Effect of intraoperative nerve monitoring on postoperative vocal cord palsy rates after thyroidectomy: European multicentre registry-based study

The risk factors for postoperative temporary vocal cord paralysis after thyroid cancer surgery: an observational retrospective cohort study

OBJECTIVE

To analyze the potential factors influencing new-onset postoperative transient vocal cord paralysis (VCP) in thyroid cancer patients.

METHODS

Case information of 8340 thyroid cancer patients hospitalized at China-Japan Union Hospital of Jilin University, Jilin Province, China, in the Thyroid Surgery Department from January 2018 to December 2020 was collected retrospectively and analyzed. The possible influencing factors were analyzed using a χ2 test, rank-sum test, and multiple logistic regression analysis. A nomogram was used to construct the clinical prediction model that was validated in the validation set by receiver operating characteristic, calibration curves, and Decision curve analysis.

RESULTS

The strengthening the reporting of cohort, cross-sectional, and case-control studies in surgery (STROCSS) guideline was followed to conduct a retrospective cohort study. A total of 8340 patients, including 1817 (21.8%) men and 6523 (78.2%) women, were enrolled in this study. The rate of temporary VCP was 3.6% (308/8340). Based on the results of postoperative laryngoscopy, the patients were divided into VCP group and non-VCP group. Comparative analysis between the groups revealed that potential factors associated with postoperative transient VCP were tumor location on the dorsal side of the gland ( P =0.042), ultrasound showing a maximum nodal diameter >1 cm ( P =0.002), multifocal carcinoma ( P <0.001), invasion of surrounding tissue ( P =0.005), lymph node metastases in the central compartment ( P =0.034), lateral cervical lymph node metastasis ( P <0.001), and prolonged operation ( P <0.001). A multiple logistic regression analysis showed that the independent risk factors in postoperative transient VCP were T stage (OR=1.411, P =0.013, 95% CI: 1.075-1.853), multifocal carcinoma (OR=1.532, P =0.013, 95% CI: 1.095-2.144), and duration of surgery (OR=1.009, P <0.001, 95% CI: 1.006-1.012). Finally, a clinical prediction model was established via a nomogram and was validated in the validation set, although its diagnostic efficacy needs to be improved further.

CONCLUSION

High T stage, multifocal carcinoma, and prolonged operation time may be independent risk factors for the occurrence of postoperative transient VCP in patients undergoing initial surgery for thyroid cancer.

Outcomes of Immediate Total Thyroidectomy in First-Side Loss of Neuromonitoring Signal

Importance

Use of intraoperative neuromonitoring (IONM) during thyroidectomy can nearly eliminate the risk of postoperative bilateral vocal cord palsy (VCP) by indicating staged surgery in cases of loss of signal (LOS) on the first side of planned total thyroidectomy. However, aborting planned total thyroidectomy may lead to persistence of symptoms, delay in adjuvant treatment, and patient inconvenience and distress. There are few data to guide a selective approach to total thyroidectomy in patients with first-side LOS.

Objective

To investigate outcomes of immediate bilateral surgery in patients undergoing total thyroidectomy with first-side LOS.

Design, Setting, and Participants

This cohort study was a retrospective review of outcomes for patients undergoing thyroidectomy between January 2016 and July 2023 at an academic tertiary referral center for thyroid surgery. Consecutive patients scheduled for total thyroidectomy using IONM were included. Exclusion criteria were preoperative VCP, deliberate sacrifice of recurrent laryngeal nerve (RLN), inadvertent RLN resection, and surgery performed without IONM.

Exposures

Total thyroidectomy performed using IONM.

Main Outcome Measures

Vocal mobility on first postoperative day as assessed by flexible laryngoscopy; secondary outcome measures included subjective voice assessment, other postoperative complications, and long-term vocal mobility.

