[Efficacy of prevention of recurrent laryngeal nerve injury in thyroid surgery]. / Effektivnost' profilaktiki povrezhdenii vozvratnogo gortannogo nerva pri operatsiyakh na shchitovidnoi zheleze.

OBJECTIVE: To evaluate the effectiveness of prevention of recurrent laryngeal nerve injury depending on thyroid gland lesion and extent of surgery. MATERIAL AND METHODS: There were 2412 thyroid surgeries between 2000 and 2020. Patients were divided into the main group (1689 patients) and the control group (729 patients). Patients with nodular thyroid gland lesions prevailed in both groups (987 (58.4%) and 415 (56.9%), respectively). All ones underwent atraumatic extrafascial desection and thyroid resection (ultrasonic scalpel). RESULTS. T: He upper laryngeal nerve injury occurred in 35 cases (1.4%). The number of surgeries with thyroid remnant preservation was significantly lower in the main group. The number of procedures with subtotal thyroid resection and thyroidectomy increased by 2.4 times (from 414 to 1010 operations, p<0.05). CONCLUSION: Improvement of surgical treatment of thyroid gland lesions consisting in new operative technique of recurrent laryngeal nerve isolation using ultrasonic scalpel reduces the incidence of recurrent laryngeal nerve injury from 2.3% to 1%. At the same time, the number of extended procedures in the main group significantly exceeded that in the control group (by 2.5 times).

Double Recurrent Laryngeal Nerve with Thyroid Carcinoma.

The most important and serious complication of thyroid surgery is recurrent laryngeal nerve (RLN) injury, and it has been noted that this risk increases considerably in the presence of anatomical variations. Double recurrent laryngeal nerve (DRLN) is very rare among RLN anatomical variations. There are only a few case reports on DRLN in the literature It is crucial to possess surgical expertise and ensure complete visualization of the nerve to minimize the likelihood of RLN injury. Intraoperative nerve monitoring (IONM) is particularly useful in identifying anatomical variations. In a 54-year-old woman undergoing diagnostic left lobectomy+isthmectomy, a left DRLN was identified during intraoperative exploration and meticulous nerve exploration with the assistance of IONM monitoring verified that the impulse conduction in both branches was identical. The surgical procedure was successfully performed without causing any harm to the nerve. Based on the case reports in the literature and our experience with this patient, we believe that surgical expertise and the utilization of IONM can decrease RLN nerve damage and reveal its anatomical variations during thyroid surgery.

Intraoperative Adjuncts in Thyroid Surgery.

Thyroidectomy is relatively safe and often can be done as a minimally invasive procedure. Although they may be associated with a learning curve, thoughtful use of intraoperative adjuncts such as energy devices, recurrent laryngeal nerve monitoring, and parathyroid autofluorescence have the potential to make incremental improvements in the safety and efficiency of thyroid surgery. Perhaps many of these adjuncts may be of greatest benefit when used routinely by less experienced surgeons or selectively in higher-risk operations, although their adoption in practice continues to increase overall.

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.

Impact of Intermittent Intraoperative Neuromonitoring (IONM) on the Learning Curve for Total Thyroidectomy by Residents in General Surgery.

INTRODUCTION: Recurrent laryngeal nerve (RNL) identification constitutes the standard in thyroidectomy. Intraoperative nerve monitoring (IONM) has been introduced as a complementary tool for RLN functionality evaluation. The aim of this study is to establish how routine use of IONM can affect the learning curve (LC) in thyroidectomy. METHODS: Patients undergoing total thyroidectomy performed by surgery residents in their learning curve course in 2 academic hospitals, were divided into 2 groups: Group A, including 150 thyroidectomies performed without IONM by 3 different residents, and Group B, including 150 procedures with routine use of intermittent IONM, by other 3 different residents. LC was measured by comparing operative time (OT), its stabilization during the development of the LC, perioperative complication rate. RESULTS: As previously demonstrated, the LC was achieved after 30 procedures, in both groups, with no differences due to the use of IONM. Similarly, there were no significant differences among the 2 groups, and between subgroups independently matched, for both OT and complications, even when comparing RLN palsy. Direct nerve visualization and IONM assessment rates were comparable in all groups, and no bilateral RLN palsy (transient or permanent) were reported. No case of interrupted procedure to unilateral lobectomy, due to evidence of RLN injury, was reported. CONCLUSIONS: The study demonstrates that the use of IONM thyroid surgery, despite requiring a specific training with experienced surgeons, does not particularly affect the learning curve of residents approaching this kind of surgery, and for this reason its routine use should be encouraged even for trainees.

