Normative Intra-operative Electrophysiologic Waveform Analysis of Superior Laryngeal Nerve External Branch and Recurrent Laryngeal Nerve in Patients Undergoing Thyroid Surgery

Background

Injury to the external branch of the superior laryngeal nerve (EBSLN) can occur during superior pole dissection in thyroid surgery; the EBSLN injury rate is reported as high as 28 % (Cernea et al., Head Neck 14:380–383, 1992). Injury to the EBSLN leads to variable symptoms that may be overlooked, but that can be significant, especially to professional speakers and singers. Intraoperative nerve monitoring (IONM) is employed widely to aid in nerve identification. We report on normative electroneuromyography (EMG) data on EBSLN-IONM and cricothyroid muscle (CTM) twitch response during stimulation as an aid to EBSLN identification.

Methods

A prospective study of the SLN and the recurrent laryngeal nerve (RLN) IONM data in 72 consecutive thyroid surgeries was carried out. All patients underwent preoperative and postoperative laryngeal exams, and patients with abnormal preoperative laryngeal function were excluded. Normative EMG data and CTM twitch response during EBSLN stimulation were recorded and analyzed.

Results

Stimulation of the EBSLN resulted in a positive CTM twitch response in 100 %, whereas EMG response was recordable in 80 %. Electromyographic amplitude was ~1/3 of ipsilateral RLN amplitude and did not change through the case with multiple stimulations. Stimulation of the EBSLN was similar for men and women and at 1 and 2 mA stimulation levels.

Conclusions

Intraoperative nerve monitoring of the EBSLN aids in EBSLN identification and provides electroneuromyographic information in 80 % of cases. The laryngeal head of the sternothyroid muscle is a useful landmark to locate EBSLN.     

Recurrent Laryngeal Nerve Identification and Assessment during Thyroid Surgery: Laryngeal Palpation

Electrical identification and monitoring of the recurrent laryngeal nerve (RLN) has been proposed as an adjunct to standard visual identification of the nerve during thyroid and parathyroid surgery. This study was undertaken to assess laryngeal palpation as an intraoperative technique for identifying and assessing the RLN during surgery and to investigate the relation between laryngeal palpation and associated laryngeal electromyographic (EMG) activity. The postcricoid region of the larynx during surgery was palpated through the posterior hypopharyngeal wall to sense posterior cricoarytenoid muscle contraction in response to ipsilateral RLN stimulation (i.e., the laryngeal twitch response.) Laryngeal palpation was performed in a series of 449 consecutive thyroid and parathyroid surgeries with 586 RLNs at risk. All patients underwent preoperative and postoperative laryngoscopy to assess vocal cord mobility. In a subset of patients, laryngeal palpation and simultaneous laryngeal EMG recordings were compared during intraoperative RLN stimulation. In this series, there was no permanent RLN paralysis. There was one case of temporary RLN paralysis secondary to neural stretch that resolved 6 weeks postoperatively (temporary paralysis rate: 0.2% of patients, 0.2% of nerves at risk). Intraoperative laryngeal palpation of the laryngeal twitch response reliably correlated with normal postoperative vocal cord function. Loss of the laryngeal twitch response occurred in the single case of temporary paralysis in the setting of an anatomically intact nerve. Laryngeal palpation correlated well with simultaneous laryngeal EMG activity. There were no palpation-induced laryngeal injuries or laryngeal edema. There were also no RLN injuries due to repetitive neural stimulation. Intraoperative laryngeal palpation during RLN stimulation is a safe, reliable method for neural monitoring that can assist in RLN identification and assessment during thyroid and parathyroid surgery. Most importantly, it provides important prognostic information regarding ipsilateral vocal cord function at the completion of the initial side of the thyroid or parathyroid surgery. Intraoperative laryngeal palpation allows the surgeon to stage contralateral surgery if RLN damage is diagnosed, thereby avoiding the potential for bilateral vocal cord paralysis. We believe that laryngeal palpation is useful as an adjunct to formal EMG monitoring during thyroid and parathyroid surgery.     

