The relation of recurrent laryngeal nerve to inferior thyroid artery and extralaryngeal nerve branching may increase the risk of vocal cord paralysis in thyroidectomy.

PURPOSE: The anatomical variations of the recurrent laryngeal nerve (RLN) are common during thyroidectomy. We aimed to evaluate the risk of RLN paralysis in case of its anatomical variations, retrospectively. METHODS: The patients with primary thyroidectomy between January 2016 and December 2019 were enrolled. The effect of age, gender, surgical intervention, neuromonitorisation type, central neck dissection, postoperative diagnosis, neck side, extralaryngeal branching, non-RLN, relation of RLN to inferior thyroid artery (ITA), grade of Zuckerkandl tubercle on vocal cord paralysis (VCP) were investigated. RESULTS: This study enrolled 1070 neck sides. The extralaryngeal branching rate was 35.5%. 45.9% of RLNs were anterior and 44.5% were posterior to the ITA, and 9.6% were crossing between the branches of the ITA. The rate of total VCP was 4.8% (transient:4.5%, permanent: 0.3%). The rates of total and transient VCP were significantly higher in extralaryngeal branching nerves compared to nonbranching nerves (6.8% vs. 3.6%, p = 0.018; 6.8% vs. 3.2%, p = 0.006, respectively). Total VCP rates were 7.2%, 2.5%, and 2.9% in case of the RLN crossing anterior, posterior and between the branches of ITA, respectively (p = 0.003). The difference was also significant regarding the transient VCP rates (p = 0.004). Anterior crossing pattern increased the total and transient VCP rates 2.8 and 2.9 times, respectively. CONCLUSION: RLN crossing ITA anteriorly and RLN branching are frequent anatomical variations increasing the risk of VCP in thyroidectomy that cannot be predicted preoperatively. This study is the first one reporting that the relationship between RLN and ITA increased the risk of VCP.

Administration of neostigmine after tracheal intubation shortens time to successful intraoperative neuromonitoring during thyroid surgery: a randomized controlled trial.

This prospective, randomized controlled trial evaluated the effect of neostigmine for intraoperative neuromonitoring (IONM) during thyroid surgery. Forty subjects undergoing thyroidectomy with IONM, randomized into neostigmine administration after tracheal intubation (Group N, n = 20) or control treatment with normal saline (Group C, n = 20), completed the trial. Electromyography amplitudes of the vagus nerve (V1) were recorded before thyroid dissection. The time from the initial V1 signal check to successful V1 stimulation was recorded. In Group N, all the patients had a successful V1 signal at the first check, whereas ten (50%) patients in Group C had a time delay between the initial V1 check and successful V1 (p < 0.001). The mean delay time among the delayed patients in Group C was 11.2 ± 1.4 min. The mean time from skin incision to successful V1 stimulation was significantly shorter in Group N than in Group C (15.4 ± 2.4 min vs. 19.9 ± 5.7 min, p = 0.003). In Groups N and C, the mean V1 amplitudes were 962.2 ± 434.5 µV vs. 802.3 ± 382.7 µV (p = 0.225), respectively, and the mean R1 amplitudes were 1240.0 ± 836.5 µV vs. 1023.4 ± 455.8 µV (p = 0.316), respectively. There was one bucking event in Group N. In conclusion, neostigmine administration immediately after tracheal intubation can be useful to reverse neuromuscular blockade for successful IONM in thyroid surgeries.

Thyroidectomy in Australia 2022: lessons from 21,000 consecutive cases.

