Diagnosis, anatomy, and electromyography profiles of 73 nonrecurrent laryngeal nerves.

BACKGROUND: The purpose of this work was to compare methods of detecting nonrecurrent laryngeal nerves (NRLNs). METHODS: Specificity and sensitivity were compared in three NRLN detection methods: CT, electromyography (EMG), and A-B point comparison. RESULTS: A total of 73 intraoperative pictures and 36 CT details of NRLNs are presented. Incidence of NRLN was 0.39%. Type I NRLN accounted for 50.7%, type IIA 45.2%, type IIB 4.1%. The NRLN median latency was 2.13 ms vs 3.00 ms median in an RLN control group (P < .001). When the threshold was set to 2.5 ms, EMG latency detection had 96.7% sensitivity and 91.6% specificity for detecting NRLN, and the A-B point comparison algrithm had 97.3% sensitivity and 92.5% specificity. Combining EMG latency detection with A-B point comparison achieved 100% sensitivity and specificity for detecting NRLN. CONCLUSION: This is the largest series of NRLN presented in the literature. Latency shorter than 2.50 ms combined with the A-B point comparison method is the ideal algorithm procedure for early NRLN identification.

Successful Prediction of a Left Nonrecurrent Laryngeal Nerve in a Patient With Right-Sided Aorta and Aberrant Left Subclavian Artery.

BACKGROUND: Left nonrecurrent laryngeal nerve (LNRLN) is an extremely rare anatomic variant. The development of such anatomic variation requires the regression of both the fourth (aortic arch) and sixth (ductus arteriosus, DA) arches on the left side. Preoperative prediction of this variant is difficult but might reduce risk of nerve injury. METHODS: A 34-year-old female was indicated for thyroidectomy for a 2.4 cm follicular neoplasm and Graves' disease. Due to a positive medical history of 22q11.2 microdeletion and unexplained left vocal cord paralysis, a preoperative chest computed tomography (CT) scan was obtained and revealed a right-sided aorta (RSA) and aberrant left subclavian artery (ALSA) without Kommerell's diverticulum. A left-sided NRLN was then highly suspected. RESULTS: Thyroidectomy was performed under general anesthesia with the utilization of intraoperative laryngeal nerve monitoring. A LNRLN was confirmed intraoperatively. CONCLUSIONS: Right-sided aorta and ALSA indicate embryologic regression of the left fourth primitive aortic arch. The absence of Kommerell's diverticulum at the origin of the ALSA indicates the lack of high-pressure blood flow from the pulmonary artery to the ALSA through the ductus arteriosus during embryogenesis, suggesting the embryologic regression of the left sixth primitive aortic arch. The presence of all 3 radiologic features thus highly suggests the possibility of a LNRLN.

Right-sided aortic arch and aberrant left subclavian artery with or without a left nonrecurrent inferior laryngeal nerve.

BACKGROUND: In thyroid surgery, preserving the recurrent laryngeal nerve (RLN) is crucial for preventing postoperative phonatory dysfunction. Right nonrecurrent laryngeal nerves (NRLNs) are not particularly rare, and they are vulnerable to injury during surgery. This anomaly is associated with a right aberrant subclavian artery. Thus, a right-sided aortic arch with an aberrant left subclavian artery (LSA) suggests a possible left NRLN. METHODS: We report the cases of 4 patients with right-sided aortic arch and aberrant LSA. Preoperative imaging studies revealed those anomalies, but no signs of situs inversus. During the surgeries, only 1 of the 4 cases had a left NRLN. We retrospectively evaluated the patients' imaging studies. RESULTS: An aortic diverticulum was found at the point at which the aberrant LSA originated in the 3 patients with left-RLNs, but not in the patient with the left-NRLN. CONCLUSION: In right-sided aortic arch + aberrant LSA cases, the absence of an aortic diverticulum suggests a left NRLN. © 2016 Wiley Periodicals, Inc. Head Neck 38: First-E2511, 2016.

Recognition and Surgical Techniques for Management of Nonrecurrent Laryngeal Nerve during Carotid Endarterectomy.

