Varied Recurrent Laryngeal Nerve Course Is Associated with Increased Risk of Nerve Dysfunction During Thyroidectomy: Results of the Surgical Anatomy of the Recurrent Laryngeal Nerve in Thyroid Surgery Study, an International Multicenter Prospective Anatomic and Electrophysiologic Study of 1000 Monitored Nerves at Risk from the International Neural Monitoring Study Group

The recurrent laryngeal nerve and extralaryngeal branches in relation to the inferior thyroid artery, Berry's ligament, tracheal groove, and Zuckerkandl tubercle: an experience of 60 thyroidectomies

AIM

The aim of this study was to examine the anatomical variations of the inferior laryngeal nerve compared with its extralaryngeal branches, the inferior thyroid artery, Berry's ligament, the tracheal groove, and the tubercle of Zuckerkandl, as encountered during thyroid gland operations. This is a case series conducted at the Anticancer Hospital of Thessaloniki "Theageneio" between October 2021 and May 2022.

Paradigms of intraoperative neuromonitoring in paediatric thyroid surgery

The larynx of children and adolescents is still in the developmental phase and the anatomical structure is still very small and sensitive. The higher malignancy and faster progression of some paediatric thyroid cancers make surgery more difficult. Intraoperative neuromonitoring (IONM) is frequently used in thyroid surgery as an effective means of securing the recurrent laryngeal nerve (RLN). Little information is available on the clinical efficacy of IONM in paediatric surgery. In addition, classic IONM techniques such as reinforced tracheal tube models with integrated surface electrodes are not standardised for children and adolescents. The use of innovative devices such as laryngeal masks with surface electrodes and thyroid cartilage receiving electrodes could replace monitoring tubes as a new form of IONM. Tracheal intubation in children needs to be performed by a highly experienced anaesthetist. The continued maturation of AI technology could be attempted in the future in conjunction with IONM to further reduce RLN injuries in children and adolescents. This article describes the anatomical features of the paediatric larynx, which differ from those of adults, and the advantages and shortcomings of IONM techniques for thyroid surgery in this population. The use of IONM in paediatric surgery is a complex technique and should be performed by experienced thyroid surgeons with in-depth IONM training. The use of IONM should be standardised within the clinical parameters of children.

Effectiveness and feasibility of nerve real-time monitoring and intermittent monitoring in endoscopic thyroidectomy: a multicenter retrospective cohort study of 1621 patients

BACKGROUND

Protecting recurrent laryngeal nerve (RLN) and external branch of the superior laryngeal nerve (EBSLN), a crucial indicator for assessing the quality of thyroid surgery, poses a challenge in endoscopic thyroidectomy. The aim of this study was to investigate the effectiveness and feasibility of nerve real-time monitoring and intermittent monitoring in endoscopic thyroidectomy.

METHODS

In this retrospective cohort study, patients underwent endoscopic thyroidectomy were included, and the characteristics and outcomes of real-time monitoring and intermittent monitoring groups were compared. Thereafter, the outcomes of four surgical types (unilateral lobectomy, total thyroidectomy, unilateral lobectomy + lymph node dissection (LND), and total thyroidectomy + LND) were compared in both groups.

RESULTS

A total of 1621 patients were enrolled. Compared to intermittent monitoring group, real-time monitoring group significantly shortened operation durations in the four surgical types (30.8±6.1 min vs. 35.7±5.7 min, 54.7±4.4 min vs. 59.1±5.2 min, 39.3±4.6 min vs. 42.0±4.7 min, 59.1±4.9 min vs. 66.0±5.8 min, respectively). As for surgical complications, compared to intermittent monitoring group, real-time monitoring group had lower rates of transient vocal cord paralysis among the four surgical types (0.0 vs. 3.3%, 0.0% vs. 4.0%, 0.8 vs. 3.2%, 2.8 vs. 6.7%, respectively), and lower rates of EBSLN injury (1.1 vs. 4.4%, 0.0 vs. 12.0%, 0.8 vs. 3.8%, 0.9 vs. 4.8%, respectively). Clinicopathologic characteristics and postoperative inflammatory reactions were similarly paralleled in both groups.

CONCLUSION

Implementation of real-time monitoring in endoscopic thyroidectomy effectively protects the RLN and EBSLN while shortening operation duration, demonstrating its feasibility and efficacy in enhancing nerve protection and surgical efficiency.