Intraoperative Neuromonitoring of Recurrent Laryngeal Nerve During Thyroidectomy with Adhesive Skin Electrodes

World Journal of Surgery - Alternative methods to overcome limitations of electromyogram (EMG) tube applied for intraoperative neuromonitoring (IONM) of recurrent laryngeal nerve (RLN) during...     

Intraoperative Nerve Monitoring Can Reduce Prevalence of Recurrent Laryngeal Nerve Injury in Thyroid Reoperations: Results of a Retrospective Cohort Study

Background

The prevalence of recurrent laryngeal nerve (RLN) injury is higher in repeat than in primary thyroid operations. The use of intraoperative nerve monitoring (IONM) as an aid in dissection of the scar tissue is believed to minimize the risk of nerve injury. The aim of this study was to examine whether the use of IONM in thyroid reoperations can reduce the prevalence of RLN injury.

Methods

This was a retrospective cohort study of patients who underwent thyroid reoperations with IONM versus with RLN visualization, but without IONM. The database of thyroid surgery was searched for eligible patients (treated in the years 1993–2012). The primary outcomes were transient and permanent RLN injury. Laryngoscopy was used to evaluate and follow RLN injury.

Results

The study group comprised 854 patients (139 men, 715 women) operated for recurrent goiter (n = 576), recurrent hyperthyroidism (n = 36), completion thyroidectomy for cancer (n = 194) or recurrent thyroid cancer (n = 48), including 472 bilateral and 382 unilateral reoperations; 1,326 nerves at risk (NAR). A group of 306 patients (500 NAR) underwent reoperations with IONM and 548 patients (826 NAR) had reoperations with RLN visualization, but without IONM. Transient and permanent RLN injuries were found respectively in 13 (2.6 %) and seven (1.4 %) nerves with IONM versus 52 (6.3 %) and 20 (2.4 %) nerves without IONM (p = 0.003 and p = 0.202, respectively).

Conclusions

IONM decreased the incidence of transient RLN paresis in repeat thyroid operations compared with nerve visualization alone. The prevalence of permanent RLN injury tended to be lower in thyroid reoperations with IONM, but statistical validation of the observed differences requires a sample size of 920 NAR per arm.     

Intraoperative Monitoring of the Recurrent Laryngeal Nerve in Thyroid Surgery

BACKGROUND: Recurrent laryngeal nerve (RLN) palsy ranks among the leading reasons for medicolegal litigation of surgeons because of its attendant reduction in quality of life. As a risk minimization tool, intraoperative nerve monitoring (IONM) has been introduced to verify RLN function integrity intraoperatively. Nevertheless, a systematic evidence-based assessment of this novel health technology has not been performed. METHODS: The present study was based on a systematic appraisal of the literature using evidence-based criteria. RESULTS: Recurrent laryngeal nerve palsy rates (RLNPR) varied widely after thyroid surgery, ranging from 0%-7.1% for transient RLN palsy to 0%-11% for permanent RLN palsy. These rates did not differ much from those reported for visual nerve identification without the use of IONM. Six studies with more than 100 nerves at risk (NAR) each evaluated RLNPR by contrasting IONM with visual nerve identification only. Recurrent laryngeal nerve palsy rates tended to be lower with IONM than without it, but this difference was not statistically significant. Six additional studies compared IONM findings with their corresponding postoperative laryngoscopic results. Those studies revealed high negative predictive values (NPV; 92%-100%), but relatively low and variable positive predictive values (PPV; 10%-90%) for IONM, limiting its utility for intraoperative RLN management. CONCLUSIONS: Apart from navigating the surgeon through challenging anatomies, IONM may lend itself as a routine adjunct to the gold standard of visual nerve identification. To further reduce the number of false negative IONM signals, the causes underlying its relatively low PPV require additional clarification.     

