Parikh Pooja, Cheongsiatmoy Justin, Shilian Parastou, Gonzalez Andres A
Surgical Neurophysiology Program, Department of Neurology, University of Southern California, Los Angeles, California, U.S.A.
J Clin Neurophysiol. 2018 Mar;35(2):155-158. doi: 10.1097/WNP.0000000000000454.
Transcranial motor evoked potentials (TcMEPs) are the preferred modality to monitor the integrity of motor pathways during surgery. Recently, it has also been used as a method to help with detection of nerve roots injuries. Adequate baseline muscle responses are vital to detect nerve injury. We have observed that TcMEP responses are not homogeneous across multiple myotomes, but this has not been studied systematically. Our objective is to determine whether there are any relative differences in amplitude or morphology of TcMEPs across various lower extremity muscles.
Clinical and neurophysiological monitoring data from patients who had lumbar spine surgery were obtained retrospectively. Transcranial motor evoked potential responses were evaluated for each limb in the quadriceps, tibialis anterior, and intrinsic foot muscles. We compared TcMEP responses between these muscle groups using paired t-test statistical analysis. Each limb was analyzed separately. Only limbs without deficit in the interested muscle groups were included for analysis.
A total of 40 patients and 69 limbs were included for analysis. The mean TcMEP amplitude difference between the tibialis anterior and quadriceps muscles was 458 µV (P < 0.0001), and between intrinsic feet and quadriceps muscles was 541 µV (P < 0.0001). Proximal muscles also demonstrated a significantly smaller number of TcMEP phases than their distal counterparts.
Transcranial motor evoked potential amplitudes are significantly smaller in proximal lower extremity muscles compared with distal lower extremity muscles. The observed difference might be due to cortical representation or higher subcutaneous tissue in thigh muscles.
经颅运动诱发电位（TcMEPs）是手术中监测运动通路完整性的首选方式。最近，它也被用作一种帮助检测神经根损伤的方法。足够的基线肌肉反应对于检测神经损伤至关重要。我们观察到经颅运动诱发电位反应在多个肌节中并不均匀，但尚未对此进行系统研究。我们的目的是确定经颅运动诱发电位在下肢不同肌肉之间的幅度或形态是否存在任何相对差异。
回顾性收集接受腰椎手术患者的临床和神经生理监测数据。对股四头肌、胫前肌和足部固有肌的每个肢体的经颅运动诱发电位反应进行评估。我们使用配对t检验统计分析比较这些肌肉群之间的经颅运动诱发电位反应。每个肢体单独分析。仅纳入感兴趣肌肉群无功能障碍的肢体进行分析。
共纳入40例患者和69个肢体进行分析。胫前肌和股四头肌之间经颅运动诱发电位的平均幅度差异为458微伏（P < 0.0001），足部固有肌和股四头肌之间为541微伏（P < 0.0001）。近端肌肉的经颅运动诱发电位相位数量也明显少于其远端对应肌肉。
与下肢远端肌肉相比，下肢近端肌肉的经颅运动诱发电位幅度明显较小。观察到的差异可能是由于皮质代表区或大腿肌肉中较高的皮下组织所致。
