Nervus Laryngeus Inferior Non Recurrens and Lusorial Artery

Abstract

The non-recurrent inferior laryngeal nerve (NRILN) occurs at a frequency of about 0.5% and usually on the right side (1). The non-recurrent course of the nerve is associated with an atypical course of the right subclavian artery coming from the left aortic arch (lusorial artery) (2). In this case, the inferior laryngeal nerve (ILN) leaves the cervical part of the vagal nerve. During embryological development, the ILN embraces the fourth right aortic arch that will form the right subclavian artery. However, in case of atypical regression of the fourth right aortic arch, the ILN embraces the third right aortic arch and will leave the vagal nerve at the level of the carotid bifurcation taking a direct course to the larynx (3).Preoperatively, the atypical course of the ILN might be identified indirectly using a barium swallow test or an angiography (Figs. 1 and 2) revealing a lusorian artery (4). However, during thyroid surgery, intraoperative neurostimulation (IONS) permits identification of an NRILN very easily (Fig. 3) and, as a consequence, a lusorial artery can be found during transsternal lymph node dissection (Figs. 4 and 5). The intraoperative detection of an NRILN using IONS is more practicable and cheaper when compared with preoperative imaging procedures (5). Furthermore, identification of the NRILN using IONS may lead to a reduction of inferior laryngeal nerve palsy (5). References1. Proye CAG, Carnaille BM, Goroppoullos A 1991 Nonrecurrent and recurrent inferior laryngeal nerve: a surgical pitfall in cervical exploration. Am J Surg 162:495-496.

Latencies Shorter than 3.5 ms After Vagus Nerve Stimulation Signify a Nonrecurrent Inferior Laryngeal Nerve Before Dissection

“…5,6,15 In theory, this goal is achievable by screening all patients for the presence of an aberrant subclavian artery before any dissection is performed in the neck, using ultrasonography, computed tomography, magnetic resonance, or angiography. 6,9,11,12 With an estimated prevalence of 0.5% to 1.0%, however, this anomaly is so rare that such indiscriminate screening is unlikely to be cost-effective.…”

“…Because most affected individuals remain asymptomatic, the anomaly is frequently uncovered by imaging studies for unrelated conditions. 4,6,[8][9][10][11][12] If not recognized preoperatively by imaging or on cervical exploration, the NRLN may incur serious damage, giving rise to permanent nerve palsy in at least 10% of patients. 6 Such damage can be kept to a minimum if the nonrecurrent nerve is identified before dissection.…”

Intraoperative Monitoring of the Recurrent Laryngeal Nerve in Thyroid Surgery

“…With EMG documentation: RLN stimulation with registration of the elicited laryngeal muscle activity through (1) endoscopic insertion of the electrodes into the vocal fold [31–37], (2) open insertion into the vocal muscle through the cricothyroid ligament [6, 38–48]; or (3) with the use of endotracheal surface electrodes [16, 47, 49–68].…”

“…A variety of different techniques that have been described in the literature can be subdivided into two major categories according to their ability to record and document electromyographic (EMG) signals: Without EMG documentation: RLN stimulation with observation of posterior cricoarythenoid muscle contraction or palpation [17–23]; glottic pressure response monitoring [24–26]; or intraoperative inspection of vocal cord function [27, 28, 29, 30]. With EMG documentation: RLN stimulation with registration of the elicited laryngeal muscle activity through (1) endoscopic insertion of the electrodes into the vocal fold [31–37], (2) open insertion into the vocal muscle through the cricothyroid ligament [6, 38–48]; or (3) with the use of endotracheal surface electrodes [16, 47, 49–68]. …”

Rekurrens- und Nebenschilddrüsenpräparation in der Schilddrüsenchirurgie

“…Ein bei ca. 0,5% der Schilddrüsenoperation zu findender nonrekurrenter N. recurrens [10,33] ist aus embryologischen Gründen fast immer rechts (. Abb.…”