Aygun Nurcihan, Mihmanli Mehmet, Isgor Adnan, Uludag Mehmet
Department of General Surgery, University of Health Sciences Turkey, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Turkey.
Department of General Surgery, Memorial Sisli Hospital, Istanbul, Turkey.
Sisli Etfal Hastan Tıp Bul. 2022 Mar 28;56(1):145-153. doi: 10.14744/SEMB.2022.25874. eCollection 2022.
We observed significant contractions in the cricothyroid muscle (CTM) after recurrent laryngeal nerve (RLN) stimulation in some patients. We aimed to evaluate whether these contractions resulted from the laryngeal-muscle movement due to the contraction of other intrinsic muscles or actual CTM contraction, with objective real-time intraoperative electromyography (EMG) recordings.
This study was performed prospectively in 106 consecutive patients who underwent intraoperative neural monitoring-guided primary thyroid surgery due to various thyroid diseases between February-2015 and February-2016. After completion of the thyroidectomy procedure; the RLN, vagus nerve (VN), external branch of the superior laryngeal nerve (EBSLN), plexus pharyngeus (PP), and contralateral EBSLN (CEBSLN) were stimulated and the responses from the CTM and CPM were recorded and evaluated by EMG through needle electrodes.
182 CTMs of 106 patients, with the mean age of 45, were evaluated regarding their innervation patterns. Positive EMG waveforms were achieved from 181 CTMs with EBSLN stimulation. A total of 132 (74%) positive EMG responses were recorded after the stimulation of 179 RLNs. The mean amplitude obtained with CTM EMG with RLN stimulation was 5.5% of that with EBSLN stimulation. The CTM amplitude was 39% of the vocal cord amplitude with RLN stimulation. Positive EMG responses of 96 CTMs (55%) with VN stimulation were recorded. The mean amplitude through CTM EMG with VN stimulation was 6% of that with EBSLN stimulation. Positive EMG responses were achieved from 10 (0.6%) CTMs with the stimulation of 170 PPs. The mean amplitude obtained from CTMs with PP stimulation was 4.3% of that with EBSLN stimulation. Positive EMG amplitudes of 35 (67%) CTMs were obtained with stimulation of 52 CEBSLN. Temporary vocal cord paralysis was detected in six patients (5% of patients and 3.3% of the nerves) postoperatively.
The RLN contributes significantly to the innervation of the CTM. Despite the findings associated with the contribution of the PP and CEBSLN to the CTM innervation, further studies are needed. We are of the opinion that these are among the significant factors that contribute to the differences in clinical findings between patients with EBSLN injuries.
我们观察到部分患者在喉返神经（RLN）刺激后环甲肌（CTM）出现明显收缩。我们旨在通过术中客观实时肌电图（EMG）记录，评估这些收缩是由于其他固有肌收缩引起的喉肌运动，还是CTM的实际收缩。
本研究前瞻性纳入了2015年2月至2016年2月期间因各种甲状腺疾病接受术中神经监测引导下原发性甲状腺手术的106例连续患者。甲状腺切除术后，刺激RLN、迷走神经（VN）、喉上神经外支（EBSLN）、咽丛（PP）和对侧EBSLN（CEBSLN），并通过针电极记录CTM和环杓后肌（CPM）的反应，用EMG进行评估。
对106例平均年龄45岁患者的182条CTM的神经支配模式进行了评估。EBSLN刺激时，181条CTM获得了阳性EMG波形。179条RLN刺激后共记录到132条（74%）阳性EMG反应。RLN刺激时CTM的EMG平均振幅为EBSLN刺激时的5.5%。RLN刺激时CTM振幅为声带振幅的39%。VN刺激时，96条CTM（55%）记录到阳性EMG反应。VN刺激时CTM的EMG平均振幅为EBSLN刺激时的6%。170条PP刺激时，10条（0.6%）CTM获得阳性EMG反应。PP刺激时CTM的平均振幅为EBSLN刺激时的4.3%。52条CEBSLN刺激时，35条（67%）CTM获得阳性EMG振幅。术后6例患者（占患者的5%和神经的3.3%）检测到暂时性声带麻痹。
RLN对CTM的神经支配有显著贡献。尽管有证据表明PP和CEBSLN对CTM神经支配有贡献，但仍需进一步研究。我们认为这些是导致EBSLN损伤患者临床结果差异的重要因素。