In this article, we aim to describe our modern-day approach to total thyroidectomy, detailing the subtle refinements of our technique, as it has evolved over three decades and 21 000 cases. Since Delbridge's seminal paper in 2003, the major changes to our approach include a retrograde approach to the recurrent laryngeal nerve that allows dissection of the distal RLN from fascial bands within the ligament of Berry before medialisation of the thyroid lobe. Routine use of intraoperative nerve monitoring systems has increased our awareness of temporary neuropraxia, facilitated a reduction in the risk of bilateral RLN palsy and improved our identification and preservation of the external branch of the superior laryngeal nerve. The increasing use of advanced energy devices has been associated with a reduction in post-operative haematoma rates. We adopt a low threshold to parathyroid auto-transplantation, unless all glands are assessed to be clearly not at risk, and routinely supplement patients with Caltrate in the immediate post-operative period to minimize the risk of symptomatic hypocalcaemia. Ultimately, when we reflect on the subtle refinements that have contributed to improved outcomes, the fundamental principles of exposure and dissection that have evolved over decades remain the basis of our surgical approach and must continue to do so.

Intraoperative trans-laryngeal ultrasound (LUSG) of the vocal cord is a novel method of confirming the recurrent laryngeal nerve (RLN) integrity during thyroid and neck surgery.

BACKGROUND: Eliciting a normal electromyography signal has been the usual method to confirm the functional integrity of the recurrent laryngeal nerve during intraoperative nerve monitoring. Given that oscillations of the vocal cord can be detected with trans-laryngeal ultrasound when the ipsilateral recurrent laryngeal nerve is stimulated with the endotracheal tube in situ, we aimed to compare the accuracy and cost of this novel method with the conventional electromyography method. METHODS: Consecutive patients who underwent elective thyroid, parathyroid or neck dissection procedures were included. The NIM-Neuro 3.0 system was used. Endotracheal tube-based surface electrodes were utilized for electromyography signal recording. Standard anesthetic technique was adopted. Recurrent laryngeal nerve integrity was verified by both detection methods (laryngeal ultrasound and electromyography) independently. Vocal cord function was validated by flexible direct laryngoscopy postoperatively. For each method, concurrence with flexible direct laryngoscopy was defined as "true-positive" or "true-negative," based on the presence or absence of vocal cord paresis. Accuracy was calculated as the sum of all true positives and negatives divided by the total of nerves-at-risk. The cost of each method was calculated. RESULTS: One hundred and four patients were eligible. Total number of nerves-at-risk was 155. Based on flexible direct laryngoscopy findings, the test sensitivity, specificity, positive predictive value, and negative predictive value of intraoperative laryngeal ultrasound were 75.0%, 99.3%, 85.7%, and 98.6%, respectively, while those of electromyography were 87.5%, 98.0%, 70.0%, and 99.3%, respectively. The prognostic accuracy in laryngeal ultrasound versus electromyography was comparable (98.1% vs 97.4%). The cost of the laryngeal ultrasound per operation was less than electromyography ($82 vs $454). CONCLUSION: Laryngeal ultrasound has a similar detection accuracy to electromyography during intraoperative nerve monitoring. Apart from being a cheaper alternative, laryngeal ultrasound may be useful when there is unexplained loss of electromyography signals during surgery and may play a role in the intraoperative nerve monitoring troubleshooting algorithm.

Improving Voice Outcomes After Thyroid Surgery - Review of Safety Parameters for Using Energy-Based Devices Near the Recurrent Laryngeal Nerve.

Technological advances in thyroid surgery have rapidly increased in recent decades. Specifically, recently developed energy-based devices (EBDs) enable simultaneous dissection and sealing tissue. EBDs have many advantages in thyroid surgery, such as reduced blood loss, lower rate of post-operative hypocalcemia, and shorter operation time. However, the rate of recurrent laryngeal nerve (RLN) injury during EBD use has shown statistically inconsistent. EBDs generate high temperature that can cause iatrogenic thermal injury to the RLN by direct or indirect thermal spread. This article reviews relevant medical literatures of conventional electrocauteries and different mechanisms of current EBDs, and compares two safety parameters: safe distance and cooling time. In general, conventional electrocautery generates higher temperature and wider thermal spread range, but when applying EBDs near the RLN adequate activation distance and cooling time are still required to avoid inadvertent thermal injury. To improve voice outcomes in the quality-of-life era, surgeons should observe safety parameters and follow the standard procedures when using EBDs near the RLN in thyroid surgery.

