Influence of rocuronium on achieving optimal vagal stimulation during intraoperative nerve monitoring in thyroid surgery

BackgroundIn the present study we determine the feasibility of intraoperative neuromonitoring following the administration of a nondepolarizing neuromuscular blocking agent during thyroid operations, as well as the influence of rocuronium on the achievement of optimal vagal stimulation during intraoperative neuromonitoring in thyroid surgery. We further investigate whether accelerometry is a reliable approach to obtaining an ipsilateral vagus signal prior to recurrent laryngeal nerve dissection.MethodsIncluded in the study were 61 thyroidectomized patients whose demographic data, indications, type of surgery, vagus, and recurrent nerve values before and after resection were obtained. We created five groups of patients based on the twitch values recorded during ipsilateral vagus stimulation prior to the recurrent laryngeal nerve dissection: (1) <10%, (2) 11–25%, (3) 26–50%, (4) 51–75% and (5) >75%.ResultsThe average electromyography amplitudes of the vagus nerve prior to the determination of the recurrent laryngeal nerve for each group were 552 μV, 463 μV, 543 μV, 513 μV and 551 μV, respectively. No difference between the groups was observed in this regard (p > 0.05).ConclusionIt can be expected that as soon as the effects of neuromuscular blockers on the peripheral muscles begin to abate, it will be possible to obtain the ipsilateral vagus signal prior to recurrent laryngeal nerve dissection at the desired levels. It can be concluded from this study that accelerometry using the pollicis muscle is an unreliable tool for the interpretation of the proper electromyography signals of the vagus nerve prior to the determination of the recurrent laryngeal nerve.     

Intraoperative neuromonitoring in thoracoscopic excision of brachial plexus schwannoma

Mediastinal schwannoma arising from brachial plexus are rare, but their surgical treatment could be challenging with a minimally invasive approach, given their position. Furthermore, their proximity to brachial plexus nerve fibres raises the risk for postoperative upper limb deficits. A 72-year-old man presented mediastinal schwannoma arising from the T1 nerve root. Complete surgical excision was achieved via video-assisted thoracic surgery with the aid of intraoperative neuromonitoring, and no postoperative neurological deficit developed after the intervention. Using intraoperative neuromonitoring, radical minimally invasive surgical treatment can be safely achieved for mediastinal schwannoma arising from brachial plexus.     

Intraoperative neuromonitoring of the recurrent laryngeal nerve - results and learning curve

Intraoperative neuromonitoring was introduced in thyroid surgery several years ago resulting in a facilitated identification of the recurrent laryngeal nerve and less recurrent laryngeal nerve injuries. Between 1999 and 2004 data of all patients (n=937) undergoing thyroid resection were recorded prospectively and analyzed yearly. The intraoperative identification of recurrent laryngeal nerve succeeded in 99.2% (1665 nerves at risk). The percentage of completely resecting surgical procedures raised from 17% to 56%. Minimal vocal cord dysfunction associated with hematoma and edema in most cases was diagnosed laryngosopically in 1.4-2.4%. Transient recurrent nerve palsies were seen in 2.3% without changes throughout the years.The permanent palsy rate of 0.8% in the first years decreased. No permanent palsies were diagnosed in the last 3 years. Routine introduction of intraoperative neuromonitoring in thyroid surgery is associated with a demonstrable learning curve lasting several years. Permanent palsy rate is decreased. The rate of minimal vocal cord movement disorders and transient recurrent laryngeal nerve palsies is not changed.     

