Blood distribution to the anterior spinal artery from each segment of intercostal and lumbar arteries.

AIM: Prevention of paraplegia, a serious complication of surgery for thoracoabdominal aortic aneurysm, has been well documented. However no assured prophylaxis against this complication has yet been found. Spinal ischemia is believed to be the major cause of paraplegia. We conducted an experimental study to define the development of paraplegia with regard to the blood supply to the spinal cord. METHODS: A porcine model was used to evaluate blood distribution to the anterior spinal artery. Colored silastic agent was selectively injected into the intercostal and lumbar arteries, and distribution to the anterior spinal artery was evaluated on 50 animals. The intercostal and lumbar arteries were ligated in the segments where the blood supply to the anterior spinal artery would be interrupted. Whether or not paraplegia developed was checked 2 days later. RESULTS: Colored silastic agent arrived at the anterior spinal artery from all segments of the 8th intercostal to 4th lumbar arteries. Two of 9 pigs (22.2%) that underwent ligation of the segments from the 9th intercostal to 2(nd) lumbar artery suffered paraplegia. In 3 non-paraplegic pigs, colored silastic agent injected into the preserved arteries was found to have covered a wider range. CONCLUSION: All the intercostal and lumbar arteries supplied blood to the anterior spinal artery. When large segments of intercostal and lumbar arteries were ligated, the blood flow from the preserved segments acquired increased dominance. The possibility exists that any intercostal and lumbar artery can supply blood to the spinal cord and become collateral circulation to the anterior spinal artery.