The anatomy of the spinal cord collateral circulation.

Abstract

Spinal cord injury remains a devastating complication of the treatment of extensive thoracoabdominal aortic aneurysms (TAAA), whether by open surgery or endovascular strategies. Although the incidence and pattern of occurrence of spinal cord injury have been changing in recent years, the threat of possible paraplegia or paraparesis continues to deter patients from undergoing elective operations to prevent rupture of extensive TAAA. A better understanding of the anatomy and physiology of the spinal cord circulation have in recent years led to a reduction in the risk of postoperative spinal cord ischemia; further insights should soon enable us to make postoperative paraplegia and paraparesis a very rare complication of TAAA treatment. A number of clinical and experimental findings led us to question the traditional view that spinal cord perfusion is dependent principally upon a single prominent branch from the descending aorta with a distinctive hairpin configuration, the so-called artery of Adamkiewicz (1). We proposed instead the existence of an extensive collateral network that supports spinal cord perfusion. This collateral network includes all the segmental arteries (SAs), both intercostal and lumbar: they send branches to the anterior spinal artery (ASA), the major artery within the spinal canal. In addition to multiple SA inputs, the ASA is also potentially fed by an extensive epidural arterial network, and by a dense array of small vessels which supply the paraspinal musculature. All these vessels are interconnected, and have major anastomoses with the subclavian arteries cranially, and the hypogastric arteries caudally. This extensive collateral network allows compensatory flow to the spinal cord when some of the direct inputs to the ASA are compromised during repair