REGIONAL ADENOSINE ATTENUATES POSTISCHEMIC SPINAL-CORD INJURY

Purpose: Operations on the thoracic and thoracoabdominal aorta are ass ociated with postoperative paraplegia rates as high as 20% to 30%. Att empts to reduce this complication have focused on decreasing the energ y needs of the spinal cord with protective agents such as hypothermia and barbiturates or on increasing blood flow with various shunts. This study explores the hypothesis that perfusion of the spinal cord with hypothermic solutions or with adenosine will prevent or ameliorate par aplegia. Methods: New Zealand white rabbits underwent 40 minutes of in frarenal aortic isolation. The infrarenal aorta is the primary source of spinal cord blood supply in the New Zealand white rabbit. Control r abbits sustained aortic occlusion without any protective measures. The remaining animals were randomized into three groups that underwent ao rtic cross-clamping with various protective adjuncts. Group I received regional aortic hypothermia perfusion, group II received systemic ade nosine, and group Ill received regional aortic perfusion with high-dos e adenosine. Results: Neurologic function was graded according to the Tarlov scale (0 = no movement, 1 = slight movement, 2 = sits with assi stance, 3 = sits alone, 4 = weak hop, 5 = normal hop). After 96 hours animals were euthanized, and spinal cords were harvested for histologi c examination. The nonparaplegic animals in group I had a mean Tarlov score of 1.5, whereas those in group III had a mean score of 3.4. Hist ologic studies on spinal cord tissue revealed no significant differenc es between the study groups. Conclusions: These data demonstrate that administration of regional adenosine attenuates ischemic injury associ ated with aortic occlusion in this experimental model.