显露喉返神经在甲状腺切除术中的临床意义

目的探讨甲状腺手术中显露喉返神经对防止喉返神经损伤的价值。方法回顾性分析2 481例甲状腺手术患者的临床资料,其中术中显露喉返神经组1 425例和非显露喉返神经组1 056例,比较两组间并发喉返神经损伤的几率。结果显露喉返神经组喉返神经暂时性损伤31例,损伤率为2.18%,无永久损伤病例;非显露喉返神经组喉返神经损伤44例,损伤率为4.17%,其中暂时损伤39例,永久损伤为5例。两组喉返神经损伤率比较差异有统计学意义(P<0.01)。结论甲状腺手术术中显露喉返神经对保护喉返神经是安全和有效的,对预防或避免医源性喉返神经损伤有重要意义。     

Standardization of Intraoperative Neuromonitoring of Recurrent Laryngeal Nerve in Thyroid Operation

Background  

The lack of standardized procedures of intraoperative neuromonitoring (IONM) during thyroid operations may lead to highly variable results, and many of these results can cause misleading information and, conversely, increase the risk of recurrent laryngeal nerve (RLN) injury. Therefore, standardization of IONM procedures is necessary.     

Recurrent Laryngeal Nerve Diameter Increases During Thyroidectomy

Background

Temporary recurrent laryngeal nerve (RLN) palsy after thyroidectomy is usually due to a neurapraxia. Voice changes after thyroidectomy, in the absence of RLN palsy, are common. We postulated that this is due to edema and consequent increased diameter of the RLN during thyroidectomy. The aim of this study was to document changes in the diameter of the RLN during surgery.

Methods

A consecutive series of 110 RLNs was prospectively analyzed in 75 patients. The RLN was measured on identification and removal of the lobe. Electromyogram (EMG) amplitudes were recorded concurrently after neurostimulation. Univariate and multivariate analyses were performed.

Results

The mean increase in RLN diameter was 0.71 from 1.95 mm (P < 000.1). Right and left RLNs were similar diameter. On univariate and multivariate analysis, factors predictive of increased RLN diameter were increasing age (P = 0.04) and increased difference in EMG amplitude (P = 0.01). There was a mean increased EMG amplitude of 101 from 493.5 μV (P < 0.001). On univariate and multivariate analyses, factors predictive of increased difference in EMG amplitude were decreasing age (P = 0.01) and increased difference in RLN diameter (P = 0.02). There was a statistically significant positive relationship between increased diameter of RLN and increased EMG amplitude (R ² = 0.04). The temporary RLN palsy rate was 3%.

Conclusions

The small numbers of temporary RLN palsies prevent correlation with increased diameter of RLN. However, this may explain voice changes after thyroidectomy without RLN palsy. The observed increase in RLN diameter is probably due to edema; its cause is unknown. The increased EMG amplitude seen with increasing RLN diameter may reflect increased excitability of ionic channels in neurons.     

Recurrent Laryngeal Nerve Monitoring during Thoracoscopic Esophagectomy

Introduction

There have been several reports on the feasibility and curability of thoracoscopic esophagectomy, which may reduce injury to the thoracic cage and decrease the invasiveness of surgery. Although the recurrent laryngeal nerve (RLN) is identified and kept intact during operations, RLN palsy sometimes occurs. Currently, surgical aides, including intraoperative neurological monitoring, are being utilized to avoid RLN injury during thyroid surgery. This system is utilized during thoracoscopic esophagectomy in the prone position.

Patients and methods

Seven consecutive patients (six men, one woman; age range 62–74 years; mean 68 years) were included. Patients underwent general anesthesia and were intubated using the NIM TriVantage? electromyography (EMG) tube. One-lung ventilation was performed with an endobronchial blocker. Thoracoscopic esophagectomy was performed in the prone position. The nerve stimulator was calibrated to 0.5 mA, and after the RLN was visually identified it was subsequently stimulated, which also confirmed normal machine functioning. In some situations, in the absence of a response, stimuli were increased to 1.0 mA and then 2.0 mA.

Results

Intraoperatively, all seven patients had their nerve signals monitored. In one case, a nerve signal disappeared after complete lymph node dissection along the left RLN. This system could identify the site of injury, and the thoracoscopic magnified view allowed the disrupted point to be located precisely. When we checked VTR after surgery, the source of injury was one point tension of the nerve pulled by fiber during lymph node dissection.

