Implantation of Intracranial Electrodes Predicts Worse Outcome in Mesial Temporal Lobe Epilepsy

-OBJECTIVE: Anteromesial resection is an effective method for treating seizures arising from the medial tem-poral lobe, as these cases are often the most straightfor-ward and have the best outcomes. Nevertheless, some patients who go on to have a mesial resection are rec-ommended to have an implantation of electrodes before surgery. Whether the need for such an implant alters the rate of seizure freedom is not well-studied in this particular subgroup of epilepsy patients.-METHODS: We performed a retrospective review of consecutive anteromesial surgeries for medial temporal lobe epilepsy performed between 2005 and 2020. Of a total of 39 patients, 19 required electrode implantation (electrode group) and 20 did not (no-electrode group). The primary outcomes assessed were reduction in seizure frequency and Engel score. Complication rates were also compared.-RESULTS: Postresection seizure frequency reduction was nonsignificantly higher in the no-electrode group (97.0 +/- 10.3%) than in the electrode group (88.5 +/- 23.7%, P = 0.15). The rate of Engel I outcome was nonsignificantly higher in the no-electrode group (84.2%) than in the electrode group (65.0%, P = 0.17). Major complication rates were nonsignif-icantly higher in the no-electrode group (15.8 +/- 1.9%) than in the electrode group (5.0 +/- 1.1%, P = 0.26). Power analysis revealed that 74 patients would need to be included in each group to reach statistical significance.-CONCLUSIONS: Although not statistically significant, our study showed a trend for improved seizure control if a decision was made not to implant electrodes prior to potentially curative anteromesial resection. Engel I outcome in this group reached approximately 85%. A larger multi-instiutional study may be required to reach statistical significance.