Echotexture of recurrent laryngeal nerves: the depiction of recurrent laryngeal nerves at high-frequency ultrasound during radical thyroidectomy.

Introduction: To investigate the ultrasound characteristics of recurrent laryngeal nerves (RLNs) during radical surgery for thyroid cancer and to enhance the understanding of RLN ultrasound features. Methods: From October 2021 to December 2022, a prospective study was conducted involving 24 patients scheduled for bilateral thyroid surgery. Near the conclusion of the surgery, intraoperative ultrasonography of the RLN within the tracheoesophageal groove was performed using a 15-7 MHz transducer. The thickness and width of the RLN were measured during the procedure. Results: The internal architecture of the RLN was observed to consist of multiple hypoechoic, parallel, but discontinuous linear hyperechoic areas separated by bands. In the normal RLN group, the diameter of the RLN was relatively consistent, with thickness ranging from 2.20 to 2.71 mm (mean: 2.48 ± 0.14 mm) and width from 1.25 to 1.70 mm (mean: 1.45 ± 0.11 mm). Both weight and the body mass index (BMI) showed a statistically significant correlation with RLN thickness (Weight: r=0.544, P=0.001; BMI: r=0.605, P=0.001). The BMI also showed a statistically significant correlation with the RLN width (r=0.377, P=0.033). In the RLN invasion group, the width of invaded RLNs ranged from 1.9 to 2.3 mm (mean: 2.10 ± 0.11 mm), while the width of non-invaded RLNs ranged from 2.6 to 3.2 mm (mean: 2.93 ± 0.20 mm). Conclusions: Ultrasound effectively reveals the structural features of the RLN and enhances sonographers' understanding of RLN characteristics.

Assessment of Changes in the Quality of Voice in Post-thyroidectomy Patients With Intact Recurrent and Superior Laryngeal Nerve Function.

Background Thyroidectomy is a routinely performed surgical procedure used to treat benign, malignant, and some hormonal disorders of the thyroid that are not responsive to medical therapy. Voice alterations following thyroid surgery are well-documented and often attributed to recurrent laryngeal nerve dysfunction. However, subtle changes in voice quality can persist despite anatomically intact laryngeal nerves. This study aimed to quantify post-thyroidectomy voice changes in patients with intact laryngeal nerves, focusing on fundamental frequency, first formant frequency, shimmer intensity, and maximum phonation duration. Methodology This cross-sectional study was conducted at a tertiary referral center in central India and focused on post-thyroidectomy patients with normal vocal cord function. Preoperative assessments included laryngeal endoscopy and voice recording using a computer program, with evaluations repeated at one and three months post-surgery. Patients with normal laryngeal endoscopic findings underwent voice analysis and provided feedback on subjective voice changes. The PRAAT version 6.2 software was utilized for voice analysis. Results The study included 41 patients with normal laryngoscopic findings after thyroid surgery, with the majority being female (85.4%) and the average age being 42.4 years. Hemithyroidectomy was performed in 41.4% of patients and total thyroidectomy in 58.6%, with eight patients undergoing central compartment neck dissection. Except for one patient, the majority reported no subjective change in voice following surgery. Objective voice analysis showed statistically significant changes in the one-month postoperative period compared to preoperative values, including a 5.87% decrease in fundamental frequency, a 1.37% decrease in shimmer intensity, and a 6.24% decrease in first formant frequency, along with a 4.35% decrease in maximum phonatory duration. These trends persisted at the three-month postoperative period, although values approached close to preoperative levels. Results revealed statistically significant alterations in voice parameters, particularly fundamental frequency and first formant frequency, with greater values observed in total thyroidectomy patients. Shimmer intensity also exhibited slight changes. Comparison between hemithyroidectomy and total thyroidectomy groups revealed no significant differences in fundamental frequency, first formant frequency, and shimmer. However, maximum phonation duration showed a significantly greater change in the hemithyroidectomy group at both one-month and three-month postoperative intervals. Conclusions This study on post-thyroidectomy patients with normal vocal cord movement revealed significant changes in voice parameters postoperatively, with most patients reporting no subjective voice changes. The findings highlight the importance of objective voice analysis in assessing post-thyroidectomy voice outcomes.

Current Knowledge on the Use of Neuromonitoring in Thyroid Surgery.

