Regional adenosine attenuates postischemic spinal cord injury

Purpose: Operations on the thoracic and thoracoabdominal aorta are associated with postoperative paraplegia rates as high as 20% to 30%. Attempts to reduce this complication have focused on decreasing the energy 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 paraplegia. Methods: New Zealand white rabbits underwent 40 minutes of infrarenal aortic isolation. The infrarenal aorta is the primary source of spinal cord blood supply in the New Zealand white rabbit. Control rabbits sustained aortic occlusion without any protective measures. The remaining animals were randomized into three groups that underwent aortic cross-clamping with various protective adjuncts. Group I received regional aortic hypothermia perfusion, group II received systemic adenosine, and group III received regional aortic perfusion with high-dose adenosine. Results: Neurologic function was graded according to the Tarlov scale (0 = no movement, 1 = slight movement, 2 = sits with assistance, 3 = sits alone, 4 = weak hop, 5 = normal hop). After 96 hours animals were euthanized, and spinal cords were harvested for histologic 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. Histologic studies on spinal cord tissue revealed no significant differences between the study groups. Conclusions: These data demonstrate that administration of regional adenosine attenuates ischemic injury associated with aortic occlusion in this experimental model.