Conclusions

Intraoperative RLN monitoring during thoracoscopic esophagectomy in the prone position, with one-lung ventilation performed using the TriVantage? EMG tube and a bronchial blocker, is technically feasible, easy, and reliable.     

Intraoperative neuromonitoring for thyroid malignancy surgery: technical notes and results from a retrospective series

This study evaluates the role of intraoperative neuromonitoring (IONM) for thyroidectomy performed in cancer patients with emphasis on postoperative recurrent laryngeal nerve paralysis (RLNP). The study is a retrospective series comprising 76 thyroidectomy alone (control group) versus 76 thyroidectomy with IONM. In the control group the laryngeal nerves have been identified by visualization solely. In the IONM group both vagal nerve and RLN have been localized and monitored during thyroid resection. The main surgical outcome was RLN morbidity. All patients undergo pre- and postoperative laryngeal examination. Overall RLN morbidity was 3.9% in the IONM group and 9.2% in the control group (P < 0.05). There have been two cases of permanent RLNP (2.6%) in the control group and one in the IONM group (1.3%), one case of bilateral RLN injury in the control group. The incidences of temporary RLNP in the IONM group have been 2.6 versus 6.5% in the control group. IONM is an effective procedure in thyroid cancer patients.     

Intraoperative Monitoring of External Branch of the Superior Laryngeal Nerve: Functional Identification,Motor Integrity,and its Role on Vocal Cord Function

ABSTRACT

Purpose: Beside recurrent laryngeal nerve (RLN), protection of the external branch of the superior laryngeal nerve (EBSLN) is required for complication-free thyroid surgery. This study investigates the contribution of intraoperative neuromonitoring (IONM) to identification and motor integrity of the EBSLN. Methods: This prospective study was performed on 245 EBSLNs in 147 patients with thyroid surgery. The rate of visual identification, contribution of IONM to functional localization, the rate and levels of recordable waveform amplitude from vocal cord (VC) movement were determined during surgery. Results: 164 (66.9%) EBSLNs were visually identified and additional 74 branches were functionally identified by IONM. Additional identification rate of IONM was 30.2%. Seven (2.9%) EBSLNs could not be identified during surgery. Cricothyroid muscle (CTM) twitch established functional integrity in 97.1% of EBSLNs. Electrophysiological stimulation of 151 (63.4%) EBSLNs created waveform amplitude >100 µV that mean amplitude level was calculated as 186 µV, and an amplitude >300 µV was recorded in 19 of 151 (12.6%) EBSLNs. Conclusions: In addition to visual identification, surgeons can functionally localize the EBSLN with the assistance of IONM that CTM twitch is a reliable evience for functional integrity of the EBSLN. In the majority of patients, stimulation of the EBSLN creates recordable waveform amplitude thus the EBSLN appears to be a second source of motor innervations for intrinsic laryngeal muscles.     

Palpatory Method Used to Identify the Recurrent Laryngeal Nerve during Thyroidectomy

The major complication of thyroid surgery, occurring in 1% to 6% of cases, is injury to the recurrent laryngeal nerve (RLN). A simple method to identify the RLN during thyroid surgery is described by the authors. It consists in palpation of the nerve caudally to the inferior pole of the thyroid, after the nerve has been made taut by the upward and medial traction of the thyroid gland. This method was used on 47 human cadavers and 45 patients with benign thyroid diseases. It made it possible to identify the RLN in all of the cadavers and 52 of the 55 identifications during 45 thyroidectomies (in 10 total thyroidectomies the identification was bilateral). Laryngeal motility was normal in all patients at postoperative laryngoscopy. Using the palpation before dissection in the region of the inferior thyroid artery, the traditional viewing method became easier and safer, reducing the risk of injury where it is most likely to occur to the nerve.     

