The non-recurrent inferior laryngeal nerve (NRILN) is a nerve anomaly that can be associated with an increased risk of vocal fold paralysis. The purpose of this study wasto report three new cases of this anomaly, underline the necessity of recognizing its possibility for the prevention of intra-operative nerve damage and a review of the literature.

Three cases of thyroid surgery associated with right NRILN are reported.

Two patients underwent bilateral thyroidectomy for a multinodular goitre and for a toxic multinodular goitre respectively. The third patient had a right lobectomy and isthmectomy for a thyroid nodule. All patients had identification of the recurrent laryngeal nerve on the left sideand NRILN on the right side. The diagnosis of the NRILN was made per-operatively on all cases. A post-operative computed tomography (CT) scan in two patients, showed a retrooesophageal aberrant right subclavian artery. Post-operatively, all patients had normal vocal fold function on laryngoscopy.

The NRILN is a rare anomaly but overlooking its possibility may lead to severe operative morbidity. This is an additional argument in favour of systematic dissection of the recurrent inferior laryngeal nerve during thyroid surgery.

An anatomical study of 50 fresh adult human cadavers was performed in order to verify prevalence of Galen’s anastomosis (GA) and to evaluate whether factors such as gender, ethnicity, side of the neck, and individual stature may interfere with GA prevalence. The results were analysed using the Chi-square test, Student t-test, and F-Snedecor test. GA was observed in 87 of 100 dissections. There was no statistically significant difference regarding GA prevalence between groups separated by ethnicity (p = 0.853), gender (p = 0.198), side of the neck (p = 0.766), or individual height (p = 0.199). Therefore, the GA was a frequent anatomical finding, and this result was not influenced by any studied factor. Comparing our data with previous studies, we also concluded that the GA seems to play an important role in the innervation of the larynx, even though its function remains unclear. Also, it is reasonable to consider GA a constant anatomical constituent.

The nonrecurrent laryngeal nerve is vulnerable during thyroid surgery. Pre-operative recognition of this nerve allows surgeons to avoid injuring the nerve. This anomaly depends upon the aortic arch anomaly and, therefore, in some cases, surgeons are able to predict the presence of this nerve pre-operatively by chest X-ray or barium swallow. Two patients with nonrecurrent laryngeal nerve are reported, one of whom, a 48-year-old man, had an abnormal shadow of the aortic arch, which led to confirmation of a right aberrant subclavian artery. Barium swallow plays a decisive role in the diagnosis of nonrecurrent laryngeal nerve, and this test is mandatory in patients who complain of difficulty in swallowing.