Condition of Adrenergic Innervation Apparatus of the Thyroid Gland, Blood and Lymph Vessels, and Lymph Nodes during Correction of Hypothyrosis.

We used specific histochemical fluorescence-microscopic method of visualization of catecholamines to study adrenergic innervation of the thyroid gland tissue, blood vessels of the thyroid gland, cervical lymphatic vessel and lymph nodes in rats during correction of hypothyroidism with a bioactive formulation (Vozrozhdenie Plus balm with Potentilla alba L.). In experimental hypothyroidism, adrenergic innervation of the thyroid gland and the wall of the cervical lymph node, concentrated mainly along the arterial vessels and the cervical lymphatic vessel, retained its structural formations (plexuses and varicosities), but diffusion of catecholamines outside these formations was observed. Correction with the bioactive formulation restored of the contours of the nerve plexuses and varicosities and their brighter fluorescence in the thyroid gland and cervical lymphatic vessel and node. During correction of hypothyroidism with the bioactive formulation, reorganization of regional lymphatic vessels and nodes was more pronounced than reorganization of the thyroid gland.

Intraoperative nerve monitoring is associated with a lower risk of recurrent laryngeal nerve injury: A national analysis of 17,610 patients.

BACKGROUND: Based on current evidence, the benefit of intraoperative nerve monitoring (IONM) in thyroid surgery is equivocal. METHODS: All patients who underwent planned thyroid surgery in the 2016-2018 ACS NSQIP procedure-targeted thyroidectomy dataset were included. Multivariable regression analyses were performed to examine the association between nerve monitoring and recurrent laryngeal nerve (RLN) injury while adjusting for patient demographics, extent of surgery, and perioperative variables. RESULTS: In total, 17,610 patients met inclusion criteria: 77.8% were female, and the median age was 52 years. IONM was used in 63.9% of cases. Of the entire cohort, 6.1% experienced RLN injury. Cases with IONM use had a lower rate of RLN injury compared to those that did not use IONM (5.7% vs. 6.8%, p = 0.0001). After adjustment, IONM was associated with reduced risk of RLN injury (OR 0.69, 95% CI 0.59-0.82, p < 0.0001). CONCLUSIONS: Nationally, IONM is used in nearly two thirds of thyroid surgeries. IONM is associated with a lower risk of recurrent laryngeal nerve injury.

Recurrent Laryngeal Nerve Injury After Thyroid Surgery: An Analysis of 11,370 Patients.

BACKGROUND: Recurrent laryngeal nerve (RLN) injury is a well-known, potentially serious complication of thyroid surgery. We investigated factors associated with RLN injury during thyroid surgery using a multi-institutional data set. MATERIALS AND METHODS: Patients who underwent either lobectomy or total thyroidectomy were abstracted from the American College of Surgeons National Surgical Quality Improvement Program thyroidectomy-specific database (2016-2017). Baseline and operative factors associated with RLN injury ≤30 d of surgery were analyzed using bivariate and multivariate methods. Secondary complications of interest included unplanned reintubation and hypocalcemia. RESULTS: RLN injury occurred in 6.0% (n = 677) of the 11,370 patients included in the study. The RLN injury rate varied significantly based on the primary indication for surgery, from 4.3% in patients undergoing surgery for a single nodule to 9.0% in patients undergoing surgery for differentiated cancer (P < 0.01). RLN injury occurred more often in thyroidectomies than lobectomies (6.9% versus 4.3%, P < 0.01) and in surgeries without intraoperative nerve monitoring (6.5% versus 5.6%, P = 0.01). After multivariate adjustment, RLN injury was independently associated with age ≥65 y [odds ratio (OR) 1.6, 95% confidence interval (CI) 1.3-2.0], total thyroidectomy (OR = 1.4, 95% CI 1.1-1.6), and diagnosis of thyroid malignancy (OR = 2.1, 95% CI = 1.6-2.7) (all P < 0.001) but not intraoperative RLN monitoring (OR = 0.9, 95% CI = 0.7-1.0, P = 0.06). CONCLUSIONS: In this large multi-institutional study, RLN injury ≤30 d of surgery occurred in nearly 6% of thyroid surgeries. This comprehensive analysis of RLN injury can be used to guide informed consent discussions and aid surgeons in identifying candidates who may be at higher risk for injury.

