Piediction of spinal cord function by transcranial magnetic evoked compound muscle action potential and spinal cord potential

诱发复合肌肉动作电位（ECMAP）作为脊髓损伤指标的有效性尚未建立在运动功能的神经生理监测。研究ECMAP确定的脊髓损伤临界点，以预测患者术后运动功能的结果。使用了10只猫。开颅手术后，对运动区进行电刺激。记录桡侧腕伸肌EGMAP和C6水平脊髓诱发电位（ESCP）。给予5只猫不同数量和频率的刺激，以表征最大ECMAP振幅的刺激条件。另5只猫在C3节段进行脊髓分级压迫，记录EGMAP和ESCP。此后唤醒3只猫，并在3周后评估其运动功能。记录EGMAP的最大振幅，以响应5个连续的500 Hz刺激。脊髓压迫引起EGMAP波幅降低，潜伏期延长。ESCPs也表现出幅度下降和延长的潜伏期下压缩。即使ECMAP消失，ECMAP的振幅也从未低于对照值的60%。实验后3周未出现运动功能障碍。ECMAP是检测脊髓运动功能损害的一种非常敏感的神经生理学监测方法。然而，仅凭ECMAP而不使用ESCP很难预测预后，因此，建议同时使用EGMAP和ESCP来预测术后运动功能的结果。

The validity of the evoked compound muscle action potential (ECMAP) as an index of spinal cord injury has not been established in neurophysiological monitoring of motor function. The critical point of the spinal cord injury determined by ECMAP was investigated to predict the postoperative outcome of the patient's motor function. Ten cats were used. After craniotomy, electric stimuli were applied to the motor area. EGMAP from extensor carpi radialis muscle and evoked spinal cord potential (ESCP) from C6 level were recorded. Five cats were given stimulation of varying numbers and frequencies to characterize the stimulus condition for maximum ECMAP amplitude. The other five cats underwent graded compression of the spinal cord given at C3 level and EGMAPs and ESCPs were recorded. Three cats were awakened thereafter, and their motor function was assessed 3 weeks later. The maximum amplitude amplitude of the EGMAP was recorded in response to 5 consecutive stimuli at 500 Hz. Compression of the spinal cord caused a decrease in the amplitude of the EGMAP and prolongation of the latency under compression. ESCPs also showed a decrease in amplitude and prolongation of the latency under compression. The amplitude (of the ECMAP never fell below 60% of the control value even when ECMAPs disappeared. No motor dysfunction was encountered 3 weeks after the experiment. ECMAP is a very sensitive neurophisiological monitoring method for detection of the jeopardizing of spinal cord motor function. However, it is difficult to predict the prognosis based on ECMAP without the use of ESCP.Therefore, simultaneous use of EGMAP and ESCP is recommended to predict the postoperative outcome of the motor function.