Long term analysis of the epileptic outcome in a consecutive series of 50 patients with "non-enhancing" IDH-mutated gliomas with a mean follow-up of 70 months

Patients with low-grade gliomas tipically experience seizures at the onset and are generally treated with surgery that, especially when radical and uncomplicated, can ensure good post operative seizure control. There is very little data available to understand the evolution of seizures throughout the history of these patients. This retrospective study aims to analyze long-term epileptic data of 50 consecutive patients who underwent resection of non-enhancing IDH-mutated glioma between 2006 and 2020. Several factors were analyzed with a mean follow-up of 70 months. During the follow-up, 28 patients experienced seizures (56%), of which 11 were uncontrolled (39.3%), while 22 patients did not experienced seizures (44%). The average time of first postoperative seizure was 30 months. The only significant variables in the univariate analyses were GTR ( p  = 0.019), preoperative seizures control ( p  = 0.029) and radiological progression during the follow up ( p  = 0.002). The only independent predictor in a multivariate logistic regression was the progression of the disease (OR 5.145, 95% CI 0.188–3.162, p  = 0.03). A ROC curve based on recurrence or absence of seizures was computed and the optimal threshold of residual tumor volume was 0.5 cm ³ . Kaplan-Meier approach showed no significant differences between the two groups in terms of overall survival ( p  = 0.76) and progression free survival ( p  = 0.054). Our data show that, in the long term, the only risk factor for the recurrence of epilepsy may be the recurrence of the disease itself. Conversely, the presence or absence of seizure control does not seem to be significantly correlated with overall survival and progression free survival