Soft tissue injury events associated with neural integrity monitoring endotracheal tubes: A MAUDE database analysis.

OBJECTIVE: Neural integrity monitoring (NIM) endotracheal tubes are widely used to provide intraoperative monitoring of the recurrent laryngeal nerve during certain neck surgeries, especially thyroidectomy, in order to reduce the risk of nerve injury and subsequent vocal fold paralysis. The unique design of NIM tubes and the increased technical skill required for correct placement compared to standard endotracheal tubes may increase the risk of upper aerodigestive tract soft tissue injury. This study aims to describe adverse events related to NIM endotracheal tubes. STUDY DESIGN: Retrospective cross-sectional study. SETTING: The US Food and Drug Administration's MAUDE database (2010-2022); (Manufacturer and User Facility Device Experience). METHODS: The MAUDE database was queried for reports of adverse events that resulted in patient soft tissue injury involving the use of endotracheal tubes approved by the Food and Drug Administration. RESULTS: There were 28 reported soft tissue injuries, with all events being related to the NIM EMG family of endotracheal tubes manufactured by Medtronic Xomed, Inc. Overall, 24 were categorized as device-related adverse events, and 4 were unspecified in the event description. The most common soft tissue injuries were edema (n = 7) and perforation (n = 7), each accounting for 25 % of adverse events. The second most common injury type was laceration (n = 4), representing 14 % of all adverse events. Overall, 9 patients (32 %) in our cohort required a surgical intervention to treat their injuries, which consisted of 6 tracheotomies and 3 instances of suture repair. CONCLUSIONS: The most commonly reported types of soft tissue injury included edema and perforation, followed by laceration. Increased awareness of device-related patient injuries associated with NIM endotracheal tubes can be used to better inform surgeons and anesthesiologists during the process of intubation and surgical decision-making.

Fluorescence imaging to visualize the recurrent laryngeal nerve during thyroidectomy procedures: analysis of 65 cases and 81 nerves.

BACKGROUND: Recurrent laryngeal nerve (RLN) injury after thyroidectomy is relatively common. Locating the RLN prior to thyroid dissection is paramount to avoid injury. We developed a fluorescence imaging system that permits nerve autofluorescence. We aimed to determine the sensitivity and specificity of fluorescence imaging at detecting the RLN relative to thyroid and other background tissue and compared it to white light. METHODS: In this prospective study, 65 patients underwent thyroidectomy from January to April 2022 (16 bilateral thyroid resections) using white and fluorescent light. Fluorescence intensity [relative fluorescence units (RFU)] was recorded for RLN, thyroid, and background. RFU mean, minimum, and maximum values were calculated using Image J software. Thirty randomly selected pairs of white and fluorescent light images were independently reviewed by two examiners to compare RLN detection rate, number of branches, and length and minimum width of nerves visualized. Parametric and nonparametric statistical analysis was performed. RESULTS: All 81 RNLs observed were visualized more clearly under fluorescence (mean intensity, µ = 134.3 RFU) than either thyroid (µ = 33.7, p < 0.001) or background (µ = 14.4, p < 0.001). Forest plots revealed no overlap between RLN intensity and that of either other tissue. Sensitivity and specificity for RLN were 100%. All 30 RLNs and all 45 nerve branches were clearly visualized under fluorescence, versus 17 and 22, respectively, with white light (both p < 0.001). Visible nerve length was 2.5 × as great with fluorescence as with white light (µ = 1.90 vs. 0.76 cm, p < 0.001). CONCLUSIONS: In 65 patients and 81 nerves, RLN detection was markedly and consistently enhanced with autofluorescence neuro-imaging during thyroidectomy, with 100% sensitivity and specificity.