Association Between Recurrent Laryngeal Nerve Calibre and Body Figure: A Preoperative Tool to Assess Thin-Diameter Nerves in Thyroidectomy.

Inadvertent recurrent laryngeal nerve (RLN) injury is a major complication of thyroidectomy. This study aimed to investigate the association between preoperative clinical parameters and RLN size prediction. Total thyroidectomy and thyroid lobectomy data were collected between January 2014 and April 2017. Routine identification of the recurrent laryngeal nerves was performed, while intraoperative findings (nerve diameter, thyroid gland weight, intraoperative neuromonitoring (IONM) use, and signal recording) and demographic data were collected for analysis. A total of 848 patients with 1357 RLNs at risk were enrolled in this study. RLN diameter was thinner in females, those with body height <160 cm, and those with a BMI <25 (all p < 0.001). RLN diameter was directly proportional to age, body weight, height, and BMI. RLN diameter was thinner (1.71 mm vs. 1.55 mm, p = 0.039) and branched nerve incidence was higher (18.5% vs. 29.7%, p = 0.09) in the postoperative RLN injury group. Branched nerves were more frequently encountered in female patients (female vs. male: 28.8% vs. 18.7%, p = 0.004). The risk of RLN palsy in intraoperative IONM loss patients was 27 times higher compared to that in IONM normal patients (1.55% vs. 30%, p < 0.001). Thinner nerves did not yield a higher rate of IONM signal loss. Thinner nerves and higher palsy rates could be anticipated in females, younger age groups, those with shorter stature, and those with low BMI. RLN diameter was not associated with the rate of IONM signal loss.

Investigation on EMG Profiles of the Superior Laryngeal Nerve in a In Vivo Porcine Model.

BACKGROUND: The electromyographic (EMG) profiles of external branch of the superior laryngeal nerve (EBSLN) have been defined and the optimal intensity of the stimulation of EBSLN in an in vivo porcine model has been explored. MATERIALS: EMG was simultaneously registered by the surface of endotracheal tube and needle electrodes by applying a monopolar stimulation probe in 12 piglets (22 EBSLNs). Vagal nerve (VN), RLN and EBSLN were excited to record the EMG tracings and cricothyroid muscle twitch (CTM). VN, RLN and EBSLN were stimulated from 0.1 to 1.0 mA. Cmin and Cmax have been defined as the minimum and maximal stimulation to evoke an EMG response. RESULTS: The stimulation resulted in a dose-response curve. Cmin were 0.19 mA (0.04-0.4), 0.19 mA (0.08-0.3) and 0.21 mA (0.1-0.4) for EBSLN, RLN and VN (p > 0.05) respectively. Cmax were 0.6 mA along with an amplitude value of 396 ± 330 µV, 0.5 mA including 1058 ± 382 µV, 0.8 mA coupled with 870 ± 382 µV, equally for EBSLN, RLN and VN (p > 0.05) respectively. No asymmetry of amplitude responses each side for EBSLN, RLN and VN (p = 0.317, p = 0.203 and p = 0.468, respectively) was noted. The amplitudes of EBSLN were significantly lower than RLNs and VN (42% of RLN and 50% of VN amplitude rates). Also, CTM twitch was always detectable with the stimulation of EBSLN. CONCLUSIONS: Cmin and Cmax of EBSLN were comparable to RLN and VN standards. The amplitude stimulus-response curves of RLN, VN and EBSLN were highly variable. It has been suggested to apply a stimulation of 1.0 mA and a visual appreciation of CTM twitch for the identification of EBSLN.

Seizure duration may increase thyroid-stimulating hormone levels in children experiencing a seizure.

