Refining postoperative monitoring of recurrent laryngeal nerve injury in esophagectomy patients through transcutaneous laryngeal ultrasonography.

BACKGROUND: Recurrent laryngeal nerve injury (RLNI) leading to vocal cord paralysis (VCP) is a significant complication following minimally invasive esophagectomy (MIE) with upper mediastinal lymphadenectomy. Transcutaneous laryngeal ultrasonography (TLUSG) has emerged as a non-invasive alternative to endoscopic examination for evaluating vocal cord function. Our study aimed to assess the diagnostic value of TLUSG in detecting RLNI by evaluating vocal cord movement after MIE. METHODS: This retrospective study examined 96 patients with esophageal cancer who underwent MIE between January 2021 and December 2022, using both TLUSG and endoscopy. RESULTS: VCP was observed in 36 out of 96 patients (37.5%). The incidence of RLNI was significantly higher on the left side than the right (29.2% vs. 5.2%, P < 0.001). Postoperative TLUSG showed a sensitivity and specificity of 88.5% (31/35) and 86.5% (45/52), respectively, with an AUC of 0.869 (P < 0.001, 95% CI 0.787-0.952). The percentage agreement between TLUSG and endoscopy in assessing VCP was 87.4% (κ = 0.743). CONCLUSIONS: TLUSG is a highly effective screening tool for VCP, given its high sensitivity and specificity. This can potentially eliminate the need for unnecessary endoscopies in about 80% of patients who have undergone MIE.

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 Causes and Laryngeal Electromyography Characteristics of Unilateral Vocal Fold Paralysis.

OBJECTIVE: To investigate the causes and laryngeal electromyography (LEMG) characteristics of unilateral vocal fold paralysis (UVFP). METHODS: We retrospectively analyzed the history and LEMG of 337 patients with unilateral vocal fold immobility. The etiology was reviewed and the characteristics of LEMG (including spontaneous potential, recruitment potential, evoked potential, synkinesia, and et al.) were analyzed. RESULTS: The causes included injury (177 cases, 52.5%), idiopathic causes (72 cases, 21.4%), infection (61 cases, 18.1%), tumor and compressive factors (27 cases, 8.0%). Among the injury group, 161 cases were caused by surgery (111 cases of thyroid surgery), and 16 cases were caused by trauma. LEMG showed that complete nerve injury was present in 72.9% of the injury group, 66.7% of the tumors or compressive factors group, 49.2% of the infection group, and 44.4% of the idiopathic group. Of the 337 patients, 136 patients (40.4%) had synkinesia in the posterior cricoarytenoid muscles, and only two of these patients also had synkinesia in the thyroarytenoid muscles. The proportion of complete recurrent laryngeal nerve (RLN) injury in patients with synkinesia was higher than that of patients without synkinesia. CONCLUSION: The main cause of vocal fold paralysis is neck surgery, most commonly thyroid surgery. Patients with different causes of paralysis had different severities of RLN injury. LEMG showed that surgery or trauma accounted for the highest proportion of complete nerve injury. Patients with severe RLN injury were more prone to synkinesia, and the posterior cricoarytenoid muscles were more likely to have synkinesia than the thyroarytenoid muscles.

Incidence of Dysphonia and Dysphagia Exceeds Recurrent Laryngeal Nerve Injury During Thyroid Surgery.

