Transcortical versus Transsylvian Approach for Insular Gliomas: A Systematic Review and Meta-Analysis

Insular gliomas can be resected via a transcortical (TC) or transsylvian (TS) approach. The TC approach avoids injury to the middle cerebral artery (MCA) and is considered suitable for gliomas with opercular spread. The TS approach is limited by bridging veins and a surgical "blind spot" for larger gliomas. We aimed to compare the TC and TS approaches for the resection of insular gliomas. A systematic review of the literature was performed using PubMed, Scopus, and Web of Science databases from inception to November 20, 2022, following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Primary outcomes included the extent of resection (EOR), postoperative deficits, and immediate and delayed complications of both approaches. Summary estimate of proportion, random effects, and confidence intervals (CIs) were calculated using R (statistical package). Sixteen studies with 1,517 patients (56.5% male) were included. The mean age ± standard deviation (SD) of patients was 43.6 ± 6.8 years. The predominant presenting symptom was first-onset seizure (62.8%), followed by headache (∼10%). There was a slight predominance of right-sided gliomas (52.5%). Pathology revealed a slight abundance of low-grade (WHO grade I or II) histology (51.5%) compared with 48.5% high-grade (WHO grade III or IV). A greater pool proportion of 0.44 (CI: 0.28-0.61) for gross total resection and 0.19 (CI: 0.10-0.34) for partial resection was found for the TC approach compared with the TS approach. For subtotal resection, the TS approach had a higher pooled proportion (0.47 [CI: 0.40-0.54]) than the TC approach (0.41 [CI: 0.24-0.60]). Postoperative speech deficits (0.04 [95% CI: 0.02-0.11]) and motor deficits (0.10 [95% CI: 0.07-0.15]) were more frequent with the TS approach compared with the TC approach. Our study confirms that the TC approach results in a higher proportion of gross total resection of insular gliomas compared with the TS approach, with fewer postoperative speech and motor deficits.