Supplementary Material for: Isolated intramedullary spinal cord metastasis from nasopharyngeal carcinoma: a case report and systematic review

Background Nasopharyngeal carcinoma (NPC) is rare, with distant metastases often found in bones, lungs, and liver. Intramedullary spinal cord metastasis (ISCM) is extremely uncommon, and the optimal treatment remains unclear. We report a case of isolated ISCM in a patient with NPC and provide a systematic review of the literature. Methods A 31-year-old male with stage IVA (T4N2M0) NPC received induction chemotherapy, followed by concurrent chemoradiation. The patient later developed isolated ISCM without other locoregional or distant metastases. Surgical resection and postoperative radiotherapy were then performed. A systematic literature search followed PRISMA guidelines using the MEDLINE and EMBASE databases to identify articles describing ISCM in NPC. The extracted data included the demographics, staging, treatment, and outcomes. Results Among 1040 articles (1970‒2024), 42 met the initial criteria, and seven specifically addressed ISCM. Only 3 cases involved truly isolated intramedullary metastases. ISCM is likely to spread through cerebrospinal fluid dissemination. Most reports describe palliative treatments, including surgery, radiation, and chemotherapy. Conclusions Isolated ISCM from NPC is extremely rare. Aggressive local therapy may improve symptoms and prolong patient survival. Multimodal approaches, including surgery and radiotherapy, are often required; however, the overall prognosis remains unknown.