Laschinger J C, Owen J, Rosenbloom M, Cox J L, Kouchoukos N T
Division of Cardiothoracic Surgery, Washington University School of Medicine, St. Louis, MO.
J Vasc Surg. 1988 Jan;7(1):161-71.
Spinal cord monitoring during thoracic aneurysmectomy by somatosensory evoked potentials has been criticized for its failure to measure anterior (motor) spinal cord function. We have developed a clinically applicable, noninvasive technique for intraoperative monitoring of motor evoked potentials (MEP), which allows direct functional assessment of spinal cord motor tracts during thoracic aortic occlusion. Twelve dogs underwent continuous intraoperative monitoring of MEP before, during, and after thoracic aortic cross-clamping. Motor tract response to noninvasive cord stimulation (5 to 10 mA, 0.02 msec, 4.3 H2) was recorded by subcutaneous electrodes placed along the length of the spine (T-10, L-1, and L-4). Six animals (group I) subjected to aortic cross-clamping alone demonstrated a characteristic time- and level-dependent deterioration and loss of MEP. Ischemic cord dysfunction (as determined by time from clamping to loss of MEP) progressed from the distal to the proximal cord (L-4 = 11.3 +/- 1.5 minutes; L-1 = 14.9 +/- 2.3 minutes; T-10 = 16.9 +/- 2.3 minutes; p less than 0.05 between all levels). Reperfusion of the distal aorta 20 minutes after clamping resulted in MEP return that progressed from the proximal (T-10) to distal (L-1 and L-4) cord. In another six animals (group II), distal perfusion (mean blood pressure = 95 mm Hg) was maintained for 1 hour after cross-clamping by left atrial-femoral artery bypass. Normal configuration and amplitude of MEP was maintained throughout the cross-clamping period. These data suggest that distinctive changes in MEP indicative of reversible ischemia of spinal cord motor tracts occur after aortic cross-clamping. Such ischemia begins in the most distal cord, exhibits upward progression with time, and can be prevented by maintenance of adequate distal aortic perfusion. Clinical use of MEP monitoring during thoracic aneurysmectomy may provide a method for intraoperative assessment of the adequacy of motor tract perfusion.
胸主动脉瘤切除术中通过体感诱发电位监测脊髓，因其未能测量脊髓前部（运动）功能而受到批评。我们已经开发出一种临床适用的、非侵入性的运动诱发电位（MEP）术中监测技术，该技术可在胸主动脉阻断期间对脊髓运动束进行直接功能评估。12只犬在胸主动脉交叉钳夹前、钳夹期间和钳夹后接受了MEP的连续术中监测。通过沿脊柱长度（T - 10、L - 1和L - 4）放置的皮下电极记录运动束对非侵入性脊髓刺激（5至10 mA，0.02毫秒，4.3赫兹）的反应。仅接受主动脉交叉钳夹的6只动物（I组）表现出MEP特征性的时间和水平依赖性恶化及消失。缺血性脊髓功能障碍（根据从钳夹到MEP消失的时间确定）从脊髓远端向近端发展（L - 4 = 11.3±1.5分钟；L - 1 = 14.9±2.3分钟；T - 10 = 16.9±2.3分钟；各水平之间p < 0.05）。钳夹20分钟后远端主动脉再灌注导致MEP恢复，从近端（T - 10）向远端（L - 1和L - 4）脊髓发展。在另外6只动物（II组）中，交叉钳夹后通过左心房 - 股动脉旁路维持远端灌注（平均血压 = 95毫米汞柱）1小时。在整个交叉钳夹期间MEP的形态和振幅保持正常。这些数据表明，主动脉交叉钳夹后MEP出现明显变化，提示脊髓运动束可逆性缺血。这种缺血始于脊髓最远端，随时间向上发展，可通过维持足够的远端主动脉灌注来预防。胸主动脉瘤切除术中MEP监测的临床应用可能为术中评估运动束灌注是否充足提供一种方法。
