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

Abstract

The importance of the extent of resection (EOR) has been widely demonstrated as the main predictor for survival, nevertheless its effect on tumor related epilepsy is less investigated. A total of 155 patients were enrolled after a first-line surgery for supratentorial Diffuse Low Grade Gliomas (DLGGs). Postoperative seizure outcome was analyzed stratifying the results by tumor volumetric data and molecular markers according to 2016 WHO classification. Receiver operating characteristic (ROC) curves were computed to asses EOR, residual tumor volume, and ∆T2T1 MRI index (expressing the tumor growing pattern) corresponding to optimal seizure outcome. A total of 70.97% of patients were seizure-free 18 months after surgery. Better seizure outcome was observed in IDH1/2 mutated and 1p/19q codeleted subgroup. At multivariate analysis, age (p = 0.014), EOR (p = 0.030), ∆T2T1 MRI index (p = 0.016) resulted as independent predictors of postoperative seizure control. Optimal parameters to improve postoperative seizure outcome were EOR ≥ 85%, ∆T2T1 MRI index ≤ 18 cm 3 , residual tumor volume ≤ 15 cm 3 . This study confirms the role of EOR and tumor growing pattern on postoperative seizure outcome independently from the molecular class. Higher ∆T2T1 MRI index, representing the infiltrative component of the tumor, is associated with worse seizure outcome and strengthens the evidence of common pathogenic mechanisms underlying tumor growth and postoperative seizure outcome.to manifest with focal and focal-to-bilateral tonic-clonic seizures, and more than 50% of cases show pharmaco-resistance, which contributes negatively on quality of life [3][4][5]. Recent studies have pointed out that epileptogenesis and tumor growth in DLGG may share common pathogenic mechanisms that can influence each other, thus representing two aspects of the same disease [6]. In this context, several genetic alterations have been identified as risk factors of glioma-related epilepsy. Mutations of the gene encoding the isocitrate-dehydrogenase1 (IDH1) and 2 (IDH2) can be found in about 70%-80% of DLGG [7]. 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 epilep...

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Risk Assessment by Pre-surgical Tractography in Left Hemisphere Low-Grade Gliomas

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