Tumor surgery within cerebral eloquent areas: A two-institutions experience

Introduction: Tumor surgery within eloquent areas represents a formidable challenge and the use of electrical cortico-subcortical stimulation mapping (ESM), allows to localize sensorimotor and language areas and pathways. Our aim is to point out methodological issues of ESM and its impact on outcome at the light of a prospective analysis of a two-institution series of 159 patients with lesions involving eloquent areas with a lengthy follow up. Material and Methods: All patients operated on for lesions involving eloquent areas between May 2000 and May 2010 at the Neurosurgical Department of the Neurological and Neurosurgical Hospital 'P. Wertheimer' in Lyon (France) and at the Neurosurgical Department of the University Hospital in Catanzaro (Italy), were enrolled prospectively in our study. Results: Of 159 consecutive patients, 141 of them underwent surgical removal of the lesion with the aid of electrical cortico-subcortical stimulation mapping integrated in a setting of intraoperative localization of anatomic landmarks for eloquent areas. For the remaining 18 patients ESM was not deemed useful or feasible: 15 patients received a biopsy and 3 patients received tumor debulking under general anesthesia. For patients operated with ESM, it was possible to achieve a gross total removal of the lesion in 67,4% of cases (95 patients). One patient died in the immediate postoperative period for a pulmonary embolism. At a total mean follow-up of 62.8 months 78 patients were alive, 62 of which were recurrence free and had a KPS of 70% or more, while the other 80 patients had a mean survival time of 23.9 months, with a mean high quality survival period (KPS ≥ 70) of21.6 months. Discussion and Conclusion: Intraoperative electrical language and motor mapping, when feasible and indicated, consistently localizes eloquent cortical areas and subcortical pathways and allows to set the tumor resection boundaries according to functional limits, with a favorable impact on survival and quality of life. Integration of neurofunctional data with anatomic landmarks is nonetheless useful to expedite the surgical procedure and improve specificity and sensibility of functional mapping