Usefulness of direct electrical stimulations during surgery for gliomas located within eloquent brain regions

Glioma surgery in functional areas has undergone a dramatic development these last few years, thanks to improvements in both intraoperative functional imaging and direct electrical stimulation of cortical areas or association pathways. The goal of these techniques to achieve complete as possible surgical removal of tumors located in eloquent areas (sensitive, motor and language areas) with minimal risk of permanent sequelae. To be reliable, a rigorous methodology is required. Current cortical mapping is very easy to achieve, whereas mapping of association pathways will require much more experience. In case of tumors located in somatosensorial or language areas, the difficulties related to accurate sub cortical localization are combined with these of local anesthesia and the best task choice to evaluate the integrity of cognitive functions. These functional techniques allow total or sub total removal in 52% to 76.2% of patients. Transient worsening is observed in 13% to 80% of the patients; the rate of permanent sequelae averages 4%.