Utilization of recurrent laryngeal nerve monitoring during thyroid surgery in China: a point prevalence survey (2015-2023)

BACKGROUND

The survey aimed to elucidate the complete range of national practices, including all technical and non-technical aspects, as well as surgical stratification and maturation, of the use of intraoperative neuromonitoring (IONM) during thyroid surgery in China.

MATERIALS AND METHODS

Six national questionnaires, developed by the Chinese Neural Monitoring Study Group (CNMSG) between 2015 and 2023, were used to collect and analyze data regarding the clinical application, education, and scientific research related to IONM in Chinese medical institutions.

RESULTS

Among the surveyed hospitals, 45% reported an average annual surgical volume exceeding 3000 cases, with 82.5% performing more than 80% of the surgeries for malignant thyroid tumors. Additionally, 97.5% of the hospitals reported a less than 3% incidence of postoperative hoarseness with IONM. Statistical analysis from 2011 to 2015 found that the incidence of postoperative hoarseness decreased by 30% in 2013 compared with 2011, when the technology was introduced. Preoperative and postoperative laryngoscopies were routinely performed by 82.5% and 15% of the hospitals, respectively. For 65% of the hospitals, the publication of the Chinese edition of neuromonitoring guidelines in 2013 prompted the utilization of IONM technology. An average annual number of IONM applications exceeding 500 cases (18.5% the average volume) was reported by 80% of the hospitals, while 62.5% reported a cumulative number of applications greater than 5000 cases (47.1% the average cumulative volume). Regarding technical parameters, 75% of the hospitals reported an intraoperative V1 amplitude of greater than 500 µV, and 70% reported an intraoperative loss of signal (LOS) rate of less than 3%. 92.5% of the surveyed hospitals believed that IONM could help identify dissociated nerves, and 95% of the surveyed hospitals believed that IONM could reduce nerve damage. However, 72.5% of the respondents thought that cost was the main limitation. Furthermore, 67.5% of the hospitals reported that half of their thyroid surgical team members were trained in IONM, with 17.5% reporting that all team members were trained. Areas for reinforced training included IONM research methods and directions (72.5%) and analysis and treatment of abnormal EMG signals (72.5%). Research projects related to IONM were conducted by 42.5% of the hospitals, while 52.5% had published papers on neuromonitoring.

CONCLUSIONS

IONM was independently and incrementally associated with the annual surgical volume. This survey emphasized the importance of national collaboration and/or a registry for the uptake, consolidation, and development of CNMSG consensus.

Thyroid Radiofrequency Ablation-Thermal Effects on Recurrent Laryngeal Nerve Using Continuous Intraoperative Neuromonitoring Animal Model

OBJECTIVE

When performing radiofrequency ablation for thyroid nodules, it is essential to avoid thermal injury to the recurrent laryngeal nerve. This porcine animal model study used continuous intraoperative neuromonitoring to investigate the thermal safety parameters of thyroid radiofrequency ablation.

STUDY DESIGN

Porcine animal study.

SETTING

University animal laboratory.

METHODS

Twelve piglets were tested at different radiofrequency power levels, and the real-time electromyography signal changes were recorded under continuous intraoperative neuromonitoring. The spread heat study (8 piglets) included spontaneous recovery tests and cold water irrigation tests to investigate the safety distance from the recurrent laryngeal nerve to the active tip during 5-second activation with standard stimulation patterns. The residual heat study (4 piglets) investigated the safety cooling durations by touching the recurrent laryngeal nerve with the tip after a 5-second activation.

RESULTS

In the spread heat study, substantial signal attenuation events were observed at an spread heat distance of 2, 3, 5, and 5 mm when the power was set as 10, 20, 30, and 50 W, respectively. No signal recovery could be observed in 20 minutes with or without cold water irrigation in the injured recurrent laryngeal nerve area. The residual heat study shows the residual thermal effect of the tip is minimal, and no substantial signal attenuation event was observed at all experiments.

CONCLUSIONS

This innovative study established the thermal safety parameters for radiofrequency ablation in a porcine model at various power levels, which can potentially assist operators in delineating a precise ablation field and providing effective thyroid ablation treatment safely.

