745 Contribution of Intraoperative Corticosubcortical Stimulations in Surgery of Low-grade Gliomas: A Comparative Study between Two Series without and with Functional Mapping

Abstract

INTRODUCTION: Despite a growing use of intraoperative functional mapping in surgery of supratentorial hemispheric low-grade gliomas (LGGs), very few comparative studies of patients operated on without and with direct cortical and subcortical electrical stimulations (DES) in the same institution were reported in the literature. Here, we compare the rate of LGG surgeries performed in eloquent areas, the rate of postoperative sequelae, and the quality of resection during two consecutive periods in the same department: the first one without the use of intraoperative electrophysiology, the second one with DES. METHODS: From 1985 to 1996, 100 patients harboring a supratentorial LGG underwent surgery with no functional mapping (S1). From 1996 to 2003, 122 patients were operated on in the same department for a supratentorial hemispheric LGG using intraoperative corticosubcortical DES (S2). RESULTS: Comparison between the two series showed that 35% of LGG were operated on in eloquent areas (S1) versus 62% (S2) (P < 0.0001), with 17% of severe permanent deficits (S1) versus 6.5% (S2) (P < 0.019). On control magnetic resonance imaging, 37% of resections were subtotal and 6% total (S1), versus respectively 50.8% and 25.4% (S2) (P < 0.001). CONCLUSION: Our results allow for the first time a quantification of the contribution of intraoperative cortico-subcortical DES during LGG resection. Indeed, the use of this method leads to 1) the extension of indications of LGG surgeries within eloquent areas, 2) a decrease of the risk of sequelae, and 3) an increase of the quality of tumor resection.