OBJECTIVES: To determine the prevalence of separate and combined voice and swallowing impairments before and after total thyroidectomy and to delineate risk factors for these symptoms. METHODS: Retrospective review of 592 consecutive patients who underwent total thyroidectomy from July 2003 to August 2015. RESULTS: Combined voice and swallowing problems occurred preoperatively in 4.7% (11/234), 3.3% (3/92), and 6.0% (16/266) of patients with malignancy, hyperthyroidism, and benign euthyroid disease, respectively. Postoperatively, prevalence was 5.1%, 2.2%, and 1.9%, respectively. Benign euthyroid disease (20.7%) had the greatest risk of preoperative dysphagia (P = 0.003) and the largest glands (P < 0.001). Comparing before and after surgery, the cancer and benign euthyroid groups had decreased dysphagia (cancer: 11.5% vs. 6.0%, P = 0.034; benign: 20.7% vs. 3.8%, P < 0.001) but increased dysphonia (cancer: 19.2% vs. 28.6%, P = 0.017; benign: 15.8% vs. 27.1%, P = 0.002). Overall, 23/592 (3.9%) developed new dysphagia and 122/592 (20.6%) developed new dysphonia after surgery. Intraoperative recurrent laryngeal nerve transection occurred in 12 cases (2.0%). CONCLUSIONS: Total thyroidectomy resolved dysphagia but increased dysphonia in benign and malignant euthyroid patients. Voice and swallowing problems following thyroidectomy occurred more frequently than intraoperative recurrent laryngeal nerve transection, confirming symptoms often occur in the absence of suspected nerve injury.

Recurrent laryngeal nerve paresis in benign thyroid surgery with and without intraoperative nerve monitoring.

BACKGROUND: Recurrent laryngeal nerve (RLN) paresis is a rare but serious complication in thyroid surgery. Intermittent intraoperative nerve monitoring (IONM) was thought to prevent paresis of the RLN, but until today data are not conclusive. Our objective was to confirm the hypothesis that IONM can reduce paresis of RLN compared to nerve visualization alone. Therefore, we examined one of the largest cohorts ever evaluated of a tertiary referral center for endocrine surgery undergoing thyroid surgery for benign thyroid disease. METHODS: Overall, 2097 patients who underwent thyroid surgery for benign thyroid disease in 2016 and 2017 were evaluated. RLN was identified by IONM or visualization only. Preoperative and postoperative laryngoscopic examination was used to evaluate RLN paresis. Patients' characteristics and perioperative data were extracted retrospectively. RESULTS: Overall, 1963 patients (2720 nerves at risk [NAR]) were included in this study: 378 surgeries with IONM (560 NAR) and 1585 without IONM (2160 NAR). Transient and permanent RLN pareses were found in 13 (3.4%; NAR=2.3%) and one (0.3%; NAR=0.2%) nerve treated with IONM vs. 37 (2.3%; NAR=1.7%) and five (0.3%; NAR=0.2%) nerves without IONM (P=0.507; NAR P=0.654), respectively. CONCLUSIONS: Using intermittent IONM, our retrospective study could not demonstrate a significant decrease of RLN pareses in patients undergoing thyroid surgery for benign thyroid disease. This is probably explained by the very low overall number of RLN pareses in our department. Nevertheless, because of patients' safety to avoid any bilateral RLN pareses, we recommend IONM in bilateral resections.

Routine Exposure Versus Non-Exposure of Recurrent Laryngeal Nerve during Thyroid Surgery: Our Experience of 300 Cases.

