10084- STMO-5 A CASE OF GLIOBLASTOMA SURGERY NEAR THE LANGUAGE AREA SAFELY REMOVED USING INTRAOPERATIVE LANGUAGE AREA MONITORING BASED ON GAMMA OSCILLATION REGULARITY ANALYSIS.

Abstract We have been performing safe and reliable brain tumor surgery by visualizing epileptic lesions and areas of reduced brain function using gamma oscillation regularity analysis. In this report, we describe our experience of surgery in a case of glioblastoma near the language area in which intraoperative language monitoring using this analysis enabled safe and aggressive removal of the tumor. The patient was a male in his 50s. He was rushed to another hospital due to a seizure. A contrast-enhanced MRI scan of the head showed a ring-shaped lesion with a maximum diameter of 70 mm in the left frontal to temporal lobes, which was suspected to be a glioblastoma, and the patient was transferred to our hospital for treatment. At the time of transfer, the patient had mild dysarthria and confusion symptoms, and the dominant language hemisphere was on the left side in the WADA test. Aphasia symptoms worsened while the patient was waiting for surgery, and the language area was evaluated intraoperatively using cortico-cortical evoked potential (CCEP) and gamma oscillation regularity analysis. Gamma oscillation regularity analysis revealed increased gamma oscillation regularity in areas that were excited by electrical stimulation via white matter fibers, and these areas were consistent with the language areas inferred by CCEP and could be better localized. Aggressive tumor resection was performed under intraoperative language area monitoring. There was no worsening of symptoms, and the preoperative aphasia symptoms resolved postoperatively. In this case, we were able to perform intraoperative language monitoring by taking advantage of the increase in gamma oscillation regularity in the areas excited by electrical stimulation via white matter fibers. Intraoperative gamma oscillation regularity analysis is very useful in brain tumor surgery and may become a new technique for intraoperative brain function monitoring.