腔镜甲状腺切除术中喉返神经的显露

目的探讨腔镜甲状腺切除术中喉返神经的显露技巧,避免因显露而造成的喉返神经医源性损伤。方法2011年4月～2012年4月,行胸乳晕人路腔镜下甲状腺切除术17例。于乳腺前皮下置入troear,注入CO2（压力6mmHg）建立操作空间,用超声刀显露喉返神经。结果17例均顺利完成喉返神经显露,其中7例行腔镜双侧甲状腺腺叶手术（6例双侧叶结节和1例甲状腺癌）,5例行一侧甲状腺叶切除术（一侧腺叶多发结节）,5例行一侧腺叶次全切除术。喉返神经主干位于甲状腺下动脉之前、之后和动脉分叉之间的比例分别为17．6％（3／17）、47．1％（8／17）和35．3％（6／17）,术后未见声音嘶哑等发生。结论尽管甲状腺下动脉与喉返神经的关系不固定,应用甲状腺囊外解剖和上翻技术,在切除腺体的同时可以显露喉返神经,减少喉返神经损伤。     

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??A clinical comparative study of real-time recurrent laryngeal nerve moniroring versus conventional exposure during reoperation of thyroid gland LIU Kun-peng, DAI Wen-jie. Department of Thyroid-breast-cell-transplantation Surgery,the First Affiliated Hospital of Harbin Medical University, Harbin150001,China
Corresponding author??DAI Wen-jie??E-mail??davidhmu@163.com
Abstract Objective To compare the difference between real-time recurrent laryngeal nerve??RLN?? monitoring and routine exposure, and investigate the clinical value of intraoperative recurrent laryngeal nerve monitoring (IONM) during reoperative thyroid surgery. Methods The clinical data of 118 patients underwent a reoperation for thyroid in Department of Thyroid-breast-cell-transplantation Surgery, the First Affiliated Hospital of Harbin Medical University from May 2014 to May 2016 were analyzed retrospectively. There were 45 patients with normal preoperative laryngoscope result who were reoperated with IONM combined with the naked eye recognition and protection—the nerve monitoring group. The 45 patients with normal preoperative laryngoscope result who were reoperated by using the method of exposing RLN routinely were selected as the control group—routine exposure group via the random number table method and the principle of 1??1. Recognition rate of RLN, confirming the identification time, transient RLN injury, permanent RLN injury, intraoperative blood loss and the amount of postoperative drainage were compared and analyzed. Results In routine exposure group, RLN was identificated successfully in 39 patients, and the confirmation time is (3.4±0.9) min. The remaining 6 patients (13.3%) had not successfully identified the RLN. Through careful dissection during the operation, confirmation time of RLN was prolonged to (16.5±3.2) min. Through the application of the neural monitoring combined with naked eye recognition, the recognition rate of RLN was 100%, and confirmation time was (2.2±0.8) min. Temporary and permanent RLN injury rate in the nerve monitoring group was lower than that in the conventional exposure group??6.7% vs. 22.2% (P<0.05), 0 vs. 2.2% (P>0.05). Intraoperative blood loss and the amount of postoperative drainage in the nerve monitoring group were less than those in the routine exposure group????12.2±2.9??mL vs.??13.1±1.8??mL??P>0.05??,??40.6±2.8??mL vs.??50.8±3.2??mL??P<0.05??. Conclusion Compared with the conventional exposure, IONM can speed up the recognition of RLN during reoperation of thyroid gland, improve the recognition rate of RLN??reduce the rate of RLN injury and the amount of postoperative drainage. When the dangerous area of RLN is operated??changes in the amplitude of EMG signals can be found by continuous real-time monitoring to ensure the safety of the operation.     

