Laryngeal Nerve In Thyroid Surgery Research Articles

Clinical Factors Associated with Difficulty in Identifying the Recurrent Laryngeal Nerve in Thyroid Surgery

Clinical Factors Associated with Difficulty in Identifying the Recurrent Laryngeal Nerve in Thyroid Surgery

Prognostic model of the absence of larynx motility recovery in unilateral lesions of the recurrent laryngeal nerve in thyroid surgery

One of the most serious complications in thyroid surgery is damage to the recurrent laryngeal nerve, which can significantly worsen the patient’s quality of life, so predicting the course of the disease is very important, as it contributes to timely and targeted aid to patients and the determination of optimal treatment tactics.
 Objective — construction of the prognostic model of the absence of larynx motility recovery in unilateral lesions of the recurrent laryngeal nerve in thyroid surgery
 Materials and methods. In the years 2018 — 2021, a prospective single‑center study was conducted at the Ukrainian Scientific and Practical Center of Endocrine Surgery, Transplantation of Endocrine Organs and Tissues of the Ministry of Health of Ukraine. Investigation involved 164 patients after thyroidectomy with unilateral motility disorder of the larynx. The investigated patients are divided into two groups: the main group (n = 33) included patients with unilateral paralysis of larynx (the mean age 49.7 ± 11.1 years), and control group consisted of 131 patients with unilateral paresis of larynx (the mean age 43.2 ± 14.6 years).
 Results. Prognostication of disease was conducted by means of three methodologies. The method of statistical analysis of Wald was conducted taking into account the most meaningful informing laryngoscopy signs with their gradations (9 laryngoscopy signs and 1 sign that is related to age), that were distinguished by us in previous prognostic research. Diagnostic coefficients and information measures of Kullback J of selected features were determined and a special template was developed using the MS Excel program to automate diagnostic analysis. Method of binary logistic regression allows the expectation of dependence of binary initial variable (present/absent paralysis) after influence of factor variables. Three factor signs that remained after recalculation have been investigated. To ensure quick and convenient execution of calculations, a corresponding template has also been created in the MS Excel program. The prognostic express test, which enabled us to build an easy‑to‑use test based on the most significant two predictors and their gradations, which were converted into ranks. A comparison of the occurrence of paresis/paralysis of the larynx was made for different sums of ranks.
 Conclusions. The diagnostic method based on the sequential Wald analysis, despite good performance in the case of a definite result, gave about 25 % indeterminate results and therefore needs further improvement based on a more representative sample. The diagnostic model built using binary logistic regression led to good results, but working with it requires a personal computer and an appropriate template for calculations in the Excel program. The prognostic express test, which is based on the consideration of only two predictors, is convenient, does not require complex calculations and provides an acceptable level of sensitivity and specificity, which can be widely used in the clinical practice of first‑line otorhinolaryngologists for a timely decision on further conservative or surgical treatment.

Injury of the external branch of the superior laryngeal nerve in thyroid surgery

Injury of the external branch of the superior laryngeal nerve is one of the complications in thyroid surgery, the frequency of which varies within very wide limits due to the difficulties in diagnosis. The complaints relate to a change in voice tone, which significantly impairs the quality of life of patients, especially those with voice profession. The most accurate specific method for diagnosis is electroneuromyography but this technique is very difficult to perform and not used in routine practice. To diagnose the lesion of the external branch of superior laryngeal nerve the authors used laryngoscopy, laryngostroboscopy and spectral analysis of the voice, which revealed the frequency of nerve injury and dynamic monitoring of voice recovery in the patient.
 Objective — to examine the frequency of lesions of the external branch of superior laryngeal nerve in thyroid surgery on the basis of changes in the laryngoscopic picture, spectral analysis of the voice and dynamic monitoring of their recovery during treatment
 Materials and methods. The study was conducted in the surgical department of the Ukrainian Scientific and Practical Center for Endocrine Surgery, Transplantation of Endocrine Organs and Tissues MOH of Ukraine with involvement of 241 operated patients. Examination of the larynx and voice examination were performed before surgery, on the 2 — 3 days and 6 and 12 months after surgery. Diagnosis was performed using methods: videolaryngoscopy, videolaryngostroboscopy, spectral analysis of the voice.
 Results. Clinical signs of trauma to the external branch of the superior laryngeal nerve were found in 8 (3.3 %) patients out of 241 operated. Patients received a course of phonopedia and stimulation therapy in the absence of contraindications. Voice recovery over time was recorded in 7 (87.5 %) patients, no voice recovery in 1 (0.4 %).
 Conclusions. Injury of the external branch of superior laryngeal nerve after surgery on the thyroid gland is a complication after thyroid surgery which does not happen often (3.3 %). This complication is very difficult to detect, considering inconspicuous symptoms, the lack of specificity of the laryngoscopic picture and the peculiarities of diagnostic methods. It is not always possible to fully restore the voice when the external branch of the superior laryngeal nerve is damaged (permanent injury accounts for 0.4 % of the total number of operations on the thyroid gland and 85.0 % of the total number of patients with damage to the external branch of the superior laryngeal nerve), which requires dynamic monitoring of patients and timely treatment administration.