术中持续与间断神经监测技术在腔镜辅助甲状腺手术中的对比研究

目的对比持续术中神经监测(C－IONM)和间断性术中神经监测(I－IONM)在腔镜辅助甲状腺手术中的临床效果。 方法回顾性分析2016年5月至2018年12月59例接受腔镜辅助甲状腺手术的患者资料，根据不同术中神经监测方式分为C－IONM组和I－IONM组。采用SPSS 21.0统计软件进行分析，迷走神经及喉返神经功能评估采用( ±s)表示，行独立t检验；喉返神经损伤情况行χ²检验。P<0.05为检验标准。 结果两组术中神经监测时间差异无统计学意义(P>0.05)。59例患者共解剖显露喉返神经86条，其中11条术中出现肌电图( EMG)振幅下降>50%，且在停止手术操作后10 min内均逐渐恢复至初始R1信号水平的70%以上，平均恢复时间为(6.7±2.5) min，两组患者术中喉返神经损伤及恢复情况差异无统计学意义(P>0.05)。两组患者术毕时EMG振幅和潜伏期较同组APS电极刺激初始时变化差异无统计学意义(P>0.05)。光镜下两组迷走神经和喉返神经结构正常，纤维细胞完整，无神经束水肿及神经内血管损伤发生。 结论腔镜辅助甲状腺手术中C－IONM技术和I－IONM技术在降低迷走神经和喉返神经损伤方面疗效近似，两种神经监测技术对患者神经功能变化无影响，均安全可靠。     

Evaluation of Intraoperative Recurrent Nerve Monitoring in Thyroid Surgery

Surgical exposure of the recurrent laryngeal nerve decreases the incidence of nerve injuries during thyroid surgery. Intraoperative neuromonitoring was introduced to facilitate identification and protection of the recurrent laryngeal nerve. Between February 1996 and June 2002 a total of 288 patients underwent thyroid surgery with intraoperative identification and intraoperative neuromonitoring of the recurrent laryngeal nerve. The overall incidences of permanent and transient recurrent nerve palsy (considered as a percentage of the nerves at risk) were 1.4% and 8.7%, respectively. Results were stratified in benign, malignant, and recurrent thyroid disease. Intraoperative function testing revealed a positive predictive value of 33% and negative predictive value of 99%. We concluded that the incidence of recurrent nerve lesions in benign, malignant, and recurrent thyroid disease was not lowered by the use of intraoperative neuromonitoring. Although an intact nerve can be verified by the neuromonitoring, the loss of nerve function cannot be reliably identified.     

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甲状腺手术造成喉神经损伤是困扰医患双方的难题。术中喉神经保护的重要性毋庸置疑。然而,各级医生对喉神经变异的识别、保护方法的选择,甚至显露技术的经验,参差不齐,缺乏指南及规范。改良传统的手术方式,放弃甲状腺囊内切除等盲目操作,进一步提高保护意识,全面掌握甲状腺术中喉神经解剖特征、手术理念、操作技巧,术中常规显露喉神经,辅助术中神经监测手段,可显著降低术后喉神经损伤发生率,提高手术安全性、彻底性。     

A case of schwannoma of the intrathoracic vagus nerve]

A 42-year-old female was noted to have a mediastinal mass on routine chest roentgenogram. She was asymptomatic and physical examination was unremarkable. Computed tomography of the chest confirmed the presence of a 3.5 cm well circumscribed mass in the middle mediastinum adjacent to the aortic arch. Operation was performed. A solitary middle mediastinal tumor was readily apparent at the aortic arch to the left subclavian artery, originating from the vagus nerve superior to the take-off of the recurrent laryngeal nerve. Excision was possible by enucleation of the mass. The postoperative period was uneventful, although there was paralysis of the left vocal cord as evidenced by hoarseness. Histologically the diagnosis of a schwannoma of the vagus nerve was made.     

The inferior non recurrent laryngeal nerve: a major surgical risk during thyroidectomy

It is now widely established that systematic intraoperative location and diligent dissection of the recurrent inferior laryngeal nerve during thyroidectomy are the keystones to assure its anatomic and functional preservation. The possibility of abnormal routes, like a non-recurrent cervical course of the inferior laryngeal nerve is an additional major argument for its systematic identification to avoid surgical damage. In 2517 cervicotomies performed between 1992 and 1997 for at least right thyroid lobe excision or parathyroid glands exploration, 20 cases of non recurrent laryngeal nerve were identified (0.79%). The embryological nature of such a nervous anatomical variation results originally from a vascular disorder, named arteria lusoria in which the fourth right aortic arch is abnormally absorbed, being therefore unable to drag the right recurrent laryngeal nerve down when the heart descends and the neck elongates during embryonic development. The surgeon must be aware of the possibility of a non recurrent laryngeal nerve, which arises directly from the cervical vagus and therefore represents a severe potential pitfall during thyroidectomy. Given the absence of reliable clinical symptoms and signs or investigations indicating preoperatively the possibility of a non recurrent nerve, guidelines are given to prevent intraoperatively this major surgical risk.     

