A Novel Surgical Landmark to Identify the Recurrent Laryngeal Nerve

Background: Although several surgical landmarks have been proposed to localize the recurrent laryngeal nerve (RLN), there is still no reliable landmark. Aims: To validate the reliability of a novel reference point at the intersection of the inferior border of the cricopharyngeal muscle and the inferior cornu of thyroid cartilage for locating the RLN. Study Design: Cadaver dissection study in the academic department of otolaryngology-head and neck surgery. Methods: Sixty-four RLNs in cadavers were assessed, and measurements of different surgical landmarks in conjunction with the proposed surgical landmark were obtained. Descriptive statistics, Pearson's chi-squared test, and Student's t-test were performed to analyze the data using GraphPad Prism (version 9.4.1; Dotmatics, Boston, Massachusetts, USA). Results: The average distance from the proposed landmark to the RLN was 2.3 ± 0.85 mm. The RLN was located just posterior to the reference point in 95.31% of the cadavers. The RLN passed under the inferior constrictor muscle in 90.63% of the cadavers. There was no statistically significant difference between right- and left-sided RLNs in terms of their relation with the reference point. Conclusion: The proposed reference point can be used as a reliable landmark to locate the RLN. This reference point may help surgeons during difficult thyroidectomy surgeries by providing an additional anatomical landmark.

Left non-recurrent inferior laryngeal nerve in a patient with right-sided aortic arch and aberrant left subclavian artery.

Non-recurrent inferior laryngeal nerve (NRILN) is rare but one of the important anatomical variations in thyroid and parathyroid surgery. Almost all cases were observed on the right side with aberrant right subclavian artery and left NRILN have been reported in only five cases so far. Here, we reported a 38 year-old Japanese male with left NRILN accompanying adenomatous goiter. He was referred to our hospital for the surgical treatment of left thyroid goiter. Preoperative computed tomography revealed right-sided aortic arch and aberrant left subclavian artery with no signs of complete situs inversus viscerum, suggesting possible left NRLN. Left hemithyroidectomy was performed using nerve monitoring system. Intraoperatively, left recurrent laryngeal nerve was not identified along tracheoesophageal groove, but directly originated from vagal nerve and was running horizontally to larynx. Mobility of vocal cords were not impaired and postoperative course was uneventful. During thyroid surgery for the patients with right-sided aortic arch, meticulous care should be taken using nerve monitoring system to avoid nerve injury.

Intraoperative Neurological Monitoring During Neck Dissection for Esophageal Cancer With Aberrant Subclavian Artery.

We report a case of esophageal cancer with a non-recurrent inferior laryngeal nerve associated with aberrant right subclavian artery that was treated by neck dissection using intraoperative neurological monitoring followed by thoracoscopic esophagectomy. A 76-year-old man had dysphagia. Endoscopy revealed thoracic esophageal cancer, and computed tomography revealed the presence of an aberrant right subclavian artery between the esophagus and vertebrae. We performed neck dissection followed by thoracoscopic esophagectomy. During the neck dissection, we confirmed a non-recurrent inferior laryngeal nerve through intraoperative neurological monitoring. No postoperative complications were observed, and the patient was discharged 19 days after surgery. We recommend using intraoperative neurological monitoring to avoid injury to the non-recurrent inferior laryngeal nerve associated with the aberrant right subclavian artery.

Diverse Anatomical Configuration Of Recurrent Laryngeal Nerve In Relation To Inferior Thyroid Artery, An Experience With 51 Thyroidectomies.

BACKGROUND: Objective of the study is to elaborate the anatomical variants of recurrent laryngeal nerve in relation to inferior thyroid artery, encountered during thyroidectomy operation. It is descriptive, case series, conducted at the Department of Ear Nose & Throat, Combined Military Hospital, Abbottabad. The study was conducted from January 2016 to September 2017. METHODS: Fifty-one patients underwent extra-capsular thyroidectomy in general anaesthesia. The dissection was carried out in a standard way in all patients. Recurrent laryngeal nerves were identified and exposed in every patient, and their anatomical relations were recorded in database. RESULTS: Recurrent laryngeal nerve was seen over riding the ramification of inferior thyroid artery in majority of left sided dissected specimen, however on the right side the principal nerve was found to be ascending through the branches of inferior thyroid artery.. CONCLUSIONS: Iatrogenic vocal cord paralysis has sinister implication on quality of life of the patient undergoing thyroidectomy. Anatomic variants of recurrent laryngeal nerve are well known and frequent. The disastrous outcome of inadvertent recurrent laryngeal nerve trauma can be adequately prevented by thoroughly knowing its anatomical variants, and intra-operatively identifying and exposing the principal nerves.

