Transcortical versus transsylvian approaches for adult insular glioma resection: a systematic review with subanalysis by Berger–Sanai segmentation

Insular gliomas pose a neurosurgical challenge due to their deep location and proximity to other structures. The transsylvian (TS) and transcortical (TC) approaches remain the main techniques, guided by the Berger–Sanai (BS) classification. This study compares outcomes across BS zones. A systematic literature review, following PRISMA 2020 guidelines, was conducted in PubMed, Embase, Cochrane Library, and Google Scholar (2010–2025), including adult patients undergoing insular glioma resection via TS or TC approaches, stratified by BS zones. Studies reporting Extent of Resection (EOR) and neurological outcomes were eligible. Data quality was assessed and results were synthesized according to tumor location and surgical approach. As only previously published data were analyzed, ethical approval was not required. Fourteen studies (1,225 patients: 990 TC; 235 TS) were included. TC predominated and generally achieved higher EOR, while TS produced similar results in favorable regions, especially BS Zones I–II. Overall, permanent deficits were uncommon. Zone I consistently allowed maximal safe resection; Zone II showed a trade-off between EOR and ischemic risk, with mixed evidence and a slight advantage for TS. Zones III–IV were sparsely reported, with data favoring TC for deeper control. Both approaches permit safe resection with low rates of permanent morbidity. TC remains the dominant strategy and often attains superior EOR, whereas TS is a viable alternative in BS Zones I–II. Consistent outcome metrics and BS zonal stratification are crucial to refine surgical selection and optimize decision-making.