Predicting Extent of Resection and Neurological Outcome for Insular Gliomas: An Analysis of Two Available Classifications

<b>Background/Objectives</b>: Insular gliomas are rare entities whose surgical resection presents a significant challenge due to their close relationship with crucial white matter bundles and deep perforating arteries. The Berger-Sanai classification is a well-established system based on dividing the insula into four quadrants. In contrast, the Kawaguchi grading system focuses on the tumor's behavior and vascular infiltration. In this study, we compared these two systems in terms of surgical and clinical outcomes. <b>Methods</b>: A retrospective single-center consecutive series of patients treated for insular gliomas was analyzed. <b>Results</b>: A total of 43 patients were analyzed, with a mean age of 47 years. The average preoperative KPS was 92.6, and seizures were the most common presenting symptom. The mean extent of resection (EOR) was 92.2%. Both the Berger-Sanai and Kawaguchi classifications influenced the EOR, but the former showed a moderate-to-strong correlation with expected resection rates. Postoperative clinical outcomes were related to both classification systems, but this association was lost at the 6-month follow-up. Additionally, lower Kawaguchi grades were associated with significant postoperative MRI hyperintensities on DWI sequences and higher rates of intraoperative neuromonitoring (IONM) alterations, which translated into worse postoperative clinical conditions. <b>Conclusions</b>: The Berger-Sanai and Kawaguchi classification systems are both significantly related to the EOR in insular gliomas; however, only the Berger-Sanai system shows strong predictive value regarding resection rates. Both systems serve as good prognostic tools for determining short-term postoperative clinical outcomes, but significant DWI hyperintensities and IONM alterations are specifically associated with the Kawaguchi system.