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

BACKGROUND: 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. METHOD: 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. RESULTS: 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%). CONCLUSION: The NRLN is a rare variation of the RLN. From our experience, we recommend the guidelines will help surgeons to avoid NRLN injury.

Prevalence of the right nonrecurrent inferior laryngeal nerve in a series of 100 total thyroidectomies / Prevalencia del nervio laríngeo inferior derecho no recurrente en una serie de 100 tiroidectomías totales

SUMMARY: The right nonrecurrent inferior laryngeal nerve (NRILN) is a rare occurrence generally associated with an aberrant right subclavian artery. Its prevalence ranges from 0.3 to 1.8 %. It is found mainly in thyroid surgeries, the most frequently performed cervical surgeries. This neural anomaly is almost never diagnosed preoperatively. Dysphagia may be a warning symptom, sometimes being incorrectly related to esophageal compression due to a goiter or thyroid cancer. The postoperative diagnosis of an accompanying aberrant right subclavian artery should be done to confirm the clinical picture and inform the patient of any possible future medical/ surgical procedures. The aim of this work is to determine the prevalence of the NRILN in patients undergoing total thyroidectomy in two reference centers for head and neck surgery in Paraguay. Prospective cross-sectional study in a series of 100 consecutive total thyroidectomies in the INCAN and the ORL Service in the Hospital Central of the IPS. 100 patients underwent a total thyroidectomy, 90 of whom were women. The average age was 47 years. 6 % also underwent a neck dissection for thyroid cancer. The preoperative diagnosis was multinodular goiter (MNG) in 84 cases and thyroid cancer in the remaining 16 (16 %). In one man aged 47 years (1 %) operated on for MNG and presenting slight to solid dysphagia, there was difficulty finding the right NRILN. It was located at the level of the lower edge of the inferior pharyngeal constrictor and its downward anomalous course was proven. Postoperatively, after confirmation of the diagnosis that the thyroid pathology was benign, a color echo-Doppler and a CT angiography corroborated the diagnosis of an associated aberrant right subclavian artery. Given the difficulty in locating the recurrent inferior laryngeal nerve in thyroid surgery, it is advisable to consider the possibility that it may be nonrecurrent and should be looked for at the level of its entrance to the larynx below the inferior constrictor. In such cases it is recommended that the patient be examined postoperatively to rule out an associated vascular anomaly. A tomography study of each patient with a thyroid pathology and dysphagia could contribute to the diagnosis of the vascular anomaly and maximize precautions in the nerve dissection, including use of a neurostimulator. The NRILN is a rare entity. In this case study, it represents 1 % of the patients operated on for thyroid pathology in the INCAN and IPS in a 1-year period (July 2016 - June 2017).

RESUMEN: El nervio laríngeo inferior no recurrente (NLINR) del lado derecho es una entidad rara asociada generalmente a una arteria lusoria. Su prevalencia oscila entre el 0,3 al 1,8 %. Su hallazgo se da sobre todo en cirugías tiroideas, al ser éstas las cirugías cervicales más frecuentemente realizadas. El diagnóstico preoperatorio de esta anomalía nerviosa es realizado en contadas ocasiones. La disfagia puede ser un síntoma de alerta ante esta situación, siendo a veces erróneamente relacionada con la compresión esofágica por un bocio o cáncer tiroideo. El diagnóstico postoperatorio de arteria lusoria acompañante debería realizarse para certificar el cuadro e informar al paciente ante eventuales procedimientos médico-quirúrgicos futuros. El objetivo de este trabajo consisitó en determinar la prevalencia del nervio laríngeo inferior no recurrente en los pacientes operados de tiroidectomía total en dos centros de referencia en cirugía de cabeza y cuello del Paraguay.Estudio prospectivo de corte transversal en una serie de 100 tiroidectomías totales consecutivas, operados en el INCAN y el Servicio de ORL del Hospital Central del IPS. Fueron sometidos a tiroidectomía total 100 pacientes, de los cuales 90 fueron del sexo femenino. La edad promedio fue de 47años. En 6% se realizó además vaciamiento cervical por cáncer de tiroides. El diagnóstico preoperatorio fue bocio multinodular (BMN) en 84 casos y cáncer de tiroides en los restantes 16 (16%). En un varón de 47 años, (1%) operado por bocio multinodular, y que refería disfagia leve a sólidos, se tuvo dificultad para encontrar al nervio laríngeo inferior derecho. Siendo el mismo localizado a nivel del margen inferir del constrictor inferior de la faringe y comprobándose su trayecto anómalo descendente. En el postoperatorio, una vez confirmado el diagnóstico de benignidad de la patlogía tiroidea, se realizó un ecodoppler color y una angiotomografía que corroboraron el diagnóstico de arteria lusoria asociada. Ante la dificultad en localizar al nervio laríngeo inferior recurrente en una cirugía tiroidea, es conveniente considerar la posibilidad de que el mismo sea no recurrente e ir a buscarlo a nivel de su ingreso a la laringe por debajo del constrictor inferior. En estos casos conviene estudiar al paciente en el postoperatorio para descartar una anomalía vascular asociada. El estudio tomográfico en todo paciente portador de patología tirroidea y disfagia podría contribuir al diagnóstico de la anomalía vascular y extremar los recaudos en la disección del nervio, incluso utilizando el neuroestimulador. El NLINR es una entidad rara. En esta casuística representa el 1 % de los pacientes operados por patología tiroidea en el INCAN e IPS en el periodo de 1 año (julio 2016/ junio 2017).