Alternative Techniques for Intraoperative Neuromonitoring in Thyroid Surgery

Intraoperative Neuromonitoring (IONM) using endotracheal tube with surface electrodes has gain acceptance as an adjunct tool to preserve the recurrent laryngeal nerve in thyroid surgery. The electromyographic (EMG) tube based IONM has many advantages and is well validated, but it also has some disadvantages. This article is written to review alternative techniques for IONM in thyroid surgery except EMG tube.

Optimization of Intraoperative Neural Monitoring of the Recurrent Laryngeal Nerve in Thyroid Surgery

The application of intraoperative neural monitoring (IONM) has been widely accepted to improve surgical outcomes after thyroid surgery. The malfunction of an IONM system might interfere with surgical procedures. Thus, the development of anesthesia modalities aimed at ensuring functional neuromonitoring is essential. Two key issues should be taken into consideration for anesthetic management. Firstly, most patients undergo recurrent laryngeal nerve monitoring via surface electrodes embedded in an endotracheal tube. Thus, advanced video-assisted devices might optimize surface electrode positioning for improved neuromonitoring signaling accuracy. Secondly, neuromuscular blocking agents are routinely used during thyroid surgery. The ideal neuromuscular block should be deep enough for surgical relaxation at excision and recovered enough for an adequate signal f nerve stimulation. Proper neuromuscular block management could be achieved by titration doses of muscle relaxants and reversal agents.

Predictive indicators of an unfavorable prognosis for the restoration of laryngeal functions in unilateral lesions of the recurrent laryngeal nerve in thyroid surgery

Recurrent laryngeal nerve (RLN) damage in thyroid surgery is a very dangerous complication. An otolaryngologist, especially at pri­mary care institutions,should administer conservative or surgical treatment in a timely manner and depending on the type of nerve damage (transient, permanent), i. e., to analyze possible prognosis of the disease. Only few studies to predict disease developmentin RLN have been performed. One of the most modern and informative methods is laryngeal electromyography using needle electrodes, but despite the sufficient number of patients with this pathology, in most medical institutions in Ukraine it is not performed, given the technical difficulties of implementation, invasiveness and difficulty in interpreting the results of this method.Aim — to analyze the laryngoscopic signs of paresis and paralysis of the larynx in thyroid surgery and to identify the most significant from them, which together can serve as prognostic criteria of the lack of recovery of laryngeal mobility (paralysis).Materials and methods. A single-site prospective study was conducted in the years 2018—2021 that involved 164 patients with postoperative laryngeal movement disorders, who were divided into two groups: subjects with laryngeal paralysis (n = 33) and patients with laryngeal paresis (n = 131). All patients underwent phoniatric examination. The following signs have been identified: general signs, including age, number of operations, scope of surgical intervention, and 18 laryngoscopicsigns, each of them had two to seven grades. For the convenience, the grades were coded with numbers and, if possible, arranged in ascending order of severity. The obtained results were processed with Fisher angular transformation.Results. Among 18 laryngoscopic and general signs, 10main (predictors) were identified, that affect the absence or presence of laryngeal paralysis. They included:elements of mobility of the paralyzed vocal cords (VC) (absent), flotation of the «paralyzed» VC (insignificant and pronounced), mobility of the arytenoid cartilage (absent), closure of the VC (complete non-closure), synchronicity of oscillations VC (absence of movement of the paralyzed VC), restriction of the movement of the «paralyzed» VC (absent (the GE is motionless), level of the VC in the vertical plane (not on the same level), the tension of the median edge of the VC (incurvate), patient’s age > 45 years, the position of the «paralyzed» VC (median and intermedian). The mathematical analysis showed that none of the isolated laryngoscopic signs can be used as an independent criterion in assessing the predictions of the laryngeal mobilityrestoration.Conclusions. Prognostic laryngoscopic signs of recurrent laryngeal nerve damage in the thyroid surgery allow to create a prognostic model of recovery or lack of recovery of laryngeal motility, which is important for the appointment of timely adequate treatment.

