A newly identified variation at the entry of the recurrent laryngeal nerve into the larynx

Objectives: We aimed to highlight a new anatomical variation of the recurrent laryngeal nerve (RLN), and to emphasize its implications for thyroid surgery. Methods: A prospective study was carried out in a group of 3,078 consecutive thyroidectomies from 1998 to 2008. Total, near-total, subtotal, and partial thyroidectomy were performed for various thyroid diseases. The RLN was routinely identified and exposed in its entire course until the entry into the larynx. The postoperative complications of patients with different variations were compared. Results: 4,241 RLNs were successfully identified in all patients unilaterally or bilaterally. In addition to extralaryngeal branching and nonrecurrent laryngeal nerves, an unreported variation was identified in 44 RLNs (1.04%) at their entries into the larynx. The variation happened at the trunk or the branches of the RLN entering the larynx far from the posterior of cricothyroid joint, and the entry was higher than the superior cornu of the thyroid cartilage and the arch of the cricoid. The median distance from the entry to the posterior of cricothyroid joint was more than 5 mm. As the trunk or the branches had to travel along the lateral edge of the upper 1/3 of the thyroid before entering the larynx, the incidence of RLN palsy was higher than that in extralaryngeal branching variations (p < .05). Conclusion: This newly discovered variation of the RLN is more vulnerable to injury and should be brought to the attention of surgeons.