Combined functional mapping using electrocorticograms and electrocortical stimulation for brain tumor resection

Abstract

It is practically important to identify and monitor the eloquent brain functions for maximal resection of brain tumors. Although electrocortical stimulatio (ECS) with awake craniotomy or implanted subdural electrodes is the gold-standard for brain mapping, it always contains the risks of seizure and pain. Recent studies reported that the electrocorticogram (ECoG) might have great potential to identify language centers by emphasizing high frequency oscillations. We performed detailed functional mapping using ECS and ECoG for a patient with a brain tumor located near the language-related area. We focused on the high frequency components of ECoG between 60 and 120 Hz, the high Gamma activity (HGA) range. HGA induced by a word-reading task appeared around 600 msec after stimulus onset in the posterior language area, which was confirmed by ECS. In addition, HGA clearly delineated functional dynamics related to the reading task from the occipital to the frontal and temporal regions. We believe that ECoG mapping could become an alternative to ECS mapping and awake craniotomy.