Echo-guided identification of key lumbar arteries supplying the spinal cord in a canine model.

The aim of this study was to anatomically verify echo-guided identification of key lumbar arteries supplying blood to the spinal cord and to examine whether changes in nerve root motion could be used for detecting malperfusion following aortic cross-clamping. In two beagle dogs, nerve root motion was monitored through the intervertebral disc using transesophageal echocardiography. Communications between each lumbar artery and the spinal vasculature were assessed by echogenic signals in the spinal cord following saline injection into each lumbar artery. Nerve root motion immediately disappeared after clamping the aorta and recovered as soon as it was declamped. These changes were induced specifically by clamping the aorta at the first lumbar level. The changes were instantaneous and may be beneficial because of minimal ischemic insult of the spinal cord. In dog #1, the result of the saline injection test was anatomically verified with the presence of a spinal branch. However, in dog #2 echogenic signals appeared in the muscles as well as in the spinal artery. A morphological study showed no spinal branch of the lumbar artery but only an indistinct artery in the intervertebral foramen. These findings probably account for those cases in humans where there is unsuccessful visualization of the Adamkiewicz artery by angiography. Consequently, the above two assessments identified the key artery. Cessation of nerve root motion following segmental clamping of the aorta and echogenic signals in the spinal cord following saline injection into a lumbar artery may represent the key artery with respect to hemodynamics and perfusion, respectively.