Abstracts

Rationale: Laser interstitial thermal therapy (LiTT) has increasingly been employed as a surgical option for patients with mesial temporal lobe epilepsy. This study aimed to describe mesial temporal lobe ablation volumes and seizure outcomes following LiTT. Methods: This was a multi-institution, retrospective review of seizure outcomes and ablation volumes following LiTT for medically intractable mesial temporal lobe epilepsy between October 2011 and October 2015. .Pre-ablation and post-ablation follow up volumes of mesial temporal structures were measured using Freesurfer, and the volume of ablated tissue was measured on intraoperative MRI using a supervised spline-based edge-detection algorithm. Results were compared between those patients who were seizure free and those who continued to experience seizures, to determine seizure outcomes. Results: There were twenty-three patients who underwent mesial temporal LiTT in this cohort. Fifteen patients (65%) had left sided procedures. The median follow up was 17.6 months (range 2.8-55 months). The mean ablation volume was 6888mm3. At last follow up, thirteen (57%) of these patients were seizure free. There was no correlation with ablation volume and seizure freedom (p=0.15). Eleven of eleven (100%) of patients with formal postoperative visual field evaluations had new postoperative visual field deficits. Conclusions: In this study, there was no significant correlation between the ablation volume after LiTT and seizure outcomes, however larger numbers may support this. Further studies are required to determine whether ablation of specific regions of the mesial temporal lobe may have a greater effect on seizure outcomes. Funding: No funding was received for this abstract