BACKGROUND: Aneurysms of the anterior spinal artery are extremely rare. Unlike intracranial saccular aneurysms, they do not occur at branch points, are typically pseudoaneurysms, and rupture secondary to a dissection. They typically present with subarachnoid hemorrhage and demonstrate clinical and radiographic improvement over time without treatment. METHODS: We present here the first case to date of a ruptured anterior spinal artery aneurysm with clinical and radiographic progression treated with Onyx embolization. Our patient was unique in the presentation with acute onset of spinal cord injury American Spinal Injury Association B and an extensive thoracolumbar subdural hematoma. RESULTS: An emergent skip-level laminectomy and subdural decompression were performed with no improvement in examination. This was followed by progressive radiographic enlargement of the aneurysm, treated successfully with Onyx embolization. CONCLUSIONS: We analyze this case and review the literature on thoracic anterior spinal artery and artery of Adamkiewicz aneurysms.