Thyroid surgery rates have tripled over the past three decades, making it one of the most frequently performed procedures within general surgery. Thyroid surgery is associated with the possibility of serious postoperative complications which have a significant impact on the patient's quality of life. Recurrent laryngeal nerve (RLN) palsy and external branch of the superior laryngeal nerve (EBSLN) palsy are, next to hypoparathyroidism and postoperative bleeding, some of the most common complications. The introduction of neuromonitoring into thyroid surgery, which enabled both the confirmation of anatomical integrity and the assessment of laryngeal nerve function, was a milestone that began a new era in thyroid surgery. The International Neural Monitoring Study Group has produced a standardization of the technique of RLN and EBSLN monitoring during thyroid and parathyroid surgery, which in turn increased the prevalence of neural monitoring during thyroidectomy. The current status of IONM and the benefits of its use have been presented in this publication.

Anatomical variations of recurrent laryngeal nerve: a systematic review and meta-analyses.

PURPOSE: The aim of this systematic review and meta-analysis was to systematically review and perform a meta-analysis on the anatomical variations of the RLN. METHODS: We performed online research for studies that addressed anatomical variations of the RLN and laterality, published between 2015 and 2021. We found 230 articles, and nine were included. RESULTS: Eight variations were found, with Type I prevailing (41.17%; 95% CI 19.44-64.88), extra laryngeal divergence of the RLN. The other types were: II-fan shape; III-distance greater than 5 mm to the cricothyroid joint; IV-thickening and adipopexy in the elderly; V-non-recurrent laryngeal nerve; VI-intracranial branch; VII-tortuous ascending RLN; and VIII-combination between the inferior branch of the NV and the ascending trunk of the RLN. Types I (p = 0) and III (p < 0.01) prevailed on the left and types II (p < 0.01) and V (p < 0.01) on the right. CONCLUSIONS: It was observed that variations occurred due to the path of the RLN to the entrance to the larynx, its shape, and the age of the evaluated individual. The most frequent variation and side were, respectively, Type I, extra laryngeal divergence and left.

Protect the recurrent laryngeal nerves in US-guided microwave ablation of thyroid nodules at Zuckerkandl tubercle: a pilot study.

BACKGROUND: To evaluate the safety and efficacy of US-guided microwave ablation in patients with thyroid nodules at Zuckerkandl tubercle. METHODS: 103 consecutive patients with thyroid nodules at Zuckerkandl tubercle (ZTTN) were enrolled in this study from November 2017 to August 2021. Prior to the surgery or US-guided microwave ablation (MWA), preoperative ultrasound visualization of the recurrent laryngeal nerve (RLN) and ZTTN was performed, the size and the position relationship between them were observed. Patients were followed up at 1, 3, 6, and 12 months after MWA and the volume reduction rates (VRR) of the thyroid nodules were analyzed. RESULTS: All patients successfully had the RLN and ZTTN detected using ultrasound before surgery or ablation with a detection rate of 100%. For the 103 patients, the majority of ZTTN grades were categorized as grade 2, with the distance from the farthest outside of ZTTN to the outer edge of thyroid ranging between 6.0 and 10.0 mm. The position relationship between ZTTN and RLN was predominantly type A in 98 cases, with type D observed in 5 cases. After MWA, the median nodule volume had significantly decreased from 4.61 (2.34, 8.70) ml to 0.42 (0.15, 1.41) ml and the VRR achieved 84.36 ± 13.87% at 12 months. No nodules regrew throughout the 12-month follow-up period. Of the 11 patients experienced hoarseness due to RLN entrapment before ablation, 7 recovered immediately after separation of the RLN and ZTTN during MWA, 2 recovered after one week, and the other 2 recovered after two months. CONCLUSIONS: The RLN is closely related to ZTTN and mainly located at the back of ZTTN. The RLN can be separated from ZTTN by hydrodissection during MWA. US-guided MWA is a safe and effective treatment for ZTTN.

Effect of ultrasound-guided internal branch of superior laryngeal nerve block on quality of anesthesia recovery in patients undergoing intracranial tumor surgery: a retrospective study / 中华麻醉学杂志

Objective:To evaluate the effect of ultrasound-guided internal branch of superior laryngeal nerve(ibSLN) block on the quality of anesthesia recovery in the patients undergoing intracranial tumor surgery.Methods:The data from patients of either gender, aged 18-65 yr, with a body mass index of 18-28 kg/m 2, who underwent intracranial tumor surgery from December 2022 to October 2023, were retrospectively collected. Patients were divided into control group (group C) and ultrasound-guided ibSLN block group (group U). Bilateral ibSLN block was performed with 0.375% ropivacaine hydrochloride 2 ml.The tracheal extubation time, emergence time, development of cardiovascular events within 15 min after extubation, emergence agitation, Ramsay sedation score, Steward recovery score, visual analogue scale scores at 10 min after extubation and development of postoperative sore throat and hoarseness in postanesthesia care unit were recorded. Results:Compared with group C, the incidence of emergence agitation, Ramsay sedation score, visual analogue scale scores and sore throat were significantly decreased, the incidence of hoarseness was increased ( P<0.05), and no significant change was found in the extubation time, emergence time and Steward recovery score in group U( P>0.05). No hypertension, hypotension, tachachycardia and bradycardia were found in two groups. Conclusions:Ultrasound-guided ibSLN block can improve the quality of anesthesia recovery in the patients undergoing intracranial tumor surgery.