The presence of a nonrecurrent laryngeal nerve (NRLN) during carotid endarterectomy (CEA) may significantly limit the exposure of the surgical field during this operation. Although its reported incidence is rare, NRLN typically overlies the carotid bifurcation and failure to recognize this anatomic variation increases the risk of NRLN injury. A retrospective chart review of all patients who underwent CEA for hemodynamically significant extracranial carotid stenosis between January 2005 and December 2014 was performed. All patients with NRLN encountered intraoperatively were identified. Clinical outcomes, surgical techniques, and complications were reviewed and reported. Four left-sided NRLN were identified and 4 were right sided. No cranial nerve deficits or injuries occurred after CEA in patients where NRLN was encountered. Two distinct surgical techniques were used to manage patients with NRLN and they are discussed in detail.

Characteristic travelling patterns of non-recurrent laryngeal nerves.

BACKGROUND: The non-recurrent laryngeal nerve is subject to potential injury during thyroid surgery. Intra-operative identification and preservation of this nerve can be challenging. Its presence is associated with an aberrant subclavian artery and the developmental absence of the brachiocephalic trunk. This study aimed to evaluate the incidence of non-recurrent laryngeal nerves and present a new classification system for the course of these nerves. METHODS: Non-recurrent laryngeal nerves were identified on the right side in 15 patients who underwent thyroidectomy. The incidence of non-recurrent laryngeal nerves (during thyroidectomy) and aberrant subclavian arteries (using neck computed tomography) was evaluated, and the course of the nerves was classified according to their travelling patterns. RESULTS: The overall incidence of non-recurrent laryngeal nerves was 0.68 per cent. The travelling patterns of the nerves could be classified as: descending (33 per cent), vertical (27 per cent), ascending (20 per cent) or V-shaped (20 per cent). CONCLUSION: Clinicians need to be aware of these variations to avoid non-recurrent laryngeal nerve damage. A retroesophageal subclavian artery (on neck computed tomography) virtually assures a non-recurrent laryngeal nerve. This information is important for preventing vocal fold paralysis. Following a review of non-recurrent laryngeal nerve travelling patterns, a new classification was devised.

Prediction of nonrecurrent laryngeal nerve before thyroid surgery--experience with 1825 cases.

BACKGROUND: Nonrecurrent laryngeal nerve (NRLN) is a rare anatomic anomaly, which often co-occurs with aberrant right subclavian artery (ARSA). With this large case series, we present our experience of predicting the presence of NRLN by the means of chest X-ray film, thoracic computed tomography (CT), and ultrasonography. MATERIALS AND METHODS: A prospective, nonrandomized study has been carried out. A total of 1825 patients with various thyroid disorders scheduled for surgery were recruited between January 2006 and July 2012. All patients underwent preoperative chest X-ray examination. Those suspected with ARSA further underwent thoracic CT scan. Unsuspected patients who had NRLN revealed by surgery were analyzed with ultrasonography postoperatively. RESULTS: A total of 41 patients (2.25%) were suspected to have ARSA by X-ray, of those 19 (46.3%) were confirmed by thoracic CT and proven to have NRLN upon subsequent surgery. No NRLN injury was inflicted. For the remaining 22 cases, CT scan suggested a normal right subclavian artery and none had NRLN upon surgery. For the 1784 unsuspected patients, 4 (0.22%) were discovered to have NRLN upon surgery, of those one was injured. For the 19 predicted NRLN, the time used for identifying the nerve was significantly shorter than the four cases with unsuspected NRLN (t = -15.978; P = 0.000). After the operation, all these unsuspected NRLN were confirmed to have ARSA by ultrasonography. CONCLUSIONS: Patients scheduled for thyroid surgery should be screened for ARSA upon routine chest X-ray and thyroid ultrasonography before surgery. Detection of ARSA can accurately predict the existence of NRLN; hence prevent NRLN injury during subsequent surgery.

Anomalous relationship of coexisting ipsilateral recurrent and nonrecurrent inferior laryngeal nerves during thyroid surgery.

