Cataloging of Resection for Glioblastoma in Patients Previously Deemed “inoperable” Using Functional or Structural Imaging

Introduction: Maximal safe resection remains a cornerstone of neurosurgical treatment for high-grade gliomas, with increased resection associated with improved outcomes. However, patients are often deemed "inoperable" based on radiological studies, which may not be as accurate as intraoperative direct electrical stimulation (DES) mapping. This can preclude an opportunity for otherwise safe resection. Here, we report the functional outcomes of glioblastoma multiforme (GBM) cases, initially considered inoperable by referring physicians, that underwent resection with DES.

Methods: An institutional retrospective review (2011–2024) was conducted on single-lesion GBM patients with a prior history of imaging and biopsy at an outside medical center were identified. After preoperative structural and functional imaging, DES-guided resections were performed, and functional outcomes were recorded. Data on demographics, tumor characteristics and operative reports were analyzed on StataIC16.1.

Results: Of 700 single-lesion GBMs identified, 50 patients met inclusion criteria with 41.7% were male and 58.3% were female. All patients presented with Karnofsky Performance Scale (KPS) scores of ≥ 70. The mean tumor size was 3.31 ± 1.14 cm, with 58.3% cases involving eloquent cortex on imaging. Intraoperative DES was performed 58.3% cases, with eloquent sites identified in 28.6% cases. Gross total resection was achieved in 83.3% cases, 8.3% achieving maximal gross total resection and 8.3% subtotal resection 8.3%. The mean length of stay was 1.42 ± 0.67 days, and 91.7% were free of any perioperative complications. No new postoperative neurological deficits were identified, and the mean improvement in modified Rankin Scale (mRS) score was -0.75 ± 0.62. The mean follow-up period was 13.9 ± 1.0 days.

Conclusion : DES mapping remains an essential tool in defining tumor resection margins and allowed for safe resection in these 50 cases of previously diagnosed "inoperable" GBM. Thus, while radiological studies can guide surgical planning, they alone cannot determine tumor resectability.