State of the art of neuromonitoring in thyroid surgery

Thyroidectomy is a common procedure in endocrine surgery, frequently performed to treat benign and malignant thyroid conditions. Recurrent laryngeal nerve (RLN) injury, a major complication, underscores the necessity for meticulous nerve dissection during surgery. Intraoperative neuromonitoring (IONM) has emerged as a valuable adjunct to visual identification in RLN preservation. This review synthesizes current literature on IONM in thyroid surgery, emphasizing its role in enhancing RLN integrity assessment and reducing surgical complications such as vocal cord paralysis. IONM techniques include intermittent and continuous monitoring, each offering distinct benefits in nerve function evaluation. While debate persists regarding IONM's efficacy in mitigating unilateral RLN injuries, protocols integrating IONM data have significantly reduced the incidence of bilateral RLN injury, exemplifying advancements in surgical safety. Challenges remain, including variability in study outcomes and the optimal timing of IONM application.

A Novel Surgical Landmark to Identify the Recurrent Laryngeal Nerve

Background

Although several surgical landmarks have been proposed to localize the recurrent laryngeal nerve (RLN), there is still no reliable landmark.

Aims

To validate the reliability of a novel reference point at the intersection of the inferior border of the cricopharyngeal muscle and the inferior cornu of thyroid cartilage for locating the RLN.

Study Design

Cadaver dissection study in the academic department of otolaryngology-head and neck surgery.

Methods

Sixty-four RLNs in cadavers were assessed, and measurements of different surgical landmarks in conjunction with the proposed surgical landmark were obtained. Descriptive statistics, Pearson’s chi-squared test, and Student’s t-test were performed to analyze the data using GraphPad Prism (version 9.4.1; Dotmatics, Boston, Massachusetts, USA).

Results

The average distance from the proposed landmark to the RLN was 2.3 ± 0.85 mm. The RLN was located just posterior to the reference point in 95.31% of the cadavers. The RLN passed under the inferior constrictor muscle in 90.63% of the cadavers. There was no statistically significant difference between right- and left-sided RLNs in terms of their relation with the reference point.

Conclusion

The proposed reference point can be used as a reliable landmark to locate the RLN. This reference point may help surgeons during difficult thyroidectomy surgeries by providing an additional anatomical landmark.

Surgical Management of Substernal Thyroid Goiters

Substernal thyroid goiters can present with progressive symptoms involving compression of vital structures such as the esophagus, trachea, or large vessels. A multidisciplinary approach is critical when diagnosing and treating these patients. This article discusses patient presentation, workup, and management options for patients with substernal goiter as well as surgical pearls to minimize risk of complications.

Global scientific trends on thyroid disease in early 21st century: a bibliometric and visualized analysis

Background

Bibliometrics has been used to analyze the literature in the field of thyroid disease studies in the early 21st century, indicating the changes in current international study trends.

Methods

In this study, a bibliometric analysis of data retrieved from the Web of Science (WoS) database was conducted, and the publication trends and thematic evolution in the field of thyroid disease research from January 1, 2000, to November 16, 2022, were analyzed. A total of 69283 articles related to thyroid diseases were evaluated for their characteristics, including annual publication volume, countries, journals, institutions, authors, keywords, and references. VOSviewer was utilized to perform the analysis of co-authorship, co-citation, co-occurrence and descriptive.

Results

The annual publication volume of thyroid disease research literature showed a fluctuating upward trend from 2000 to 2021, exceeding 5,000 articles for the first time in 2021. The United States (16120 counts, 678255 cities) ranks first in terms of publication volume and citation. Thyroid (n=3201) and Journal of Clinical Endocrinology&Metabolism (n=140399) are the most prolific and cited journals, respectively. The organization with the highest publication volume and citation frequency is Harvard University (1011 counts, 59429 cities), Miyauchi Akira (n=422), Schlumberger, and Martin (n=24839) possess the highest publication volume and citation frequency, respectively. Co-occurrence analysis of 307 keywords with frequencies of more than 20 resulted in 6 clusters (1): Thyroid dysfunction and diseases (2); mechanism of occurrence and development of thyroid cancer (3); autoimmune thyroiditis (4); scope and postoperative management of thyroid surgery (5); fine needle aspiration of thyroid nodules (6); radioactive iodine therapy for thyroid cancer. Active monitoring, thermal ablation, Lenvatinib, and long noncoding RNA refer to the latest keywords. Discussing the six clusters helps scholars to determine the scope and direction of studies.

