Influence of Recurrent Laryngeal Nerve Variations on Vocal Cord Paralysis

Objective: Vocal cord paralysis (VCP) due to recurrent laryngeal nerve (RLN) injury is a significant potential complication of thyroid and parathyroid surgery. The aim of this study was to investigate the influence on VCP of the anatomical relationship of the RLN to the inferior thyroid artery (ITA) and extralaryngeal branching of the RLN. Materials and Methods: The data of 123 patients (95 female, 28 male; mean age: 46+13.6 years), a total of 204 neck sides, who underwent a thyroidectomy and/or a parathyroidectomy performed with intraoperative nerve monitoring between March and December 2015 were evaluated retrospectively. Preoperative and postoperative vocal cord examinations were performed in all cases. RLN branching at a distance of >5 mm with both branches entering the larynx was considered extralaryngeal branching of the nerve. Age, gender, nerve side, RLN branching, and the relationship between the RLN and the ITA were evaluated to assess the possible effect on VCP. Results: Of the 204 neck sides, 11 (5.4%) RLNs developed VCP. Ten cases were temporary (4.9%) and 1 (0.5%) was permanent. There was no significant difference in age, gender, nerve side, or RLN-ITA relationship in the VCP cases. Extralaryngeal branching was detected in 42 (22.7%) of 185 nerves, and the rate of total and transient VCP was significantly higher in branching nerves than in nonbranching nerves (11.9% vs 3.5%, p=0.034; 11.9% vs 2.8%, p=0.030, respectively). Conclusion: RLN branching is a potential risk factor for total and transient VCP; awareness of this anatomical variation and complete exposure during thyroid surgery are crucial to the prevention of RLN iniury.