Results

Among 400 patients undergoing planned total thyroidectomy (mean age, 50.5 years [range, 4-88 years]; 318 female [79.5%]), 51 (12.8%) had first-side LOS, of whom 37 (9.3%) had persistent LOS. Twenty-nine patients (56% of procedures with first-side LOS, including 18 with persistent LOS) proceeded to immediate total thyroidectomy. Postoperatively, 16 patients (55% of patients undergoing total thyroidectomy following first-side LOS, including 14 of 18 with persistent LOS) had impaired vocal mobility. One patient had bilateral VCP that did not require tracheostomy, and 2 had postoperative hypoparathyroidism. Of those whose surgery was aborted after first-side LOS, 8 of 22 (36%) underwent completion thyroidectomy at a later stage. In those undergoing completion thyroidectomy, 2 of 8 (25%) had temporary VCP after the second surgery, 2 (25%) had permanent hypoparathyroidism, and 1 (12.5%) developed inoperable cancer. Postoperative VCP was fully reversible in all but 1 patient.

Conclusion and Relevance

Among patients planned for total thyroidectomy who develop first-side LOS, immediate total thyroidectomy may be considered among those who have pressing reasons for same, and where surgical difficulties might be anticipated in a secondary surgery.

Cost-effectiveness of intraoperative neural monitoring of recurrent laryngeal nerves in thyroid lobectomy for papillary thyroid carcinoma

Purpose

Recurrent laryngeal nerve injury after thyroid surgery may cause vocal cord palsy (VCP), which leads to unexpected additional costs. In recent years, intraoperative neural monitoring (IONM) has been used to lower the incidence rate of VCP. This study aimed to analyze postoperative management costs for patients with papillary thyroid carcinoma (PTC).

Methods

We analyzed the medical records of patients who underwent lobectomy for PTC from September 2018 to August 2019 at The Catholic University of Korea, Seoul St. Mary's Hospital. A total of 411 patients were enrolled and all the patients had voice examinations. We investigated the total costs in the IONM and non-IONM groups during a maximum 1-year follow-up and calculated the additional costs due to VCP by subtraction of the mean values in each group.

Results

The incidence rate of VCP was 3.9% (16 of 411). Extrathyroidal extension was related to VCP in Cox regression tests and accounted for 3.2% (13 of 411). VCP rate did not show a significant difference between the IONM and non-IONM groups (4.1% vs. 3.8%, P = 0.883). Total costs for postoperative management were higher in the IONM group than in the non-IONM group (US $328.2 ± $220.1 vs. $278.7 ± $141.4, P < 0.05). However, the additional costs due to VCP were significantly lower in the IONM group than in the non-IONM group ($474.1 ± $150.3 vs. $568.9 ± $367.6, P < 0.005).

Conclusion

The use of IONM can mitigate the increase in costs by saving additional expenses associated with VCP.

Continuous Intraoperative Nerve Monitoring of a Non-Recurrent Laryngeal Nerve: Real-Life Data of a High-Volume Thyroid Surgery Center

Thyroid surgery is associated with a risk of injury to the recurrent laryngeal nerve, especially in the presence of anatomical variants such as a non-recurrent laryngeal nerve (NRLN). Injury to the nerve leads to transient or permanent vocal cord palsy (VCP). A novel method to prevent VCP is continuous intraoperative nerve monitoring (cIONM), but less is known about the applicability of this method in patients with NRLN. The aim of this study was to evaluate our own data regarding feasibility and detailed characteristics of cIONM in NRLN patients. We performed a monocentric retrospective cohort analysis including clinical data and intraoperative nerve monitoring data (measured by Inomed Medizintechnik GmbH, Emmendingen, 'C2' and 'C2 Xplore' device) of all thyroid surgery patients, showing NRLN between 2014 and 2022. Of 1406 patients who underwent thyroid surgery with cIONM between 2014 and 2022, 12 patients (0.9%) showed NRLN intraoperatively. Notably, cIONM was feasible in eight patients (67%). In all cases the onset latency of the right vagus nerve was shorter (<3.0 ms) than usually expected, suggesting that a short latency might be suitable to distinguish NRLN. None of the patients had a post-operative VCP. Overall, cIONM appears to be feasible and safe in NRLN patients and provides helpful information to prevent VCP.