Clinical study on ultrasound-guided superior laryngeal nerve block combined with cricothyroid membrane puncture for awake tracheal intubation in difficult airways / 中国基层医药

Objective:To evaluate the clinical efficacy of ultrasound-guided superior laryngeal nerve block combined with cricothyroid membrane puncture for awake tracheal intubation in difficult airways.Methods:A total of 80 patients scheduled for general anesthesia surgery owing to difficult airways at Marine Police Corps Hospital of Chinese People's Armed Police Force from August 2019 to February 2023 were included in this prospective study. These patients were randomly divided into a control group and an observation group ( n = 40 per group). Both groups of patients underwent fiberoptic bronchoscope-guided awake tracheal intubation through the nasal route. Before intubation, the control group received surface anesthesia combined with cricothyroid membrane puncture anesthesia, while the observation group received superior laryngeal nerve block combined with cricothyroid membrane puncture anesthesia. During the intubation process, hemodynamic indicators of the patients were monitored, the duration of the intubation operation was recorded, and the degree of sedation and cough response was evaluated. Before and after intubation, the levels of serum stress response factors were determined, and the satisfaction level of patients with the intubation operation was investigated. Results:At the time points T1 (immediately after the tracheal tube enters the glottis) and T2 (after the tracheal tube enters the trachea), the heart rate in the observation group was (84.08 ± 8.25) times/minute and (82.64 ± 7.81) times/minute, respectively, and the mean arterial pressure in the observation group was (92.57 ± 8.32) mmHg (1 mmHg = 0.133 kPa) and (103.27 ± 9.16) mmHg, respectively, which were significantly lower compared with those in the control group ( t = 5.92-12.56, all P < 0.001). At T1 and T2, there was no significant difference in blood oxygen saturation (SpO 2) between the observation and control groups ( t = 0.34-0.43, P = 0.652-0.726). The duration of the intubation operation in the observation group was (8.96 ± 1.15) minutes, which was significantly shorter than (11.47 ± 1.39) minutes in the control group ( t = 6.84, P < 0.001). The Ramsay sedation score during intubation in the observation group was 3 (2,3) points, which was significantly higher than 2 (1,3) points in the control group ( Z = 9.26, P < 0.001). The cough response score in the observation group was 1 (0,1) point, which was significantly lower than 1 (0, 2) points in the control group ( Z = 4.37, P < 0.001). The serum levels of stress response factors norepinephrine and adrenaline in the observation group were significantly lower than those in the control group ( t = 14.58-25.94, both P < 0.05). The overall patient satisfaction in the observation group was 97.50%, which was significantly higher than that in the control group ( χ2 = 4.51, P = 0.034). Conclusion:Superior laryngeal nerve block combined with cricothyroid membrane puncture can be used for anesthetic management of awake nasal tracheal intubation in difficult airways. This combined approach can improve patient hemodynamic stability and sedation, shorten the duration of intubation, reduce stress responses during intubation, and enhance patient satisfaction.

Transection Of Sternothyroid Muscle Increases The Rate Of Exposure Of The External Branch Of The Superior Laryngeal Nerve During Thyroidectomy.

Objectives: To assess the benefits of transection of the sternothyroid muscle compared to conventional approach for detecting the external branch of the superior laryngeal nerve while dealing with the upper pole of the thyroid gland. METHODS: The randomised controlled clinical trial was conducted at Kafrelsheikh University Hospital, Egypt, from January 2021 to January 2022, and comprised patients who were eligible for total thyroidectomy and met the American Thyroid Association guidelines. They were randomised and divided into conventional approach group A and sternothyroid muscle transection approach group B. The rate of exposure of the external branch of the superior laryngeal nerve, injury, classification, operative time and voice outcomes at 2 weeks and 3 months post-intervention were noted in both the groups. Data was analysed using SPSS 22. RESULTS: Of the 102 patients, 50(49%) were in group A; 5(10%) males and 45(90%) females with mean age 40.48±12.58 years and mean body massindex 30.676±2.305. There were 52(51%) patientsin group B; 5(9.6%) males and 45(90.4%) females with mean age 39.67±11.60 years and mean body mass index 30.096±2.776. The rate of external branch of the superior laryngeal nerve identification was higher and the operative time was shorter in group B compared to group A (p=0.05). No significant difference was noted in terms of voice outcomes either at baseline or at any of the two follow-up points between the groups (p>0.05). CONCLUSIONS: The transection of sternothyroid muscle improved the rate of external branch of the superior laryngeal nerve exposure and preservation compared to the conventional technique during thyroidectomy.

