Trans-Sylvian and Transanterior Ascending Ramus Approach for Insular Gliomas at Zone I: 2-Dimensional Operative Video

Abstract

Insular gliomas present significant challenges because of their deep-seated location and proximity to critical structures, including Sylvian veins, middle cerebral arteries, lenticulostriate arteries, 1 long insular arteries, 2 and functional cortices. 3-6 The Berger-Sanai classification categorizes them into 4 zones (I-IV), providing a framework for understanding insular gliomas. 7 The key factors for successful insular glioma removal are achieving the greatest insular exposure and surgical freedom. 3 Given that the trans-Sylvian approach 8,9 creates a narrow, linear surgical window, 3 regardless of the zones, various surgical options have been employed, such as the trans-Sylvian approach with bridging vein cuts and the transcortical approach through functionally silent cortex. 3,7,9-13 Dissecting sulci in glioma surgeries has proven beneficial. 14-16 In this video publication, we dissected the anterior ascending ramus (AAR) and the Sylvian fissure, creating a triangular window instead of a linear one. A 74-year-old right-handed woman with a zone I insular glioma underwent a trans-Sylvian and trans-AAR approach, achieving total resection of the tumor without new neurological deficits. This approach provided maximum exposure of the insular region, offering a wide view from the anterior limiting sulcus to the anterior half of the superior limiting sulcus of the insula. The histological diagnosis revealed a rare adult pilocytic astrocytoma at the insula, documented in only one case report. 17 The AAR, 4 defined as a lateral sulcus (Sylvian fissure) branch, 18 is present in 98.89% of hemispheres 19 ; therefore, this surgical approach demonstrates broad applicability to zone I insular tumors. The patient provided consent for the procedure and the publication of her image under institutional review board approval (G23-08).