The technique of thyroidectomy has been in evolution for many years. It is a basic rule of surgery that an important structure of a human body must be recognized certainly during the surgical procedure in order to prevent its damage. The purpose of this study was to evaluate our routine identification and without identification of recurrent laryngeal nerve during thyroidectomy aiming to lessen the inadvertent injury of the recurrent laryngeal nerve. This retrospective clinical controlled study was performed in the Department of ENT and Head-Neck Surgery, BIRDEM General Hospital and the Department of General Surgery, BIRDEM General Hospital, Dhaka, Bangladesh from January 2014 to December 2018. Patients undergoing indirect laryngoscopy with normal vocal cords and those with carcinoma and re-do surgery having normal vocal cords were included in this study. Patients were excluded like containing hoarseness voice, abnormal movements of vocal cord. The total number of patients was 300 and these patients were randomly divided into two groups of 150 each using random number tables. In Group A the recurrent laryngeal nerves were identified by exposing the inferior thyroid artery and markedly seen in its entire course. Where as, in Group B, nerves were not identified during the operation. Immediate post operative direct laryngoscopy was performed by a surgeon with the help of an Anesthesiologist for the assessment of vocal cords. Patients with either persistent hoarseness of voice or not were followed up with indirect laryngoscopy or fiber optic laryngoscopy (FOL) at three and six months. In Group A, out of 150 patients, 6(4%) patients developed transient unilateral paralysis, resulting in slight hoarseness of voice postoperatively. The voice improved within 6 weeks. While 2(1.3%) patients developed permanent unilateral paralysis of recurrent laryngeal nerve. The voice and cord movement did not return to normal even after 6 months in one case while other one improved within the period of 6 months. In Group B, out of 150 patients, 14(9.3%) patients developed transient paralysis. Out of 14 transient paralysis 11 were unilateral and 3 were bilateral nerve paralysis. The voice was improved within 6 months in all of unilateral and bilateral transient paralyzed cases. While 6(4%) patients developed permanent paralysis of recurrent laryngeal nerve. Out of 6 permanent paralysis 2 cases were of bilateral recurrent laryngeal nerve paralysis required immediate tracheostomy. Rest 4 cases of unilateral permanent nerve paralysis, hoarseness of voice occurred but improved in 2 cases during the period varying from 2 to 6 months while in other 2 cases, it persisted even after 6 months. Frequency of recurrent laryngeal nerve palsies was significantly lower in Group A as compared to Group B. This difference remained statistically significant (p=0.046) between the two groups in terms of type of thyroid diseases, type of surgeries and number of surgeries. For essentially eliminating the risk of nerve injury during surgery, recurrent laryngeal nerve should be exposed and identified routinely in its entire course.

Intraoperative Nerve Monitoring in Thyroidectomies for Malignancy: Does It Matter?

BACKGROUND: Recurrent laryngeal nerve (RLN) injury and postoperative hypocalcemia are potential complications of thyroidectomy, particularly in malignancy. Intraoperative nerve monitoring (IONM) remains controversial. We sought to evaluate the impact of IONM on these complications using a national data set. METHODS: The American College of Surgeons National Surgical Quality Improvement Program thyroidectomy-targeted data set was queried for patients who underwent thyroidectomies from 2016 to 2017. Patients were grouped according to IONM use. Logistic regression models were constructed to evaluate associations of variables with 30-day hypocalcemic events (HCEs) and RLN injury. Associations were expressed as odds ratios (ORs) with 95% confidence intervals (95% CIs). A subgroup analysis was performed of patients with malignancy. RESULTS: A total of 9527 patients were identified; 5969 (62.7%) underwent thyroidectomy with IONM and 3558 (37.3%) without. By multivariable analysis, IONM had protective associations with HCE (OR = .81, 95% CI = .68-.96; P = .013) and RLN injury (OR = .83, 95% CI = .69-.98; P = .033). Malignancy increased risk of HCE (OR = 1.21, 95% CI=1.01-1.45; P = .038) and RLN injury (OR = 1.22, 95% CI = 1.02-1.46; P = .034). A large proportion (5943/9527, 62.4%) of patients had malignancy; 3646 (61.3%) underwent thyroidectomy with IONM and 2297 (38.7%) without. In the subgroup analysis, IONM had stronger protective associations with HCE (OR = .73, 95% CI = .60-.90; P = .003) and RLN injury (OR = .76, 95% CI = .62-.94; P = .012). DISCUSSION: Malignancy was associated with increased risk of HCE and RLN injury. Intraoperative nerve monitoring had a protective association with HCE and RLN injury, both overall, and in the malignant subgroup. Intraoperative nerve monitoring was correlated with improved thyroidectomy outcomes, especially if the indication was malignancy. This warrants further study to clarify cause and effect.

Intraoperative Posterior Cricoarytenoid Muscle Electromyography May Predict Vocal Cord Function Prognosis after Loss of Signal during Thyroidectomy.