Hemithyroidectomy, does the indication influence the outcome?

PURPOSE

Hemithyroidectomies are mainly performed for two indications, either therapeutically to relieve compression symptoms or diagnostically for suspicious nodule(s). In case of the latter, one could consider the approach to be rather extensive since the majority of patients have no symptoms and will have benign disease. The aim of this study is to investigate the complication rates of diagnostic hemithyroidectomy and to compare it with the complication rates of compressive symptoms hemithyroidectomy.

METHODS

Data from patients who had undergone hemithyroidectomy either for compression symptoms or for excluding malignancy were extracted from a well-established Scandinavian quality register (SQRTPA). The following complications were analyzed: bleedings, wound infections, and paresis of the recurrent laryngeal nerve (RLN). Risk factors for these complications were examined by univariable and multivariable logistic regression.

RESULTS

A total of 9677 patients were included, 3871 (40%) underwent surgery to exclude malignancy and 5806 (60%) due to compression symptoms. In the multivariable analysis, the totally excised thyroid weight was an independent risk factor for bleeding. Permanent (6-12 months after the operation) RLN paresis were less common in the excluding malignancy group (p = 0.03).

CONCLUSION

A range of factors interfere and contribute to bleeding, wound infections, and RLN paresis after hemithyroidectomy. In this observational study based on a Scandinavian quality register, the indication "excluding malignancy" for hemithyroidectomy is associated with less permanent RLN paresis than the indication "compression symptoms." Thus, patients undergoing diagnostic hemithyroidectomy can be reassured that this procedure is a safe surgical procedure and does not entail an unjustified risk.

Hereditary Endocrine Tumor Registries

Context

Endocrine neoplasia syndromes are phenotypically complex, and there is a misconception that they are universally rare. Genetic alterations are increasingly recognized; however, true prevalence is unknown. The purpose of a clinical registry is to monitor the quality of health care delivered to a specified group of patients through the collection, analysis, and reporting of relevant health-related information. This leads to improved clinical practice, decision-making, patient satisfaction, and outcome.

Objective

This review aims to identify, compare, and contrast active registries worldwide that capture data relevant to hereditary endocrine tumors (HETs).

Methods

Clinical registries were identified using a systematic approach from publications (Ovid MEDLINE, EMBASE) peer consultation, clinical trials, and web searches. Inclusion criteria were hereditary endocrine tumors, clinical registries, and English language. Exclusion criteria were institutional audits, absence of clinical data, or inactivity. Details surrounding general characteristics, funding, data fields, collection periods, and entry methods were collated.

Results

Fifteen registries specific for HET were shortlisted with 136 affiliated peer-reviewed manuscripts.

Conclusion

There are few clinical registries specific to HET. Most of these are European, and the data collected are highly variable. Further research into their effectiveness is warranted. We note the absence of an Australian registry for all HET, which would provide potential health and economic gains. This review presents a unique opportunity to harmonize registry data for HET locally and further afield.

Real-world EUROCRINE® registry data challenge the reliability of Bethesda cytopathology for thyroid surgery indication

Objectives

Fine-needle aspiration cytology (FNAC) is recommended by international guidelines for the preoperative evaluation of suspicious thyroid nodules >1 cm. Despite robust evidence from endocrine centers demonstrating the key role of FNAC results for the indication of surgery, the method is not routinely used in European clinics. The database EUROCRINE^®, which was introduced in 2015 with the scope of registering operations of the endocrine system, allows for a large-scale analysis of the current service reality in Europe concerning FNAC use and associated accuracy.

Methods

Operations performed to "exclude malignancy", registered from January 2015 to December 2018 in EUROCRINE^®, were analyzed. Parameters of accuracy were calculated for FNAC. FNAC results were considered "test positive" in the case of Bethesda category IV, V, and VI, since these categories usually prompt surgical interventions in European centers for thyroid surgery. Bethesda category II and III were considered "test negative".