Efficacy of ultrasound-guided superior laryngeal nerve block combined with intravenous anesthesia for improving pediatric fiberoptic bronchoscopy / 中华麻醉学杂志

Objective:To evaluate the efficacy of ultrasound-guided superior laryngeal nerve block(SLNB) combined with intravenous anesthesia for improving pediatric fiberoptic bronchoscopy.Methods:Forty pediatric patients of either sex, aged 3-6 yr, of American Society of Anesthesiologists Physical Status classificationⅠor Ⅱ, with body mass index of 18-24 kg/m 2, undergoing fiberoptic bronchoscopy in Cangzhou Central Hospital in 2022, were divided into 2 groups ( n=20 each) by a random number table method: ultrasound-guided SLNB plus intravenous anesthesia group (group A) and topical anesthesia plus intravenous anesthesia group (group B). After sedation with dexmedetomidine and esketamine, ultrasound-guided bilateral SLNB was performed with 1% lidocaine 0.5 ml (for each side)in group A, and topical anesthesia was performed with 1% lidocaine in nasal and pharyngeal cavities in group B. After completion of the surgery procedure, propofol was continuously infused at 5 mg·kg -1·h -1 until completion of diagnosis and treatment. An increment of propofol 1 mg/kg was intravenously given if severe bucking or body movement occurred during operation. Mean arterial pressure (MAP), heart rate (HR) and SpO 2 were recorded on admission to the operating room (T 0), immediately after sedation (T 1), immediately after bronchoscopy entering the glottis (T 2), 5 min after start of treatment (T 3) and at the end of examination (T 4). The occurrence of intraoperative hypoxemia, HR <60 bpm, and MAP <50 mmHg were recorded, and the additional dose of propofol was recorded. The venous blood samples were collected at T 0 and T 4 to determine plasma cortisol concentrations by chemiluminescence.The surgeon′s satisfaction score was recorded. The complications of SLNB were also recorded within 2 h after operation in group A. Results:Compared with group B, HR was significantly decreased at T 2 and T 3, SpO 2 was increased, the intraoperative additional dosage of propofol and incidence of hypoxemia were decreased, and the surgeon′s satisfaction score was increased, and the concentrations of cortisol were decreased at T 4 in group A ( P<0.05). No HR<60 bpm and MAP<50 mmHg were found in two groups. No SLNB-related complications were observed after operation in group A. Conclusions:Ultrasound-guided SLNB combined with intravenous anesthesia is safer for pediatric fiberoptic bronchoscopy and can improve the analgesic effect and is more helpful in inhibiting intraoperative stress responses when compared with conventional anesthesia.

Surgical treatment and prognosis values of extranodal extension to recurrent laryngeal nerve in papillary thyroid carcinoma.

PURPOSE: Recurrent laryngeal nerve (RLN) invasion by extranodal extension (ENE) is a rare condition that may occur in papillary thyroid cancer (PTC), and it has never been characterised in the literature.Our research aims to investigate the clinical significance of ENE to RLN including its effect on vocal cord function, relationship with the aggressive behaviour of PTC, and optimal surgical methods. METHODS: A total of 3119 patients, including 2868 patients without RLN invasion, 251 patients with RLN invasion [categorised into the ENE invasion group (n = 55) and extrathyroidal extension (ETE) invasion group (n = 196)] were analyzed retrospectively. Data on clinicopathological characteristics, vocal cord paralysis (VCP), postoperative complications, surgical methods, rates of recurrence and metastasis were collected. Predictive disease-free survival (DFS) was analysed using the Kaplan-Meier method. RESULTS: The ENE invasion group showed a similar rate of VCP and DFS compared with the ETE invasion group (P = 0.15, P = 0.38, respectively). Sharp separation applied on the invaded nerves preserves the visual integrity of the RLN without significantly reducing the DFS (P > 0.05). ETE or ENE to RLN, lymph nodes metastasis (LNM), and T4 stage were independent factors for total recurrence [P = 0.04, hazard ratio (HR), 1.97 (1.04-3.75); P = 0.00, HR, 4.63 (2.24-9.54); P = 0.00, HR, 3.63 (1.94-6.77); P = 0.00, HR, 6.1 (3.24-11.50)]. RLN invasion, both by ETE or ENE, was significantly associated with reduced DFS (P = 0.00; P = 0.00, respectively). CONCLUSIONS: ENE to RLN, while rare, has not previously been well-studied. Our interesting premise and important findings including ENE to RLN has the same poor prognostic impact on recurrence as does invasion of the RLN by ETE and surgical management for the invaded RLN that preserves its visual integrity without compromising DFS. Those novel findings indicate that ENE to RLN could be considered as an additional factor beyond post-operative disease status and risk stratification, and it would be a valuable addition to further individualise treatment/surveillance for PTC.