PURPOSE: Intraoperative posterior cricoarytenoid muscle (PCAM) electromyography (EMG) may be useful for predicting postoperative vocal cord function (VCF) and prognosis of vocal cord palsy (VCP) in patients with intraoperative loss of signal (LOS). MATERIALS AND METHODS: Thirty out of 395 patients having LOS detected by intraoperative neural monitoring (IONM), were applied intraoperative PCAM EMG. RESULTS: VCP was present in all Type 1 injury RLNs (16) (100%) and in 8 (57%) of 14 RLNs with Type 2 injury (p = 0.005). 14 out of 30 LOS patients (47%) had positive PCAM EMG amplitudes. The sensitivity, specificity, positive and negative predictive values and accuracy rates for predicting postoperative VCP via PCAM EMG, were calculated as 66.7%, 100%,100%, 42.86% and 73.33%. The negative PCAM EMG was related to VCP in both Type 1 and Type 2 LOS. VCP recovery time of Type 1 LOS patients was significantly longer than that of Type 2 LOS patients (p = 0.009). In Type 2 LOS, VCP recovery time was significantly longer in negative PCAM EMG patients compared to positive PCAM EMG patients (p = 0.046). CONCLUSION: Negative PCAM EMG is associated with the postoperative VCP. Type 1 injury results in VCP regardless of PCAM EMG results, and VCF recovers after a longer period compared to Type 2 LOS.In Type 2 LOS, positive PCAM EMG may result in VCP by 40%. However, the presence of negative PCAM EMG is related to the postoperative VCP in all patients and the recovery time is longer compared to positive PCAM EMG patients.

Comparison of stimulating dissector and intermittent stimulating probe for the identification of recurrent laryngeal nerve in reoperative setting.

PURPOSE: Recurrent laryngeal nerve (RLN) paralysis is one of the most devastating complications after thyroidectomy. Thyroid reoperation is a great challenge for surgeons due to anatomical distortion and fibrosis and associated with a higher risk of RLN injury. In this study, we aimed to compare stimulating dissector (SD) with intermittent stimulating probe (ISP) in thyroid reoperations. This study is the first one which compares the impact of different nerve stimulating devices in thyroid reoperations. METHODS: Included in this randomized prospective study were patients who had a bilateral subtotal thyroidectomy and would undergo a completion thyroidectomy due to a diagnosis of thyroid papillary cancer between January 2015 and January 2017. Patients were divided into two groups as SD group and ISP group. Age, sex, nerve amplitudes, latencies, the first identification time of RLN and complications were compared in both groups. RESULTS: A total of 32 patients, 16 in both groups, were included in the study. The demographics, nerve signal amplitudes and latencies were similar in both groups (p > 0.05). The mean RLN identification time in the SD group was 17.4 ± 4.3 min, which was significantly shorter than those in the ISP group (mean 21.3 ± 3.9) (p = 0.014). CONCLUSION: The first identification of RLN in the thyroid reoperations was faster with the use of SD than with the use of the ISP. Since the electromyographic amplitudes of RLN and vagus nerve with using SD were similar to the bipolar ISP, SD can be used safely for thyroid reoperations.

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.

Value of Neurostimulation Plus Laryngeal Palpation to Predict Postoperative Vocal Fold Motility.

BACKGROUND: The aim of this study was to evaluate the reliability of intraoperative neuromonitoring through recurrent laryngeal nerve stimulation and simultaneous laryngeal palpation (NSLP) in predicting postoperative vocal cord palsy and in providing useful information in the decision to perform a staged surgery in initially planned total thyroidectomy. MATERIALS AND METHODS: A retrospective review was performed involving 552 patients for whom a total thyroidectomy was planned. In all patients, preoperative and postoperative laryngoscopy was performed. The incidence of vocal cord palsy was calculated on 1104 nerves at risk. RESULTS: Sensitivity and specificity of NSLP were 0.9411 and 0.9925 respectively. The positive predictive value was 0.7804, the negative predictive value was 0.9981, the false positive rate was 0.8%. In 41 patients (7.4%) the initial surgical strategy was changed into a staged procedure. Nine patients (21.9%) were false positive, 32 patients (78.1%) were true positive. Finally, a two-stage thyroidectomy was performed in 27 of 41 patients. CONCLUSIONS: High sensitivity and specificity confirm the validity of NSLP in predicting postoperative vocal cord palsy and in driving a possible staged thyroidectomy, both in benign thyroid disease and in differentiated thyroid carcinoma.