Conclusion

Over the past two decades, the literature related to thyroid diseases has increased year by year, with closer collaboration between countries, institutions, and authors. In this study, the global trends, research hotspots, emerging subjects, and basic knowledge of literature related to thyroid diseases were respectively elucidated, which will facilitate researchers in this field to seek better development.

Clinical and Economic Evaluation of Ultrasound-Guided Radiofrequency Ablation vs. Parathyroidectomy for Patients with Primary Hyperparathyroidism: A Cohort Study

RATIONALE AND OBJECTIVES

To compare the clinical and economic effects of ultrasound (US)-guided radiofrequency ablation (RFA) with parathyroidectomy (PTX) for primary hyperparathyroidism (PHPT).

MATERIALS AND METHODS

From April 2014 to April 2021, 123 PHPT patients who received US-guided RFA or PTX were studied. Propensity score (PS) matching was used to balance the baseline data of the two groups. The rates of cure, recurrent and persistent PHPT, and complications were compared. A Chinese healthcare system perspective cost minimization analysis was conducted.

RESULTS

After PS matching, 37 patient pairs (1:1) were created for the two groups. Follow-up was 27.2 ± 10.6 months and 28.8 ± 16.1 months for the RFA and PTX groups, respectively. At the last follow-up, there was no evidence of differences regarding clinical cure rate between the two groups (RFA vs. PTX, 91.9% vs. 94.6%, p = 1.000). Recurrent PHPT did not develop in any patient. One patient in each group had persistent PHPT. The incidence of complications and side effects, except postoperative pain (RFA vs. PTX, 16.2% vs. 40.5%, p = 0.020), were no significant difference between the two groups (all, p > 0.05). The incremental cost was -$284.00; thus, RFA was more cost-effective. For patients with employee medical insurance or resident medical insurance, the incremental costs (RFA vs. PTX) were -$391.94 and -$49.43, respectively.

CONCLUSION

There were no significant differences in efficacy and safety between RFA and PTX. As the incremental cost for RFA compared with PTX was negative, RFA may be used as a more cost-effective nonsurgical treatment alternative for PHPT.

Management of surgical diseases of thyroid gland indications of the United Italian Society of Endocrine Surgery (SIUEC)

A task force of the United Italian society of Endocrine Surgery (SIUEC) was commissioned to review the position statement on diagnostic, therapeutic and health‑care management protocol in thyroid surgery published in 2016, at the light of new technologies, recent oncological concepts, and tailored approaches. The objective of this publication was to support surgeons with modern rational protocols of treatment that can be shared by health-care professionals, taking into account important clinical, healthcare and therapeutic aspects, as well as potential sequelae and complications. The task force consists of 13 members of the SIUEC highly trained and experienced in thyroid surgery. The main topics concern clinical evaluation and preoperative workup, patient preparation for surgery, surgical treatment, non-surgical options, postoperative management, prevention and management of major complications, outpatient care and follow-up.

A Prospective Study of Electromyographic Amplitude Changes During Intraoperative Neural Monitoring for Open Thyroidectomy

BACKGROUND

Intraoperative nerve monitoring (IONM) of the vagus and recurrent laryngeal nerve (RLN) enables prediction of postoperative nerve function. The underlying mechanism for loss of signal (LOS) in a visually intact nerve is poorly understood. The correlation of intraoperative electromyographic amplitude changes (EMG) with surgical manoeuvres could help identify mechanisms of LOS during conventional thyroidectomy.

METHODS

A prospective study of consecutive patients undergoing thyroidectomy was performed with intermittent IONM using the NIM Vital nerve monitoring system. The ipsilateral vagus and RLN was stimulated, and vagus nerve signal amplitude recorded at five time points during thyroidectomy (baseline, after mobilisation of superior pole, medialisation of the thyroid lobe, before release at Ligament of Berry, end of case). RLN signal amplitude was recorded at two time points; after medialisation of the thyroid lobe (R1), and end of case (R2).