One of the most important complications of thyroid surgery is inferior laryngeal nerve injury. Variations of inferior laryngeal nerve may increase the risk of iatrogenic injury. Coexistence of ipsilateral nonrecurrent laryngeal nerve and recurrent laryngeal nerve is a very rare variation, and sufficient data are not available on the anatomical and functional relationship of the 2 branches and probable clinical outcomes resulting from the injury of one of them. Herein, we present a case with coexistence of nonrecurrent laryngeal nerve and ipsilateral recurrent laryngeal nerve and discuss the clinical importance of this rare variation.

Anatomical anomalies of the laryngeal branches of the vagus nerve in pigs (Sus scrofa).

To delineate the anomaly and frequency of their occurrence in a pig model, we reported the topography of the vagus laryngeal branches and compared the differences with humans. Thirty sides of cervical vagus nerve in 15 fresh cadavers (Sus scrofa) were microdissected. We measured the branch diameters and lengths of the laryngeal branches using a Vernier caliper with a resolution of 0.01 mm. Two patterns of the vagus laryngeal branches were shown: 56.7% with the cranial laryngeal nerve (CLN) and 43.3% without the CLN. The diameters and the length of the CLN were not affected by the side of the neck (P > 0.05), but the diameters of the recurrent laryngeal nerve (RLN) and the nodose ganglion were significantly different between left and right sides (P < 0.05). The left RLN was thinner than the right side in diameter (P < 0.05). Four of the 30 sides had anastomoses between the vagus and the cervical sympathetic chain. There were some differences between the pig anatomy and human anatomy, but the patterns were largely similar. The similarities support the utility of this model, which is closer in size to humans than the standard rodent models.

Lateral congenital anomalies of the pharyngeal apparatus: part III. cadaveric representation of the course of second and third cleft and pouch fistulas.

"Stepladder" surgery for fistula from second or third pharyngeal cleft and pouch is "blind." Neither intraoperative methylene blue injection and probing nor preoperative imaging (fistulogram ultrasound, computed tomography, magnetic resonance imaging) reveal three-dimensional anatomic relations of fistulas. This article describes the most common second and third fistula courses and demonstrates representation of their tracts with wires in human cadavers. A second cleft and pouch fistula, at its external opening, pierces superficial cervical fascia (and platysma), then investing cervical fascia, and travels under the sternocleidomastoid muscle, superficial to the sternohyoid and anterior belly of omohyoid. It ascends along the carotid sheath, and at the upper border of the thyroid cartilage it pierces the pretracheal fascia. Characteristically, it courses between the carotid bifurcation and over the hypoglossal nerve. After passing beneath the posterior belly of the digastric muscle and the stylohyoid, it hooks around both glossopharyngeal nerve and stylopharyngeus muscle. The fistula reaches the pharynx below the superior constrictor muscle. The course of a third cleft and pouch fistula is similar until it has pierced pretracheal fascia; then it passes over the hypoglossal nerve and behind the internal carotid, finally descending parallel to the superior laryngeal nerve, reaching the thyrohyoid membrane cranial to the nerve.

Anomalies associated with aberrant right subclavian arteries. A case report

Anomalies in the aortic arch are a consequence of disorders in the development of the double primitive aortic arch system. We report a case of variation in the great vessels of the aortic arch, with an aberrant right subclavian artery being observed during a routine dissection. This variation was associated with a tight trachea in its distal end and a right lung devoid of the horizontal fissure, with a lack of tissue in the anterior segment of the superior lobe and in the lateral and medial segments of the middle lobe. The two common carotid arteries arose from a common trunk and the right recurrent laryngeal nerve was absent. On the basis of the literature, we review the incidence of the anatomical variation, its embryological explanation, and its clinical consequences (AU)

No disponible

[Non-recurrent inferior laryngeal nerves and sympathetic-inferior laryngeal anastomotic branches: 6 years' personal experience]. / Il nervo laringeo inferiore non ricorrente e le anastomosi con il simpatico cervicale. La nostra esperienza di 6 anni.