Neuromonitoring of recurrent laryngeal nerves in thyroid surgery comparative study of visualisation and electrophysiology methods.

Úvod: Poranění zvratného nervu je jedna z nejzávažnějších komplikací chirurgie štítné žlázy, chirurgie příštítných tělísek a chirurgie krčních obratlů. V literatuře se popisuje poranění zevní větve hrtanových nervů jako méně časté. Tato komplikace je natolik vážná, že může vést k invalidizaci hlasových profesionálů (učitelů, herců, zpěváků, profesionálních řečníků a manažerů). Současná klinická praxe je spojena se zvýšeným úsilím o peroperační ochranu funkce zvratných nervů využíváním elektrofyziologické monitorace funkce inervace hrtanu a současné vizualizace zvratných nervů. Metody: Design studie je prospektivní observační. Ze souboru 100 po sobě jdoucích operací byly chirurgy náhodně vytvořeny dvě skupiny: Skupina A - s použitím neuromonitoringu (IONM) a skupina B - identifikace a vizualizace zvratného nervu (NLR) bez IONM. Jeden tým chirurgů byl složen z experta (více než 1000 provedených operací) a začínajícího chirurga (méně než 100 operací) a druhý ze dvou zkušených chirurgů (jeden více než 150 operací a druhý více než 500 operací). Každý tým byl zapojen do operací několikrát v týdnu. Porovnání bylo provedeno statistickými metodami a pomocí indexu poranění zvratného nervu (recurrent nerve injury - IRI). Cílem studie je porovnat incidenci parézy zvratných nervů při využití neuromonitorace (IONM) a využití peroperační vizualizace anatomicky neporaněného nervu dvěma týmy chirurgů. Výsledky: Bylo analyzováno 100 operací, respektive 50 operací ve skupině A a 50 ve skupině B. Skupina A zahrnovala 43 totálních thyreoidektomií a 7 hemithyreoidektomií a byly zjištěny dvě dočasné jednostranné parézy. Skupina A měla IRI=1,075. Skupina B zahrnovala 48 totálních thyreoidektomií a 2 hemithyreoidektomie. V této skupině byly zjištěna také dvě jednostranné dočasné parézy zvratného nervu. Skupina B měla IRI=1,02. Uvedené hodnoty IRI tak charakterizují asymetrické soubory, i tato drobná asymetrie je ve výsledku hodnoty patrna. Celková incidence poranění zvratných nervů v celém souboru operovaných sledovaného roku, ve kterém byl výběr pacientů dle metodiky této práce, byla 1,3 %. V souboru bylo 16 dočasných a 4 permanentní parézy zvratného nervu ve všech případech na jedné straně. Ve sledovaném období nebyla zjištěna ani jediná oboustranná paréza trvalá ani dočasná. Index IRI pro operace štítné žlázy v uvedeném období byl 2,26. Tento soubor byl srovnáván se soubory skupiny A a skupiny B a výsledky nevykazují statisticky významné rozdíly na hladině významnosti 1 % (p=0,01). Závěr: Studie neprokázala statisticky významné rozdíly incidence poranění zvratného nervu (trvalá jednostranná paréza) v závislosti na chirurgické technice bez využití IONM a s využitím IONM prováděných chirurgem s rozdílnou zkušeností v chirurgii štítné žlázy. Studie prokázala, že IONM může pomoci vyrovnat handicap u začínajících a méně zkušených chirurgů a omezit incidenci morbidity zvratného nervu v chirurgii štítné žlázy.

Comprehensive Comparison of Right and Left Recurrent Laryngeal Nerves in the Tracheoesophageal Groove.

