Correlation between localization of supratentorial glioma to the precentral gyrus and difficulty in identification of the motor area during awake craniotomy.

OBJECTIVE

Identification of the motor area during awake craniotomy is crucial for preservation of motor function when resecting gliomas located within or close to the motor area or the pyramidal tract. Nevertheless, sometimes the surgeon cannot identify the motor area during awake craniotomy. However, the factors that influence failure to identify the motor area have not been elucidated. The aim of this study was to assess whether tumor localization was correlated with a negative cortical response in motor mapping during awake craniotomy in patients with gliomas located within or close to the motor area or pyramidal tract.

METHODS

Between April 2000 and May 2019 at Tokyo Women's Medical University, awake craniotomy was performed to preserve motor function in 137 patients with supratentorial glioma. Ninety-one of these patients underwent intraoperative cortical motor mapping for a primary glioma located within or close to the motor area or pyramidal tract and were enrolled in the study. MRI was used to evaluate whether or not the tumors were localized to or involved the precentral gyrus. The authors performed motor functional mapping with electrical stimulation during awake craniotomy and evaluated the correlation between identification of the motor area and various clinical characteristics, including localization to the precentral gyrus.

RESULTS

Thirty-four of the 91 patients had tumors that were localized to the precentral gyrus. The mean extent of resection was 89.4%. Univariate analyses revealed that identification of the motor area correlated significantly with age and localization to the precentral gyrus. Multivariate analyses showed that older age (≥ 45 years), larger tumor volume (> 35.5 cm3), and localization to the precentral gyrus were significantly correlated with failure to identify the motor area (p = 0.0021, 0.0484, and 0.0015, respectively). Localization to the precentral gyrus showed the highest odds ratio (14.135) of all regressors.

CONCLUSIONS

Identification of the motor area can be difficult when a supratentorial glioma is localized to the precentral gyrus. The authors' findings are important when performing awake craniotomy for glioma located within or close to the motor area or the pyramidal tract. A combination of transcortical motor evoked potential monitoring and awake craniotomy including subcortical motor mapping may be needed for removal of gliomas showing negative responses in the motor area to preserve the motor-related subcortical fibers.