Intraoperative Neural Monitoring for Early Vocal Cord Function Assessment After Thyroid Surgery: A Systematic Review and Meta-Analysis.

Objective This study evaluated the diagnostic accuracies of various forms of intraoperative neural monitoring (IONM) in terms of predicting vocal cord palsy after thyroidectomy. Methods Two authors independently reviewed the six databases (PubMed, the Cochrane database, Embase, the Web of Science, SCOPUS, and Google Scholar) from their dates of inception to March 2021. Intraoperative electromyographic neuromonitoring (IONM) was compared with laryngoscopic detection (the reference method). True-positive, true-negative, false-positive, and false-negative data were extracted from each study. Methodological quality was evaluated using the Quality Assessment of Diagnostic Accuracy Studies ver. 2 tool. Results Twenty-seven prospective or retrospective studies were included. The diagnostic odds ratio for IONM was 152.9623 ([95% confidence interval [75.4249; 310.2085]. The area under the summary receiver operating characteristic curve was 0.966. The sensitivity, specificity, negative predictive value, and positive predictive value were 0.8219 ([0.6862; 0.9069]), 0.9783 ([0.9659; 0.9863]), 0.9943 ([0.9880; 0.9973]), and 0.5523 ([0.4458; 0.6542]), respectively. The correlation between sensitivity and false-positive rate was 0.200, indicating the absence of heterogeneity. Subgroup analysis showed that the diagnostic accuracies of the continuous IONM was higher than those of intermittent IONM, and recent publications (> 2011) was higher than early publication (< 2010). Conclusions As the technology and knowledge of IONM have been accumulated and progressed over the past decades, the predictive value of IONM in postoperative vocal cord palsy has also improved. Moreover, the advances of continuous IONM technology could make a breakthrough in vocal cord evaluation after thyroid surgery.

Identification of the recurrent laryngeal nerve during thyroidectomy can affect the complication rate.

AIM: Identification of recurrent laryngeal nerve (RLN), performed via different techniques, decreases nerve injury during thyroidectomy. We aimed to evaluate the effect of different anatomic levels at which RLN was identified on postoperative complications. MATERIAL AND METHODS: The patients underwent total thyroidectomy or lobectomy without lymph node dissection were included. Two different surgical methods were performed: thyroidectomy identifying RLN at level of inferior thyroid artery (ITA) (Group 1); at level of Berry's ligament (Group 2). Patients were evaluated with indirect laryngoscopy on 3rd postoperative day, if nerve damage was determined, at each six months. Nerve damage and postop hypocalcemia were accepted transient up to 6th month, permanent after 6th month. Total serum calcium levels were postoperatively measured on 24th and 48th hours, and then monthly. RESULTS: Unilateral and bilateral RLN damage were detected as 4.4% and 2.2% in Group 1; and 8% and 2.67% in Group 2, respectively. The frequency of RLN damage was similar (p=0.62). Postoperative hypocalcemia was significantly higher in Group 1 (p=0.04); hypocalcemia was similar (p=0.149). One patient in Group 1, and 2 patients in Group 2 had f superior laryngeal nerve (SLN) injury. Three patients from each group showed permanent hypocalcemia. One patient in Group 1, and two in Group 2 developed permanent hoarseness. DISCUSSION: RLN injury was similar in both groups, however, temporary hypocalcemia was more frequent in patients undergone thyroidectomy with RLN identification at ITA level. CONCLUSIONS: Devascularization of parathyroid glands may be accused. Future studies are needed. KEY WORDS: Recurrent laryngeal nerve, Thyroidectomy.