OBJECTIVE: A left-sided cervical approach to esophageal mobilization is considered safer given the perceived oblique path and more lateral orientation of the right recurrent laryngeal nerve (RLN) in the tracheoesophageal groove. Given the risk of recurrent laryngeal nerve, the current study investigated if there are differences in right and left RLN location in the tracheoesophageal groove. METHODS: Right and left RLNs were carefully exposed in human cadavers. Comparison of location was determined at tracheal rings 2, 4, and 6 using 3 parameters: depth of the RLN from the anterior margin of the tracheal ring, lateral distance of the RLN from the posterior margin of the tracheal ring, and distance of the RLN to the anterior midline trachea following the curvature of the trachea. Statistical analysis was used to determine differences between the right and left sides. RESULTS: Compared with the right RLN, the left RLN was slightly over 1 mm deeper at the second tracheal ring. Despite this trend, there was no significant difference in RLN location between individual sides or as an aggregate for any of the 3 parameters at tracheal rings 2, 4, or 6. CONCLUSIONS: Careful characterization of RLN location precludes avoiding hoarseness, aphonia, and vocal cord paralysis. Counter to common surgical perception and educational beliefs, this study demonstrated that right and left RLN anatomical courses do not significantly differ along the trachea. Therefore, ensnarement on either side during a blind mobilization of the cervical esophagus is equally likely to occur.

HIF-1α-Mediated, NADPH Oxidase-Derived ROS Contributes to Laryngeal Airway Hyperreactivity Induced by Intermittent Hypoxia in Rats.

Obstructive sleep apnea, similar to intermittent hypoxia (IH) during sleep, is associated with laryngeal airway hyperreactivity (LAH). IH-induced laryngeal oxidative stress may contribute to LAH, but the underlying mechanism remains unknown. Conscious rats were subjected to repetitive 75 s cycles of IH for 7 or 14 consecutive days. Reflex apneic responses to laryngeal provocations with chemical stimulants were measured to reflect laryngeal reflex reactivity. Compared with control rats, rats exposed to IH for 14 days, but not for 7 days, displayed enhanced apneic response to laryngeal chemical stimulants. The apneic response to chemical stimulants, but not to mechanical stimulation, was totally abolished by perineural capsaicin treatment of superior laryngeal nerves (SLNs) or by the sectioning of the SLNs, suggesting that the reflex was mediated through capsaicin-sensitive SLNs. Daily intraperitoneal administration of N-acetyl-L-cysteine [NAC, a reactive oxygen species (ROS) scavenger], apocynin (an inhibitor of NADPH oxidase) or YC-1 (an inhibitor of HIF-1α), but not their vehicles, largely attenuated this augmented apneic response in 14 days IH rats. Laryngeal lipid peroxidation (an index of oxidative stress) was elevated in 7 days IH rats and 14 days IH rats, and was abolished by any of these three pharmacologic interventions. The protein expression of HIF-1α (an index of HIF-1 activation) and p47phox subunit in the membrane fraction (an index of NADPH oxidase activation) in the laryngeal tissues increased in 14 days IH rats; the former was reduced by NAC, whereas the latter was inhibited by YC-1. These results suggest that 14 days of IH exposure may sensitize capsaicin-sensitive SLNs and result in exaggerated apneic reflex response to laryngeal chemical stimulants. This phenomenon depends on the action of HIF-1α-mediated, NADPH oxidase-derived ROS.

Patient Perception of Swallowing after Thyroidectomy in the Absence of Laryngeal Nerve Injury.

INTRODUCTION: Swallowing and voice alterations may manifest in patients with thyroid disease, especially after thyroidectomy. OBJECTIVE: To identify the prevalence of patients with complaints of swallowing disorders after thyroidectomy and to evaluate patients' perceptions regarding swallowing before and after the procedure. METHODS: A prospective longitudinal study was performed with 26 consecutive patients undergoing a private service thyroidectomy, in which the presence of swallowing dysfunction was evaluated using validated questionnaires that addressed the perception of swallowing by patients before (on the day of surgery) and after the surgery (on the first postoperative day). RESULTS: Of the 26 patients, 18 (69.2%) were subjected to total thyroidectomy and 8 to partial thyroidectomy. Analysis of the domains of the Swallowing Handicap Index questionnaire showed higher scores when evaluated on the first postoperative day, demonstrating a significant worsening in swallowing after the procedure. The same result was demonstrated for the final score of swallowing perception, with 15.3 and 30.8% of patients reporting moderate alterations before and after the thyroidectomy, respectively, and 11.5% reporting the alterations as severe. Swallowing and vocal symptoms on the first postoperative day were more prevalent in the procedure than previously mentioned. Eight patients (30.8%) noted swallowing alterations before the procedure, compared with 80.8% (21 cases) after thyroidectomy. CONCLUSION: There was a prevalence of 42.3% in swallowing complaints on the first postoperative day, regardless of the lesion in the laryngeal innervation, and this prevalence was significantly higher than that prior to the procedure.

Intraoperative neuromonitoring by vagus nerve stimulation in thyroid surgery: Clinical assessment of recurrent and superior laryngeal nerves.

