P10.08 Resection of gliomas initially deemed to be inoperable

Background: Maximal safe resection is a primary objective in the management of gliomas. Despite this, surgeons and referring physicians may, on the basis of radiologic studies alone, assume a glioma to be unresectable due to its proximity to areas of presumed functional eloquence. Because non-invasive studies, including functional MRI, may not localize brain functions, such language, with particularly high fidelity, this simplistic approach may exclude some patients from what could be a safe resection. Intraoperative direct electrical stimulation (DES) allows for the accurate localization of functional areas, thereby enabling maximal resection of tumors, including those that may appear inoperable based solely on radiologic studies. Here we describe the extent of resection and functional outcomes following resections of tumors deemed inoperable by referring physicians and neurosurgeons. Methods: We retrospectively examined the cases of 58 adult patients who underwent glioma resections within six months of undergoing brain biopsies of supposedly inoperable gliomas at outside hospitals. We characterized the extent of resection and six-month functional outcomes for this population. Results: Intraoperative DES mapping was performed on 96.6% of patients (56 of 58). Nearly half of patients (46.6%, 27 of 58) underwent an awake surgical procedure with DES. Overall, the mean extent of resection was 87.6% ± 13.6% (range, 39.0% to 100%). Gross total resection (resection of >99% of the pre-operative tumor volume) was achieved in 29.3% of patients (17 of 58). Sub-total resection (95-99% resection) and partial resection (<95% resection) were achieved in 12.1% (7 of 58) and 58.6% of patients (34 of 58), respectively. Of the cases that involved partial resection, the mean extent of resection was 79.4% ± 12.2%. Six months after surgery, no patient was found to have a new post-operative neurologic deficit. The majority of patients (87.9%, 51 of 58) were free of neurologic deficits both pre- and post-operatively. The remainder of patients exhibited either residual but stable deficits (5.2%, 3 of 58), or complete correction of pre-operative deficits (6.9%, 4 of 58). Conclusions: The use of DES enabled maximal safe resections of tumors that were deemed inoperable by referring physicians and neurosurgeons. With rare exceptions, the resectability of a glioma cannot be determined solely by radiologic studies