Surgical Anatomy of Non-Recurrent Inferior Laryngeal Nerves Observed Between 2011–2023

Abstract

Abstract Purpose: To avoid complications during thyroid surgery, it is important to be aware of anatomical variations. This study aimed to analyze the clinical aspects of non-recurrent inferior laryngeal nerves (NRILNs) at a hospital in Japan. Methods: We retrospectively analyzed thyroid surgery cases at our institution over the last 12 years (2011–2023). The study included 2187 patients (1676 women, 76.6%) who underwent total thyroidectomy (TT; N = 512) or hemithyroidectomy (HT; N = 1611). The HT group included 850 right and 761 left thyroidectomies, and 82 patients underwent complementary TTs (40 right and 42 left). The total number of inferior laryngeal nerves identified during surgery was 2717 (1402 right and 1315 left). All patients underwent preoperative neck and thoracic computed tomography (CT) and neck ultrasonography (US). NRILN is classified into two types: Type 1, in which the NRILN branches at the level of the inferior thyroid artery and ascends along the trachea; and Type 2, in which the NRILN branches at the level of the superior pole of the thyroid gland and runs directly to the larynx. Results: We identified 12 NRILN cases. The nerve anomaly was diagnosed preoperatively in all patients. Of these cases, eight were Type 1 and four were Type 2. No inferior laryngeal nerve injury was observed after surgery. Conclusion: To avoid inferior laryngeal nerve injury, preoperative diagnosis of NRILNs is essential. NRILN is associated with an aberrant right subclavian artery; hence, its presence should be evaluated using routine US and CT before surgery.