Epileptogenic LGG surgery with seizure freedom purpose: Supratotal resection (ETT-SpTR) based on Electrocorticography and navigated transcranial magnetic stimulation.

BACKGROUND: Low-grade gliomas (LGG)-related seizures may persist after gross total resection (GTR). Supratotal resection (SpTR) seems to have better seizure outcomes, likely due to removing the epileptogenic peritumoral neocortex. However, its role in achieving postoperative seizure freedom remains poorly considered, likely because SpTR is achievable in only one out of three patients. METHODS: We retrospectively analyzed a prospectively collected series of epileptogenic surgically resected LGGs. Intraoperative Electrocorticography (iECoG) guided the extension of GTR to areas with interictal activity and negative on navigated Transcranial Magnetic Stimulation (nTMS). Patients were divided into Group I (GTR) and Group II [iECoG nTMS Tailored - SpTR (ETT-SpTR)], and we compared the seizure outcomes at follow-up (minimum 12 months). We also compared the rate of postoperative neurological deficits. RESULTS: Thirty patients were included. Group I (n = 15) showed only a 20% rate of seizure freedom (Engel IA), compared to 86.6% in Group II (n = 15, p = 0.0001). Neurological outcomes showed no differences between groups. Four patients (13.3%) with resection margins < 1 cm from nTMS-positive points developed transient deficits; no deficits were observed for distances > 1 cm. CONCLUSION: The ETT-SpTR is more frequently achievable than radiologically defined SpTR. In our experience, ETT-SpTR yields better seizure outcomes without compromising functional outcomes compared to GTR. In our cohort, iECoG is a reliable technique for identifying LGG-related epileptogenic foci, while nTMS is a trustworthy method for predicting postoperative deficits.