脊髓分级缺血再灌注损伤对运动诱发电位的影响

The effects of graded spinal cord ischemia/reperfusion injury on motor evoked potentials

目的通过比较不同程度脊髓缺血再灌注损伤(SCIRI)对运动诱发电位(MEP)的影响,探讨MEP在SCIRI后肢运动功能诊断及预后中的价值。方法采用肾下腹主动脉阻断模型,分别阻断兔腹主动脉15 min、30 min、45min和60 min后再灌注,建立不同程度SCIRI,于缺血前、缺血期间、再灌注期间监测MEP,术后采用神经功能评分(NFS)后肢运动功能,再灌注48 h进行脊髓病理学观察。结果阻断腹主动脉血流30 min、45 min、60 min后开放表现出轻、中、重不同程度缺血再灌注损伤脊髓的病理学特点。不同程度SCIRI可造成MEP明显变化,MEP波幅较潜伏期恢复迅速,损伤越重,电位越低。脊髓轻度缺血再灌注损伤时,MEP波幅和潜伏期分别明显延长及减小,NFS、MEP波幅和潜伏期恢复迅速;脊髓中度缺血再灌注损伤时,MEP波幅和潜伏期下降更加显著,NFS和MEP不能完全恢复且恢复缓慢;脊髓重度缺血再灌注损伤时,NFS、MEP波幅和潜伏期均不能够恢复至术前水平。再灌注2 h MEP波幅变化分别与再灌注2 d后的Jacobs评分(r=-0.838)和斜板试验(r=-0.901)显著相关。结论MEP能敏感而准确地反映SCIRI后运动功能的损伤程度,术中MEP监测可作为判断运动功能预后的可靠指标。

Objective By investigate the characteristics of graded spinal cord ischemia/reperfusion injury（SCIRI）on the motor eoked potentials（MEP） to study the diagnostic and prognostic value of MEP for the motor function of hind extremities.Methods The pathological characters with mild,moderate and severe SCIRI can be simulated by declamping after 30 min,45 min and 60 min infrarenal aortic cross-clamping in rabbits respectively.MEP was monitored during the preischemia,the period of ischemia and reperfusion.Neurologic function score（NFS） was used to assess the motor function of hind extremities.The lesion and damage to the spinal cord tissue were assessed with histological analysis after reperfusion 48 hour.Results MEP changed significantly with graded SCIRI and was much quicker in the recovery of amplitude than latency during SCIRI.The more sever the lesion,the lower the potentials.It showed that after spinal cord was mild injured during ischemia/reperfusion the latency of MEP increased and the amplitude of MEP decreased,but NFS and MEP recovered rapidly.MEP latency increased obviously and amplitude decreased progressively during moderate spinal cord ischemia/reperfusion,but NFS and MEP recovered slowly and incompletely.NFS and MEP could not restore to the level of preischemia during serious SCIRI.Changes in amplitude of MEP recorded after reperfusion 2 hour were collaborate significantly with Jacobs score（r =-0.838,P 0.01） and Rivlin inclined plane（r =-0.901,P 0.01） assessed after reperfusion 2 days later,and can be used as a prognostic index for the motor function of hind extremities.Conclusions MEP monitoring during operation can be used as a reliable parameter for the motor function prognosis of hind extremities,because it reflects sensitively and accurately the severity of motor function during SCIRI.