Transcortical insular glioma resection: clinical outcome and predictors

J Neurosurg 131:706–716, 2019

Insular lobe gliomas continue to challenge neurosurgeons due to their complex anatomical position. Transcortical and transsylvian corridors remain the primary approaches for reaching the insula, but the adoption of one technique over the other remains controversial. The authors analyzed the transcortical approach of resecting insular gliomas in the context of patient tumor location based on the Berger-Sinai classification, achievable extents of resection (EORs), overall survival (OS), and postsurgical neurological outcome.

METHODS The authors studied 255 consecutive cases of insular gliomas that underwent transcortical tumor resection in their division. Tumor molecular pathology, location, EOR, postoperative neurological outcome for each insular zone, and the accompanying OS were incorporated into the analysis to determine the value of this surgical approach.

RESULTS Lower-grade insular gliomas (LGGs) were more prevalent (63.14%). Regarding location, giant tumors (involving all insular zones) were most prevalent (58.82%) followed by zone I+IV (anterior) tumors (20.39%). In LGGs, tumor location was an independent predictor of survival (p = 0.003), with giant tumors demonstrating shortest patient survival (p = 0.003). Isocitrate dehydrogenase 1 (IDH1) mutation was more likely to be associated with giant tumors (p < 0.001) than focal tumors located in a regional zone. EOR correlated with survival in both LGG (p = 0.001) and higher-grade glioma (HGG) patients (p = 0.008). The highest EORs were achieved in anterior-zone LGGs (p = 0.024). In terms of developing postoperative neurological deficits, patients with giant tumors were more susceptible (p = 0.038). Postoperative transient neurological deficit was recorded in 12.79%, and permanent deficit in 15.70% of patients. Patients who developed either transient or permanent postsurgical neurological deficits exhibited poorer survival (p < 0.001).

CONCLUSIONS The transcortical surgical approach can achieve maximal tumor resection in all insular zones. In addition, the incorporation of adjunct technologies such as multimodal brain imaging and mapping of cortical and subcortical eloquent brain regions into the transcortical approach favors postoperative neurological outcomes, and prolongs patient survival.