Clinical validation of NerveTrend versus conventional i-IONM mode of NIM Vital in prevention of recurrent laryngeal nerve events during bilateral thyroid surgery: A randomized controlled trial.

BACKGROUND: The aim of this study was to test the hypothesis that use of NerveTrend™ mode of intermittent neuromonitoring (i-IONM) during thyroidectomy may identify and prevent impending recurrent laryngeal nerve (RLN) injury. METHODS: A randomized clinical trial. The primary outcome was prevalence of RLN injury on postoperative day 1. In NerveTrend™ group the i-IONM stimulator was used for trending of amplitude and latency changes from initial vagal electromyographic baseline to tailor surgical strategy. RESULTS: Some 264 patients were randomized into the intervention versus the control group, 132 patients each. RLN injury was found on postoperative day 1 in 5/264 (1.89%) nerves at risk (NAR) versus 12/258 (4.65%) NAR whereas staged thyroidectomy was used in 0/132 (0.00%) versus 6/132 (4.54%) patients (p = 0.067 and p = 0.029, respectively). CONCLUSION: The use of NerveTrend™ mode resulted in tendency towards reduced RLN injury on postoperative day 1 and significant decrease of need for a staged thyroidectomy.

Recurrent laryngeal never monitoring versus non-monitoring in parathyroid surgery.

Background: Although intraoperative neural monitoring (IONM) is well established in thyroid surgery, it is less commonly analyzed in parathyroid operations. This study presents the results of IONM for primary and secondary hyperparathyroidism surgery. Methods: We retrospectively assessed 270 patients with primary hyperparathyroidism (PHPT), 53 patients with secondary hyperparathyroidism (SHPT), and 300 patients with thyroid cancer from June 2010 to June 2022 in one hospital in China. The follow-up was 12 months. Demographic, electromyography data from IONM, laboratory, and clinical information were collected. Laryngoscopy was collected from 109 patients with PHPT in whom IONM was not used. All groups were assessed by Pearson's chi-square test and Fisher's exact probability method to verify the relationship between parathyroid size and location, duration of surgery, preoperative concordant localization, laryngeal pain, IONM outcomes, cure rate, and RLN injury. Visual analog scale (VAS) assessed laryngeal pain. RLN outcomes were measured according to nerves at risk (NAR). Results: The study comprehended 918 NAR, that is 272, 105, 109, and 432 NAR for PHPT, SHPT with IONM, PHPT without IONM, and thyroid surgery control group, respectively. IONM successfully prevented RLN injury (P<0.001, P=0.012): Fifteen (5.51%) RLNs experienced altered nerve EMG profiles during surgery, and five (1.84%) experienced transient RLN injury in PHPT patients. Five (4.76%) RLNs were found to have altered EMG profiles during surgery, and one (0.95%) RLN had a transient RLN injury in SHPT patients. There was no permanent nerve injury (0.00%) in this series. There was no association between location, gland size, preoperative concordant localization, cure rate, duration of surgery, and IONM (P >0.05). Duration of surgery was associated with postoperative pharyngeal discomfort (P=0.026, P=0.024). Transient RLN injury was significantly lower in patients with PHPT who underwent IONM than in those who did not. Intraoperative neuromonitoring played an effective role in protecting the recurrent laryngeal nerve (P=0.035). Compared with parathyroidectomy, thyroidectomy had a higher rate of RLN injury (5.32%, P<0.001). Conclusion: IONM for SHPT and PHPT offers rapid anatomical gland identification and RLN functional results for effective RLN protection and reduced RLN damage rates.

