AB004. Transsylvian approach for radical resection of insular gliomas: emphasizing the importance of the transsylvian approach for elderly patients with Zone II and III insular gliomas

Background: Insular gliomas present significant challenges due to their deep-seated location and proximity to critical structures, including sylvian veins, middle cerebral arteries (MCAs), lenticulostriate arteries, long insular arteries, and functional cortices and white matter tracts. The Berger-Sanai classification categorizes them into four zones (I–IV), providing a framework for understanding insular gliomas. The key factors for successful insular glioma removal are achieving the greatest insular exposure and surgical freedom. There are two main types of approach methods, such as transsylvian approach with meticulous wider dissection of the sylvian fissure and transcorticosubcortical approach with intraoperative functional brain mapping under awake surgery to remove the functionally silent cortices and white matter tracts. Because splitting the distal sylvian fissure is more challenging, a transcortical approach through the parietorolandic operculum in awake patients has been reported to be more effective access to the posterior insular gliomas (Zone II and III) in the dominant hemisphere. The object of this study emphasize the importance of the transsylvian approach for radical resection of insular gliomas.

Methods: We retrospectively analyzed our experiences with radically resected insulo-opercular gliomas. Basically, we pursue the transsylvian approach for resecting insular gliomas without removal of any normal brain.

Results: Motor pathways running beneath the parietorolandic operculum can be damaged by ischemia caused by sacrificing the medullary arteries (MAs) arising from the pial arteries of the M3 and M4 portions of the MCA. Motor deficit after resection of this area was significantly found in the elderly patients. This phenomenon might be described by the age-associated decreasing the vascular reserve capacity. Autopsy brains showed that the sclerotic rate of the MAs increased with age and hypertension. Even with the intraoperative functional brain mapping, we cannot avoid the ischemic complication caused by sacrificing the MAs during stepwise removal of the functionally silent cortices and white matter tracts.

Conclusions: We make a suggestion not to remove the parietorolandic operculum in elderly patients with insular gliomas located at Zone II and III. Distal transsylvian approach should be applied.

Keywords: Elderly; insular glioma; transsylvian approach; Zone II/III