Identification of recurrent laryngeal nerve: a dilemma in thyroid surgery

<p class="abstract"><strong>Background: </strong>Surgery of the thyroid gland is one of the most common surgical procedures performed. Recurrent laryngeal nerve injury is the most dreaded complication of thyroid surgery. Hence reducing intraoperative injury is of utmost importance. Routine dissection and identification of the recurrent nerve remain controversial.</p><p class="abstract"><strong>Methods:</strong> This study consists of 70 patients who underwent thyroid surgery. This study was conducted at our institute during the period of 2 years (2018-2020). Patients were evaluated and operated. Patients with thyroid diseases and normal vocal cords were allocated to two groups randomly; in group A the nerve was identified and in group B the nerve was not identified.</p><p class="abstract">Results: Most of the patients participating in the study were in the age group of 33-42 years. Male to female disease ratio was 0.13:1. In our study out of 70 patients who underwent thyroid surgery, 18 (25.71%) patients suffered from recurrent laryngeal nerve palsy. Amongst those 18 patients, 2 palsies (5.71%) were in Group A and 16 palsies (45.71%) were in Group B. Recurrent laryngeal nerve most commonly lied posterior to the inferior thyroid artery on both right (65.38%) as well as left side (45.45%). Most commonly injured recurrent laryngeal nerve was the right sided recurrent laryngeal nerve (77.77%).</p><p class="abstract"><strong>Conclusions:</strong> Careful dissection of nerve during thyroid surgery eliminates the risk of recurrent laryngeal nerve injury. A thorough knowledge of thyroid gland, recurrent laryngeal nerve and its anatomical relations and variations is of utmost importance in preserving the recurrent laryngeal nerve in thyroid surgery.</p>

Visual identification and neuromonitoring vs. no sighting the external branch of the superior laryngeal nerve in thyroid surgery: a randomized clinical trial.

To evaluate the incidence of external branch of the superior laryngeal nerve (EBSLN) injuries after thyroid surgical procedures with or without the functional and visual identification of the EBSLN before ligation at the superior thyroid pole. Patients with papillary thyroid carcinoma (PTC) enrolled from a single tertiary referral academic medical center were assigned to functional and visual identification of EBSLN group (study group) or no identification of EBSLN group (controlled group). The main outcome measures were the incidence of EBSLN injury detected by the intraoperative neuromonitoring and Voice Handicap Index-10 (VHI-10) and Impairment Index-5 (VII-5) valuation questionnaires. Postoperative complications were recorded. A total of 140 (50.4%) patients were enrolled in study group and 138 (49.6%) in controlled group. In the study group, 110 (39.3%) EBSLNs were direct visual recognized and 170 (60.7%) nerves were visually identified with the help of neuromonitoring. Three patients in the study group and two patients in the controlled group were diagnosed with vocal cord paralysis. Six (4.4%) patients in the identification group and 37 (27.2%) patients in the no identification group presented no response from the stimulation of sternothyroid-laryngeal triangle. The VII-5 scores of the study group were significantly higher than those of the controlled group at one and three months postoperatively (P = 0.024 and P = 0.034). With significant lower scores of VII-5 and VHI-10, functional and visual identification of EBSLN might be necessary during thyroid surgery to protect the structural integrity and motor activity of the nerve.

Immediate Intraoperative Repair of the Recurrent Laryngeal Nerve in Thyroid Surgery.

Recurrent laryngeal nerve (RLN) injury is a recognized risk during thyroid and parathyroid surgery and can result in significant morbidity. The aim of this review paper is to consider the optimal approach to the immediate intraoperative repair of the RLN during thyroid surgery. A PubMed literature search was performed from inception to June 2020 using the following search strategy: immediate repair or repair recurrent laryngeal nerve, repair or reinnervation recurrent laryngeal nerve and immediate neurorraphy or neurorraphy recurrent laryngeal nerve. Methods of immediate intraoperative repair of the RLN include direct end-to-end anastomosis, free nerve graft anastomosis, ansa cervicalis to RLN anastomosis, vagus to RLN anastomosis, and primary interposition graft. Techniques of nerve repair include micro-suturing, use of fibrin glue, and nerve grafting. Direct micro-suture is preferable when the defect can be repaired without tension. Fibrin glue has also been proposed for nerve repair but has been criticized for its toxicity, excessive slow reabsorption, and the risk of inflammatory reaction in the peripheral tissues. When the proximal stump of the RLN cannot be used, grafting could be done using transverse cervical nerve, supraclavicular nerve, vagus nerve, or ansa cervicalis. Current evidence is low-level; however, it suggests that when the RLN has been severed, avulsed, or sacrificed during thyroid surgery it should be repaired intraoperatively. The immediate repair has on balance more advantages than disadvantages and should be considered whenever possible. This should enable the maintenance of vocal cord tone, better and prompter voice recovery and avoidance of aspiration. Laryngoscope, 131:1429-1435, 2021.

