Clinical characteristics and surgical outcomes of intradural spinal metastases: a comparative analysis between intramedullary and extramedullary lesions

Purpose: Intradural spinal metastases, including intramedullary (IM) and intradural extramedullary (IDEM) lesions, are rare manifestations of advanced systemic malignancy, and the role of surgery remains controversial. This study aimed to clarify how anatomical compartments influence surgical intent, feasibility, and postoperative neurological outcomes. Methods: We retrospectively reviewed fifteen consecutive patients who underwent surgery for intradural spinal metastases between 2010 and 2024. Lesions were classified as IM (n = 6) or IDEM (n = 9). Clinical presentation, operative characteristics, extent of resection, and adjuvant therapy were evaluated. Neurological function was assessed using the modified McCormick scale (MMCS) before and after surgery. Results: IM lesions were more frequently associated with severe preoperative neurological impairment and were predominantly located in the thoracic spine, whereas IDEM lesions were distributed across cervical, thoracic, and lumbar levels. Gross total resection was achieved more often in IDEM lesions (44.4%) than in IM lesions (16.7%). Postoperatively, neurological function improved in 5 patients (33.3%), remained stable in 6 (40.0%), and deteriorated in 4 (26.7%). Although improvement occurred in both groups, IDEM lesions more often achieved a favorable final functional status (MMCS grades I–II), whereas IM lesions frequently showed limited functional recovery. No perioperative complications were observed. Conclusions: Surgical intervention for intradural spinal metastases may be considered selectively as part of a multidisciplinary palliative strategy focused on neurological function. Anatomical compartment influences surgical feasibility, intent, and achievable outcomes. IDEM lesions may allow resection with functional recovery in selected patients, whereas IM lesions generally require a conservative, function-preserving approach with clearly defined goals.