Intrathyroidal carotid artery and nonrecurring right recurrent laryngeal nerve: A case report.

BACKGROUND: When performing thyroidectomy, knowledge of normal anatomy and variants is vital to avoid injuring nearby structures. Typically, the bilateral carotids course posterolateral to the thyroid gland. We describe a rare variant of an intrathyroidal carotid artery, not previously described in the literature. METHODS: A 23-year-old woman with a strong family history of thyroid cancer presented with a left thyroid nodule, and a fine-needle aspiration biopsy revealing papillary thyroid carcinoma. She underwent total thyroidectomy. RESULTS: Intraoperatively, the carotid was found coursing centrally through the right lobe parenchyma, associated with an ipsilateral nonrecurrent recurrent laryngeal nerve (NRLN) entering the cricothyroid joint superolaterally. CONCLUSION: This is, to our knowledge, the first report of such an anatomic variant in the medical literature. Aberrant carotid artery anatomy may potentially cause life-threatening surgical complications and should be considered preoperatively. Furthermore, recognition of concurrent recurrent laryngeal nerve (RLN) anomalies with vascular variations allows identification of nonrecurrent nerves.

Aberrant right subclavian artery ("arteria lusoria") without the known associated nerve anomaly: an "anomaly of the anomaly"? A clinical case and review of the literature.

The "non-recurrent" course of the inferior laryngeal nerve (ILN) is an anatomical variant which must be borne in mind during thyroid surgery. The "non-recurrent" course of the ILN on the right side is associated with the aberrant right subclavian artery (arteria lusoria), and, on the left, is described in situs viscerum inversus. We present a case in which the "arteria lusoria" was not associated with the non-recurrent right ILN. The aims of this paper are to report this "anomaly of the anomaly" to surgeons who may be unaware of it on the one hand and on the other to emphasize that this is the only case so far reported in the literature. Moreover we proposed to explain embryologically these unexpected findings.

Non-recurrent laryngeal nerve with a coexisting contralateral nerve demonstrating extralaryngeal branching.

Non-recurrence and extralaryngeal branching are 2 of the more frequently encountered anomalies of the recurrent laryngeal nerve. If not anticipated intraoperatively, these abnormalities can put the nerve at risk, with subsequent vocal cord palsy. It is therefore important to report on and understand these abnormalities. We present a unique case of a non-recurrent laryngeal nerve with a coexisting contralateral nerve demonstrating extralaryngeal branching. This case allows us to demonstrate the importance of arteria lusoria in head and neck surgery, and to conclude that non-recurrence and extralaryngeal branching can occur separately within individual nerves in the same patient. The case also highlights the importance of a systematic intraoperative approach to the identification of every recurrent laryngeal nerve, especially in bilateral procedures having already exposed an anomalous nerve on one side.

Preoperative computed tomography diagnosis of non-recurrent laryngeal nerve in patients with esophageal carcinoma.

