|Year : 2019 | Volume
| Issue : 1 | Page : 39-41
Nonrecurrent laryngeal nerve: A rare but predictable variation
Deepak Janardhan1, Shirish Patil2, Shaji Thomas1, Sandeep Suresh2
1 Department of Surgical Oncology, Regional Cancer Centre, Trivandrum, Kerala, India
2 Regional Cancer Centre, Trivandrum, Kerala, India
|Date of Web Publication||1-Apr-2019|
Dr. Shirish Patil
Regional Cancer Centre, Trivandrum, Kerala
Source of Support: None, Conflict of Interest: None
A 40-year-old female was evaluated for left thyroid swelling and, after left hemithyroidectomy (p T2 N0M0) with intermediate risk as per the American Thyroid Association Guidelines, was referred for completion thyroidectomy as the final histology was papillary carcinoma. A contrast-enhanced computed tomography evaluation of the neck was done, which revealed a suspicious nodule in the right lower pole of the thyroid gland, and a mention of anomalous right subclavian artery was reported. Intraoperative findings were confirmed.
Keywords: Aberrant subclavian artery, nonrecurrent laryngeal nerve, thyroidectomy
|How to cite this article:|
Janardhan D, Patil S, Thomas S, Suresh S. Nonrecurrent laryngeal nerve: A rare but predictable variation. Thyroid Res Pract 2019;16:39-41
|How to cite this URL:|
Janardhan D, Patil S, Thomas S, Suresh S. Nonrecurrent laryngeal nerve: A rare but predictable variation. Thyroid Res Pract [serial online] 2019 [cited 2020 Jun 1];16:39-41. Available from: http://www.thetrp.net/text.asp?2019/16/1/39/255306
| Introduction|| |
Nonrecurrent laryngeal nerve (NRLN) is a rare anomaly that head and neck surgeons encounter a surprise during thyroid surgeries. However, meticulous dissection helps not only to identify but also to preserve the integrity of the nerve. However, in the era where imaging is an integral part of presurgical workup protocol, the presence of such an entity can be predicted, rather than being an on-table surprise for the surgeon. Hence, this case report intends the same.
| Case Report|| |
A 40-year-old female was evaluated for left thyroid swelling and, after left hemithyroidectomy (p T2 N0M0) with intermediate risk as per the American Thyroid Association Guidelines, was referred for completion thyroidectomy as the final histology was papillary carcinoma. A contrast-enhanced computed tomography (CT) evaluation of the neck was done, which revealed a suspicious nodule in the right lower pole of the thyroid gland, and a mention of anomalous right subclavian artery was reported. The subclavian artery was noted to arise from the arch of aorta and traversed posterior to the esophagus to the right side as shown in the serial CT scan images [Figure 1], [Figure 2], [Figure 3]. Laryngoscopic evaluation revealed both vocal cords to be mobile. Intraoperatively, after ligating the superior pedicle and identifying the parathyroid on the left side, the tubercle of Zuckerkandl was identified and lifted after ligating the terminal branches of inferior thyroid artery close to the gland. Posterior to the branches of the inferior thyroid artery, transversely running NRLN was identified and traced till the carotid sheath [Figure 4].
|Figure 1: Aberrant subclavian artery (arteria lusoria) originating from arch of aorta and traversing posterior mediastinum|
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|Figure 2: Arteria lusoria. Aberrant right subclavian artery traversing posterior to trachea and esophagus|
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|Figure 4: Right nonrecurrent laryngeal nerve arising from the vagus, traversing parallel and posterior to the inferior thyroid artery, after completion thyroidectomy and suture ligation of inferior thyroid artery|
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| Discussion|| |
The motor supply to the laryngeal muscles is by recurrent laryngeal nerve. It normally loops around the right subclavian artery or the ligamentum arteriosum on the left side, to traverse through the trachea esophageal groove to reach the cricothyroid joint supplying all intrinsic muscles of larynx, except cricothyroid, along with laryngeal sensation. However, in <1% cases, there is a possibility of anomalous origin of subclavian artery (arteria lusoria), which during embryonic development fails to pull the nerve down, in to the mediastinum. Instead, it takes a transverse course to the larynx. A similar scenario occurs on the left side when there is situs inversus. This entity, hence, named as NRLN by Steadman has a documented incidence of 0.3%–0.8% on the right side and <0.004% on the left side.,,,
Three types of NRLN have been reported in literature:,,
- Type 1: Arises directly from vagus and runs together with superior thyroid vessels
- Type 2A: Parallel transverse path, over the trunk of inferior thyroid artery
- Type 2B: Parallel transverse path, under the trunk or between the inferior thyroid artery branches as seen in our case.
The presence of arteria lusoria can be ascertained on CT scan on identifying aberrant subclavian artery traversing posterior to the esophagus or absence of a right brachiocephalic trunk. The role of intraoperative neuromonitoring in thyroid surgery, though at its infancy due to cost constrains, can differentiate non-RLN and sympathetic anastomosis with the recurrent laryngeal nerve.
Overlooking such a rarity can lead to iatrogenic injury to the nerve and vocal cord palsy causing hoarseness of voice and aspiration, and those with poor pulmonary reserve may end up in pneumonitis and ventilatory supports.
| Conclusion|| |
Nonrecurrent laryngeal nerve is rare anomaly. However, prior prediction using CT with meticulous intraoperative dissections can prevent iatrogenic injury to the nerve by novice surgeons, avoiding further morbidity.
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.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]