The incidence and possible association of inferior laryngeal nerve and sympathetic anastomotic branch anomalies were evaluated in this study. Non-recurrent inferior laryngeal nerves stem from vascular anomalies involving the right subclavian artery and aortic arches during embryological development. These anomalies usually have no functional consequences (except for occasional dysphagia), but are potentially dangerous during thyroid surgery, occurring in about 1% of cases. Sympathetic-inferior laryngeal anastomotic branches are described in about 1.5% of cases, and may be confused with non-recurrent inferior laryngeal nerves. 1473 patients submitted to total thyroidectomy for benign disease over the period 2001-2006 were evaluated. Four non-recurrent inferior laryngeal nerves (incidence: 0.27%) and 11 sympathetic-inferior laryingeal anastomotic branches (incidence: 0.74%) were observed. Out of a total of 25 definitive inferior laryngeal nerve lesions, 1 occurred in a case of non-recurrent inferior laryngeal nerve. Awareness of the anatomical anomalies described and accurate surgical technique, including a constant search for the inferior laryngeal nerve, are the requirements for identification of non-recurrent inferior laryngeal nerves and sympathetic-inferior laryngeal anastomotic branches. During the pre-operative workup, ultrasonographic study of the right subclavian artery may be advisable in order to rule out alterations of its origin and course.

A left nonrecurrent inferior laryngeal nerve in a patient with right-sided aorta, truncus arteriosus communis, and an aberrant left innominate artery.

The identification and prevention of injury to the inferior laryngeal nerve is one of the main issues in thyroid surgery. Sound knowledge of anatomic variants of the nerve is of major importance. In rare cases the nerve does not run the recurrent way and it is therefore difficult to identify the nerve. Abnormal developments of the aortic arch during embryogenesis include malformation of the great vessels and can be the reason for anatomic abnormalities. A cause for a nonrecurrent nerve on the right side is the so-called lusorian artery, a right retroesophageal subclavian artery. Left-sided nonrecurrent nerves are seldom if ever documented. Only two cases have been published so far of patients with situs inversus viscerum, where left nonrecurrent nerves were associated with inverse, left-sided lusorian arteries.

Non-recurrent laryngeal nerve related to thyroid surgery: report of three cases.

PURPOSE OF THE STUDY: We aimed to highlight a rare anatomical variation involving the recurrent laryngeal nerve, and to emphasise its implications for thyroid surgery. MATERIALS AND METHODS: Over a period of 13 years, 993 patients underwent thyroid surgery; 1557 recurrent laryngeal nerves (887 on the right side) were exposed. RESULTS: Three non-recurrent laryngeal nerves were found on the right side, associated with a retro-oesophageal subclavian artery. One case was suspected before surgery. DISCUSSION: Several variations in the path and branches of the recurrent laryngeal nerve have been reported in the literature. The frequency of occurrence of a non-recurrent laryngeal nerve is about 1 per cent, for patients undergoing thyroid surgery. Other surgically relevant anatomical variations of the recurrent laryngeal nerve include associations with the inferior thyroid artery and the presence of nerve branches. CONCLUSION: The recurrent laryngeal nerve must be carefully dissected and totally exposed during thyroid surgery in order to best preserve its function. Moreover, the thyroid surgeon must be aware of the existence of anatomical variations, which are not as rare as one may think.

[Diagnostic complexities and anatomical surprises in a case of thyroid surgery for papillary carcinoma]. / Complessità diagnostiche e sorprese anatomiche in un caso di chirurgia tiroidea per carcinoma papillare.

We present the case of a male patient who needed surgery for a large undefined submandibular schwannoma and a small contralateral thyroid carcinoma associated with cervical lymph nodes of a dubious nature. During the operative procedure all the pathological conditions were resolved, with some remarkable surprises. A non-functioning parathyroid adenoma was found and removed. A fairly unusual anatomical complication was also detected with regard to the right inferior laryngeal nerve, i.e. an anastomotic branch connecting the main trunk to the vagus nerve.

