Migratory low velocity intradural lumbosacral spinal bullet causing cauda equina syndrome: report of a case and review of literature

Background Migration of the bullet within the spinal subarachnoid space has long been recognized as unusual complication of spinal gunshot injury. Objective We report a case of migratory low velocity intradural lumbosacral spinal bullet causing cauda equina syndrome. The relevant literature is reviewed and all cases of migratory spinal bullet are summarised, and management strategies are discussed. Study design Literature review. Methods A 32-year-old male suffered abdominal gunshot injury for which emergency laparotomy and repair of colonic perforation were performed. The bullet was seen lodged within the sacral spinal canal behind the S1 vertebral body. The probable entry point was at L2-L3 level. Caudal migration of the bullet within the spinal subarachnoid space leads to the appearance of cauda equina syndrome. Results Bullet was retrieved following upper sacral and lower lumbar laminectomy. Prone positioning of the patient had lead to cranial migration of the bullet at L4 level which was confirmed on fluoroscopy. Laminectomy had to be extended upwards with the patient in reverse Trendelenburg position for bullet removal. Conclusions Caudal migration of the bullet within the lumbosacral subarachnoid space results in cauda equina syndrome. Surgical retrieval of the bullet ensures the early recovery of neurological symptoms. Prone patient positioning can influence bullet location. Intraoperative fluoroscopy prior to skin incision is essential in addition to preoperative imaging to locate the bullet and thus avoid incorrect lower level laminectomy. Trapping the bullet after durotomy using suction and dissector in reverse Trendelenburg position is a useful aid in bullet removal.