Intramedullary Metastases to Conus Medullaris: A Review of the Literature with a Case Illustration

Introduction: Intramedullary metastases to the conus medullaris spinalis (IMCM) pose a rare problem in neurosurgical oncology and are usually encountered as a complicated clinical scenario in the setting of advanced systemic malignancy with poor overall survival. Despite the progress in interdisciplinary oncological care, their management remains complicated. Research Question: We performed a PRISMA-guided literature search to achieve a pooled analysis of all previously reported IMCM cases that contained detailed clinical data on this problem to investigate the currently employed management options and respective outcomes. We obtained a clinical vignette and performed a comprehensive narrative review of IMCM management. Materials and Methods: The PubMed/MEDLINE/Google Scholar, Cochrane and Embase databases were systematically searched according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. All relevant publications retrieved were subjected to full-text analysis in detail and pertinent information was extracted. Results: The most common systemic primary tumor site as the origin of IMCM was the lung, followed by the breast. Overall, the pooled median survival was 6 months (range 0.5-36 months). Patients who received both surgery and radiation therapy had the longest overall survival (OS) (mean 9.9 months) and those who received no oncological treatment (neither surgery nor adjuvant therapy) had the shortest OS (mean 3.6 months). In cases where surgical resection was performed as part of the treatment plan for metastases, those with partial tumor resection had a more favorable neurological outcome than patients who underwent aggressive gross total resection. Conclusions: Based on the results of our analysis, we find that diligent microsurgical resection (subtotal or total) followed by radiation therapy appears as an effective and suitable treatment in select patients with IMCM. When surgery is not feasible as part of the treatment algorithm, radiation therapy alone (conventional or radiosurgery) also appears to be a suitable treatment option that confers a benefit to the patient.