Continuous neuromonitoring during radiofrequency ablation of benign thyroid nodules provides objective evidence of laryngeal nerve safety.

INTRODUCTION: The recurrent laryngeal nerves(RLN) run immediately posterior to the thyroid capsule and could be injured during thyroid radiofrequency ablation(RFA). This study assesses whether RLN functional integrity is altered during RFA using continuous intraoperative neuromonitoring(CIONM). METHODS: Prospective case series of twenty nodules treated with RFA under general anesthesia utilizing the laryngeal adductor reflex(LAR) for CIONM. RESULTS: Thirteen nodules abutted the posterior thyroid capsule and 'danger triangle' for RLN injury. The ablative field did not breach the posterior capsule; 40 W was the maximal power used adjacent to the capsule. No patient experienced significant LAR amplitude alterations. Pre and postoperative laryngoscopy and voice assessments were comparable. At 12 months' median follow-up, no patient displayed posterior nodule regrowth. CONCLUSIONS: This prospective case series supports the premise that benign nodule RFA is safe with regards to RLN functional integrity provided the posterior capsule is not breached by the ablation zone and posterior power is ≤ 40 W.

Development of In-Office Laryngeal Nerve Conduction Studies: Computed Tomography and Cadaveric Study.

OBJECTIVES/HYPOTHESIS: In-office recurrent laryngeal nerve conduction studies (NCSs) are a technique that can potentially provide information about laryngeal innervation. NCS is essential in the management of other neuropathies including carpal tunnel syndrome and spinal cord injury. We hypothesize that laryngeal NCS may have similar utility in managing patients with vocal fold paralysis, atrophy, and neurodegenerative disease. NCSs are technically challenging because they require transcervical stimulation of the recurrent laryngeal nerve (RLN). This study combines radiographic data with cadaveric dissection to describe the anatomic parameters for optimal RLN stimulation. STUDY DESIGN: Radiographic and Cadaveric Study. METHODS: Fifty computed tomography scans were reviewed to determine the dimensions for ideal needle electrode placement. These values were compared to measurements from 12 fresh human cadaveric neck dissections. Ultrasound imaging was utilized in select cases. The neck was dissected to assess the accuracy of electrode placement. RESULTS: Radiographically, the mean transcervical depth to the RLN was 33.2 mm ± 8.3 mm in males versus 29.4 mm ± 9.4 mm in females. The working space between the lateral trachea and carotid artery was 15.3 mm ± 3.6 mm on the right and 14.1 mm ± 2.9 mm on the left. After placement of stimulating electrodes into the cadaveric neck, the electrode tips were consistently within 8 mm of the RLN. Ultrasound guidance improved placement accuracy of the stimulating electrode. CONCLUSIONS: Laryngeal NCSs can provide detailed and objective information about laryngeal innervation that could dramatically improve the management of various neuropathies. In-office NCSs require technical precision, and this study describes anatomic factors that may affect the feasibility of performing this technique. LEVEL OF EVIDENCE: NA Laryngoscope, 131:1566-1569, 2021.

Intraoperative Neuromonitoring in Thyroid and Parathyroid Surgery.

Background: It has been reported that the incidence of recurrent laryngeal nerve (RLN) injury is higher in an operational procedure in the thyroid and parathyroid region. Elevating voice pitch is achieved by the cricothyroid contraction, which in turn is innervated by the external branch of the superior laryngeal nerve (EBSLN). Due to the subtle nature and clinical variability of EBSLN damage, diagnosis may be difficult. The use of intraoperative neuromonitoring (IONM) as a supplement to enhance surgical identification in thyroid and parathyroid operation appeared to have collected momentum with operators. Methods: IONM clinical usage rationale, efficiency, and safety profile are discussed in this overview in thyroid and parathyroid surgery. Results: IONM usage incurred numerous skepticisms in decreasing the frequency of EBSLN or RLN injury. However, a recent article has shown the efficacy and benefits of using IONM in thyroid and parathyroid procedures. IONM facilitates the recognition of RLN and EBSLN, verifies its functional integrity, localizes the site of a nerve injury, and gives postsurgical function feedback. This technique has been successful in reducing rates of bilateral laryngeal paralysis, with the elevated safety profile for surgical patients. Conclusions: It is recommended using IONM in all thyroidectomies and in high-risk parathyroidectomies.