Intraoperative neuromonitoring of the laryngeal nerves during thyroidectomy is a reliable method to assess nerve function. After identification of the cricothyroid ligament, a bipolar electrode is selectively inserted through the ligament into the thyroarytenoid muscle (TAM) and cricothyroid muscle (CTM). Vagus nerve stimulation then allows precise monitoring of the recurrent laryngeal nerve and the external branch of the superior laryngeal nerve (EBSLN) in the TAM and CTM, respectively. A significant muscle response (greater than 100µV) is 100% predictive of preserved laryngeal mobility, while the absence of a muscle response is 70% predictive of vocal fold paralysis with 100% sensitivity and 98% specificity. A significant thyroarytenoid muscle response is only recorded ipsilateral to the stimulation with a shorter latency on the right side. A concomitant TAM and CTM response to vagus nerve stimulation or EBSLN stimulation is observed in more than 70% of cases.

Visual and electrophysiological identification of the external branch of superior laryngeal nerve in redo thyroid surgery compared with primary thyroid surgery.

PURPOSE: Thyroid reoperations are surgically challenging because of significant anatomical variance. Visual and functional identification of the external branch of the superior laryngeal nerve (EBSLN) were studied in 2 groups of patients who underwent primary and redo thyroid surgery. METHODS: This study was conducted on 200 patients: 100 patients with redo and 100 patients with primary thyroid surgery. In addition to visual identification, nerve branches were functionally identified by intraoperative nerve monitoring (IONM). Visual, functional, and total identification rates of the EBSLN in both primary and redo surgery were determined and compared between the 2 groups. RESULTS: We attempted to identify 138 and 170 EBSLNs at risk in redo and primary surgery, respectively. Visual identification rates were 65.3% and 30.4% (P < 0.001) in primary and redo surgery groups, respectively. In total, 164 (96.5%) and 97 EBSLNs (70.3%) were identified in primary and redo surgery, respectively (P < 0.001), including the use of IONM. In primary surgery group, 53 nonvisualized EBSLNs of 164 identified nerves (32.3%) were determined by IONM alone. In redo surgery group, 55 of 97 identified nerves (56.7%) were determined by IONM alone (P < 0.001). CONCLUSION: Both visual and total identification rates of the EBSLN are significantly decreased in reoperative thyroidectomy. IONM increases the total identification rate of the EBSLN in primary and redo thyroid surgery. Electrophysiological monitoring makes a substantial contribution to the identification of the EBSLN both in primary and especially in redo thyroid surgery.

Visual and electrophysiological identification of the external branch of superior laryngeal nerve in redo thyroid surgery compared with primary thyroid surgery

PURPOSE: Thyroid reoperations are surgically challenging because of significant anatomical variance. Visual and functional identification of the external branch of the superior laryngeal nerve (EBSLN) were studied in 2 groups of patients who underwent primary and redo thyroid surgery. METHODS: This study was conducted on 200 patients: 100 patients with redo and 100 patients with primary thyroid surgery. In addition to visual identification, nerve branches were functionally identified by intraoperative nerve monitoring (IONM). Visual, functional, and total identification rates of the EBSLN in both primary and redo surgery were determined and compared between the 2 groups. RESULTS: We attempted to identify 138 and 170 EBSLNs at risk in redo and primary surgery, respectively. Visual identification rates were 65.3% and 30.4% (P < 0.001) in primary and redo surgery groups, respectively. In total, 164 (96.5%) and 97 EBSLNs (70.3%) were identified in primary and redo surgery, respectively (P < 0.001), including the use of IONM. In primary surgery group, 53 nonvisualized EBSLNs of 164 identified nerves (32.3%) were determined by IONM alone. In redo surgery group, 55 of 97 identified nerves (56.7%) were determined by IONM alone (P < 0.001). CONCLUSION: Both visual and total identification rates of the EBSLN are significantly decreased in reoperative thyroidectomy. IONM increases the total identification rate of the EBSLN in primary and redo thyroid surgery. Electrophysiological monitoring makes a substantial contribution to the identification of the EBSLN both in primary and especially in redo thyroid surgery.

O tubérculo de Zuckerkandl pode auxiliar na localização do nervo laríngeo inferior durante tireoidectomias? / Can the Zuckerkandl tubercle assist in the location of the inferior laryngeal nerve during thyroidectomies?

