New insights into surgery for brain gliomas: towards a personalized act

Surgical resection is now the first therapeutic option in glial tumors of the brain, especially in diffuse low-grade gliomas - according to the recent European guidelines which support an active strategy and not a « wait and see » attitude anymore. However, because glioma is a chronic and diffuse disease of the central nervous system (and not a tumoral mass, as claimed for a long time), surgery may generate neurological deficit, in particular for lesions located within eloquent areas. Therefore, resection should be performed according to functional (and not only oncological) boundaries, both at cortical and subcortical levels, thanks to the use of intraoperative mapping techniques in awake patients. Indeed, a recent meta-analysis of the literature investigating more than 8 000 patients who underwent surgery for low-grade and high-grade gliomas, without versus with intraoperative electrostimulation, has demonstrated that cerebral mapping enabled (i) the opening of surgical indications to regions classically considered as « inoperable » (ii) an increase of the extent of tumor resection, with a significant impact on overall survival (iii) while minimizing significantly the risk of permanent neurological morbidity. Such a surgical strategy is possible owing to the better understanding of individual neural basis underlying sensorimotor, language, cognitive and behavioral functions, through a rigorous study of the anatomo-functional connectivity (« hodotopy ») and mechanisms of brain plasticity. This hodotopical and dynamic view (and not localizationist and rigid view) of cerebral organization opens the door to a personalized surgical management.