RESULTS

A total of 100 consecutive patients undergoing thyroidectomy were studied with 126 RLN at risk. The overall rate of LOS was 4.0%. Cases without LOS demonstrated a highly significant vagus nerve median percentage amplitude drop at medialisation of the thyroid lobe (- 17.9 ± 53.1%, P < 0.001), and end of case (- 16.0 ± 47.2%, P < 0.001) compared to baseline. RLN had no significant amplitude drop at R2 compared to R1 (P = 0.207).

CONCLUSIONS

A significant reduction in vagus nerve EMG amplitude at medialisation of the thyroid and the end of case compared to baseline indicates that stretch injury or traction forces during thyroid mobilisation are the most likely mechanism of RLN impairment during conventional thyroidectomy.

Use of neuromuscular blockade for neck dissection and association with iatrogenic nerve injury

BACKGROUND

Cranial nerve injury is an uncommon but significant complication of neck dissection. We examined the association between the use of intraoperative neuromuscular blockade and iatrogenic cranial nerve injury during neck dissection.

METHODS

This was a single-center, retrospective, electronic health record review. Study inclusion criteria stipulated patients > 18 years who had ≥ 2 neck lymphatic levels dissected for malignancy under general anesthesia with a surgery date between 2008 - 2018. Use of neuromuscular blockade during neck dissection was the primary independent variable. This was defined as any use of rocuronium, cisatracurium, or vecuronium upon anesthesia induction without reversal with sugammadex prior to surgical incision. Univariate tests were used to compare variables between those patients with, and those without, iatrogenic cranial nerve injury. Multivariable logistic regression determined predictors of cranial nerve injury and was performed incorporating Firth's estimation given low prevalence of the primary outcome.

RESULTS

Our cohort consisted of 925 distinct neck dissections performed in 897 patients. Neuromuscular blockade was used during 285 (30.8%) neck dissections. Fourteen instances (1.5% of surgical cases) of nerve injury were identified. On univariate logistic regression, use of neuromuscular blockade was not associated with iatrogenic cranial nerve injury (OR: 1.73, 95% CI: 0.62 - 4.86, p = 0.30). There remained no significant association on multivariable logistic regression controlling for patient age, sex, weight, ASA class, paralytic dose, history of diabetes, stroke, coronary artery disease, carotid atherosclerosis, myocardial infarction, and cardiac arrythmia (OR: 1.87, 95% CI: 0.63 - 5.51, p = 0.26).

CONCLUSIONS

In this study, use of neuromuscular blockade intraoperatively during neck dissection was not associated with increased rates of iatrogenic cranial nerve injury. While this investigation provides early support for safe use of neuromuscular blockade during neck dissection, future investigation with greater power remains necessary.

Intraoperative neuromonitoring of the recurrent laryngeal nerve is indispensable during complete endoscopic radical resection of thyroid cancer: A retrospective study

Objective

Complete endoscopic radical resection of thyroid cancer, especially through the areolar approach, can achieve curative and acceptable cosmetic effects in patients with differentiated thyroid carcinoma. However, some inherent characteristics of endoscopic procedures hamper functional protection of the recurrent laryngeal nerve (RLN). Intraoperative neuromonitoring (IONM) is considered the most important accessory to protect the nerves during conventional radical thyroidectomy. This study aimed to evaluate the feasibility and necessity of IONM during complete endoscopic radical resection of thyroid cancer.

Methods

A total of 106 patients with differentiated thyroid carcinoma were enrolled in the study between February 2013 and April 2018. Based on the use of the IONM technique, all patients were divided into the IONM (n = 54) and non-IONM groups (n = 52). Overall, 66 RLNs were involved in the IONM group, and 61 RLNs were involved in the non-IONM group. The time and ratio of RLN identification and the number of transient and permanent RLN injuries between both groups were compared.

Results

Compared to the non-IONM group, the IONM group required less time for RLN identification (3.05 ± 1.58 vs. 9.36 ± 4.82 min, p < .01). The ratio of RLN identification in the IONM group was much higher than that in the non-IONM group (100.00% vs. 88.52%, p = .01). A significant difference was observed in RLN transient injury between the two groups (one case accounting for 1.51% in the IONM group vs. eight cases accounting for 13.11% in the non-IONM group; p = .03).

Conclusion

IONM significantly improved RLN identification and reduced transient RLN injuries during complete endoscopic radical resection.

Level of Evidence

3b.