RESUMO Objetivo: avaliar se a projeção lateral da glândula tireoide, chamada tubérculo de Zuckerkandl (TZ), pode auxiliar o cirurgião na identificação do nervo laríngeo inferior durante a tireoidectomia convencional aberta. Métodos: estudo prospectivo de 51 pacientes submetidos à tireoidectomia, com um total de 100 lobos tireoidianos ressecados, e observação da presença ou não do TZ em dimensões suficientes para ser identificado sem magnificação de imagem, suas dimensões de base e altura, sua localização na glândula e sua relação anatômica com o nervo laríngeo inferior. Resultados: o TZ estava presente em 68 dos 100 lobos de tireoide analisados (68%). A dimensão média da base foi 6,7mm no lado direito e 7,1mm no lado esquerdo, e a altura média foi 5,7mm no lado direito e 6,1mm no lado esquerdo. Na maioria dos lobos estudados, o tubérculo tinha altura mínima de 5mm (55,9%) sem diferença significativa entre o lobo direito e esquerdo da glândula tireoide. Durante a cirurgia, 100% dos TZ identificados estavam anteriores ao nervo laríngeo inferior, imediatamente abaixo da entrada do nervo na laringe. Conclusão: o TZ é bastante frequente e em dimensões suficientes para ser usado como referência anatômica na localização intraoperatória do nervo laríngeo inferior, próximo à sua entrada na laringe, junto com as demais referências anatômicas.

ABSTRACT Objective: to evaluate whether the lateral projection of the thyroid gland, called Zuckerkandl's tubercle (ZT), can assist the surgeon in identifying the inferior laryngeal nerve during conventional open thyroidectomy. Methods: we conducted a prospective study with 51 patients submitted to thyroidectomy, with a total of 100 resected thyroid lobes, and observed the presence or absence of ZT in sufficient dimensions to be identified without image magnification, its base and height, its location in the gland, and its anatomical relationship with the inferior laryngeal nerve. Results: ZT was present in 68 of the 100 thyroid lobes analyzed (68%). The mean base was 6.7mm on the right side and 7.1mm on the left side, and the average height was 5.7mm on the right side and 6.1mm on the left side. In most of the lobes studied, the tubercle had a minimum height of 5mm (55.9%), with no significant difference between the right and left lobes of the thyroid gland. During surgery, 100% of the identified ZTs were anterior to the inferior laryngeal nerve, just below the nerve entry in the larynx. Conclusion: the ZT is a quite frequent entity and large enough to serve as an intraoperative anatomical reference for the inferior laryngeal nerve, next to its entry in the larynx, along with other anatomical references.

Intraoperative Corticosteroids for Voice Outcomes among Patients Undergoing Thyroidectomy: A Systematic Review and Meta-analysis.

OBJECTIVE: To determine if a preoperative dose of intravenous corticosteroids reduces the risk of postoperative recurrent laryngeal nerve palsy and improves subjective voice outcomes among patients undergoing thyroidectomy. DATA SOURCES: PubMed, Cochrane database, and EMBASE. REVIEW METHODS: Randomized controlled trials comparing corticosteroids with placebo on voice outcomes in thyroid surgery were extracted with standardized search criteria. Systematic review and meta-analysis were performed. With random effects models, trial data were pooled to determine the overall rate of recurrent laryngeal nerve palsy as well as secondary outcomes of adverse events, including wound infection and hyperglycemia. RESULTS: Four studies with a total of 517 patients met inclusion criteria. The overall rate of recurrent laryngeal nerve palsy was 5.78%. There was no difference in the rate of palsy between the corticosteroid and placebo groups (risk ratio, 0.70; 95% CI, 0.34-1.44). There was also no difference between the groups in regard to wound infection, healing, or hyperglycemia. CONCLUSIONS: Preoperative corticosteroids do not appear to reduce the risk of recurrent laryngeal nerve palsy following thyroid surgery. There is insufficient evidence to assess its effect on subjective voice outcomes. More robust randomized controlled trials are needed to assess the effectiveness of perioperative steroids in improving voice outcomes after thyroidectomy.

External laryngeal nerve landmarks revisited.

BACKGROUND: Because external laryngeal nerve (ELN) iatrogenic damage is frequent during neck surgery, its precise localization has been highly recommended. This study analyzes the different surgical landmarks previously proposed and the anatomy of the collateral and terminal branches of the ELN. METHODS: The necks of 157 (77 men and 80 women) human adult embalmed cadavers were examined. The ELN origin, length, and relationship to different landmarks were recorded and results statistically compared with those previously reported. RESULTS: The ELN is located deep to the ascending pharyngeal vein in 100% of patients. In most patients, it crosses the carotid axis at the thyroid artery origin level (47% of patients), passes medial to it (89% of patients), and shows an intramuscular trajectory through the inferior constrictor of the pharynx (80% of patients). CONCLUSION: The ELN position, in relation to classical landmarks, is highly variable. The most reliable relationships are those with the ascending pharyngeal vein or with the superior thyroid artery.