Optimizing outcomes in drug-resistant mesial temporal lobe epilepsy patients undergoing stereoelectroencephalography-guided radiofrequency thermocoagulation

Background: Mesial temporal lobe epilepsy (MTLE) epileptiform discharges have been reported to arise from the hippocampus or the extrahippocampal medial temporal cortex, such as the amygdala, and then propagate to the temporal lobe cortex. The surgical ablation of which of these structures would result in a better postoperative outcome is debatable.Objective: To assess the possible factors that might have influenced the postoperative outcome of a group of drug-resistant mesial MTLE patients who underwent stereoelectroencephalography (SEEG)-guided radiofrequency thermocoagulation (RFTC).Design: Single-center, retrospective.Methods: The present study utilized a pre- and postoperative gray matter voxel-by-voxel ablation mapping comparison approach, along with a white matter mapping of longitudinal changes in the native space technique, to evaluate the association between the post-SEEG implantation signal recordings (obtained from clinically relevant electrode contacts used during RFTC) and the post-RFTC ablation volume of the different selected regions of interest (ROIs).Results: The study included 22 patients (12 men and 10 women, mean age 28.86 +/- 14.04 years). Sixteen patients (72.72%) were seizure-free (SF), and six patients (27.27%) were non-SF. Five patients (22.72%) experienced mild side effects following RFTC. The post-RFTC follow-up period varied from 12 to 48 months, with an average of 24.17 +/- 9.86 months. The SF group was associated with a higher number of implanted electrode contacts in the amygdala that were used during RFTC, a larger preoperative volume of the amygdala; a larger ablation volume of both the amygdala and rhinal cortex. The ablation volume of the white matter was statistically similar between both groups.Conclusion: This study provides valuable insights into the significance of the amygdala and rhinal cortex as ROIs in the preoperative evaluation of patients with MTLE. Future implantation scheme plans should consider evaluating the preoperative volume of these ROIs. Additionally, increasing the number of electrode contacts implanted within these regions might be beneficial to capture more clinically relevant signals and enhance their ablation volume.