BACKGROUND: The non-recurrent laryngeal nerve (NRLN) is a rare but potentially serious anomaly that is commonly associated with the aberrant right subclavian artery (ARSA). It is easy to damage during surgical resection of esophageal cancer, leading to severe complications. METHODS: Preoperative enhanced thoracic computed tomography (CT) scans of 2697 patients with esophageal carcinoma treated in our hospital between January 2010 and December 2013 were examined. We classified the positional relationship between the right subclavian artery and the membranous wall of the trachea into two types and used this method to predicate NRLN by identifying ARSA. RESULTS: Twenty-six patients (0.96%) were identified with ARSA, all of which were cases of NRLN by CT. NRLN was identified during surgery in the 26 patients, and a normal right recurrent laryngeal nerve was observed in 2671 patients. The ARSA was detected on the dorsal side of the membranous wall of the trachea in all 26 NRLN cases, while it was detected on the ventral side in all 2671 recurrent laryngeal nerve cases. CONCLUSION: Enhanced CT scanning is a reliable method for predicting NRLN by identifying ARSA. Preoperative recognition of this nerve anomaly allows surgeons to avoid damaging the nerve and abnormal vessels during esophagectomy.

The right-sided aortic arch with unusual course of bilateral recurrent laryngeal nerves: a report of rare variations.

We describe a rare case of the right-sided aortic arch, the unusual origin of the main arterial vessels and the unusual courses of bilateral recurrent laryngeal nerves in a Japanese cadaver. Chiefly, the right-sided aortic arch turned to the left side from the dorsal part of the trachea and esophagus, and Kommerell's diverticulum was found at the end of the arch. The right common carotid artery arose from the end part of the ascending aorta, but the left common carotid artery arose from the proximal portion of the ascending aorta. The right subclavian artery arose from the upper edge of the aortic arch, but the left one arose from the front wall at the upper side of the ligamentum arteriosum. The right recurrent laryngeal nerve hooked around the aortic arch (but not the right subclavian artery) dorsoventrally, and the left recurrent laryngeal nerve hooked around the ligamentum arteriosum and arose from the ventral side (but not dorsal) of the aortic arch. These variations are very rare, and understanding them is useful and important for clinical research.

Electrophysiological identification of nonrecurrent laryngeal nerves.

OBJECTIVES/HYPOTHESIS: The nonrecurrent laryngeal nerve (NRLN) is a common anatomic variation of the right recurrent laryngeal nerve (RLN), which has been associated with an increased risk of injury during thyroid and parathyroid surgery. We suggest that early successful identification using intraoperative nerve monitoring (IONM) and preservation of this variant will help the surgeon to avoid injury to this nerve. Our objective was to examine the electrophysiological parameters of the NRLN and the efficacy of IONM for successful identification of the NRLN. STUDY DESIGN: Retrospective database analysis. METHODS: This is a retrospective study of a prospectively collected database of all patients who underwent thyroid and parathyroid surgeries by a single surgeon at a tertiary care center over 3 years (n = 481). Patients' demographic data and operative reports, including the IONM reports, were reviewed. Average stimulation thresholds with resulting amplitudes and latencies were compared. Preoperative and postoperative laryngoscopy were performed in all cases. RESULTS: We identified 15 NRLNs (2.2%) in a total 682 laryngeal nerves. No left-sided NRLNs were observed. The average right vagus latency in the NRLN group was shorter than that of the RLN group (2.40 ms ± 0.49 ms vs. 3.43 ms ± 1.03 ms; P < .001). No statistically significant difference was observed between the initial amplitudes of the right vagus nerves in the two groups (713.67 µV ± 208.71 µV vs. 816.22 µV ± 470.45 µV; P = .14). All NRLN cases exhibited normal functioning of vocal cords on postoperative laryngoscopy. CONCLUSIONS: IONM is highly effective in the identification of the NRLN. Right vagus nerve latency in the NRLN group was found to be significantly shorter than in the RLN group. Early identification of the NRLN allowed cautious preservation of the NRLN, resulting in excellent postoperative outcomes. The rate of NRLN identification may be improved by routine use of IONM. LEVEL OF EVIDENCE: 4 Laryngoscope, 127:2189-2193, 2017.

Extralaryngeal branching of the recurrent laryngeal nerve: a meta-analysis of 28,387 nerves.

