Institute of Clinical Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan; Faculty of Medicine, College of Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan; Department of Otolaryngology-Head and Neck Surgery, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan; Department of Otolaryngology, Kaohsiung Municipal Hsiao-Kang Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
Endocrine Surgery Research Center, Department of Surgical Sciences, University of Insubria, Varese-Como, Varese, Italy.
Surgery. 2014 Feb;155(2):329-39. doi: 10.1016/j.surg.2013.08.015. Epub 2013 Sep 29.
Operative traction of the thyroid lobe is a necessary component of thyroid surgery. This surgical maneuver can cause traction injury of the recurrent laryngeal nerve (RLN), and this complication has been reported to be the most common mechanism of nerve injury. The goal of this study was to investigate the electromyographic (EMG) signal pattern during an acute RLN traction injury and establish reliable strategies to prevent the injury using intraoperative neuromonitoring (IONM).
Fifteen piglets (30 RLNs) underwent IONM via automated periodic vagal nerve stimulation and had their EMG tracings recorded and correlated with various models of nerve injury.
In the pilot study, a progressive, partial EMG loss was observed under RLN tractions with different tension (n = 8). The changes in amplitudes were more marked and consistent than were the changes in latency. The EMG gradually gained partial recovery after the traction was relieved. Among the nerves injured with electrothermal (n = 4), clamping (n = 1), and transection (n = 1) models, the EMG showed immediate partial or complete loss, and no gradual EMG recovery was observed. Another 16 RLNs were used to investigate the potential of EMG recovery after different extents of RLN traction. We noted the EMG showed nearly full recovery if the traction stress was relieved before the loss of signal (LOS), but the recovery was worse if prolonged or repeated traction was applied. The mean restored amplitudes after the traction was relieved before, during, and after the LOS were 98 ± 3% (n = 6), 36 ± 4% (n = 4), and 15 ± 2% (n = 6), respectively.
RLN traction injury showed graded, partial EMG changes; early release of the traction before the EMG has degraded to LOS offers a good chance of EMG recovery. IONM can be used as a tool for the early detection of adverse EMG changes that may alert surgeons to correct certain maneuvers immediately to prevent irreversible nerve injury during the thyroid operation.
甲状腺叶的手术牵引是甲状腺手术的必要组成部分。这种手术操作会导致喉返神经（RLN）的牵引损伤，这种并发症已被报道为神经损伤最常见的机制。本研究的目的是探讨急性 RLN 牵引损伤时肌电图（EMG）信号模式，并通过术中神经监测（IONM）建立可靠的预防损伤策略。
15 头小猪（30 个 RLN）通过自动周期性迷走神经刺激进行 IONM，并记录其 EMG 轨迹，并与各种神经损伤模型相关联。
在初步研究中，在不同张力下对 RLN 进行牵引时，观察到渐进性、部分性 EMG 丧失（n=8）。与潜伏期相比，振幅的变化更为显著和一致。在解除牵引后，EMG 逐渐部分恢复。在电热（n=4）、夹闭（n=1）和横断（n=1）损伤模型中，EMG 立即出现部分或完全丧失，没有观察到逐渐的 EMG 恢复。在进一步研究不同程度的 RLN 牵引对 EMG 恢复的潜力时，我们注意到如果在信号丢失（LOS）前解除牵引，EMG 几乎可以完全恢复，但如果长时间或重复牵引，恢复情况会更差。在 LOS 之前、期间和之后解除牵引后，EMG 恢复的平均幅度分别为 98±3%（n=6）、36±4%（n=4）和 15±2%（n=6）。
RLN 牵引损伤显示出分级、部分性 EMG 变化；在 EMG 降低到 LOS 之前，早期解除牵引为 EMG 恢复提供了很好的机会。IONM 可作为早期检测不良 EMG 变化的工具，这可能会提醒外科医生立即纠正某些操作，以防止甲状腺手术中不可逆的神经损伤。