The TOFr of 0.75 to 0.85 is the optimal timing for IONM during thyroid surgery: a prospective observational cohort study.

BACKGROUD: Recurrent laryngeal nerve (RLN) injury is one of the serious complications of thyroid tumour surgery, surgical treatment of thyroid cancer requires careful consideration of the RLN and its impact on glottis function. There has been no unified standard for precise neuromuscular block monitoring to guide the monitoring of RLN in thyroid surgery. This study aimed to investigate the correlation between Train-of-four stabilization ratio (TOFr) and neural signal values of intraoperative neurophysiological monitoring (INOM) during thyroid operation, and further to determine the optimal timing for INOM during thyroid operation. METHODS: Patients scheduled for thyroid tumour resection with INOM and RLN monitoring from April 2018 to July 2018 in our center were recruited. Electromyography (EMG) signals and corresponding TOFr were collected. All nerve stimulation data were included in group VR. Vagus nerve stimulation data were included in Subgroup V. RLN stimulation data were included in Subgroup R. The timing of recording was as follows: Vagus nerve EMG amplitude after opening the lateral space between the thyroid and carotid sheath and before the initiation of thyroid dissection, RLN EMG amplitude at first recognition, RLN EMG amplitude after complete thyroid dissection (Repeat three times), and Vagus nerve EMG amplitude after resection of the thyroid (Repeat three times). Correlation analysis of continuous variables was described by a scatter diagram. Pearson correlation analysis or Spearman correlation analysis was used for the two groups of variables. RESULTS: Finally, 134 vagus nerve signals and 143 RLN signals were analysed after matching with TOFr. The EMG amplitude in the VR group and subgroups after nerve stimulation was positively correlated with TOFr (p < 0.05). In the VR, V and R group, the incidence of EMG ≥ 500 µV in the 0.75 < TOFr ≤ 0.85 interval was significantly higher than the 0 < TOFr ≤ 0.75 interval (P = 0.002, P = 0.013 and P = 0.029), and has no statistical difference compared to 0.85 < TOFr ≤ 0.95 interval (P > 0.05). CONCLUSIONS: The EMG signals of the RLN and vagus nerve stimulation during thyroid surgery were positively correlated with TOFr. TOFr > 0.75 could reflect more than 50% of the effective nerve electrophysiological signals, 0.75 < TOFr ≤ 0.85 interval was the optimal timing for IONM during thyroid surgery. TRIAL REGISTRATION: Chinese Clinical Trial Registry (ChiCTR1800015797) Registered on 20/04/2018. https://www.chictr.org.cn .

Evaluation of intraoperative neuromonitoring (IONM) data with the Mainz IONM Quality Assurance and Analysis tool.

BACKGROUND: Intraoperative neuromonitoring is widely used in thyroid and parathyroid surgery to prevent unilateral and especially bilateral recurrent nerve paresis. Reference values for amplitude and latency for the recurrent laryngeal nerve and vagus nerve have been published. However, data quality measures that exclude errors of the underlying intraoperative neuromonitoring (IONM) data (immanent software errors, false data labelling) before statistical analysis have not yet been implemented. METHODS: The authors developed an easy-to-use application (the Mainz IONM Quality Assurance and Analysis tool) using the programming language R. This tool allows visualization, automated and manual correction, and statistical analysis of complete raw data sets (electromyogram signals of all stimulations) from intermittent and continuous neuromonitoring in thyroid and parathyroid surgery. The Mainz IONM Quality Assurance and Analysis tool was used to evaluate IONM data generated and exported from 'C2' and 'C2 Xplore' neuromonitoring devices (inomed Medizintechnik GmbH) after surgery. For the first time, reference values for latency and amplitude were calculated based on 'cleaned' IONM data. RESULTS: Intraoperative neuromonitoring data files of 1935 patients consecutively operated on from June 2014 to May 2020 were included. Of 1921 readable files, 34 were excluded for missing data labelling. Automated plausibility checks revealed: less than 3 per cent device errors for electromyogram signal detection; 1138 files (approximately 60 per cent) contained potential labelling errors or inconsistencies necessitating manual review; and 915 files (48.5 per cent) were indeed erroneous. Mean(s.d.) reference onset latencies for the left vagus nerve, right vagus nerve, recurrent laryngeal nerve, and external branch of the superior laryngeal nerve were 6.8(1.1), 4.2(0.8), 2.5(1.1), and 2.1(0.5) ms, respectively. CONCLUSION: Due to high error frequencies, IONM data should undergo in-depth review and multi-step cleaning processes before analysis to standardize scientific reporting. Device software calculates latencies differently; therefore reference values are device-specific (latency) and/or set-up-specific (amplitude). Novel C2-specific reference values for latency and amplitude deviate considerably from published values.

