Estimated overall survival at 2 and 5 years was 83.8 and 69.6%, respectively, in 28 cases with insular resections for primary tumors (8 glioblastomas, 1 IDH1 mutant astrocytoma CNS WHO grade 4, 3 CNS WHO grade 3 and 8 CNS WHO grade 2 astrocytomas, 6 oligodendrogliomas CNS WHO grades 2/3, 1 ganglioglioma and 1 dysembryoplastic neuroepithelial tumor CNS WHO grade 1). Here, IDH1 is linked to ganglioglioma.