|Year : 2019 | Volume
| Issue : 2 | Page : 63-65
Nonrecurrent laryngeal nerve: A rare clinical presentation in thyroid surgery- A report of 2 cases
Darshan Virendrakuma Doshi, Bhavya N Shah
Head and Neck Cancer Surgery, Head and Neck Cancer Care, Naranpura, Ahmedabad, Gujarat, India
|Date of Submission||25-Jan-2019|
|Date of Acceptance||02-Jun-2020|
|Date of Web Publication||14-Aug-2020|
Darshan Virendrakuma Doshi
Head and Neck Cancer Care, 404 and 408, Dev Arcade, Near Naranpura Railway Crossing, Naranpura, Ahmedabad - 380 013, Gujarat
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Surgical damage to the inferior laryngeal nerve is one of the most feared complications of thyroid surgery. A detailed knowledge of anatomical variations is necessary. Nonrecurrent inferior laryngeal nerve is a rare anomaly on the right side and is exceptional on the left. The typical course of the inferior laryngeal nerve is due to the embryological development of the aortic arch and supra-aortic vessels, and nonrecurrence is associated with a vascular anomaly such as a right retroesophageal subclavian artery. The nervous anomaly on the left side is possible only with the occurrence of cardiac dextroposition (situs inversus) and a left retroesophageal subclavian artery. The situation is more dangerous when a nonrecurrent branch of the inferior laryngeal nerve is associated with a recurrent branch. This anomaly does not appear to be associated with a vascular anomaly in all cases. We came across two cases of NRLN after performing 965 thyroid surgeries.
Keywords: Nonrecurrent, inferior laryngeal nerve, rare presentation
|How to cite this article:|
Doshi DV, Shah BN. Nonrecurrent laryngeal nerve: A rare clinical presentation in thyroid surgery- A report of 2 cases. J Laryngol Voice 2019;9:63-5
| Introduction|| |
The presence of right nonrecurrent laryngeal nerve (NRLN) is a very rare anomaly, with an average incidence of 0.3%–1.0%. It is only found on the right side except in rare cases of situs inversus where it may be present on the left side, its incidence being 0.004%. Steadman was the first to observe a nonrecurrence of the inferior laryngeal nerve in a cadaver in 1863. Nonrecurrent laryngeal nerve (NRLN) has been classified as Type 1 arises directly from the vagus nerve and travels along with the superior thyroidal vessels. Type 2 NRLN follows a horizontal path in connection with the inferior thyroid artery. The presence of a complaint of dysphagia and X-ray suggestive of situs inversus may hint toward encountering a nonrecurrent laryngeal nerve during the surgery. In the absence of these evidences, it is very difficult to predict the existence of nonrecurrent laryngeal nerve preoperatively. Hence, detailed anatomical knowledge and meticulous surgical dissection are absolutely imperative to preserve the function of nonrecurrent inferior laryngeal nerve and its variations.
| Case Reports|| |
Case report 1
A 26-year-old Indian female presented to the hospital with a painless anterior neck mass that had gradually become larger over a period of 2 years. She had no toxic symptoms, difficulty in swallowing, or hoarseness of voice. On clinical examination, a solitary thyroid nodule was palpated on the right side. It measured 4 cm × 3 cm and was firm in consistency. An indirect laryngoscopic examination showed normal vocal cord function. Ultrasound revealed a solitary thyroid nodule without retrosternal extension and internal calcification. Fine-needle aspiration cytology revealed a benign thyroid nodule. The patient underwent hemithyroidectomy. During the surgery, the right recurrent laryngeal nerve (RLN) was not encountered at the tracheoesophageal groove and a further exploration caudally failed to disclose the nerve. However, when the Zuckerkandl tubercle (ZT) of the thyroid gland was lifted up and rotated medially, the NRLN was seen curving down from the top [Figure 1]. The identification of the NRLN was aided by the exposure of ZT. The nerve was traced proximally and was found to be arising directly from the vagus nerve at the level of the inferior thyroid artery. Hemithyroidectomy was completed, and postoperative vocal function was normal. Postoperative period was uneventful.
|Figure 1: Zuckerkandl tubercle of the thyroid gland is lifted up and rotated medially and the NRLN is seen curving down from the top|
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Case report 2
A 32-year-old Indian female presented to Goenka Hospital, Gandhinagar, for painless anterior neck mass that had gradually become larger over a period of 4 years. She had no toxic symptoms, difficulty in swallowing, or hoarseness of voice. On clinical examination, multiple thyroid nodules were palpated in both lobes of the thyroid. The size of the left lobe of the thyroid was 6 cm × 4 cm and the right lobe was 5 cm × 5 cm. An indirect laryngoscopic examination showed normal vocal cord function. Ultrasound revealed multiple thyroid nodules without retrosternal extension and internal calcification. Fine-needle aspiration cytology revealed a benign thyroid nodule. The patient underwent total thyroidectomy. During the surgery, the right RLN was not encountered at the tracheoesophageal groove and a further exploration caudally failed to disclose the nerve. However, when the ZT of the thyroid gland was lifted up and rotated medially, the NRLN was seen curving down from the top [Figure 2]. The identification of the NRLN was aided by the exposure of ZT. The nerve was traced proximally and was found to be arising directly from the vagus nerve at the level of the inferior thyroid artery. On the left side, the nerve anatomy was normal. Total thyroidectomy was completed, and postoperative vocal function was normal. Postoperative period was uneventful.
|Figure 2: The nonrecurrent inferior laryngeal nerve running transversely parallel to the inferior thyroid artery|
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| Discussion|| |
We encountered NRLN two times after performing 965 thyroid operations in 11 years. NRLN arises directly from the vagus nerve, and in most instances, the nerve is associated with right aberrant subclavian artery., Nonetheless, the occurrence of NRLN in the absence of vascular anomaly has also been observed in other series., The NRLN is usually found running directly to the larynx at the level of the superior pole of the thyroid. In addition, Steadman et al. described two types of NRLN passage from the vagus nerve to the right thyroid lobe: the horizontal and the descending. Others have reported a small RLN with a major nonrecurrent nerve., It is good practice that we should not cut any nerve like structure passing medially towards larynx from the carotid sheath until the normal recurrent laryngeal nerve is being identified. There are not only multiple branches to be considered but also the variability in the position of RLNs. Furthermore, in the presence of a noticeable ZT, the nerve can be identified confidently. When a nerve of diminished caliber is observed in the usual recurrent course, careful and meticulous dissection cephalad should be continued to demonstrate a possible merger of ipsilateral recurrent and NRLN. The clinical symptoms such as dysphagia lusoria and the presence of aberrant right subclavian artery play a major role in the preoperative diagnosis.,, The artery aberrant right subclavian can occasionally be seen on the standard chest radiograph and barium swallow. The NRLN is vulnerable to injury during dissection if one is not familiar with the surgical anatomy and course of this rare condition. These cases draw the attention of NRLN, which was not associated with any vascular abnormalities. In our cases, the nerves were running transversely parallel to the inferior thyroid artery and hence were Type 2 [Figure 2].
| Conclusion|| |
Nonrecurrent inferior laryngeal nerve is a rare anomaly which should always be kept in mind during thyroid dissection. A comprehensive anatomical understanding and meticulous surgical dissection following anatomical landmarks should be done to preserve the nerve and its function.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
We are thankful to Atmavallabh Hospital, Idar, and Goyanka Hospital, Gandhinagar, for allowing to use medical records to present in the journal.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]