Comparison of Recurrent Laryngeal Nerve Injury during Thyroidectomy with and Without Routine Identification of the Nerve Peroperatively.

Thyroidectomy is one of the commonest operative procedures performed in the neck and injury to recurrent laryngeal nerve (RLN) is not uncommon. It results in hoarseness to serious respiratory distress depending on the extent of the injury. The incidence of RLN injury varies widely and is multifactorial depending on the extent of surgical procedures, experience and expertise of the surgeons, nature of the thyroid diseases and a wide range of anatomical variations. Peroperative routine identification of the nerve during thyroidectomy can be a way to prevent injury. Despite recommendation for identification of the RLN peroperatively in thyroid surgery, a debate still exists whether the nerve to be identified peroperatively or not, to avoid its inadvertent injury. The aim of this study was to compare the incidence of RLN injury between two groups where RLN was identified peroperatively in one group and the nerve was not attempted for identification in the other group in thyroid surgery. A comparative cross-sectional study was carried out in the department of surgery and otolaryngology at Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, Bangladesh from June 2018 to November 2019, on patients who underwent elective thyroid surgery. Patients were included in RLN identified group and in RLN not identified group, by individual surgeons' preference to identify or not to identify the RLN peroperatively. Peroperative identification of the nerve was done by direct visualization. All cases were evaluated for vocal cord palsy preoperatively, during extubation and postoperatively. Patient's particulars, other parameters and perioperative data were recorded. A total of 80 cases were included in this study, 40 cases (50.0%) in the peroperative RLN identified group and 40 cases (50.0%) in the RLN not identified group. Unilateral RLN palsy was encountered in 2.5% (2 cases) in the RLN identified group and 6.3% (5 cases) in the nerve not identified group (p value 0.192). Transient unilateral RLN palsy was seen in 7.5% (6 cases) of patients; 2.5% (2 cases) in the RLN identified group and 5.0% (4 cases) in the RLN not identified group. And 1.3% (1 case) of permanent unilateral RLN palsy was encountered in this study, which was in the RLN not identified group; there was no permanent palsy in the RLN identified group. We did not encounter any bilateral RLN palsy. There was no statistically significant difference in the incidence of RLN injury between the peroperatively RLN identified group and no attempt to identify the nerve group despite recommendation for peroperative RLN identification in thyroid surgery to avoid its inadvertent injury. However, from this study, we recommend peroperative RLN identification in thyroid surgery to enhance surgical skill.

Effectiveness of the recurrent laryngeal nerve monitoring during endoscopic thyroid surgery: systematic review and meta-analysis.

