Postoperative Seizure Control in Adult Diffuse Insular Gliomas Presenting with Seizures: A Retrospective Single-Center Experience and Proposal of a Novel Risk Scoring System

Background: Studies on insular gliomas (IGs) generally focus on the oncological endpoints with a relative scarcity of literature focusing on the seizure outcomes. Objectives: To study the predictors of long-term postoperative seizure control in IG and propose a novel risk scoring system. Methods: Histopathologically proven, newly diagnosed adult IGs (>18 years) operated over a 10-year period were studied for postoperative seizure control as per International League Against Epilepsy (ILAE) grades at 6 weeks and at last follow-up (minimum of 6 months, median 27 months). Logistic regression analysis was performed and regression coefficients with nearest integers were used to build a risk prediction model. Receiver operator curve (ROC) analysis determined the predictive accuracy of this model. Results: The 6-week postoperative seizure freedom dropped to 41% at the last follow-up. The seizure-free group lived longer (100.69 months, 95% CI = 84.3-116.99 (60%)) than those with persistent postoperative seizures (27.92 months, 95% CI = 14.99-40.86). Statistically significant predictors (preoperative seizure control status, extent of resection, tumor extension to temporal lobe, and lack of postoperative adjuvant therapy) were used to compute a risk score, the score ranging from 0 to 9. A score of four most optimally distinguished the risk of postoperative seizures with an area under the ROC of 91.4% (95% CI: 84.1%, 98.7%, P < 0.001). Conclusion: In our experience, around 60% of patients obtained seizure freedom after surgery, which reduces over time. Control of seizures paralleled survival outcomes. Our proposed scoring system may help tailor management strategies for these patients.