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.

Automated summary

Anteromesial resection is an effective treatment for seizures arising from the medial temporal lobe. However, the need for electrode implantation before surgery may not significantly affect the rate of seizure freedom in these patients. Our study suggests that omitting electrode implantation may lead to improved seizure control.