Duplication of recurrent laryngeal nerve in thyroid surgery – a rare anatomical variation

A single recurrent laryngeal nerve on each side is a constant finding in all thyroid surgery. It is crucial to preserve the function of vocal cord during thyroid surgery by identifying the course of the nerve. But anatomical variations of the nerve may be encountered which increases the likelihood of iatrogenic injury. We here in report two cases of duplication of recurrent laryngeal nerve and its surgical importance. Keywords: Reccurent laryngeal nerve (RLN), Thyroidectomy, Duplication.

A prospective study: Zuckerkandl tubercle an important anatomical landmark in identification of recurrent laryngeal nerve in thyroid surgery

Introduction: The Zuckerkandl tubercle (ZT) is an anatomic landmark that can be used for the identification of the RLN intra-operatively. A prospective study was carried out on patients who underwent thyroidectomies, from September 2016. All cases were admitted from Surgery and ENT Outpatient department. The cases were studied according to proforma. Written informed consent was taken Conclusion: Zuckerkandl's tubercle which is defined as posterior exterior of lateral lobes of the thyroid gland is a common anatomical structure found in the majority of cases. Excision of the tubercle requires fine and meticulous dissection with great case because of close relationship between ZT and RLN. Identification of ZT, an understanding of the relationship between the ZT and RLN and isolation of the nerve before dissection of ZT are essential for performing safe thyroid surgery.

Anatomical Variations in Recurrent Laryngeal Nerves in Thyroid Surgery.

To study terminal bifurcation of recurrent laryngeal nerves (RLNs) with original direction to larynx entry and to decrease the risk of vocal cord paralysis in thyroid patients. The RLNs of 294 patients (482 sides) were dissected according to the branches into the larynx, and the original direction of each RLN trunk in thyroid surgery was recorded. (1) About 30.9% of the RLNs gave off multiple branches into the larynx. (2) Two and 3 branches of RLNs into the larynx were found in 25.5% and 5.4% of the cases, respectively. (3) In 0.4% or 2 cases, the RLN trunk combined with the inferior branch of the vagus nerve. (4) Nonrecurrent laryngeal nerve appeared in 2 cases. (5) On the left side, 68.0%, 25.6%, and 6.4% of cases were found with 1, 2, and 3 bifurcations of RLN to larynx entry, respectively. On the right side, 69.8%, 25.8%, and 4.4% cases were identified with 1, 2, and 3 bifurcations of RLN to larynx entry, respectively. (6) The combining dissection approach was proved as successful and safe for protecting the RLN with no permanent RLN paresis. Because of the anatomical variation in RLNs with extralaryngeal bifurcation, it is necessary to increase the awareness of surgeons about these variations so as to protect bifurcated nerves in thyroid surgery.

Trans-thyroid cartilage recording for neural monitoring of the recurrent laryngeal nerve in thyroid surgery.

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Intraoperative Neuromonitoring of the laryngeal nerves in thyroid surgery

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Nonrecurrent laryngeal nerve in thyroid surgery: Frequency, anatomical variations according to a new classification and surgery consideration.

The nonrecurrent laryngeal nerve (NRLN) is a rare embryologically derived variant of the RLN. We aimed to identify the proportion of NRLN (during thyroidectomy), classify clinical NRLN types, and recommend some surgical considerations. In this prospective study, from May 2017 to September 2018, our hospital carried out 2158 thyroid operations. We reported the NRLN rate and distinguished NRLN into four types. Overall, NRLN had an incidence rate of 0.74% (16 out of 2158 total thyroid surgeries). We did not detect any patient with left-sided NRLN. The traveling patterns of the nerves could be classified as descending (12.5%), vertical (25%), ascending (37.5%), or V-shaped (25%). The NRLN is a rare variation of the RLN. From our experience, we recommend the guidelines will help surgeons to avoid NRLN injury.

