Comparative study between ischemic preconditioning and cerebrospinal fluid drainage as methods of spinal cord protection in dogs.

OBJECTIVE This study compares the effects of immediate ischemic preconditioning based on somatosensory evoked potential (SSEP) monitoring with those of cerebrospinal fluid drainage in a model of descending thoracic aorta occlusion in dogs. METHOD Eighteen dogs were submitted to spinal cord ischemia induced by descending thoracic aortic cross-clamping for 60 minutes. The Control Group underwent only aortic cross-clamping (n=6). The Ischemic Preconditioning Group (IPC) underwent ischemic preconditioning (n=6) and the Drainage Group underwent cerebrospinal fluid drainage (n=6), immediately before aortic cross-clamping. An independent observer assessed neurological status according to the Tarlov score. The animals were sacrificed and spinal cord harvested for histopathologic study. RESULTS Aortic pressure before and after the occluded segment was similar in the three groups. Seven days after the procedure, Tarlov scores were significantly higher only in the Drainage Group when compared to the Control Group (p<0.05). Lower SSEP recovery times were also observed with cerebrospinal fluid drainage during the final reperfusion period (p<0.01). In the histopathologic study, stain showed less significant neuronal necrosis in the thoracic and lumbar gray matter in animals submitted to both methods of spinal cord protection, with it being more pronounced in the Ischemic Preconditioning Group (p<0.001). CONCLUSION Cerebrospinal fluid drainage and immediate ischemic preconditioning seems to protect the spinal cord during descending thoracic aorta cross-clamping. Nevertheless, the obtained level of spinal cord protection seems to be more significant with cerebrospinal fluid drainage.