Neuronavigation and resection of lesions located in eloquent brain areas under local anesthesia and neuropsychological-neurophysiological monitoring

Background: The aim of this study was to determine the safety and maximal extension of tumor resection achievable with a combination of awake craniotomy under local anesthesia, neuronavigation, and continuous neuropsychological and neurophysiological monitoring in patients with lesions within the eloquent brain. Methods: We have performed 55 resections of different pathologies with neuronavigation on 52 patients from January 1998 to December 2002. Mean age was 49 years, the male to female ratio was 37 to 15. All patients underwent a continuous examination by a neuropsychologist and repetitive cortical stimulations during the resection, and a 3-month postoperative neurological examination to determine functional outcome. Neurological outcome and results of resection of patients with gliomas were compared to a control group of 27 patients with lesions in the central region who were operated under general anesthesia during the same time period. Results: Tumor resection was stopped when a macroscopic total cytoreduction was achieved, or at the onset of neurological dysfunction. There was a higher rate of complete tumor resection (77% vs. 33%) and a lower rate of neurological deterioration (33% vs. 12%) in the study group compared to the control group. Overall, a complete resection in the study group was achieved in 40 patients (72%), a partial resection in 28%. Five patients developed a new deficit during surgery which resolved completely after a change of surgical strategy, 14 patients had a new deficit after surgery which improved within 3 months in 6 patients. There was no operative mortality. Conclusion: The combination of neuronavigation with cortical stimulation and repetitive neurological and language examinations allows a more radical resection of tumors in eloquent brain areas, otherwise considered as inoperable.