in well-selected patients with nMRI can provide favorable rates of seizure freedom. The majority of surgical failures are due to reasons that might be irremediable with another surgery such as bitemporal, extra temporal, or posterior neocortical foci. This may explain the low chance of favorable outcome following repeat surgery.