OBJECTIVE: Variations in hormone levels are a direct effect of epileptic discharges in both animals and humans, and seizure can affect the hypothalamus-pituitary-thyroid axis. The purpose of this study was to determine which parameters could affect the alternation of thyroid hormones in children experiencing seizure. METHODS: We retrospectively reviewed the medical records of 181 pediatric patients with seizure and compared three thyroid hormones (serum thyroid-stimulating hormone [TSH], free thyroxine [fT4], and triiodothyronine [T3]) between initial (admission to hospital) and follow-up (2 weeks later) testing. RESULTS: Multivariable logistic regression models were used to determine which six parameters (gender, age, seizure accompanying with fever, seizure type, seizure duration, and anti-epileptic drug medication) could help to explain the higher initial TSH levels in pediatric seizure. Only seizure duration in patients with an increase in TSH levels was significantly longer compared with patients with normal TSH at the time of initial testing. CONCLUSION: Neuronal excitability by seizure can cause thyroid hormonal changes, which likely reflects changes in hypothalamic function.

The Nerve to Thyrohyoid Muscle as a Novel Donor Nerve for Laryngeal Reinnervation.

OBJECTIVES: Recurrent laryngeal nerve (RLN) injury may be a consequence of surgical procedures of the skull base, neck, and chest, with adverse consequences to function and quality of life. Laryngeal reinnervation offers a potentially stable improvement in vocal fold position and tone. The classic donor nerve is the ansa cervicalis, but is not always available due to damage or sacrifice during previous neck surgeries. Our objective was to introduce the nerve to the thyrohyoid (TH) muscle as an alternate donor nerve for reinnervation, which has not previously been described. METHODS: Case series of two patients using the TH nerve for laryngeal reinnervation after RLN injury, with description of surgical harvest. RESULTS: Follow-up results are available for 10 months (one patient) and 3 years (one patient) demonstrating both subjective and objective improvement in function. GRBAS scores were reduced. Maximal phonation time was improved. Patient rating of voice was stable or improved postoperatively. One patient described significant preoperative dyspnea which was significantly improved postoperatively, from a score of 24 to 10 out of 40 on the dyspnea handicap index. VHI was improved in one patient, but scores elevated in the other, despite a change from "moderately severe impairment" to "normal voice" subjectively. Neither patient experienced significant complications from the procedure. CONCLUSION: Laryngeal reinnervation procedures provide good outcomes in pediatric patients. When ansa cervicalis is not available as a donor nerve, the nerve to TH provides a reasonable alternative.

Adrenergic Innervation of the thyroid Gland, Blood and Lymph Vessels, and Lymph Nodes in Hypothyroidism.

Adrenergic innervation in the tissue of the thyroid gland, blood vessels of the thyroid gland, cervical lymphatic vessel, and lymph nodes in rats with hypothyroidism was studied by using a specific histochemical fluorescent-microscopic method of visualization of catecholamines. The presence of adrenergic innervation in the blood and lymph vessels and nodes was demonstrated. In hypothyroidism, diffusion of norepinephrine from nerve fibers and varicose thickenings was observed in the wall of the upper and lower thyroid arteries and adjacent cervical lymphatic vessels and nodes.

Anatomical variation in the right non-recurrent laryngeal nerve reported from studies using pre-operative arterial imaging.

The right non-recurrent (inferior) laryngeal nerve (NRLN) is a rare anatomical variant associated with an arterial anomaly, the aberrant right subclavian artery (ARSA), that is detectable by pre-operative imaging (POI) using computed tomography and/or ultrasound. Most surgical studies have utilized two major types, NRLNs arising near the upper pole of the thyroid gland (type 1), vs. at a lower level (type 2) but with two subtypes defined by relationships to the inferior thyroid artery (ITA). This review found 8 English language surgical studies using POI that reported at least 1 NRLN and had anatomical information; of the 88 right NRLNs, 69.3% were classified as type 2 and 30.7% as type 1. Meta-analysis yielded a weighted proportion of 74.0% for type 2, but with substantial heterogeneity. For a subgroup of 5 POI studies with information on subtypes, 22 (59.5%) of 37 type 2 nerves were type 2a (i.e., running at or above the ITA). Similarly, a separate review of large surgical series without POI found that 60.4% of all 91 type 2 NRLNs were type 2a. The study findings should be relevant to the increasing numbers of anterior neck surgeries including bilateral thyroidectomies. A need was identified for studies on inter-observer reliability (agreement) among surgeons on NRLN types, and on injury rates (and related symptoms) by the type of NRLN.

