Neurologic and Oncologic Outcomes After Surgical Resection of Intradural Extramedullary Spinal Metastases: A Systematic Review and Meta-analysis

Introduction: Intradural extramedullary (IDEM) spinal metastases create treatment challenges due to their heterogeneity in primary tumor type and complex anatomical location. Optimal treatment for such lesions remains debated. Surgical resection may benefit these patients, but literature reporting outcomes is limited, highlighting the need for a comprehensive review on the topic. This study aimed to analyze the neurologic and oncologic outcomes of surgically managed IDEM spinal metastases and compare outcomes between patients with CNS primary tumors leading to drop metastases vs. non-CNS primary tumors.

Methods: The presented systematic review and meta-analysis were performed according to PRISMA standards. Studies analyzing adults who underwent surgical resection of IDEM metastases that reported primary tumor type, preoperative neurologic status, and neurologic and survival outcomes were included. Study details, demographics, preoperative neurologic status, treatment variables, tumor characteristics, and outcomes data were collected for each eligible case in each included article. Overall outcomes, correlative regression analysis, and a sub-analysis comparing patients with CNS vs. non-CNS primary tumors were conducted.

Results: The initial search yielded 119 articles. Seventy-five were excluded through screening, which left 44 articles, encompassing 113 cases, in our final analysis. 74.1% of cases (83/112) showed neurologic improvement postoperatively, while only 7.2% of patients (8/112) experienced neurologic worsening postoperatively. Regression analysis revealed that non-gross total resection (GTR) correlated significantly with postoperative neurologic worsening (P=0.047). Alternatively, primary tumor type did not correlate with any outcome measure. Further sub-analyses demonstrated that those with primary CNS tumors were younger at date of treatment (44.0 vs. 62.0 years, P< 0.001) and had better overall survival (12.4 vs. 8.42 months, P=0.006) than those with non-CNS primaries.

Conclusion : These results suggest that surgical management is safe and effective for IDEM spinal cord metastases, particularly when GTR is thought to be achievable. Symptomatic patients likely stand to benefit most from surgery.