Optimal Monitoring Technology for Pediatric Thyroidectomy

This retrospective study aimed to describe, firstly, characteristics and outcomes of the intraoperative neural monitoring technology in the pediatric population, and secondarily the recurrent laryngeal nerve complication rate. Thirty-seven patients (age <18 years) operated on from 2015 to 2021 by conventional open thyroid surgery were included. Twenty-four (64.9%) total thyroidectomies and 13 (35.1%) lobectomies were performed. Seven central and six lateral lymph node dissections completed 13 bilateral procedures. Histology showed malignancy in 45.9% of the cases. The differences between the electromyographic profiles of endotracheal tubes or electrodes for continuous monitoring were not statistically significant. In our series of young patients, both adhesive (even in 4- or 5-year-olds) and embedded endotracheal tubes were used, while in patients 3 years old or younger, the use of a more invasive detection method with transcartilage placement recording electrodes was required. Overall, out of 61 total at-risk nerves, 5 (8.2%) recurrent laryngeal nerves were injured with consequent intraoperative loss of the signal; however, all these lesions were transient, restoring their normal functionality within 4 months from surgical procedure. To our knowledge, this is the first study of intraoperative neural monitoring management in a cohort of Italian pediatric patients.

Clinical and Anatomical Factors Affecting Recurrent Laryngeal Nerve Paralysis During Thyroidectomy via Intraoperative Nerve Monitorization

Background

Despite all the technical developments in thyroidectomy and the use of intraoperative nerve monitorization (IONM), recurrent laryngeal nerve (RLN) paralysis may still occur. We aimed to evaluate the effects of anatomical variations, clinical features, and intervention type on RLN paralysis.

Method

The RLNs identified till the laryngeal entry point, between January 2016 and September 2021 were included in the study. The effects of RLN anatomical features considering the International RLN Anatomical Classification System, intervention and monitoring types on RLN paralysis were evaluated.

Results

A total of 1,412 neck sides of 871 patients (672 F, 199 M) with a mean age of 49.17 + 13.42 years (range, 18–99) were evaluated. Eighty-three nerves (5.9%) including 78 nerves with transient (5.5%) and 5 (0.4%) with permanent vocal cord paralysis (VCP) were detected. The factors that may increase the risk of VCP were evaluated with binary logistic regression analysis. While the secondary thyroidectomy (OR: 2.809, 95%CI: 1.302–6.061, p = 0.008) and Berry entrapment of RLN (OR: 2.347, 95%CI: 1.425–3.876, p = 0.001) were detected as the independent risk factors for total VCP, the use of intermittent-IONM (OR: 2.217, 95% CI: 1.299–3.788, 0.004), secondary thyroidectomy (OR: 3.257, 95%CI: 1.340–7.937, p = 0.009), and nerve branching (OR: 1.739, 95%CI: 1.049–2.882, p = 0.032) were detected as independent risk factors for transient VCP.

Conclusion

Preference of continuous-IONM particularly in secondary thyroidectomies would reduce the risk of VCP. Anatomical variations of the RLN cannot be predicted preoperatively. Revealing anatomical features with careful dissection may contribute to risk reduction by minimizing actions causing traction trauma or compression on the nerve.

Anatomy and motor function of extra-laryngeal branching patterns of the recurrent laryngeal nerve; an electrophysiological study of 1001 nerves at risk

INTRODUCTION

Safe thyroid surgery depends on a deep knowledge of human neck anatomy, including the recurrent laryngeal nerve (RLN). Anatomic variations such as extra-laryngeal terminal branching (ETB) are common.

PATIENTS AND METHODS

We studied the ETB pattern of 1001 RLNs at risk in 596 patients. We identified and exposed the location of division points on the cervical part of bifid RLN. The function of nerve branches was assessed through intraoperative nerve monitoring (IONM).

RESULTS

Bifid RLNs was identified in 39.6% of patients. The nerve-based prevalence of ETB was 28.5%. The prevalence of ETB for the right and left RLN was 21.8% and 35.5%, respectively (p < 0.001). The location of the division point was found in the middle, distal, and proximal segments in 48.8%, 33.3%, and 18% of bifid RLNs, respectively. Electrophysiological monitoring revealed motor functions in all anterior and in 7% of posterior branches. The rate of injury was 0.4%, and 1.1% in single trunk and bifid nerves, respectively (p = 0.360), and 3.9% in nerves with proximal branching (p = 0.084).

