SPINAL-CORD ISCHEMIC-INJURY - DEVELOPMENT OF A NEW MODEL IN THE RAT

Background and Purpose Spinal cord ischemic injury (SCII) with resulti ng paralysis is a major cause of morbidity after operations on the tho racic aorta. Since the vascular supply to the spinal cord is similar i n rats and humans, the rat appears important for studies of mechanisms of injury and development of therapeutic strategies to avoid this com plication. Methods In group A rats, we induced SCII using a previously described method, by occluding the descending thoracic aorta for 15, 20, 24, or 30 minutes with the inflated balloon of a 2F Fogart cathete r inserted through the femoral artery. In group B, the catheter was in serted through the left common carotid artery, and the aorta was occlu ded just distal to the carotid origin for 20 minutes. In group C, in a ddition to the procedure described for group B, hypovolemia was induce d during a 12-minute period of aortic occlusion by equilibrating the l eft femoral artery pressure to the atmospheric pressure. The motor fun ction of the hind limbs and the associated spinal cord histopathology were studied. Results At 96 hours, 9 of 10 rats in group C were parapl egic. This rate was significantly higher than that of group A (1 of 21 , P=.00000) or group B (4 of 10, P<.03). In all groups, the histopatho logical changes became more severe from the rostral to the caudal dire ction along the spinal cord and from the peripheral to the central loc ation in transverse sections. Conclusions The combination of aortic ar ch occlusion with induced hypovolemia resulted in a reproducible model of SCII in rats.