WITHDRAWN: Non-recurrent laryngeal nerve in thyroid surgery: Frequency, anatomical variations according to a new classification and surgery consideration

WITHDRAWN: Non-recurrent laryngeal nerve in thyroid surgery: Frequency, anatomical variations according to a new classification and surgery consideration

The evolution and progress of studies of the anatomy & electrophysiology of the laryngeal nerves in thyroid surgery

Thyroid surgery has always been closely involved with the recurrent laryngeal nerve (RLN) and the external branch of the superior laryngeal nerve (EBSLN). The goal of thyroid surgery is to remove all pathological thyroid tissue while preserving the parathyroid glands and both laryngeal nerves to ensure patients the highest quality of life after the operation. The goal of this paper was to assess the evolution and progress of studies of the anatomy & electrophysiology of the laryngeal nerves in thyroid surgery. Our knowledge of the anatomy and electrophysiology of laryngeal nerves in relation to thyroid operations has evolved over the centuries from visual RLN identification to the functional RLN identification with intraoperative neural monitoring (IONM). The progress in RLN identification has changed the surgical technic, surgical strategy in order to minimize the rate of complications. Now the thyroid surgery is safe procedure with the high quality of voice after this operation.

The evolution and progress of intraoperative monitoring of the external branch of the superior laryngeal nerve in thyroid surgery

Hypoparathyroidism and recurrent laryngeal nerve (RLN) damage are the most frequent reported morbidity in thyroid surgery whereas damage of the external branch of the superior laryngeal nerve (EBSLN) has been considered to be the most neglected sequel. EBSLN injury results in subtle changes in voice as a result of dysfunction of the cricothyroid muscle (CTM): changed basic voice frequency, deterioration of voice quality in the production of high frequency sounds and reduced voice projection. Symptoms of this dysfunction are usually more notable for professional voice users and can be difficult to diagnose. EBSLN injury can happen during dissection of the vessels of the upper thyroid pole due to proximity between the nerve and these vessels. Several maneuvers can minimize the risk of injury to the EBSLN including visual identification of the nerve before ligation of the upper thyroid pole vessels and use of either a nerve stimulator or intraoperative neuromonitoring (IONM) for neuromapping and evidence of the EBSLN identification. The EBSLN monitoring is relied on evaluation of CTM twitch (present in all patients) and electromyographic curve traced by the monitor using surface tube electrodes within the vocal folds which present in the majority but not all individuals (70–80% of patients using standard EMG tubes) or approaching to 100% of patients (using NIM TriVantage tubes). IONM has a potential to increase the rate of the EBSLNs identification, diminish prevalence of neural damage, and decrease prevalence of postoperative voice impairment which has been repeatedly supported by recently published data. It is advised that at the end of upper thyroid lobe dissection the EBSLN should be stimulated at the most cranial arc of dissection to confirm not only anatomical but what is even more important functional preservation of intact neural function.

Monitoring the external branch of the superior laryngeal nerve in thyroid surgery

The superior laryngeal nerve (SLN) is a division of the vagal nerve (VN). It derives from the inferior ganglion of VN (1,2).

Non-recurrent laryngeal nerve in thyroid surgery: A report of case series in Vietnam and literature review

IntroductionThe non-recurrent laryngeal nerve (NRLN), which is found in 0.25–0.99 of the patients who undergo thyroid surgery, is a rare embryologically-derived variant of the recurrent laryngeal nerve (RLN). Identification and prevention of injury to the laryngeal nerve is one of the main issues in thyroid surgery; thus, thyroid surgeons should have adequate knowledge of all anatomical variations of the RLN. Presentation of casesAll four patients with the non-recurrent laryngeal nerve on the right side were performed thyroidectomy and discharged without any complications. During the procedure the surgeons found that the right laryngeal nerve was not recurrent and originated directly from the vagus nerve. Moreover, the right subclavian artery of these patients arose directly from the aortic arch. DiscussionNRLN can be easily damaged during surgery and its presence is closely related to subclavian artery anomaly. There are 2 types of NRLN in terms of its origin, nonetheless, in all variations of the NRLN and RLN, the nerve travels to the larynx at the level of cricothyroid joint, close to berry ligament. ConclusionThe NRLN is a rare, but clinically relevant structure and is associated to an increased risk in iatrogenic injury. Thorough anatomical knowledge and cautious dissection are essential to identify variants of RLN in order to minimize the risk of injury to the patient. Additionally, in embryological terms, the presence of NRLN is closely related to subclavian artery anomaly.