Intraoperatives Neuromonitoring bei Schilddrüsenoperationen

Intraoperative neuromonitoring (IONM) was introduced into thyroid surgery approximately 10 years ago for better identification of recurrent laryngeal nerve palsy. Since then several studies have been performed for evaluation of this new technology. IONM is superior to visual nerve identification alone for prediction of postoperative local cord function. Therefore, in bilateral procedures IONM enables intraoperative decision-making concerning resection of the second side. To avoid misinterpretation of the results of IONM a standardized approach including preoperative and postoperative laryngoscopy and preresection and postresection vagus stimulation is recommended. Trouble-shooting requires systematic checking of the device including control of electrode position (needle or tube electrodes). For expert assessment purposes documentation of the standardized application of IONM is of utmost importance.     

喉返神经监测技术在全腔镜cT_1N_(0～1a)分化型甲状腺癌根治术中的应用体会

目的:探讨喉返神经监测技术在全腔镜cT_1N_(0~1a)甲状腺癌根治手术中应用的必要性。方法:对比分析2013年2月至2016年10月完成的106例全腔镜cT_1N_(0~1a)分化型甲状腺癌根治术的临床资料,其中神经监测组54例,未监测组52例。对比分析两组喉返神经的辨识时间、辨识率、暂时性损伤及永久性损伤的差异。结果:非神经监测组中1例因误断喉不返神经而中转开放行神经吻合术;其他患者均顺利完成全腔镜手术。神经监测组在喉返神经辨识时间、辨识率方面明显优于未监测组,两组相比差异有统计学意义(P0.05)。未监测组中7条喉返神经未能明确确认。神经监测组中2条喉返神经发生暂时性损伤,其中1条于术后2周内恢复,另1条于术后4周恢复;未监测组中8条喉返神经出现暂时性损伤,其中6条于术后2周内恢复,2条于术后4周内恢复;在喉返神经暂时性损伤方面两组差异有统计学意义(P0.05)。在喉返神经永久性损伤方面两组差异无统计学意义(P0.05)。结论:喉返神经监测技术是cT_1N_(0~1a)甲状腺癌全腔镜根治手术的有效补充,可快速、有效定位喉返神经,避免出现神经损伤的严重并发症,尤其在全腔镜甲状腺癌根治术开展初期是不可或缺的。     

Neuromonitoring of the recurrent laryngeal nerve--a critical analysis of patients with postoperative nerve palsy

The transligamental intraoperative neuromonitoring of the recurrent nerve is established in many surgical clinics as an useful and reliable technique. It is especially suitable to identify the recurrent nerve and to monitor its function during thyroid operation. We have analysed 14 early postoperative recurrent nerve palsies between June 1997 and December 2000 (1,23 % related to nerves at risk). As a result of complete follow up we found 4 permanent nerve palsies (0,35 % related to nerves at risk). In 11 out of 14 cases the neuromonitoring revealed a dysfunction of the recurrent nerve. The following long distance microsurgical preparation showed no interruption of the continuity of the nerve. Knowing the fact of unilateral negative monitoring signal we adapted our operative strategy. Therefore we did not observe bilateral nerve palsies. In 3 patients we found a positive nerve signal but nevertheless these patients showed postoperative unilateral recurrent palsies. The possible reasons are discussed.We are convinced that the neuromonitoring of the recurrent laryngeal nerve is an important progress in thyroid surgery.     

