Supratotal Resection of Diffuse Frontal Lower Grade Gliomas with Awake Brain Mapping, Preserving Motor, Language, and Neurocognitive Functions.

OBJECTIVE: Extended margin tumor resection beyond the abnormal area detected by magnetic resonance imaging, defined as supratotal resection, could improve the outcomes of patients with lower grade gliomas (LGGs). The aim of the present study was to assess the surgical outcomes of awake brain mapping to achieve supratotal resection with determination of the normal brain tissue boundaries beyond the tumor of frontal LGGs, in both dominant and nondominant hemispheres.

METHODS: We analyzed the data from 9 patients with diffuse frontal LGGs who had undergone supratotal resection with awake surgery from January 2016 to November 2017.

RESULTS: The frontal aslant tract was identified as the functional boundary in 4 of 5 left frontal tumor cases (80%). Working memory impairments during dorsolateral prefrontal cortex stimulation with digit span and/or visual N-back tasks were detected in all 4 patients (100%) with right-frontal tumor. The neurocognitive outcomes were significantly improved after surgery, as shown by the mean Wechsler adult intelligence scale III scores for verbal intelligence quotient (P = 0.04) and verbal comprehension (P = 0.03) and the mean Wechsler memory scale-revised scores for generalized memory (P = 0.04) and delayed recall (P = 0.04).

CONCLUSIONS: The results of the present study have provided evidence that awake mapping can enable the preservation of higher neurocognitive function, including working memory and spatial cognition in patients with nondominant right frontal tumors. Despite the small number of cases, our findings suggest the surgical benefit of awake surgery for supratotal resection of diffuse frontal LGGs.