[COMPARISON OF HIGH GAMMA ELECTROCORTICOGRAPHY AND DIRECT CORTICAL STIMULATION MAPPING OF CORTICAL FUNCTION IN AWAKE CRANIOTOMY: INITIAL EXPERIENCE].

Introduction: The use of intraoperative electrical cortical stimulation (ECS) to map function is the standard of care in modern neurosurgery. Recently, high gamma electrocorticography (hgECOG) mapping has had encouraging results. In this study we aim to compare hgECOG and fMRI with ECS for motor and language mapping.

Methods: We retrospectively evaluated medical records of patients who underwent awake surgery for tumor resection between January 2018 and December 2021. The first 10 consecutive patients who underwent ECS and hgECOG for mapping of motor and language functions were defined as the study group. Pre- and intra-operative imaging and electrophysiology data were used for analysis.

Results: ECS and hgECOG motor mapping demonstrated functional motor areas in 71.4% and 85.7% of patients, respectively. All motor areas identified with ECS were also demonstrated using hgECOG. In 2 patients, hgECOG-based mapping demonstrated motor areas not demonstrated with ECS but present in preoperative fMRI imaging. Of the 15 hgECOG tasks performed for language mapping, the findings of 6 (40%) were in accordance with the ECS mapping. Two (13.3%), showed language areas that were demonstrated using ECS and in addition, showed areas that were not. Four mappings (26.7%) showed language areas that were not demonstrated using ECS. In 3 mappings (20%), the functional areas identified by ECS were not demonstrated by hgECOG.

Conclusions: Intraoperative hgECOG for mapping of motor and language functions provide a fast and reliable method without the risk of stimulation-induced seizures. Further studies are needed to assess functional outcome of patients undergoing hgECOG-guided tumor resection.