Ansa cervicalis as a variant of spinal accessory nerve plexus: a case report.

The ansa cervicalis is a neural loop in the neck formed by the union of two main nerve roots, namely superior and inferior roots, derived from ventral rami of the cervical nerves. With the expanding use of the ansa cervicalis for reinnervation procedures and the fact that it is located in the vicinity of major nerves and vessels of the neck, knowledge of the topography and morphology of this loop is quite necessary in the modern era. Any variation in the course, contributing roots or branching pattern of the ansa cervicalis, potentially alters and perhaps complicates the course of the procedures involving this nerve such as neurorrhaphy, skull base surgery, neck dissection, and anterior cervical spinal approach. Here, we present an unusual case of an ansa cervicalis encountered upon routine dissection of an adult male cadaver. In this case, the inferior root of the ansa cervicalis was formed by the joining of two rootlets, one originating from spinal accessory nerve and the other from a branch of the cervical plexus to the sternocleidomastoid muscle. The fibers traversing the branch of spinal accessory nerve were derived from the first segments of the cervical spinal cord. This case demonstrates a variant of the spinal accessory nerve plexus that contributed to the formation of the ansa cervicalis. Review of the literature was performed to reveal the possible clinical aspects of this anatomical variation.

Atypical anastomosis of laryngeal nerves.

The larynx and its associated structures derive their chief source of innervation from the superior and recurrent laryngeal nerves. Surgery of the larynx requires a sound knowledge of the normal anatomy as well as variations that may be encountered in this region. We report the presence of rare communications between the right external and internal laryngeal nerves as well as between the right external and inferior laryngeal nerves via a thyroid foramen. In addition, we report on bilateral innervation of the respective ipsilateral aryepiglottic, transverse, and oblique arytenoid muscles by the internal laryngeal nerve, which is contrary to the classical descriptions of this nerve. The anatomic features are described and clinical implications are highlighted.

[Two cases of nonrecurrent inferior laryngeal nerve--different branching levels from vagus nerve].

We observed two cases of nonrecurrent inferior laryngeal nerve (NRILN). Case 1, a 71 year old man was diagnosed as having papillary carcinoma. NRILN was found during his operation. It directly branched from the right cervical trunk of the vagus nerve at the level of the cricoid cartilage and then entered the larynx after running behind the thyroid gland. Case 2, a 64 year old woman was diagnosed as having primary hyperparathyroidism. In this patient, the NRILN branched at the level of the inferior pole of the thyroid gland, rose up beside the tracheal wall and entered the larynx. In both patients, preoperative CT scan and postoperative MR angiography revealed the aberrant right subclavian artery. A postoperative barium swallow test showed the compression of the esophagus by this anomalous artery in case 1. Although it is possible to predict the presence of NRILN by preoperative imaging tests, the branching level from the vagus nerve is unpredictable. Surgery must be performed with this point in mind, if the presence of NRILN is suspected.

[Non recurrent laryngeal nerve. Personal experience]. / Il nervo ricorrente che non ricorre. Esperienza personale.

PURPOSE: Damage to the recurrent laryngeal nerve (RLN) during thyroid or parathyroid surgery is the most common iatrogenic cause of vocal cord paralysis. Identification of the RLNs and meticulous surgical technique can significantly decrease the incidence of this complication. Nonrecurrent RLNs (NRRLNs) are exceedingly rare. Surgeons need to be aware of their position to avoid injuries. PATIENT AND METHODS: A retrospective review of 263 right RLN exposures (and 251 left RNL) over a 5-year period was performed. RESULTS: Two NRRLNs were encountered, for an incidence of 0.39% (0.76% only for right dissection), without anatomic anomalies on the left side. The nerve anomaly was never preoperatively diagnosed. CONCLUSION: NRRLNs are rare and is associated with a right subclavian artery arising from distal aortic arch. Awareness of their existence and correct surgical technique will prevent the surgeon from accidentally lesion of NRRLN one if it is encountered during thyroid or parathyroid surgery.