BACKGROUND: Thyroid disease is a common endocrine disorder, and thyroid surgeries and postoperative complications have increased recently. This study aimed to explore the effectiveness of intraoperative nerve monitoring (IONM) in endoscopic thyroid surgery using subgroup analysis and determine confounding factors. MATERIALS AND METHODS: Two researchers individually searched for relevant studies published till November 2022 in the PubMed, Embase, Web of Science and Cochrane Library databases. Eventually, eight studies met the inclusion criteria. Heterogeneity was assessed using the Cochran's Q test, and a funnel plot was implemented to evaluate publication bias. The odds ratio or risk difference were calculated using fixed-effects models. The weighted mean difference of continuous variables was calculated. Subgroup analysis was performed according to the disease type. RESULTS: Eight eligible papers included 915 patients and 1242 exposed nerves. The frequencies of transient, permanent and total recurrent laryngeal nerve (RLN) palsy were 2.64, 0.19 and 2.83%, respectively, in the IONM group and 6.15, 0.75 and 6.90%, respectively, in the conventional exposure group. In addition, analysis of the secondary outcome indicators for the average total length of surgery, localisation time of the RLN, recognition rate of the superior laryngeal nerve and length of incision revealed that IONM reduced the localisation time of the RLN and increased the identification rate of the superior laryngeal nerve. Subgroup analysis showed that IONM significantly reduced the incidence of RLN palsy in patients with malignancies. CONCLUSIONS: The use of IONM significantly reduced the incidence of transient RLN palsy during endoscopic thyroid surgery, but it did not significantly reduce the incidence of permanent RLN palsy. However, the reduction in the total RLN palsy was statistically significant. In addition, IONM can effectively reduce the location time of the RLN and increase the recognition rate of the superior laryngeal nerve. Therefore, the application of IONM for malignant tumours is recommended.

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.

The Effect of Patient Positioning on Intraoperative Neuromonitoring During Thyroid and Parathyroid Surgery.

BACKGROUND: Intraoperative neuromonitoring (IONM) has been accepted as a routine adjunct among surgeons who perform thyroid and parathyroid surgeries. Thyroid and parathyroid surgeries use various patient positioning strategies that have poorly understood effects on IONM. The aim of this study was to compare IONM signals between the transaxillary and transcervical approaches. METHODS: In this retrospective cohort study, we evaluated 463 adult patients who underwent a total of 502 procedures. The procedures performed included total thyroidectomy, right or left hemithyroidectomy, and parathyroidectomy. Vagus nerve and recurrent laryngeal nerve (RLN) latency and amplitude measurements were analyzed intra-operatively. The distances between the vagus nerve and the trachea were measured via ultrasound during transaxillary procedures. RESULTS: Compared to the transcervical approach, the right vagus nerve latency was significantly decreased in the transaxillary approach. Transaxillary surgery was not associated with increased latency or decreased amplitude on IONM. The distance between the vagus nerve and trachea was significantly decreased post-positioning during transaxillary approaches. DISCUSSION: Despite differences in patient positioning, a transaxillary approach was not associated with increased stress on the vagus nerve or RLN, according to IONM data. The decreased right vagus nerve latency associated with a transaxillary approach highlights the importance of considering patient positioning and laterality while interpreting IONM data.

Standardized Intraoperative Neuromonitoring Procedure is Feasible in Transoral Endoscopic Thyroidectomy.

BACKGROUND: Intraoperative neuromonitoring in thyroid surgeries has become popular, but the standardized manner of intraoperative neuromonitoring during transoral endoscopic thyroidectomy vestibular approach (TOETVA) is not well established. This study evaluated the feasibility of using a standardized intraoperative neuromonitoring method for TOETVA. METHODS: Medical records of consecutive patients who underwent TOETVA with intraoperative neuromonitoring were retrospectively reviewed. Patients were positioned before intubation to prevent tube migration, then intubated using video laryngoscopy. The electromyography amplitudes of the vagal nerves and the recurrent laryngeal nerves were checked before (V1, R1) and after (V2, R2) thyroid resection. V1 and V2 signals were evaluated using a long ball tip stimulator with a stimulus current of 3 mA. R1 and R2 signals were obtained using the stimulus current of 1 to 3 mA. RESULTS: Forty-two patients (3 males and 39 females) were included. Lobectomy was performed in 40 patients (95.2%) and total thyroidectomy in 2 (4.8%). Pathologic diagnoses were 30 papillary thyroid carcinomas, 2 follicular thyroid carcinomas, and 9 benign diseases. Conversion to open surgery occurred in 1 patient due to bleeding. Thus, 43 nerves at risk in 41 patients were analyzed. V1 and R1 signals were detected from all nerves. The mean V1 and R1 amplitudes were 738.7±391.4 µV and 804.4±347.5 µV, respectively, and 38 (88.3%) and 39 (90.7%) nerves had R1 and V1 amplitudes of more than 500 µV. There were 2 cases (4.6%) of transient recurrent laryngeal nerve injury. R2 and V2 signals were detected in the 41 remaining nerves. The mean R2 and V2 amplitudes were 917.2±505.2 µV and 715.7±356.2 µV, respectively, and 36 (87.8%) and 32 (78.0%) nerves had respective R2 and V2 amplitudes of more than 500 µV. CONCLUSIONS: Intraoperative neuromonitoring could be performed in a standardized manner in TOETVA, and the quality of intraoperative neuromonitoring was excellent. Further studies are needed to verify the feasibility of the current approach.