Learning Curve for Using Intraoperative Neural Monitoring Technology of Thyroid Cancer.

We investigated the learning curve for using intraoperative neural monitoring technology in thyroid cancer, with a view to reducing recurrent laryngeal nerve injury complications. Radical or combined radical surgery for thyroid cancer was performed in 82 patients with thyroid cancer and 147 recurrent laryngeal nerves were dissected. Intraoperative neural monitoring technology was applied and the "four-step method" used to monitor recurrent laryngeal nerve function. When the intraoperative signal was attenuated by more than 50%, recurrent laryngeal nerve injury was diagnosed, and the point and causes of injury were determined. The time required to identify the recurrent laryngeal nerve was 0.5-2 min and the injury rate was 2.7%; injuries were diagnosed intraoperatively. Injury most commonly occurred at or close to the point of entry of the nerve into the larynx and was caused by stretching, tumor adhesion, heat, and clamping. The groups are divided in chronological order; a learning curve for using intraoperative neural monitoring technology in thyroid cancer surgery was generated based on the time to identify the recurrent laryngeal nerve and the number of cases with nerve injury. The time to identify the recurrent laryngeal nerve and the number of injury cases decreased markedly with increasing patient numbers. There is a clear learning curve in applying intraoperative neural monitoring technology to thyroid cancer surgery; appropriate use of such technology aids in the protection of the recurrent laryngeal nerve.

Correlation analyses of thyroid-stimulating hormone and thyroid autoantibodies with differentiated thyroid cancer.

PURPOSE: To investigate the feasibilities and clinical values of thyroid-stimulating hormone (TSH) and thyroid autoantibodies in predicting differentiated thyroid cancer (DTC). METHODS: 500 patients with thyroid nodules who underwent surgery for the first time in our hospital from January 2014 to December 2016 were selected, including 250 patients definitely diagnosed pathologically with DTC and 250 patients definitely diagnosed with benign thyroid nodules after operation. Serum thyroglobulin antibody (TgAb), thyroid peroxidase antibody (TPOAb) and TSH levels before operation were evaluated in both groups. According to the reference ranges of TgAb and TPOAb, they were divided into negative and positive groups. According to the TSH reference range, they were divided into decreased, normal and increased groups. Statistical analyses were conducted, respectively. RESULTS: The serum TgAb level in the DTC group was significantly increased compared with that in benign thyroid nodule group (p=0.01). The positive rate of TgAb in DTC group was also significantly higher than that in benign thyroid nodule group (p<0.01). The level of serum TPOAb in the DTC group was not significantly different from that in the benign thyroid nodule group (p=0.25). The level of serum TSH in the DTC group was significantly increased compared with that in the benign thyroid nodule group (p<0.01). There was a statistically significant difference in the comparison of the distribution of TSH between the DTC group and benign thyroid nodule group (p<0.01). Univariate analysis showed that TgAb and TSH were correlated with DTC. Multivariate logistic regression analysis results showed that serum positive TgAb and increased TSH wre significantly correlated with DTC. TSH level in DTC with cervical lymph node metastasis group was significantly increased compared with DTC without such metastasis group (p<0.01). CONCLUSIONS: Increased levels of serum TgAb and TSH may be risk factors for DTC. Whether the two indicators can be used as predictors of DTC screening needs to be confirmed in large-sample prospective trials. Increased serum TSH level is closely related to DTC with cervical lymph node metastasis.

