Extent of Resection and Residual Tumor Thresholds for Postoperative Total Seizure Freedom in Epileptic Adult Patients Harboring a Supratentorial Diffuse Low-Grade Glioma

Abstract

BACKGROUND Epileptic seizures impair quality of life in diffuse low-grade glioma (DLGG) patients. Tumor resection significantly impacts postoperative seizure control, but the precise extent of resection (EOR) required for optimal seizure control is not clear yet. OBJECTIVE To identify the EOR and residual tumor volume that correlated to postoperative seizure control, defined as a total seizure freedom (Class 1A in reference to Engel classification system) with and without antiepileptic drugs in patients undergoing surgical resection of supratentorial DLGG. METHODS A retrospective review was conducted of all patients who underwent first-line surgical resection of supratentorial DLGG who presented with preoperative seizures without adjuvant oncological treatment. EOR and residual tumor volume were quantified from pre- and post-operative magnetic resonance imagings. Receiver operating characteristic curves were plotted to determine the EOR and residual tumor volume that corresponded to optimal postoperative seizure control. RESULTS Of the 346 included patients, 65.5% had controlled seizures postoperatively, with higher age at resection (adjusted OR per unit, 1.03 [95% confidence interval:1.01-1.06], P = .043) and higher percentage of resection (adjusted OR per unit, 1.02 [95% confidence interval:1.00-1.03], P < .001) found as independent predictors of postoperative seizure control. Optimal EOR was ≥91% and optimal residual tumor volume was ≤19 cc to improve postoperative seizure control. CONCLUSION Postoperative seizure control is more likely when EOR is ≥91% and/or when residual tumor volume is ≤19 cc in supratentorial DLGG gliomas who present with seizures. Resected peritumoral cortex should, however, be taken into account in future studies.

Predictors of Postoperative Seizure Outcome in Low Grade Glioma: From Volumetric Analysis to Molecular Stratification

“…The role of EOR as the strongest predictors of postoperative seizure long-term outcome ( Table 4) has recently been demonstrated in a limited number of retrospective studies [8,[15][16][17][19][20][21][22][23]. Only two investigations examined which value of EOR corresponded to the threshold above which seizure control, defined as Engel Class level, was optimal [16,17].…”

“…In a subsequent larger multi-center investigation, methodologically well-designed, Still et al demonstrated that postoperative seizure control was more likely when EOR was ≥91% and/or when residual tumor volume was ≤ 19 cc in supratentorial DLGG patients [16].…”

“…These mutations have been associated with metabolic changes that are potentially epileptogenic, in accordance with the capability of IDH-mutated glioma cells to penetrate and surround the neurons in the gray matter [8,9].Seizure outcome represents an important challenge in the daily management of DLGG patients. In particular, decision-making still varies across surgical centers given the lack of well-established and universally recognized predictors of seizure outcomes.In the last decades, numerous studies, based on the objective evaluation of the extent of resection (EOR) has been published, demonstrating that an extensive surgery leads to increased overall patient survival and decreased malignant progression [10][11][12][13][14].Although EOR has also been shown to be one of the main strongest significant predictor markers for seizure outcome [7,[15][16][17][18], its predictive role has not been completely clarified in complex predictor models for epileptic outcome stratification combining molecular and tumor volumetric data.We assessed the capability of the main clinical, molecular, and radiological data used in DLGG, including the tumor growing pattern and EOR, to predict postoperative seizure outcome, with the aim to provide useful tools for the early identification of postoperative seizure persistence and for the refinement of medical treatment tailoring in subjects with refractory epilepsy.…”

“…Although EOR has also been shown to be one of the main strongest significant predictor markers for seizure outcome [7,[15][16][17][18], its predictive role has not been completely clarified in complex predictor models for epileptic outcome stratification combining molecular and tumor volumetric data.…”

Clinical practice guidelines for the diagnosis and treatment of adult diffuse glioma‐related epilepsy

“…9,13,15,47 A recent study showed that for LGG patients with preoperative epilepsy, the postoperative seizure control was more likely when the extent of resection was over 91%. 48 Additionally, "supratotal" resection can achieve better seizure control than even gross-total resection. 49 Accordingly, for patients with GRE, the maximal safe resection is helpful to improve not only local tumor control and survival but also postoperative seizure control.…”