Intraoperative Neuromonitoring and Optical Magnification in the Prevention of Recurrent Laryngeal Nerve Injuries during Total Thyroidectomy.

Background and Objectives: Recurrent laryngeal nerve (RLN) paralysis is a fearful complication during thyroidectomy. Intraoperative neuromonitoring (IONM) and optical magnification (OM) facilitate RLN identification and dissection. The purpose of our study was to evaluate the influence of the two techniques on the incidence of RLN paralysis and determine correlations regarding common outcomes in thyroid surgery. Materials and Methods: Two equally sized groups of 50 patients who underwent total thyroidectomies were examined. In the first group (OM), only surgical binocular loupes (2.5×−4.5×) were used during surgery, while in the second group (IONM), the intermittent NIM was applied. Results: Both the operative time and the length of hospitalization were shorter in the OM group than in the IONM group (median 80 versus 100 min and median 2 versus 4 days, respectively) (p < 0.05). The male patients were found to have a five-fold higher risk of developing transient dysphonia than the females (adjusted OR 5.19, 95% IC 0.99−27.18, p = 0.05). The OM group reported a four-fold higher risk of developing transient hypocalcemia than the IONM group (OR 3.78, adjusted OR 4.11, p = 0.01). Despite two cases of temporary bilateral RLN paralysis in the IONM group versus none in the OM group, no statistically significant difference was found (p > 0.05). No permanent RLN paralysis or hypoparathyroidism have been reported. Conclusions: Despite some limitations, our study is the first to compare the use of IONM with OM alone in the prevention of RLN injuries. The risk of recurrent complications remains comparable and both techniques can be considered valid instruments, especially if applied simultaneously by surgeons.

The Importance of Mapping Vagus and Laryngeal Nerves Monitoring During Thyroid Surgery.

OBJECTIVE: To determine the location of thyroid-related nerves by nerve monitoring and demonstrate the usefulness of Nerve Integrity Monitor in thyroid surgery. STUDY DESIGN: Descriptive study. PLACE AND DURATION OF STUDY: Department of General Surgery, University of Health Sciences, Istanbul Training and Research Hospital, Turkey, from February 2017 to January 2020. METHODOLOGY: Patients, who underwent thyroid surgery, were evaluated for age, gender, preoperative diagnosis, type of surgery, histopathological result, postoperative hoarseness, and postoperative vocal cord examinations. The vagus nerve, recurrent laryngeal nerve (RLN), and superior laryngeal nerve (SLN) were mapped by nerve monitoring. RESULTS: A total of 328 patients were included in this study. On both sides, the vagus nerve was most often located in the posterior of the internal carotid artery and internal jugular vein and less frequently anterior to this vein. A total of 303 right RLNs and 305 left RLNs were verified. The SLN was visualised or motor activity was verified by nerve monitoring on the right side in 181 patients and on the left side in 179 patients. The SLN's location was classified most frequently as type I and least frequently as type IIb on the right and left sides. CONCLUSION: The reported variations, the experience of the surgeon, and these anatomical markers cannot be adequate in preventing nerve injuries. Furthermore, the variations can be identified more clearly peroperatively with the use of nerve monitoring. KEY WORDS: Laryngeal nerves, Nerve mapping, Nerve monitoring, Nervus vagus, Thyroid surgery, Zuckerkandl tubercles.

