Letters

Abstract

To the Editor: Re: Usul H, Arslan E, Cansever T, et al. Effects of clotrimazole on experimental spinal cord ischemia/reperfusion injury in rats. Spine 2008;33:2863–7. We read the article by Usul et al1 with interest and concern. They induced spinal cord ischemia via abdominal aorta (AA) clamping just below the renal artery for 45 minutes. The unreliability of this technique has been reported.2 This technique does not predictably induce pathologic (light microscopy) or behavioral changes compatible with spinal cord ischemia. However, this method is still used by some researchers. Behavior assessment has not been mentioned in the article.1 In our previous study, aneurysm clip compression of the aorta below the renal artery did not induce neurologic deficit using the Tarlov classification. We concluded that this method did not predictably produce ischemia in the spinal cord.2 To produce ischemia in the spinal cord of rats, occlusion of the aortic arch or proximal of descending aorta is recommended. The method of induction of spinal cord injury (SCI) in rats is different from rabbits due to the difference in blood supply to the spinal cord. SCI can be easily achieved by clamping the AA just below the renal artery in rabbits. Although induction of SCI in rats with occlusion of AA and “its branches” has been reported, the efficacy of this method has not yet been evaluated. It is unlikely that occlusion of the AA below the renal artery even for a 45 minutes period induces predictable SCI in rats. This is because “the great anterior radicular artery (artery of Adamkiewicz), the only feeder to the lower thoracic and lumbosacral cord, arises from T11 to T13. Thus, the clamp is often placed distal to the origin of the artery of Adamkiewicz3 so it does not reduce the blood supply to the lumbosacral spinal cord. On the other hand, increased arterial pressure proximal to the cross-clamp may contribute to preserve neurologic function after aortic occlusion.”2 Mohammad R. Rasouli, MD Vafa Rahimi-Movaghar, MD Sina Trauma and Surgery Research Center Sina hospital, Tehran University of Medical Sciences Tehran, Iran Alexander R. Vaccaro, MD Department of Orthopaedic Surgery Thomas Jefferson University Philadelphia, PA