Functional Laryngeal Results after Thyroidectomy and Extensive Recurrent Laryngeal Nerve Dissection without Neuromonitoring

Summary BACKGROUND: Permanent recurrent laryngeal nerve palsy (RLNP) is a major complication after thyroid surgery. Therefore methods are mandatory which reduce this complication. One strategy is the identification and dissection of the recurrent laryngeal nerve (RLN) in all patients as an inflexible rule. It is an ongoing discussion whether RLN neuromonitoring is helpful. METHODS: We prospectively investigated 624 surgical patients with 1076 nerves at risk (NAR) after hemithyroidectomy or total thyroidectomy because of a benign thyroid pathology (BT). In all patients, extensive nerve dissection was performed. Electrophysiological neuromonitoring was not used. All patients were investigated both pre- and postoperatively for regular laryngeal function, using indirect laryngoscopy and videostroboscopy. RESULTS: 2.4 % temporary and 0.3 % permanent RLNPs were documented respectively. CONCLUSIONS: Reviewing the literature, the total rates of (temporary and permanent) RLNPs are identical or lower in studies performing RLN dissection compared to those where no RLN dissection had been performed. Performing RLN dissection reduced the rate of permanent RLNPs. However, our results do not imply that neuromonitoring decreases the rate of permanent RLNP, since studies that included neuromonitoring did not reveal better data. Our observations also suggest that besides indirect laryngoscopy, videostroboscopy should be performed in all patients with no evidently normal bilateral laryngeal function and no normal voice quality. Failing this, the rate of false positive or negative identification of RLNP is likely to increase.     

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??Application of intraoperative neromonitoring during complex thyroid operation SUN Hui,LIU Xiao-li,FU Yan-tao,et al.Division of Thyroid Surgery,China-Japan Union Hospital of Jilin University,Changchun 130033, China Corresponding author: SUN Hui,E-mail:sunhui1229@163.com Abstract Objective Apply the intraoperative neuromonitoring ??IONM?? as an adjunct to avoid recurrent laryngeal nerve (RLN) injury during complex thyroid operation. Methods From March 2009 to July 2009, 132 pations (186 nerves at risk) underwent complex thyroidectomy with the application of IONM. Vagus nerve and RLN were tested respectively before and after resection of thyroid lobe. Video recording of cord mobility was performed routinely pre- and postoperatively. Results In addition to 4 cases with preoperative vocal cord paralysis??182 RLN after resection of thyroid lobe with a clear electromyography(EMG) and 0?? nerves experienced signal loss before closing surgical incision showed normal electrical transduction function. Accurately detect non-RLN in 2 nerves. Conclusion IONM could make RLN identification more reliabe and precise, test the functional integrity of RLN. IONM is a useful adjunct to reduce RLN palsy rate in complex thyroid operation.     

Validity of intra-operative neuromonitoring signals in thyroid surgery

Background Although intra-operative neuromonitoring (IONM) is widely used in thyroid surgery, the validity of the received IONM signals are still unknown.Method Prospective collection of data forms in 29 hospitals from 8,534 patients with 15,403 nerves at risk, who underwent surgery for benign and malignant goitre disorders between August 1999 and January 2001. IONM was performed by indirect stimulation via the vagal nerve and by direct recurrent laryngeal nerve (RLN) stimulation in 12,486 cases. IONM signals were compared with early (<14 days) and late (6 months) postoperative vocal cord function findings.Results The transient and permanent RLN palsy rate was 2.8% and 0.7%, respectively. Monitoring of the RLN function was significantly more reliable via the indirect IONM stimulation route than via the direct IONM stimulation route (specificity P<0.05). IONM by indirect stimulation via the vagal nerve reliably excluded postoperative, permanent, vocal cord palsy (specificity 97.6%, negative predictive value 99.6%). However, a changed IONM was insufficient to predict permanent RLN palsy (sensitivity 45.9%, positive predictive value 11.6%). IONM was not associated with increased general morbidity.Conclusions For intra-operative neuromonitoring, indirect stimulation of the RLN is superior to direct stimulation. An intact acoustic IONM signal is highly predictive of intact postoperative RLN function. When the IONM signal is abnormal or absent, a one-stage extensive thyroid resection should be performed only if the surgeon is absolutely convinced that the first RLN is not harmed or a total thyroidectomy is mandatory.     