INTRODUCTION: The recurrent laryngeal nerves (RLN) are branches of the vagus nerve that go on to innervate most of the intrinsic muscles of the larynx. Historically, the RLN has been considered to branch after it enters the larynx, but numerous studies have demonstrated that it often branches before. The wide variability of this extralaryngeal branching (ELB) has significant implications for the risk of iatrogenic injury. We aimed to assess the anatomical characteristics of ELB comprehensively. METHODS: Articles on the ELB of the RLN were identified by a comprehensive database search. Relevant data were extracted and pooled into a meta-analysis of the prevalence of branching, branching pattern, distance of ELB point from the larynx, and presence of positive motor signals in anterior and posterior ELB branches. RESULTS: A total of 69 articles (n = 28,387 nerves) from both intraoperative and cadaveric modalities were included in the meta-analysis. The overall pooled prevalence of ELB was 60.0 % (95 % CI 52.0-67.7). Cadaveric and intraoperative subgroups differed with prevalence rates of 73.3 % (95 % CI 61.0-84.0) and 39.2 % (95 % CI 29.0-49.9), respectively. Cadavers most often presented with a ELB pattern of bifurcation, with a prevalence of 61.1 %, followed by no branching at 23.4 %. Branching of the RLN occurred most often at a distance of 1-2 cm (74.8 % of cases) prior to entering the larynx. A positive motor signal was most often noted in anterior RLN branches (99.9 %) but only in 1.5 % of posterior branches. CONCLUSIONS: The anatomy of the RLN is highly variable, and ELB is likely to have been underreported in intraoperative studies. Because of its high likelihood, the possibility of ELB needs to be assessed in patients to prevent iatrogenic injury and long-term postoperative complications.

Aberrant position of nonrecurrent inferior laryngeal nerve: Report of 3 cases and a review of the literature.

The presence of a nonrecurrent inferior laryngeal nerve (NRILN) is a significant risk factor for nerve injury during thyroid, parathyroid, and vascular surgeries involving the paratracheal area of the head and neck. The objective of this report is to review the association between an aberrant right subclavian artery (SCA) identified on preoperative imaging and an NRILN identified intraoperatively during thyroid and parathyroid surgery. We reviewed 3 selected cases in which we preoperatively identified an aberrant right SCA and determined the intraoperative position of the inferior laryngeal nerve on the right. It is important to note that 1 of these cases demonstrated that the inferior laryngeal nerve may be found in its normal anatomic position, coursing inferiorly through the tracheoesophageal groove. This anatomic finding is unexpected in a patient with a preoperatively identified aberrant right SCA. We also performed a literature review of more than 250 cases to investigate the association between an intraoperative finding of NRILN and vascular anomalies on imaging. We found 5 reported cases that involved an aberrant right SCA, predictive of NRILN, with the nerve identified in the tracheoesophageal groove.

Efficient, effective, safe procedure to identify nonrecurrent inferior laryngeal nerve during thyroid surgery.

BACKGROUND: The nonrecurrent inferior laryngeal nerve (NRILN) is always associated with the aberrant subclavian artery. CT images can detect this vascular anomaly, which predicts an NRILN. The purpose of this study was to report our procedure to identify the NRILN in patients with the aberrant subclavian artery. METHODS: Four of 730 patients undergoing thyroid operation in our hospital were preoperatively diagnosed with aberrant subclavian artery by CT of the neck. To avoid vocal cord paralysis, we approached the vagal nerve first before dissecting the paratracheal region to discover the separation point of the NRILN from the vagal nerve. RESULTS: The NRILN was identified without difficulty in all 4 patients. No patients showed vocal cord paralysis. CONCLUSION: Approaching the vagal nerve first before dissecting the paratracheal region is an efficient, effective, and safe procedure to identify an NRILN in patients who are preoperatively diagnosed as having the aberrant subclavian artery.

Retroesophageal right subclavian artery: a case report and review of the literature.

BACKGROUND: Variations of vessels arising from the aortic arch are numerous. One of the common anatomical variations is the right subclavian artery originating as the last branch of the aortic arch. This is a report of a case of an adult male cadaver with a retroesophageal right subclavian artery. OBJECTIVE: To highlight the significance of a retroesophageal right subclavian artery, especially its clinical and surgical implications. METHOD: Is a report of a case of an anomalous vessel found during routine student dissection of the chest region in a male cadaver. RESULT: The retroesophageal subclavian artery was seen originating as the last branch from the postero-lateral aspect of the thoracic aorta at the vertebral level T4. The heart was normal with no other vascular variations seen in this region. CONCLUSION: Anatomists and pathologists mainly encounter a retroesophageal right subclavian artery by chance and is usually described as asymptomatic, but several clinical conditions have been associated with its occurrence. This is a clear example of when knowledge of an anatomical variation is helpful in clinical practice.

