Invited commentary

Abstract

The bane of thoracoabdominal aortic aneurysm repair remains postoperative paralysis and paraplegia, including the delayed-onset variety. Despite study and different strategies to prevent paralysis and paraplegia, no single method of prevention has proven to be universally applicable and effective. Dr. Acher and his group have made an important observation; despite recognition of the artery of Adamkiewicz as the critical intercostal that directly supplies the spinal cord, reimplantation of this artery, or sets of additional intercostal arteries, only makes a marginal difference in rates of postoperative paraplegia when using additional spinal cord protective strategies. Thus it is likely that these other protective strategies are critical and, despite their not providing direct spinal cord reperfusion, they provide the majority of spinal cord protection during surgical procedures. As such, the modern use of adjuncts that indirectly increase spinal cord perfusion by Starling's law (tissue perfusion = input blood pressure – tissue back pressure) make sense. Maximizing systolic blood pressure increases input pressure to the tissue; removing spinal cord fluid reduces tissue back pressure; reducing cord metabolic activity reduces the need for significant input pressure. The implications for the future in which thoracic endografts will be placed with increasing frequency are clear. As endograft placement precludes revascularization of any potential critical arteries, and patients with critical arteries cannot be predicted a priori, there will be a lower limit of paralysis risk that cannot be eliminated by endograft technology with or without the use of spinal cord protective strategies. To minimize the risk of paralysis, optimization of the indirect perfusion methods must be performed. The absolute degree of protection that intercostal artery reimplantation provides is likely to be debated in the future. The importance of intercostal reimplantation may be surgeon-dependent, with increased importance of intercostal artery reimplantation for surgeons that rely on fewer additional adjuncts than used by the authors. It also remains unclear whether the benefit of intercostal artery reimplantation is limited to a specific intercostal artery, or whether any patent intercostal artery between T8 and L1 is sufficient. However, it is clear that some patients may need intercostal artery reimplantation to prevent paralysis or paraplegia, and therefore might benefit from open repair rather than an endovascular approach. Identification of this subset of patients is currently impossible. Until then, meticulous attention to details of methods that maximize spinal cord perfusion remains critical to optimizing results and minimizing the risk of adverse outcomes. A modern theory of paraplegia in the treatment of aneurysms of the thoracoabdominal aorta: An analysis of technique specific observed/expected ratios for paralysisJournal of Vascular SurgeryVol. 49Issue 5PreviewTo demonstrate that a modern theory of paraplegia prevention in thoracoabdominal aortic (TAAA) surgery is primarily non-anatomic and derives from experimentally validated interventions that prolong the ischemic tolerance, reduce reperfusion injury, and enhance the collateral perfusion of the spinal cord with or without assisted circulation. Full-Text PDF Open Archive