Results

Of 8,791 operations, 5,780 had preoperative FNAC (65.7%). The overall malignancy rate was 28.3% (2,488/8,791). Malignancy rates were 68.8% for Bethesda VI, 69.9% for Bethesda V, 32.6% for Bethesda IV, 28.2% for III, 20.2% for Bethesda II, and 24.5% for Bethesda I. After exclusion of papillary microcarcinomas (PTMCs), the sensitivity of FNAC was 71.7% and specificity 43.5%, the positive predictive value was 29.1% and the negative predictive value 82.7%.

Conclusions

Although the indication to "exclude malignancy" was the predominant reason that prompted thyroid resection in the present cohort, FNAC was only used in about 65.7% of cases. When performed, FNAC was associated with unexpectedly low accuracy. Interestingly, in Bethesda II, 20.2% of malignant entities were present (13.3% after the exclusion of PTMCs).

The impact of intraoperative “Nerve Monitoring” in a tertiary referral center for thyroid and parathyroid surgery

The most fearsome complication in thyroid surgery is the temporary or definitive recurrent laryngeal nerve (RLN) injury. The aim of our study was to evaluate the impact of intraoperative neuromonitoring (IONM) on postoperative outcomes after thyroid and parathyroid surgery. From October 2014 to February 2016, a total of 80 consecutive patients, with high risk of RLN injuries, underwent thyroid and parathyroid surgery. They were divided in two groups (IONM group and control group), depending on whether neuromonitoring was used or not. We used the Nerve Integrity Monitoring System (NIM)-Response 3.0® (Medtronic Xomed®). The operation time (p = 0.014). and the length of hospital stay (LOS) (p = 0.14) were shorter in the IONM group. Overall mean follow-up was 96.7 ± 14.3 months. The rate of transient RLN palsy was 2.6% in IONM group and 2.5% in the control group (p = not significant). Only one case of definitive RLN injury was reported in control group. No differences were reported between the two groups in terms of temporary or definitive RLN injury. Routine use of IOMN increases the surgery cost, but overall, it leads to long-term cost savings thanks to the reduction of both operating times (106.3 ± 38.7 vs 128.1 ± 39.3, p: 0.01) and LOS (3.2 ± 1.5 vs 3.7 ± 1.5 days, p = 0.14). Anatomical visualization of RLN remains the gold standard in thyroid and parathyroid surgery. Nevertheless, IONM is proved to be a valid help without the ambition to replace surgeon's experience.

Effect of Intraoperative Neuromonitoring on the Risks of Recurrent Laryngeal Nerve Injury During Thyroidectomy: A Doubly Robust Approach

OBJECTIVE

To evaluate the relationship between the use intraoperative neuromonitoring (IONM) during thyroidectomy and the risk of recurrent laryngeal nerve (RLN)injury.

BACKGROUND

The role of IONM in reducing RLN injury during thyroidectomy remains controversial. Several studies on this topic apply conventional multivariable regression to adjust for confounding. However, estimates from this method may be biased due to model misspecification, especially with a rare outcome such as RLN injury.

METHODS

We used a pooled dataset created by linking the 2016 - 2019 NSQIP General Participant User File with the corresponding Targeted-Thyroidectomy file. The primary outcome was RLN injury rates, and the secondary outcomes were operating time and postoperative length of stay. A doubly robust (DR) estimator, in the form of an inverse-probability-weighted regression adjustment model, was used to estimate the effect of the use of IONM on the risk of RLN injury. Sensitivity analyses was performed.