Neuromonitoring in thyroid surgery: prospective evaluation of intraoperative electrophysiological responses for the prediction of recurrent laryngeal nerve injury

OBJECTIVE: We evaluated the ability of neuromonitoring to predict postoperative outcome in patients undergoing thyroid surgery for different indications. SUMMARY BACKGROUND DATA: Neuromonitoring has been advocated to reduce the risk of vocal cord palsy and to predict postoperative vocal cord function. METHODS: Three hundred twenty-eight patients (502 nerves at risk) were studied prospectively at a single center. Neuromonitoring was performed with the Neurosign 100 device by transligamental placement of the recording electrode into the vocalis muscles. Cumulative distribution of stimulation thresholds was determined by stepwise decreases in current (1 mA to 0.05 mA) for both the vagus and the recurrent nerve. Patients were grouped according to surgical risk (benign and malignant disease, reoperation for benign and for malignant disease). RESULTS: If the electrophysiological response was correlated to postoperative vocal cord function, the sensitivity of neuromonitoring was modest (86% in surgery for benign disease) to low (25% in reoperation for malignant disease); the positive predictive value was modest (overall rate 62%) but acceptable (87%) if corrected for technical problems. Specificity and negative predictive values were high (ie, overall >95%). Stimulation thresholds were not augmented in 11 patients, in whom postoperative palsy developed despite normal intraoperative recordings. Similarly, an electrical field response was elicited in 14 of 21 patients with preoperative vocal cord palsy. Electromyographic recordings did not reveal an abnormal amplitude or a decline in nerve conduction velocity. CONCLUSIONS: Neuromonitoring is useful for identifying the recurrent laryngeal nerve, in particular if the anatomic situation is complicated by prior surgery, large tissue masses, aberrant nerve course. However, neuromonitoring does not reliably predict postoperative outcome.     

Primary Peritracheal Schwannoma: Report of a Case

Posterior mediastinal tumors of neurogenic origin commonly arise from the sympathetic or intercostal nerves. However, anterior mediastinal tumors rarely originate from the vagus nerve, and primary neurogenic tumors of the trachea are extremely uncommon. A 19-year-old man was admitted to an emergency department in sudden acute respiratory distress. A tracheostomy was performed and he was transferred to our Ear Nose and Throat Department for further investigation. A bronchoscopic biopsy was taken of a mass occupying the tracheal lumen and intraoperative frozen section examination suggested a schwannoma, so tracheal resection was performed. Although rare, primary tracheal schwannoma should be considered in the differential diagnosis of sudden respiratory distress of unknown origin.     

Intraoperative electrophysiologic studies on the functions of nerve roots involved in cervical dumbbell-shaped schwannoma and their clinical utility

BACKGROUND: It is difficult to expect the degree of neurologic deficits after resection of involved nerve roots before and during the surgery for cervical dumbbell-shaped schwannoma. We present the results of studies for cervical nerve root functions in patients with cervical schwannoma using intraoperative electrophysiologic assessment and the potential of their clinical relevance is also discussed. OBJECTIVE: To present the utility of intraoperative electrophysiologic studies to detect the functions of the nerve roots involved in cervical schwannoma and adjacent nerve roots. METHODS: Five patients with dumbbell-shaped cervical schwannoma arising from the cervical nerve roots composing the brachial plexus were studied. Compound muscle action potentials (CMAPs) after stimulation of nerve roots involved in the schwannoma were recorded from upper limb muscles anatomically correspond to their myotome. Adjacent nerve roots were also stimulated. Motor-evoked potentials (MEPs) after transcranial electric stimulation were also recorded during surgery. In 3 patients, sensory nerve action potentials (SNAPs) after digital nerve stimulation were also recorded from cervical nerve roots. RESULTS: In 4 patients, CMAPs after stimulation of cervical nerve roots involved with the schwannoma were not obtained or were very small compared with those obtained after stimulation of adjacent nerve roots. In 2 of 4 patients, SNAPs after digital nerve stimulation were recorded with small amplitude from the nerve roots involved in schwannoma. Minimal (n=2, within 80% attenuation of amplitude) or no changes (n=2) were observed after total resection of the schwannoma and no apparent motor weakness occurred in these 4 patients. In a patient with cervical schwannoma involved in C8 nerve root, CMAPs with large amplitude were recorded after stimulation of the C8 nerve root. SNAPs after stimulation of digit V were recorded with larger amplitude from the T1 root compared with those recorded from the C8 nerve root. Intradural parts of the tumor arising from C8 posterior rootlets were completely removed after transaction of posterior rootlets. During removal of intraforaminal parts of the tumor, motor evoked potentials were decreased over 50% of controls. Incomplete removal was chosen to avoid deterioration of motor function. Transient dysesthesia of digit V and slight weakness occurred after surgery. CONCLUSIONS: The residual function of motor and sensory nerve roots involved with cervical schwannoma differed between individuals and could be detected using intraoperative electrophysiologic assessment.     

