NCOG-31. NEUROCOGNITIVE OUTCOME FOLLOWING AWAKE CRANIOTOMY FOR INSULAR GLIOMA RESECTION: IMPACT OF SURGICAL APPROACH AND TUMOR CLASSIFICATION

Abstract BACKGROUND Insular glioma resection harbors similar risk of neurocognitive function (NCF) decline as other tumor locations. However, differences in outcomes according to transsylvian versus transcortical surgical approach and tumor classification remain unknown. METHODS 53 patients with newly diagnosed insular glioma (47% high-grade; 23% GBM; 75% left hemisphere) underwent awake craniotomy for resection (transsylvian, 64%; transcortical, 36%). Patients completed neuropsychological testing preoperatively and <2 months postoperatively (M interval=23.7 days). Tumor location was described with Berger-Sinai zones collapsed into anterior (I and/or IV), posterior (II and/or III), superior (I and/or II), and inferior (III and/or IV) groups. Tumor extension was characterized with the Pitskhelauri system into insula only, insula with extension (lobar or medial), and predominantly (>50%) extra-insular groups. Result: Decline (z-score change<-1.0) on at least 1 test occurred in 85% of patients with largest effect (partial η2) in memory (.29–.44) and verbal fluency (.39). There was no interaction with approach on any NCF change score, though transcortical was associated with more frequent fluency decline (61% vs. 26%, p=.014). Left hemisphere tumor was associated with poorer outcome on 6/12 tests (all p<.01). Predominantly extra-insular tumors showed greater reductions in fluency (M=-1.21, SD=0.90) than insula only tumors (M=-0.10, SD=0.76; p=0.024). Number of Berger-Sanai quadrants involved was inversely associated with change in executive functioning (r=-0.34, p=.018). Poorer executive function outcome was also found in anterior (M=-0.61, SD=1.41) versus posterior tumors (M=0.86, SD=1.51; p=.014), and recognition memory outcome worse for inferior (M=-2.44, SD=1.81) than superior lesions (M=-0.31, SD=1.47; p=.021). CONCLUSIONS NCF decline is common in the early term following resection of insular glioma. While risk of verbal fluency decline may be greater for transcortical surgeries, outcomes were largely similar across approaches. In addition to hemisphere, tumor extension and insular zone localization may inform domain-specific risk of NCF decline following resection.