Safe Removal of Glioblastoma Near the Angular Gyrus by Awake Surgery Preserving Calculation Ability

—Case Report—

Abstract

A 67-year-old patient presented with progressive agraphia, alexia, and impaired ability to calculate persisting for 4 weeks. He showed preserved ability to do single-digit addition and subtraction. Magnetic resonance imaging demonstrated a tumor in the left parietal lobe. A malignant glioma was suspected, and awake craniotomy was performed to remove the tumor with functional cortical mapping to determine the cortices involved in calculation and language. His calculation ability was mapped on the angular gyrus, and partial resection of the tumor was achieved without deterioration of that ability. The histological diagnosis was glioblastoma multiforme. The patient’s calculation ability improved dramatically after the operation.