| Because of the improvement of the technology and equipment of the spine surgery, lots of risky operations can be done extensively, including the high risky spinal cord surgery which has been denied in the past, the surgery of excising the tumor and the operation of deformity remediation. But it is puzzled that even with the careful operation, there are some complication occur after surgery. How to avoid the iatrogenic complication of the spinal cord is the unsolved problem completely.The somatosensory evoked potential (SEP) was introduced during the intraoperative monitoring in 1980's. Now, the technology has developed into using both SEP and MEP, it enhance the reliability of the intraoperation monitoring, so the iatrogenic complication of the spinal cord injury decreases. Besides the factor of mechanic, the factor of biochemical and blood flow are also the cause of spinal cord injury. So we start this work on the rabbit model of spinal cord ischemia and reperfusion injury.Objectives: To investigate somatosensory evoked potential in the rabbit model of spinal cord ischemia and reperfusion injury, especially its changes during reperfusion and its relationship to hind limb motor and sensory function.Methods: The rabbits were divided into 3 groups. Acute spinal cord ischemia was induced in the anesthetized rabbits by occlusion of the infrarenal abdominal aorta just beneath left renal artery for 20minutes(Group A), 30minutes (Group B), 40minutes (Group C). Cortical somatosensoryevoked potentials, elicited by stimulating the posterior tibial nerve and recorded at the skull surface corresponding to sensory projection area was monitored immediately before and during ischemia and at different time points of reperfusion up to 6 hours after disocclusion. The different time points are 30, 60, 120, 180, 240, 360minutes. The amplitude and the latency of the SEP were recorded and measured. Hind limb motor and sensory function were evaluated and correlated with cortical somatosensory evoked potentials. Get the specimen of the spinal cord of animal Group c after 6 hours reperfusion, and observe their pathology.Results: Cortical somatosensory evoked potentials disappeared gradually after the start of occlusion and reappeared during reperfusion. But the amplitude of the wave form descended again in the later and the latency of SEP were the same as the normal spinal cord. It is found that if the amplitude>44%, there is no abnormal with the hind limb of the animal; and if the amplitude<35%, there is serious abnormal with the hind limb of the animal.Conclusions: Reperfusion injuryies to the spinal cord might occur in the rabbit model after disocclusion. Cortical somatosensory evoked potentials seemed to be a very sensitive index for spinal cord ischemia. |
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