What is the impact of continuous neuromonitoring on the incidence of injury to the recurrent laryngeal nerve during total thyroidectomy?

BACKGROUND: Continuous intraoperative neuromonitoring may facilitate reversal of intraoperative injurious operative maneuvers in comparison with intermittent intraoperative neuromonitoring. The aim of this study was to evaluate the impact of the routine use of continuous intraoperative neuromonitoring on intraoperative injuries to the recurrent laryngeal nerve. METHOD: This study was a prospective case series with retrospective analysis of consecutive patients undergoing total thyroidectomy from August 2013 to August 2019. During this period, intermittent intraoperative neuromonitoring (before Mar 2016) and continuous intraoperative neuromonitoring (after Mar 2016) were used in all patients. RESULTS: We reviewed the outcomes of 603 patients (466 female patients) comprising 236 who underwent intermittent intraoperative neuromonitoring and 367 who underwent continuous intraoperative neuromonitoring. Intraoperative adverse electromyography events (>50% decrease in amplitude between VN1 and VN2) were observed in 87 patients (14.5%) and were less frequent in the continuous intraoperative neuromonitoring group (10.6 vs 20.3%, P = .001). Intraoperative loss of signal (electromyography events with VN2 ≤100µV) were observed in 35 patients (5.8%) without any difference between the 2 groups of patients (5.2 vs 6.8%, P = .415). Postoperative recurrent laryngeal nerve palsies were observed in 36 patients (5.9%) without any difference between the 2 groups of patients (4.9 vs 7.6%, P = .168). CONCLUSION: The routine use of continuous intraoperative neuromonitoring improves the rate of intraoperative adverse electromyography events but does not impact significantly the rates of loss of signal and recurrent laryngeal nerve palsy.

A prospective study evaluating the feasibility and accuracy of very early postoperative translaryngeal ultrasonography in the assessment of vocal cord function after neck surgery.

BACKGROUND: Early recognition of postoperative vocal cord palsy enhances postoperative care. Translaryngeal ultrasonography can assess vocal cord function accurately and noninvasively, but it is unclear whether it is feasible or accurate when done immediately after extubation in the recovery room owing to possible interference from laryngeal swelling. This study assessed the feasibility and accuracy of translaryngeal ultrasonography in this setting. METHODS: Consecutive patients undergoing neck operations were subjected to translaryngeal ultrasonography and flexible direct laryngoscopy 1 day before and day 7 after thyroidectomy and parathyroidectomy. Translaryngeal ultrasonography was performed early in the recovery room immediately after extubation in the operating room. A standardized assessment protocol was used. Patient parameters were compared between those with assessable and unassessable vocal cords. RESULTS: Sixty-five patients (91 recurrent laryngeal nerves-at-risk) were analyzed after excluding 2 male patients who failed preoperative translaryngeal ultrasonography. Fifty-six patients underwent thyroidectomy and 9 parathyroidectomy. The median age (range) was 57 (46-69); 44 (68%) were women. Sixty-one patients (94%) had assessable bilateral vocal cords on translaryngeal ultrasonography in the recovery room. Translaryngeal ultrasonography in the recovery room findings corresponded completely with day-7 findings on direct laryngoscopy. Long operative time was associated with nonassessable vocal cords on translaryngeal ultrasonography in the recovery room (P = .026). CONCLUSION: Very early postoperative translaryngeal ultrasonography in the recovery room after neck surgery is highly feasible and accurate. Long operative time may hinder the use of translaryngeal ultrasonography in the recovery room.