Mechanisms and prevention of anterior spinal artery syndrome following abdominal aortic surgery.

Paraplegia or paraparesis occurring as a complication of thoracic or thoracoabdominal aortic aneurysm repair is a well known phenomenon, but the vast majority of elective abdominal aortic aneurysm repairs are performed without serious neurological complications. Nevertheless, there have been many reported cases of spinal cord ischaemia following the elective repair of abdominal aortic aneurysms (AAA); giving rise to paraplegia, sphincter incontinence and, often, dissociated sensory loss. According to the classification made by Gloviczki et al. (1991), this presentation is classified as type II spinal cord ischaemia, more commonly referred to as anterior spinal artery syndrome (ASAS). It is the most common neurological complication occurring following abdominal aortic surgery with an incidence of 0.1-0.2%. Several aetiological factors, including intra-operative hypotension, embolisation and prolonged aortic crossclamping, have been suggested to cause anterior spinal artery syndrome, but the principal cause has almost always been identified as an alteration in the blood supply to the spinal cord. A review of the literature on the anatomy of the vascular supply of the spinal cord highlights the significance of the anterior spinal artery as well as placing additional emphasis on the great radicular artery of Adamkiewicz (arteria radicularis magna) and the pelvic collateral circulation. Although there have been reported cases of spontaneous recovery, complete recovery is uncommon and awareness and prevention remains the mainstay of treatment. However, being so tragically unpredictable and random, spinal cord ischaemia after abdominal aortic operations appears to be an unpreventable event.