Medially placed vagus nerve in relation to common carotid artery: a pointer to a non-recurrent laryngeal nerve.

The aim of this study was to highlight a medialized vagus in relation to common carotid artery as an operative marker to a non-recurrent laryngeal nerve during thyroid surgeries. Three patients who underwent thyroidectomy, in who per operative diagnosis of right non-recurrent laryngeal nerve was made and the findings were confirmed radiologically by demonstration of aberrant subclavian artery were included in the study. A medially placed vagus nerve in relation to common carotid artery was the common observation in all the 3 patients. With no operative marker to identify a non-recurrent laryngeal nerve, it is more prone to injury during thyroidectomies. Vagus nerve which was constantly seen medial to the common carotid artery in all our three patients can be used as an operative marker to a non-recurrent laryngeal nerve.

Thyroid surgery in children and adolescents: a series of 65 cases.

OBJECTIVES: To describe the specificities and complications of thyroid surgery in children and adolescents. MATERIAL AND METHODS: This retrospective study was based on 64 patients under the age of 18 who underwent thyroid surgery between January 2004 and March 2012, with two operations in one case. The following data were analysed: anatomical variants of the recurrent laryngeal nerve, postoperative recurrent laryngeal nerve paralysis rate, postoperative hypoparathyroidism rate, and histological results. RESULTS: Two cases of right non-recurrent inferior laryngeal nerve were observed (2.2% of the 93 recurrent laryngeal nerves dissected). One case of persistent left recurrent laryngeal nerve paralysis was observed (1.1%) despite intraoperative recurrent laryngeal nerve monitoring. Eight cases of immediate postoperative hypocalcaemia were observed (23.5% of the 34 total thyroidectomies) and permanent hypocalcaemia was observed in 5 cases (14.7%) with a significantly lower immediate postoperative serum calcium than in the case of transient hypocalcaemia (P=0.035). Among the 11 patients operated for familial medullary thyroid carcinoma (MTC), 36.3% presented one or more sites of C-cell carcinoma. Among the 32 patients operated for thyroid nodule, 6.3% presented papillary adenocarcinoma. Histological results were benign in all other cases. CONCLUSIONS: Thyroid surgery in children and adolescents is part of global multidisciplinary management of thyroid disorders in children. Recurrent laryngeal nerve paralysis is a rare complication, but may occur despite the use of intraoperative recurrent laryngeal nerve monitoring. Permanent hypoparathyroidism is the most common complication and is correlated with immediate postoperative serum calcium. Systematic prophylactic total thyroidectomy in patients with a RET proto-oncogene mutation allowed early diagnosis of MTC in one-third of cases. In view of the low rate of malignant nodules in our series, the malignant thyroid nodule rates reported in children in the literature may be overestimated.

Preoperative diagnosis and intraoperative protection of nonrecurrent laryngeal nerve: a review of 5 cases.

BACKGROUND: Nonrecurrent laryngeal nerve (NRLN) is a risk factor for nerve injury during thyroidectomy or parathyroidectomy. It is usually associated with abnormal vasculature that can be identified by several imaging methods. The aim of this study was to retrospectively analyze the preoperative diagnosis and intraoperative protection of NRLN. MATERIAL AND METHODS: Of the 7169 patients who underwent thyroid surgery at our hospital between August 2008 and January 2013, 5 patients with NRLN were identified. Preoperative chest X-rays, neck ultrasonography (US), and computed tomography (CT) findings were reviewed. NRLNs were carefully and systematically searched for in surgery. RESULTS: Preoperative CT predicted NRLN in all 5 cases (100% accuracy). The detection rate of NRLN by CT was 0.4% (5/1170). NRLNs were confirmed in surgery. All of them were right-sided NRLN with type IIA variant. The CT scans clearly revealed the vascular anomalies. The review of US images suggested that vascular anomalies could be identified on the images in 1 patient. No postoperative complications occurred in any patient. CONCLUSIONS: The preoperative CT scan was a reliable and effective method for identifying abnormal vasculature to indirectly predict NRLN. Combining the CT and US findings with adequate surgical technique may help to reduce the risk of nerve damage, in addition to preventing nerve palsy.