Magnetic Stimulation for Increasing the Tolerance to Ischemic Change of Spinal Cord ; Prevention of Risk of Paralysis Secondary to Operation

术后截瘫是主动脉瘤手术治疗后的严重并发症之一。这种复杂情况的主要原因被认为是脊髓局部循环紊乱。在一些关于脑缺血的报道中，发现磁刺激对缺血有抵抗作用。若能有类似脑的应用来替代减少的脊髓循环，将对动脉瘤手术患者有很大的帮助。在此假设下，我们进行了一系列实验，以证实磁刺激是否能增加动物模型脊髓对缺血改变的耐受性。在大鼠中，通过将充气导管插入主动脉，然后充气，暂时切断了脊髓循环。用大运动功能测试评估神经功能缺损程度。电机功能测试结果随关机时间的长短而变化。2 .连续监测经颅磁刺激（TMS）下腓肠肌运动诱发电位（MEP）的变化。刺激组连续监测MEP，对脊髓靶区（Th11-L3）进行磁刺激预处理后，主动脉循环中断10 min。对照组同样监测，只关10分钟。刺激组与对照组对MEP的反应存在差异。刺激组关闭时间后的MEP幅值明显大于关闭时间前。相反，对照组关闭时间后的MEP值小于关闭时间前。MEP监测的脊髓神经生理功能显示了磁刺激预处理前后对暂时性缺血的不同反应。这些发现应得到其他数据的证实，如组织学变化或生化评估。未来需要进一步积累有关磁刺激引起的组织反应的数据。除了这些脊髓刺激动物实验外，我们还得到了磁刺激对自主神经系统特别是血压和心率的3周脑影响的衍生结果。少

Postoperative paraparesis is one of the serious complications after operative treatment for aortic aneurysm. A main cause of this complicated condition is regarded as disturbance of local circulation of the spinal cord. In a few reports about brain ischemia there are findings to indicate resistant effect against ischemia by magnetic stimulation. If there is a possible application by analogy with brain to substitute decreased spinal cord circulation, it could be a great help for the patient with operation for aortic aneurysm. Under this hypothesis we have performed a series of experiments in order to confirm whether magnetic stimulation could increase the tolerance to ischemic change of spinal cord in animal model or not.1.In a rat the spinal cord circulation was temporarily shut off by means of a ballooned catheter inserted into the aorta and then inflated. The degree of neurological deficit was assessed with gross motor functional test. The result of motor functional test was changeab … More le according to the duration of shut off time.2.Motor evoked potential(MEP) at the gastrocunemius muscle by transcranial magnetic stimulation(TMS) was continuously monitored before, during, and after aortic circulation shut off by inflation and deflation of the ballooned catheter.3.In stimulation group the animals under continuous monitoring with MEP measurement experienced 10 min shut off of the aortic circulation after the preconditioning by magnetic stimulation for the targeting area of spinal cord (Th11-L3). In control group the animals with same monitoring had 10 min shut off only.There was different response of MEP between in stimulation group and in control group. The amplitude of MEP after shut off time was bigger than before in stimulation group. On the contrary that of MEP after shut off time was smaller than before in control group. Neurophysiological function of the spinal cord monitored in MEP measurement revealed different response against temporary ischemia with or with out preconditioning by magnetic stimulation.These findings should be confirmed by other data like histological changes or biochemical assessment. Further accumulation of data on tissue responses caused by magnetic stimulation will be needed in future.Apart from these animal experiments with spinal cord stimulation, a derivative finding on 3-weeks effect of magnetic stimulation at brain to autonomic nerve system especially blood pressure and heart rate was obtained. Less