RESULTS

Twenty-four thousand three hundred seventy patients were evaluated, out of which 15,836 (70%) patients had IONM during thyroidectomy, and RLN injury occurred in 1,498 (6.2%) cases. Rates of RLN injury increase with increasing age and BMI and are higher in patients with a cancer diagnosis, previous neck operation, total thyroidectomy, and node dissection. DR model suggests that the use of IONM was associated with a significant reduction in overall rate of RLN injury (RR 0.77(CI, 0.68 to 0.87),P<0.001], and postoperative length of stay [-2.5 h(CI, -4.18 to - 0.81 h)P=0.004)]. However, IONM use was associated with an increase in operating time [15.41mins(CI, 13.29-14.54 mins, P<0.0001)]. Sensitivity analyses revealed that our estimates are largely robust to confounding.

CONCLUSION

In a balanced cohort of patients undergoing thyroidectomy from multiple sites and surgeons participating in NSQIP, the use of IONM during thyroidectomy was associated with reduction in RLN injury.

Human Amnion/Chorion Membrane May Reduce Transient Recurrent Laryngeal Nerve Injury During Thyroid Surgery

Recurrent laryngeal nerve (RLN) damage is a significant and prevalent complication of thyroid surgery. Based on the beneficial role of a human amnion/chorion membrane (HACM) allograft in wound management and nerve regeneration, we investigated whether placement of a commercially available HACM allograft on dissected RLN could reduce the occurrence and/or duration of RLN injury during thyroidectomy. Among 67 patients undergoing thyroidectomy, 100 at-risk nerves (exposure of at least 3 cm of RLN) received intraoperative placement of HACM; 205 at-risk RLNs without HACM in 134 matched patients served as controls. Patient-reported vocal analysis, physician-assessed vocal analysis, and laryngoscopic assessment of vocal-fold dysfunction were performed before and after surgery. At 24 h after surgery, 17 patients in the control group (12.5%) had documented voice changes; these changes persisted for at least 3 weeks in seven patients (5%). Only one patient (1.5%) in the HACM group had vocal changes at 24 h after surgery, which resolved within 1 week (P < 0.01). Intraoperative placement of the HACM allograft over at-risk RLNs during thyroidectomy may reduce the incidence, severity, and/or duration of intraoperative RLN injury, which could address a significant complication of head and neck surgery. A larger prospectively designed clinical study is warranted to further investigate a possible benefit of the HACM allograft in thyroid surgery and to begin to understand the mechanisms through which a clinical benefit might be mediated.

Clinicopathologic Characteristics and Outcomes of Massive Multinodular Goiter: A Retrospective Cohort Study

BACKGROUND

Thyroidectomy for massive goiters is challenging because of the increased risk of tracheomalacia, combined sternotomy, postoperative morbidity, and mortality, whereas studies investigating the clinicopathologic characteristics, postoperative morbidities, and surgical outcomes of massive goiters are limited.

METHODS

Patients with goiters undergoing thyroid surgery between 2009 and 2019 were retrospectively reviewed. A total of 227 patients were enrolled and divided into massive goiter group and large goiter group according to the weight of the goiter. Clinicopathologic characteristics, postoperative morbidities, and surgical outcomes were compared between the two groups.

RESULTS

Seventy-four patients (32.6%) had a goiter weighing more than 250 g and 153 patients (67.4%) were categorized in the large goiter group. Compared to large goiter patients, massive goiter patients had higher rates of retrosternal extension (82.4% vs. 30.7%), combined sternotomy (12.2% vs. 1.3%), intensive care unit admission (25.7% vs. 7.2%), transient hypoparathyroidism (41.9% vs. 25.5%), and transient recurrent laryngeal nerve palsy (10.8% vs. 3.3%) as well as prolonged length of hospital stay (P < 0.05).

CONCLUSIONS

Massive goiter patients were at increased risk of combined sternotomy, intensive care unit admission, postoperative morbidities as well as prolonged length of hospital stay after thyroidectomy compared to large goiter patients, but most of them can be treated through a cervical approach with a favorable outcome.

