Spinal cord ischemia after abdominal aortic operation: is it preventable?

PURPOSE: Spinal cord ischemia after operation on the abdominal aorta is a rare event that is attributed to variations in the spinal cord blood supply. The purpose of this study was to evaluate the possible causes of this devastating event.
METHODS: A survey of patients among the members of the Southern Association for Vascular Surgery was performed, and 18 patients were identified with spinal cord ischemia manifested by paraplegia or paraparesis after abdominal aortic operation.
RESULTS: Preoperative computed tomographic, magnetic resonance, and aortographic results did not visualize the greater radicular artery (Adamkiewicz's artery) in any patient. Eleven patients underwent resection of infrarenal abdominal aortic aneurysms (AAAs): seven of these patients had tube grafts, three had aortobifemoral grafts, and one had an aortobiiliac graft. Five other patients underwent placement of aortobifemoral grafts, and one patient underwent aortobiiliac graft placement for occlusive disease. One patient underwent suprarenal AAA resection with an interposition graft to a previous aortobiiliac graft. The mean operative time was 3 hours and 39 minutes (range, 2 hours and 45 minutes to 6 hours and 30 minutes), with a mean aortic cross-clamp time of 48 minutes (range, 24 to 97 minutes). Sixteen aortic cross-clamps were placed infrarenally and two suprarenally (one in a case of ruptured AAA, the other a suprarenal AAA). Seventeen proximal anastomoses were end to end. The average minimum systolic blood pressure during the aortic cross-clamping was 96 mm Hg (range, 80 to 130 mm Hg). All the patients had internal iliac artery flow preserved with either prograde perfusion (10 patients) or retrograde perfusion (eight patients), and one patient underwent unilateral internal iliac artery ligation because of aneurysmal disease. One aortobifemoral-graft limb necessitated thrombectomy, but no cases of massive peripheral embolization occurred. When paraplegia was suspected after operation (6 to 20 hours after surgery), five patients underwent lumbar drainage. No clinical improvement was noted.
CONCLUSION: Interference with pelvic blood supply from prolonged aortic cross clamping, intraoperative hypotension, aortic embolization, and interruption of internal iliac artery circulation have all been suggested as possible causes of spinal cord ischemia. In this survey, none of these factors proved to be significant as the sole cause of spinal cord ischemia. In the performance of an aortic operation with an end-to-end proximal anastomosis in the presence of severe external or internal iliac artery disease, there may be an increased incidence of spinal cord ischemia despite appropriate surgical techniques to ensure internal iliac perfusion. Spinal cord ischemia after abdominal aortic operations appears to be a tragically unpredictable, random, and unpreventable event.