First experiences in intraoperative neurostimulation of the recurrent laryngeal nerve during thyroid surgery of children and adolescents

Background: Intraoperative neurostimulation of the recurrent laryngeal nerve may reduce nerve palsy during thyroid surgery and is well established in adults. No data regarding the value of neuromonitoring during thyroid surgery in children have been available. Methods: In a retrospective study, the authors analyzed all children who underwent surgery in our department since 1995. Neurostimulation was performed as electromyography of the vocal muscle using an electrical stimulation electrode for identification of the recurrent nerve. Results: The authors performed thyroid resections in 97 children (mean, 11.1 years), 75 because of thyroid carcinoma. The recurrent nerve was identified in each patient. The neuromonitoring was used in 53 patients. Postoperatively, one temporary nerve palsy was identified in this group (1.89%). In the group of 44 nonstimulated patients, 2 temporary (4.55%) and one permanent nerve dysfunctions (2.27%) occurred. In all stimulated patients, the results of intraoperative neurostimulation were identical with the postoperative function of the vocal cords. Conclusions: The intraoperative neurostimulation of the recurrent laryngeal nerve is a safe and reliable procedure in children and adolescents. It may reduce nerve damage during thyroid surgery. The neuromonitoring of the recurrent nerve is of high prediction for the postoperative function of the vocal cords. J Pediatr Surg 37:1414-1418.     

术中神经监测技术在复杂甲状腺手术中的应用

目的 探讨应用术中神经监测技术（intra operative neuromonitoring,IONM）,以减少复杂甲状腺手术喉返神经损伤。方法 吉林大学中日联谊医院甲状腺外科2009年3~7月对132例复杂甲状腺手术病人,共186支高风险喉返神经行术中神经监测。在甲状腺切除前后分别探测迷走神经及喉返神经肌电信号。甲状腺手术前后常规检查声带活动度。结果 除术前声带麻痹4例,余182支喉返神经均可在甲状腺切除后测得明显肌电信号,未发生缝合切口前神经肌电信号消失,提示神经电传导功能良好。精确检出非返性喉返神经2例。结论 术中喉返神经监测使喉返神经显露更加便捷,更加确切,并可验证喉返神经功能完整性。在高风险、复杂甲状腺术中应用神经监测是降低喉返神经损伤率的一种重要辅助措施。     

Identifying the recurrent laryngeal nerve by intraoperative neuromonitoring]

301 patients underwent thyroid surgery in 1998 by using the intraoperative neuromonitoring. The documentation was done prospectively. The system of intraoperative neuromonitoring consists of a stimulation circuit and an electromyographic record. We placed the deriving electrode transligamentally through the cricothyroid membrane. By relaxometry we investigated the influence of the relaxation level on the electromyographic record of the vocal muscle. Using a standardized operative technique we found a side-related rate of primary palsy of 2.3% (n = 13), from which 61.5% (n = 8) showed to be only temporary during a postoperative follow-up period. The intraoperative neuromonitoring with the purpose of identification of the recurrent laryngeal nerve is a safe and reliable method.     