甲状腺再次手术中喉返神经实时监测与常规显露临床对比研究

目的 比较甲状腺再次手术中喉返神经实时监测与常规显露的差异,探讨术中喉返神经监测在甲状腺再次手术中应用的临床价值。 方法 回顾性分析2014年5月至2016年5月于哈尔滨医科大学附属第一医院甲状腺乳腺外科接受甲状腺再次手术118例病人资料。其中应用术中喉返神经监测联合肉眼识别保护且术前电子喉镜检查正常者45例（神经监测组）,采用随机数表法,按照1：1对照原则,选取常规显露保护喉返神经且术前电子喉镜检查正常者45例为对照组（常规显露组）。比较分析两组病人在喉返神经识别率、确认识别时间、术后暂时性喉返神经损伤、永久性喉返神经损伤、术中出血量以及术后引流量的差异。 结果 应用喉返神经常规显露肉眼识别保护法,喉返神经顺利识别39例（86.7%）,确认识别时间为（3.4±0.9）min;余6例（13.3%）常规显露未顺利识别喉返神经,经术中细致解剖确认喉返神经时间延长至（16.5±3.2）min,应用神经监测联合肉眼识别保护,喉返神经识别率为100%,确认识别时间为（2.2±0.8）min;暂时性及永久性喉返神经损伤率在神经监测组较常规显露组低,分别为6.7% vs. 22.2%（P<0.05）,0 vs. 2.2%（P>0.05）;神经监测组术中出血量及术后引流量较常规显露组少,分别为（12.2±2.9）mL vs.（13.1±1.8）mL（P>0.05）,（40.6±2.8）mL vs.（50.8±3.2）mL（P<0.05）。结论 甲状腺再次手术中,术中喉返神经监测较常规显露能加快完成喉返神经的确认识别,提高喉返神经的识别率,有效降低暂时性喉返神经损伤率,并且减少术后引流量,有利于术后恢复,在喉返神经周围危险区操作时,连续实时监测发现肌电信号振幅的危险改变,增加手术安全性。     

显露喉返神经在非神经监测与神经监测下单侧甲状腺手术中的临床分析

目的 探讨显露喉返神经在非神经监测与神经监测下单侧甲状腺手术中的临床效果分析.方法 回顾性分析南方医科大学顺德医院2019年1月至2020年11月66例单侧甲状腺手术患者临床资料,根据是否应用喉返神经监测技术分为非神经监测组和神经监测组,每组各33例.非神经监测组钝性分离直接显露喉返神经,神经监测组在神经监测提示下逐步...     

Results of Intraoperative Neuromonitoring in Thyroid Surgery and Preoperative Vocal Cord Paralysis

Background

Systematic studies of intermittent intraoperative neuromonitoring (IONM) have shown that IONM enhances recurrent laryngeal nerve (RLN) identification via functional assessment, but does not significantly reduce rates of vocal cord (VC) paralysis (VCP). The reliability of functional nerve assessment depends on the preoperative integrity of VC mobility. The present study was therefore performed to analyze the validity of IONM in patients with pre-existing VC paralysis.

Methods

Of 8,128 patients, 285 (3.5 %) with preoperative VCP underwent thyroid surgery using standardized IONM of the RLN and vagus nerves (VNs). VC function was assessed by pre- and postoperative direct videolaryngoscopy. Quantitative parameters of IONM in patients with VCP were compared with IONM in patients with intact VC function. Clinical symptoms and surgical outcomes of patients with pre-existing VCP were analyzed.

Results

A total of 244 patients revealed negative, and 41 revealed positive IONM on the side of the VCP. VCP with positive IONM revealed significantly lower amplitudes of VN and RLN than intact VN (p = 0.010) and RLN (p = 0.011). Symptoms of patients with VCP included hoarseness (25 %), dyspnea (29 %), stridor (13 %), and dysphagia (13 %); 13 % were asymptomatic. New VCP occurred in five patients, ten needed tracheostomy for various reasons, and one patient died.

Conclusions

Patients with pre-existing VCP revealed significantly reduced amplitude of ipsilateral VN and RLN, indicating retained nerve conductivity despite VC immobility. Preoperative laryngoscopy is therefore indispensable for reliable IONM and risk assessment, even in patients without voice abnormalities.