The Nonrecurrent Laryngeal Nerve Without Abnormal Subclavian Artery: Report of Two Cases and Review of the Literature

As a variant of recurrent inferior laryngeal nerve (RILN), the nonrecurrent inferior laryngeal nerve (NRILN) is closely related to the occurrence of abnormal subclavian artery (ASA). The nonrecurrent inferior laryngeal nerve has been found in patients without arterial abnormalities, which is seen in the coexistence of NRILN and RILN, but it is easily confused with sympathetic-inferior laryngeal anastomosis branch (SILAB). We encountered 2 right NRILN patients without ASA during thyroid surgery. This article summarizes the characteristics of these cases and proposes methods to distinguish the coexistence of NRILN and RILN from SILAB. So far, 11 articles have reported 16 cases of NRILN without arterial abnormalities. In patients without artery abnormality, the vagus nerve could send out a descending branch NRILN at the bifurcation of the carotid artery and enter the larynx after anastomosis with RILN. Adequate dissection of the carotid sheath may avoid confusion with SILAB, and neural monitoring is also expected to provide a reference for the identification.

Non-recurrent inferior laryngeal nerve: a case report

The incidence of Non-recurrent laryngeal nerve (NRLN) is reported to be 0.6%-0.8% on the right side and in 0.004% on the left side. Damage to this nerve during thyroidectomy may lead to vocal cord complications and should therefore be prevented. A middle-aged woman with a nodular goiter who underwent subtotal thyroidectomy for multinodular colloid goiter. We encountered a non-recurrent laryngeal nerve on the right side in a patient during surgery. We were not able to find the inferior laryngeal nerve in its usual position using the customary anatomical landmarks. Instead, it was emerging directly from the right vagus nerve at a right angle and entering the larynx as a unique non-bifurcating nerve. Nonrecurrent inferior laryngeal nerve incidence is very rare, but when present, increases the risk of damage during thyroidectomy. Hence, it is very important to be aware of the anatomical variations of the inguinal lymph node (ILN) and the use of safe meticulous dissection while looking for the nerve during thyroidectomy. The use of Intra-operative neuro-monitoring (IONM) if available in thyroid surgery allows the surgeon to recognize and differentiate branches of the inferior laryngeal nerve (ILN) from sympathetic anastomoses, as well as NRLN during surgery.