Intraoperative Neuromonitoring: Evaluating the Role of Continuous IONM and IONM Techniques for Emerging Surgical and Percutaneous Procedures

Continuous and intermittent intraoperative nerve monitoring (IONM) has become an important asset for endocrine surgeons over the past few decades. The ability to determine neurophysiologic integrity of the recurrent laryngeal nerve (RLN) and external branch of the superior laryngeal nerve (EBSLN) on top of identification and meticulous dissection of the nerve in the surgical field, has allowed for advances in technology and improved outcomes when it comes to prevention of vocal fold immobility. This article aims to compare in review continuous and intermittent nerve monitoring (CIONM, IIONM), as well as review the current paradigms of their use. This article will also discuss the future of intraoperative nerve monitoring technologies in scarless thyroid surgery and percutaneous approaches to thyroid pathology in form of radiofrequency ablation (RFA).

Clarifying optimal outcome measures in intermittent and continuous laryngeal neuromonitoring

BACKGROUND

Intraoperative neuromonitoring (IONM) techniques have evolved over the past decade into intermittent IONM (I-IONM) and continuous IONM (C-IONM) modes of application. Despite many prior publications on both types of IONM, there remains uncertainty about what outcomes should be measured for each form of IONM. The primary objective of this paper is to define categories of benefit for I-IONM/C-IONM and to clarify and standardize their reporting outcomes.

METHODS

Expert review consensus statement utilizing modified Delphi methodology.

RESULTS

I-IONM provides diagnosis, classification, and prevention of nerve injury through accurate and early nerve identification. C-IONM provides real-time information on nerve functional integrity and thus may prevent some types of nerve injury but cannot assist in nerve localization. Sudden mechanisms of nerve injury cannot be predicted or prevented by either technique.

CONCLUSIONS

I-IONM and C-IONM are complementary techniques. Future studies evaluating the utility of IONM should focus on outcomes that are appropriate to the type of IONM being utilized.

Continuous Intraoperative Recurrent Laryngeal Nerve Monitoring: Techniques, Applications, and Controversies

Purpose of Review

Purpose of the present review is to illustrate the current state of the art concerning continuous intraoperative recurrent laryngeal nerve monitoring (cIONM) for thyroid surgery.

Recent Findings

cIONM potentially leads to an improved postoperative vocal cord palsy rate, compared to the intermittent technique. There are currently two main approaches for cIONM: either conventional cIONM based on vagal nerve stimulation or experimental methods, which do not require the positioning of a vagal nerve electrode. One of these methods is the recently described technique “LAR-cIONM,” which utilizes the laryngeal adductor reflex.

Summary

cIONM represents an advancement of intermittent nerve monitoring, which allows for an immediate reaction to signal changes. Threshold values and guidelines to prevent recurrent laryngeal nerve palsy were validated for the direct stimulation of the vagal nerve and require verification for alterative cIONM methods, including LAR-cIONM.

Low-Dose of Rocuronium During Thyroid Surgery: Effects on Intraoperative Nerve-Monitoring and Intubation

BACKGROUND

Intraoperative Neurophysiological Monitoring (IONM) reduces the incidence of Recurrent Laryngeal Nerve (RLN) injuries during thyroid surgery. To preserve nerve function, long acting neuromuscular blocking agents (NMBA) should be avoided. However, NMBA are necessary for laryngoscopy and endotracheal intubation. We designed this double-blinded, randomized, placebo-controlled trial to assess if a low-dose of rocuronium given at intubation would affect the IONM data recorded before the thyroid dissection.

METHODS

Hundred patients undergoing elective thyroid surgery were randomized to receive either 0.3 mg kg^-1 of low dose rocuronium (intervention) or no-NMBA (control). Intubation was performed with video-laryngoscopy. IONM was placed on RLN and nerve stimulation was performed before and after thyroid dissection. The presence of a valid amplitude prior to dissection was defined when the IONM signal was >100 μV. Occurrence of difficult laryngoscopy was reported together with intubation details including time, difficulty and failure. The lowest peripheral saturation (SpO₂) and the number of desaturation episodes during the intubation were also registered.