Recurrent Laryngeal Nerve with Loss of Signal During Monitored Thyroidectomy: Percentage Reduction in Sum of the Amplitude of Left and Right Channel.

PURPOSE: The prognostication for the injured recurrent laryngeal nerve (RLN) with incomplete loss of signal (LOS) and its function outcome have not been well unified. A warning criterion was proposed to predict RLN injury during monitored thyroidectomy. METHODS: A retrospective review of prospectively collected data from consecutive 357 patients with 560 nerves at risk was conducted. Vocal cords mobility with laryngoscope was performed preoperatively, on the second day, and once a month postoperatively until complete recovery. Different cutoff values of the percentage reduction in sum of the amplitude of left and right channel at the end of the surgery, for postoperative vocal cord paralysis (VCP) prediction were compared. RESULTS: Percentage reduction in sum of the amplitude of left and right channel at the end of operation ranged from 30.2 to 63.6% in 27 nerves with incomplete LOS (absolute amplitude value of final R2 > 100 µV with reduction > 50% of R1). Seven (1.25%) nerves experienced transient postoperative VCP, in which one nerve with postoperative VCP showed no amplitude reduction. The positive predictive value of VCP for the sum amplitude reduction exceeding 30, 40, 50, and 60% was 22.2, 40, 85.7, and 100%, respectively. Accuracy was 96.1, 98.2, 99.6, 99.4%, respectively. CONCLUSION: Percentage reduction in sum of the amplitude of left and right channel is a meaningful method to improve the accuracy of VCP prediction. When the sum amplitude reduction ≥ 50%, surgeons should consider the possibility of postoperative VCP and correct some surgical maneuvers.

Intra-operative nerve monitoring and recurrent laryngeal nerve injury during thyroid surgery: a network meta-analysis of prospective studies.

PURPOSE: Recurrent laryngeal nerve (RLN) injury is a feared complication of thyroid surgery occurring in 1-5% of cases. The present approaches to RLN preservation include RLN visualization with no nerve monitoring (No-NM), intermittent intra-operative nerve monitoring (I-IONM) and continuous intra-operative nerve monitoring (C-IONM). There is ambiguity as to which of these strategies should be the preferred method of RLN preservation. METHODS: A systematic review of the PubMed, Embase and the Cochrane Collaboration databases was undertaken with network meta-analysis (NMA) performed according to the PRISMA and Cochrane Collaboration guidelines. A Bayesian NMA was conducted using R packages netmeta with outcomes expressed as odds ratios (ORs) with 95% credible intervals (CrI). Only prospective studies were included. RESULTS: Eighteen studies met inclusion criteria, including 22,080 patients and 40,642 nerves at risk (NAR). Overall, 23,364 NARs (57.5%) underwent I-IONM, 17,176 (42.3%) No-NM and 98 (0.2%) underwent C-IONM. There were no significant differences between groups regarding the incidence of permanent RLN injury following thyroid surgery (I-IONM vs.No-NM, OR 0.84, 95% CrI 0.55-1.19; C-IONM vs. No-NM, OR 0.44, 95% CrI 0.02-5.00). Pooled analysis showed that IONM (I-IONM or C-IONM) demonstrated a protective effect versus No-NM in reducing the incidence of transient RLN injury (OR 0.75, 95% CI 0.59-0.97, p = 0.03). CONCLUSIONS: IONM strategies did not significantly reduce the incidence of permanent RLN injury following thyroid surgery. However, the small number of C-IONM NARs limits conclusions that may be drawn. Further well-designed prospective studies will be required to definitively assess the utility of C-IONM.