Anatomic configurations of the recurrent laryngeal nerve and inferior thyroid artery

Abstract

Key words Inferior laryngeal nerve · Recurrent laryngeal nerve · Inferior thyroid artery · Thyroidectomy · Nerve injuryWe read with interest the paper by Yih-Huei Uen et al. 1 concerning the surgical anatomy of the recurrent laryngeal nerves published in the April 2006 issue of Surgery Today.Our comments are as follows.(1) Although much attention has been given to the protection of the recurrent laryngeal nerve (RLN) in thyroid surgery, cases of RLN injury are still occasionally reported in the literature. 2 Because of the importance of this phenomenon, many researchers have investigated the anatomic confi guration between the RLN and inferior thyroid artery (ITA) in cadavers or patients and frequently described three types; the RLN was in front of or behind the ITA, or between its branches. 3,4 Yih-Huei Uen et al. also investigated the relationship in 60 cases and classifi ed three types confi gurations similar to the authors. Nevertheless, we investigated the relationships in 50 specimens (100 RLNs) and found 20 different types of confi gurations. 5 The reason for this difference in the number in our classifi cations is that we have considered the relationship between the laryngeal branches of the RLN and anterior and posterior branches of the ITA. On most sides we observed that before entering the larynx, the RLN divided into two laryngeal branches, namely an anterior and a posterior branch at the level of the upper third of the thyroid gland. In this study, 5 we observed that the laryngeal branches of the RLN were either in front of or behind the ITA or its anterior and posterior branches.However, the authors did not mention the relationship between the laryngeal branches of the RLN and the ITA. We think the relationship between the anterior (motor) laryngeal branches of the RLN and the ITA should also be considered by surgeons, because the branch innervates all the laryngeal muscles except for the cricothyroid muscle. As a result we wish to ask why the authors did not consider the laryngeal branches of the RLN in their classifi cation data.(2) In their results, the authors stressed that the right and left RLN lay posterior to the ITA in 80% (48 cases) and 91.7% (55 cases), respectively.

Técnica de Horsley para la reconstrucción del nervio laríngeo

“…En su trayecto hacía la laringe, el nervio laríngeo recurrente tiene múltiples variaciones anatómicas. En los trabajos de Makay, Shao y Yalexin se han descrito hasta 20 variantes [10][11][12] , lo que explica por qué de 20 a 30 % de las lesiones quirúrgicas de una ramificación terminal no producen secuelas funcionales en la cuerda vocal ipsilateral y, asimismo, el peligro de las lesiones quirúrgicas desapercibidas con técnicas operatorias sin visualización directa del nervio laríngeo recurrente.…”

The Recurrent Laryngeal Nerve and Thyroid Surgery; Who to Scope, When to Visualize, Who to Stimulate

“…These variations can occur in the pattern of division, relations of the nerve to the inferior thyroid artery and its branches and the existence of the nerve in a non-recurrent fashion (1)(2)(3). It is worth noting that up to 28 variations have been described in anatomy studies (2). Similarly, variations have been assessed relative to the ligament of berry and the tubercle of Zuckerkandl (3).…”

“…But for the surgeon, it is easier to look at these variations relative to the inferior thyroid artery and its branches as the surgeon has to always address this artery as a step in thyroid surgery. One way is to classify the recurrent laryngeal nerve into type A (anterior to the artery), type B (between branches of the artery) or type C (posterior to the artery) (1,2). In a systematic review and meta analysis of 32 papers with 8655 recurrent laryngeal nerve sides assessing for the anatomic variation of the nerve relative to the inferior thyroid artery, Ling et al found the nerve to anterior (type A) in 20%, in between the branches (type B) in 28% and posterior(type C) in 52% of the cases (1).…”

“…Larynx and trachea form the surgical bed irrespective of extent (1). Recurrent laryngeal nerve palsy is the feared complication post thyroid surgery (2). The recurrent laryngeal nerve is a branch of the vagus nerve carrying motor and sensory supply to the larynx.…”

“…The recurrent laryngeal nerve is a branch of the vagus nerve carrying motor and sensory supply to the larynx. It has the sole motor supply to the sole abductor of the cord (posterior cricoarytenoid) (2). The following two clinical vignettes and the accompanying questions will assist us in the discussion of the topic of the recurrent laryngeal nerve during thyroid surgery.…”