International neural monitoring study group guideline 2018 part I: Staging bilateral thyroid surgery with monitoring loss of signal.

This publication offers modern, state-of-the-art International Neural Monitoring Study Group (INMSG) guidelines based on a detailed review of the recent monitoring literature. The guidelines outline evidence-based definitions of adverse electrophysiologic events, especially loss of signal, and their incorporation in surgical strategy. These recommendations are designed to reduce technique variations, enhance the quality of neural monitoring, and assist surgeons in the clinical decision-making process involved in surgical management of recurrent laryngeal nerve. The guidelines are published in conjunction with the INMSG Guidelines Part II, Optimal Recurrent Laryngeal Nerve Management for Invasive Thyroid Cancer-Incorporation of Surgical, Laryngeal, and Neural Electrophysiologic Data. Laryngoscope, 128:S1-S17, 2018.

Voice quality preservation in thyroid surgery with neuromonitoring.

PURPOSE: Voice problems are common after thyroidectomy. The aim of this study was to assess the voice related quality of life after thyroidectomy with neuromonitoring. The sociodemographic and treatment factors influencing the quality of voice after the operation were investigated. METHODS: A total of 40 patients after thyroidectomy with neuromonitoring were enrolled into the study. The voice outcome was analyzed pre and postoperatively by two validated self-assessment questionnaires: Voice Handicap Index and Voice-Related Quality of Life survey. RESULTS: All external branches of the superior laryngeal nerve were identified during the operation. There were no recurrent laryngeal nerve palsies. The mean total VHIs before and after thyroid operation were 1.2 [SD 2.564] and 2.8 [SD 6.944], respectively (p = 0.5). Preoperatively, the mean overall score for the V-RQOL was 99.6; postoperatively 98.7 (p = 0.05). A strong correlation between the V-score of the V-RQOL and O-score of the VHI before and after thyroidectomy was observed (both p < 0.001). There was no correlation between V-RQOL or VHI and sex, the kind of thyroid operations, diagnosis, thyroid function, the mean volume of the goitre, the presence of retrosternal position and the extent of thyroid operations (p > 0.05). A small correlation between the mean age of the patients and postoperative O-Score of the VHI (p = 0.007650) and between the mean age and postoperative V-Score for the V-RQOL (p = 0.00648) was observed. CONCLUSIONS: The use of neuromonitoring in thyroid surgery is beneficial for patients to improve voice quality. The identification and preservation of EBSLNs is crucial to eliminate altered voice after thyroidectomy.

Safety of high-current stimulation for intermittent intraoperative neural monitoring in thyroid surgery: A porcine model.

OBJECTIVES: During monitored thyroidectomy, displacement of the recurrent laryngeal nerve (RLN) or vagus nerve (VN) in some complicated cases can increase the risk of injury. Although increasing the stimulus current can facilitate nerve mapping and localization, the safety of a high-current stimulus remains unknown. Therefore, this study evaluated the safety of a high-current stimulus in a porcine model. METHODS: Short-duration (1 minute), high-current (3, 5, 10, 15, 20, 25, and 30 mA at 4Hz) stimulus pulses were repeatedly applied to the RLN or VN in six anesthetized piglets. The safety of the high-current stimulus pulses was assessed in terms of hemodynamic stability during VN stimulation and in terms of nerve function integrity after VN and RLN stimulation. RESULTS: During VN stimulation with a high-current stimulus pulse, sinus rhythms in all six piglets showed stable heart rates, and mean arterial pressure was unaffected. High-current stimulation of the VN and the RLN did not affect electromyography amplitude or latency. CONCLUSION: This porcine study showed that applying a short-duration, high-current stimulus pulse to the VN or RLN during monitored thyroidectomy has no harmful effects. In clinical practice, a short duration of high-current stimulus can be applied to facilitate neural mapping, especially in patients with disoriented nerve positions. LEVEL OF EVIDENCE: NA. Laryngoscope, 128:2206-2212, 2018.