Reuter D G, Tacker W A, Badylak S F, Voorhees W D, Konrad P E
Hillenbrand Biomedical Engineering Center, Purdue University, West Lafayette, Ind. 47907.
J Thorac Cardiovasc Surg. 1992 Aug;104(2):262-72.
The prevalence of morbidity is a major deterrent to the success of aortic aneurysm replacement operations. We have developed a model of spinal cord ischemia, based on the amplitude reduction of the motor-evoked potential, which produces approximately a 90% prevalence of paraplegia. Regional blood flow was studied with the use of radioactive microspheres, and results showed that there was a significant decrease in flow to the lumbar cord (85% reduction) during aortic occlusion, followed by a twofold to threefold hyperemia that persisted for 24 hours. Histopathologic examination of the cord revealed that the greater portion of microgliosis, spongiosis, and neuronal damage was confined to the gray matter of the cord, and its severity increased as one progressed caudally. The somatosensory-evoked potential disappeared before the motor-evoked potential L-2 signal in all dogs, with a mean disappearance time of 10.9 +/- 5.6 minutes, compared with 21 +/- 6.6 minutes for the motor-evoked potential. Both the sensory-evoked potential and the motor-evoked potential cord signal were present 24 hours later in all dogs tested. The peripheral nerve motor-evoked potential disappeared within 1 minute of cord ischemia, was not present 24 hours later, and hence appears to be too sensitive to use as an indicator of spinal cord damage. Plotting spinal cord motor-evoked potential amplitude reduction versus both histopathologic damage and regional blood flow revealed a positive correlation between motor-evoked potential amplitude reduction, decreased cord perfusion, and increased histopathologic damage. In addition, it may be possible to make inferences about the neurologic status of a subject based on the magnitude and time-course of the motor-evoked potential's amplitude reduction and wave morphology.
发病率是主动脉瘤置换手术成功的主要阻碍因素。我们基于运动诱发电位幅度降低建立了一种脊髓缺血模型，该模型导致截瘫的发生率约为90%。使用放射性微球研究了局部血流，结果显示在主动脉阻断期间，腰段脊髓血流显著减少（减少85%），随后出现持续24小时的两倍至三倍的充血。脊髓组织病理学检查显示，大部分小胶质细胞增生、海绵样变和神经元损伤局限于脊髓灰质，且其严重程度随尾端进展而增加。在所有犬中，体感诱发电位在运动诱发电位L-2信号之前消失，平均消失时间为10.9±5.6分钟，而运动诱发电位的平均消失时间为21±6.6分钟。在所有接受测试的犬中，24小时后感觉诱发电位和运动诱发电位脊髓信号均存在。周围神经运动诱发电位在脊髓缺血1分钟内消失，24小时后不存在，因此似乎过于敏感，不能用作脊髓损伤的指标。绘制脊髓运动诱发电位幅度降低与组织病理学损伤和局部血流的关系图，结果显示运动诱发电位幅度降低、脊髓灌注减少和组织病理学损伤增加之间呈正相关。此外，根据运动诱发电位幅度降低的程度和时间进程以及波形形态，有可能推断受试者的神经状态。
