Maximal safe resection of diffuse low-grade gliomas within/near motor areas using awake craniotomy with intraoperative cortical/subcortical mapping via direct electrical stimulation: A narrative review

Diffuse low-grade gliomas are a diverse category of neuroepithelial neoplasms, which are characterized by a low proliferation index and an indolent course with a long-term survival in comparison with high-grade gliomas. It is convinced that maximal safe resection can significantly increase survival. Multiple intraoperative techniques help neurosurgeons to maximize the resection with a safe range; however, the tumors involving motor areas are still intractable for many surgeons who believe that these tumors are unresectable. We searched on PubMed database and summarized studies and reviews about diffuse low-grade gliomas within/near motor areas. Moreover, studies about anatomy about motor area were also reviewed. In this article, we discussed the anatomy of the central lobe and supplementary motor area, including the cortex, subcortical fibers, and relevant vessels, as well as the technical details of awake craniotomy and direct electrical stimulation. At last, combined with some cases, we try to demonstrate that tumors within/near motor areas are resectable, which may cause only mild neurological deficits using awake craniotomy with intraoperative monitoring by cortical/subcortical mapping, and, furthermore, it provides a longer and better survival for those young patients.