CONCLUSIONS

The ETB prevalence is high and showing division points in different cervical segments of the RLN. All anterior branches and some posterior branches contain motor fibers. Knowledge and awareness of these anatomic and functional variations are mandatory for every thyroid surgeon to avoid misidentification and misinterpretation of human RLN anatomy.

Lymph Node Dissection Is a Risk Factor for Short-Term Cough after Pulmonary Resection

Cough is a common complication after pulmonary resection. However, the factors associated with cough that develop after pulmonary resection are still controversial. In this study, we used the Simplified Cough Score (SCS) and the Leicester Cough Questionnaire (LCQ) score to investigate potential risk factors for postoperative cough. Between January 2017 and June 2021, we collected the clinical data of 517 patients, the SCS at three days after surgery and the LCQ at two weeks and six weeks after surgery. Then, univariate and multivariate analyses were used to identify the independent risk factors for postoperative cough. The clinical baseline data of the cough group and the non-cough group were similar. However, the cough group had longer operation time and more blood loss. The patients who underwent lobectomy were more likely to develop postoperative cough than the patients who underwent segmentectomy and wedge resection, while the patients who underwent systematic lymph node dissection were more likely to develop postoperative cough than the patients who underwent lymph node sampling and those who did not undergo lymph node resection. When the same lymph node management method was applied, there was no difference in the LCQ scores between the patients who underwent wedge resection, lobectomy and segmentectomy. The lymph node resection method was an independent risk factor for postoperative cough (p < 0.001). Conclusions: Lymph node resection is an independent risk factor for short-term cough after pulmonary resection with video-assisted thoracoscopic surgery, and damage to the vagus nerve and its branches (particularly the pulmonary branches) is a possible cause of short-term cough. The mechanism of postoperative cough remains to be further studied.

Prognostic Indicators of Non-Transection Nerve Injury and Vocal Fold Motion Impairment After Thyroid Surgery - Correlation Between Intraoperative Neuromonitoring Findings and Perioperative Voice Parameters

OBJECTIVES

In patients with recurrent laryngeal nerve (RLN) injury after thyroid surgery, unrecovered vocal fold motion (VFM) and subjective voice impairment cause extreme distress. For surgeons, treating these poor outcomes is extremely challenging. To enable early treatment of VFM impairment, this study evaluated prognostic indicators of non-transection RLN injury and VFM impairment after thyroid surgery and evaluated correlations between intraoperative neuromonitoring (IONM) findings and perioperative voice parameters.

METHODS

82 adult patients had postoperative VFM impairment after thyroidectomy were enrolled. Demographic characteristics, RLN electromyography (EMG), and RLN injury mechanism were compared. Multi-dimensional voice program, voice range profile and Index of voice and swallowing handicap of thyroidectomy (IVST) were administered during I-preoperative; II-immediate, III-short-term and IV-long-term postoperative periods. The patients were divided into R/U Group according to the VFM was recovered/unrecovered 3 months after surgery. The patients in U Group were divided into U1/U2 Group according to total IVST score change was <4 and ≥4 during period-IV.

RESULTS

Compared to R Group (42 patients), U Group (38 patients) had significantly more patients with EMG >90% decrease in the injured RLN (p<0.001) and thermal injury as the RLN injury mechanism (p=0.002). Voice parameter impairments were more severe in U Group compared to R Group. Compared to U1 group (19 patients), U2 Group (19 patients) had a significantly larger proportion of patients with EMG decrease >90% in the injured RLN (p=0.022) and thermal injury as the RLN injury mechanism (p=0.017). A large pitch range decrease in period-II was a prognostic indicator of a moderate/severe long-term postoperative subjective voice impairment.

CONCLUSION

This study is the first to evaluate correlations between IONM findings and voice outcomes in patients with VFM impairment after thyroid surgery. Thyroid surgeons should make every effort to avoid severe type RLN injury (e.g., thermal injury or injury causing EMG decrease >90%), which raises the risk of unrecovered VFM and moderate/severe long-term postoperative subjective voice impairment. Using objective voice parameters (e.g., pitch range) as prognostic indicators not only enables surgeons to earlier identify patients with low voice satisfaction after surgery, and also enable implementation of interventions sufficiently early to maintain quality of life.