Left Nonrecurrent Laryngeal Nerve: A Very Unusual Finding during Thyroid Surgery

BACKGROUND: Identifying the inferior laryngeal nerve is one of the main concerns in thyroid surgery. The typical recurrent position occurs due the relative position between the vagus nerve and the larynx during the last 3 branchial arches development. In rare cases, this nerve does not loop under the right subclavian artery or the aortic arch. This abnormality is present in 0.7% of patients and is associated with the presence of anatomical vascular anomalies. The left non-recurrent inferior laryngeal nerve is an even rarer abnormality, with only six cases described in the literature to date. METHOD: A 46- years old female patient referred to total thyroidectomy for symptomatic multinodular benign goiter. RESULTS: A left non-recurrent inferior laryngeal nerve was found with difficulty and then a partial thyroidectomy was performed. CT scan showed dextroposition of the vessels of the base of the heart and an aberrant left subclavian artery. CONCLUSION: An association of a right-sided aortic arch and aberrant left subclavian artery, or the presence of situs inversus, although rare anatomical variations, are associated to a non-recurrent inferior left laryngeal nerve. Proper identifying these abnormalities may help to properly identify and salvage this structure.