Quantitative and qualitable study on the feasibility of compound muscle action potential to monitor intraoperative spinal cord function

经颅电刺激诱发的复合肌肉动作电位(CMAP)已被广泛应用于脊柱手术中的运动功能监测。它们可能反映节段性损伤以及脊髓中与运动相关的束损伤。然而，我们经历了一些患者，他们术后出现节段性运动无力，但在手术中没有任何潜在的变化。为了评价该方法对脊髓和脊神经根选择性损伤的评估效果，我们利用猫模型观察了脊髓和脊神经根白质和灰质的电位变化与选择性损伤的关系，并在20只猫的脊髓和脊神经根损伤前和损伤后获得了CMAP。分析CMAP的波幅、潜伏期和持续时间的变化。所有猫脊髓运动相关束损伤后，CMAP波幅均显著降低，但仅限于脊髓前角某一区域或单个脊神经根时，CMAP的波幅并不总是发生变化。因此，CMAP不一定能准确反映节段性损伤，应注意对CMAP的解释。

Compound muscle action potentials (CMAPs) evoked by transcranial electrical stimulation have been widely introduced to monitor motor function during spinal surgery. They may reflect segmental injuries as well as injuries to motor-related tracts in the spinal cord. However, we have experienced some patients who have developed postoperative segmental motor weakness without any potential changes during surgery. To evaluate the efficacy of this method for the evaluation of selective injuries to the spinal cord and spinal nerve root, we used a cat model to observe the relationships between potential changes and selective injuries to the white and gray matters of the spinal cord and spinal nerve roots.CMAPs were obtained before and after injury to the spinal cord and spinal nerve roots in 20 cats. Changes in the amplitude, latency, and duration of CMAPs were analyzed. CMAPs decreased in amplitude significantly after the insult to the motor-related tracts in the spinal cord in all cats, while the potentials did not always change when the insult was restricted to a limited area in the anterior horn of the spinal cord or to the single spinal nerve root, It is concluded that CMAPs may not exactly reflect segmental injury and careful attention should be paid to the interpretation of CMAPs.