RESULTS

No patients showed impaired IONM signal before dissection in both groups. Cormack-Lehane grade was higher in the intervention group (1^1;2) compared to control one (1^1;1; P = 0.046). No-NMBA patients had increased number of difficult laryngoscopies (21% versus 6%, P = 0.041) and intubations (34% versus 8%; P = 0.003) as well as a longer time to intubation (78 [55; 175] versus 55 [31; 110] sec; P = 0.006). Lower values of peripheral SpO₂ during intubation attempt were registered in the no NMBA group (99 [97; 100] versus 99 [99; 100] %; P = 0.020). However, the number of intubation failure was similar between groups (p=0.495).

CONCLUSIONS

Low-dose of rocuronium does not compromise pre-dissection IONM signal and improves intubation condition when compared to a relaxant free strategy.

New Developments in Anterior Laryngeal Recording Technique During Neuromonitored Thyroid and Parathyroid Surgery

A recurrent laryngeal nerve (RLN) injury resulting in vocal fold paralysis and dysphonia remains a major source of morbidity after thyroid and parathyroid surgeries. Intraoperative neural monitoring (IONM) is increasingly accepted as an adjunct to the standard practice of visual RLN identification. Endotracheal tube (ET) surface recording electrode systems are now widely used for IONM; however, the major limitation of the clinical use of ET-based surface electrodes is the need to maintain constant contact between the electrodes and vocal folds during surgery to obtain a high-quality recording. An ET that is malpositioned during intubation or displaced during surgical manipulation can cause a false decrease or loss of electromyography (EMG) signal. Since it may be difficult to distinguish from an EMG change caused by a true RLN injury, a false loss or decrease in EMG signal may contribute to inappropriate surgical decision making. Therefore, researchers have investigated alternative electrode systems that circumvent common causes of poor accuracy in ET-based neuromonitoring. Recent experimental and clinical studies have confirmed the hypothesis that needle or adhesive surface recording electrodes attached to the thyroid cartilage (transcartilage and percutaneous recording) or attached to the overlying neck skin (transcutaneous recording) can provide functionality similar to that of ET-based electrodes, and these recording methods enable access to the EMG response of the vocalis muscle that originates from the inner surface of the thyroid cartilage. Studies also indicate that, during surgical manipulation of the trachea, transcartilage, percutaneous, and transcutaneous anterior laryngeal (AL) recording electrodes could be more stable than ET-based surface electrodes and could be equally accurate in depicting RLN stress during IONM. These findings show that these AL electrodes have potential applications in future designs of recording electrodes and support the use of IONM as a high-quality quantitative tool in thyroid and parathyroid surgery. This article reviews the major recent developments of newly emerging transcartilage, percutaneous, and transcutaneous AL recording techniques used in IONM and evaluates their contribution to improved voice outcomes in modern thyroid surgery.

Training Courses in Laryngeal Nerve Monitoring in Thyroid and Parathyroid Surgery- The INMSG Consensus Statement

Intraoperative neural monitoring (IONM) is now an integral aspect of thyroid surgery in many centers. Interest in IONM and the number of institutions that perform monitored thyroidectomies have increased throughout the world in recent years. For surgeons considering the introduction of IONM in their practice, specific training in IONM devices and procedures can substantially shorten the learning curve. The International Neural Monitoring Study Group (INMSG) has been at the forefront of IONM technology and procedural adoption since the introduction of neural monitoring in thyroid and parathyroid surgery. The purpose of this document is to define the INMSG consensus on essential elements of IONM training courses. Specifically, this document describes the minimum training required for teaching practical application of IONM and consensus views on key issues that must be addressed for the safe and reliable introduction of IONM in surgical practice. The intent of this publication is to provide societies, course directors, teaching institutions, and national organizations with a practical reference for developing IONM training programs. With these guidelines, IONM will be implemented optimally, to the ultimate benefit of the thyroid and parathyroid surgical patients.