Contribución de la neuroestimulación a la seguridad en la extubación traqueal tras tiroidectomía total. Estudio prospectivo con electrodos de aguja

Introduction and objectivesBilateral laryngeal paralysis cause serious respiratory complications. In thyroid surgery, neuromonitoring helps in identifying the recurrent laryngeal nerve, reports on its functioning at the end of surgery, supports decision making, and may reduce the risk of bilateral paralysis. Our objective was to estimate the influence of neuromonitoring in operative strategy and extubation safety in total thyroidectomy.MethodsA non-randomized prospective study was conducted on 210 patients undergoing total thyroidectomy (420 laryngeal nerves stimulated included). We collected qualitative neuromonitoring variables (presence or absence of final signal after stimulation of the vagus nerve), and postoperative indirect laryngoscopy (normal motility or paralysis), performed until 3rd day after the surgery.ResultsThe accuracy of the test was 99.5% (95% CI 98.3 to 99.9). The positive predictive value was 100% (95% CI 99.1 to 100), which showed the high ability of neuromonitoring to predict paralysis in case of loss of signal, and the negative predictive value was 99.5% (95% CI 98.3 to 99.9), which indicated its predictive capacity for normal motility when there is a normal signal.ConclusionsIn our group of patients, recurrent laryngeal nerve monitoring was useful in total thyroidectomy as it provided information on the prognosis of laryngeal motility, and helped in making decisions during surgery when there was signal loss. Due to the risk of serious respiratory complications due to bilateral recurrent laryngeal nerve paralysis, we opted for the performing of the 2-stage total thyroidectomy in case of signal loss in the first lobectomy. Thereby, neuromonitoring contributed to the safety of the airway in tracheal extubation, aiding in the prevention of a possible bilateral laryngeal paralysis.     

Neuromonitoring of the external branch of the superior laryngeal nerve during thyroid surgery

Changes of the voice caused by injury of the external branch of the superior laryngeal nerve (EBSLN) during thyroid surgery may have essential consequences for a patient's life. Therefore, intraoperative effort has to be made to prevent EBSLN damage. Neuromonitoring has already been described as helpful to improve the identification rate of the recurrent laryngeal nerve. We describe our surgical procedure of upper thyroid pole preparation using neuromonitoring to avoid intraoperative damage of the superior laryngeal nerve. Neuromonitoring allowed safe preparation of the upper thyroid pole without injury of the ESBLN in 108 consecutive patients.     

Does intraoperative nerve monitoring reduce the rate of recurrent nerve palsies during thyroid surgery?

Two different aspects of the influence of neuromonitoring on the possible reduction of post-operative recurrent laryngeal nerve palsies require critical examination: the nerve identification and the monitoring of it's functions. Due to the additional information from the EMG signals, neuromonitoring is the best method for identifying the nerves as compared to visual identification alone. There are still no randomized studies available that compare the visual and electrophysiological recurrent laryngeal nerve detection in thyroid operations with respect to the postoperative nerve palsies. Nevertheless, comparisons with historical collectives show that a constant low nerve-palsy-rate was achieved with electrophysiological detection in comparison to visual detection. The rate of nerve identification is normally very high and amounts to 99 % in our own patients. The data obtained during the "Quality assurance of benign and malignant Goiter" study show that in hemithyreoidectomy and subtotal resection, lower nerve-palsy-rates are achieved with neuromonitoring as compared to solely visual detection. Following subtotal resection, this discrepancy becomes even statistically significant. While monitoring the nerve functions with the presently used neuromonitoring technique, it is possible to observe the EMG-signal remaining constant or decreasing in volume. Assuming that a constant neuromonitoring signal represents a normal vocal cord, our evaluation shows that there is a small percentage of false negative and positive results. Looking at the permanent recurrent nerve palsy rates, this method has a specificity of 98 %, a sensitivity of 100 %, a positive prognostic value of 10 %, and a negative prognostic value of 100 %. Although an altered neuromonitoring signal can be taken as a clear indication of eventual nerve damage, an absolutely reliable statement about the postoperative vocal cord function is presently not possible with intraoperative neuromonitoring.