The collateral network concept: A reassessment of the anatomy of spinal cord perfusion

Abstract

OBJECTIVE Prevention of paraplegia following repair of thoracoabdominal aortic aneurysms (TAAA) requires understanding the anatomy and physiology of the blood supply to the spinal cord. Recent laboratory studies and clinical observations suggest that a robust collateral network must exist to explain preservation of spinal cord perfusion when segmental vessels are interrupted. An anatomical study was undertaken. METHODS Twelve juvenile Yorkshire pigs underwent aortic cannulation and infusion of a low-viscosity acrylic resin at physiological pressures. After curing of the resin and digestion of all organic tissue, the anatomy of the blood supply to the spinal cord was studied grossly and using light and electron microscopy. RESULTS All vascular structures ≥ 8μm in diameter were preserved. Thoracic and lumbar segmental arteries (SAs) give rise not only to the anterior spinal artery (ASA), but to an extensive paraspinous network feeding the erector spinae, iliopsoas, and associated muscles. The ASA, mean diameter 134±20 μm, is connected at multiple points to repetitive circular epidural arteries with mean diameters of 150±26 μm. The capacity of the paraspinous muscular network is 25-fold the capacity of the circular epidural arterial network and ASA combined. Extensive arterial collateralization is apparent between the intraspinal and paraspinous networks, and within each network. Only 75% of all SAs provide direct ASA-supplying branches. CONCLUSIONS The ASA is only one component of an extensive paraspinous and intraspinal collateral vascular network. This network provides an anatomic explanation of the physiological resiliency of spinal cord perfusion when SAs are sacrificed during TAAA repair.

Surgical repair of descending thoracic and thoracoabdominal aortic aneurysm involving the distal arch: Open proximal anastomosis under deep hypothermia versus arch clamping technique

“…CSF drainage was used in these 7 patients (extent I or II; 100%), and in 1 of the 2 patients with DTA only (1 of 2; 50%). The results of our study support the collateral network concept described by Griepp and colleagues 13 ; occlusion of the collateral flow from the LSCA or hypogastric artery may influence spinal cord ischemia, 11 and mild or moderate hypothermia alone may not afford sufficient spinal cord protection during the clamping period. This hypothesis is also supported by data from the European Registry on Endovascular Aortic Repair Complications, 23 which showed that extensive coverage of intercostal arteries alone was not associated with spinal cord injury, but simultaneous closure of the collateral vascular territories was highly related to the development of spinal cord injury.…”

“…11,12 Furthermore, temporary occlusion of the left subclavian artery (LSCA) may potentially reduce spinal cord perfusion and increase the risk of spinal cord ischemic injury. 11,13 There is currently no consensus on the optimal method for proximal control in open repair of DTA/TAAA involving the distal arch, and previous studies on this topic have been limited. Thus, the aim of this study was to compare the clinical outcomes of DHCA versus AC in the surgical repair of DTA/TAAA involving the distal arch.…”

Anatomia da circulação medular

“…The posterior radicular artery follows a anterior radicular artery anterior radicular a., 9,10,20 medullary a., 12 anterior medullary a., 18 anterior radiculomedullary aa., 16,17 a. radicular anterior, 19 anterior spinal canal a., segmental a. 21 Ramo radicular anterior (TA)…”

Thoracic endovascular repair first for extensive aortic disease: the staged hybrid approach

“…It is no longer believed that preservation of flow to a solitary critical artery is enough to protect the spinal cord. Rather, the SAs are part of a more extensive paraspinal and intraspinal collateral network which is fed predominantly from the sub-clavian artery branches from above, and from the hypogastric artery branches from below [18]. Experimental studies have demonstrated that the collateral network undergoes remodelling after extensive segmental artery sacrifice with an increase in the diameter of the spinal artery within 24 h and further enlargement by nearly 100% within 5 days [19].…”