Investigation of recurrent laryngeal palsy rates for potential associations during thyroidectomy

Background: There are many clinical associations and potential mechanisms of injury resulting in recurrent laryngeal nerve palsy (RLNP) after thyroidectomy. One possible cause of RLNP is focal intralaryngeal compression of the recurrent laryngeal nerve (RLN), which may be associated with the tracheal tube (TT). Therefore, we examined current RLNP rates to investigate potential associations, including intralaryngeal, airway, anaesthetic and anthropometric factors. Methods: We analysed 1003 patients undergoing thyroid surgery at The Alfred from 2010 to 2017, who had anatomically intact RLNs at the conclusion of thyroidectomy. All included patients underwent pre- and post-operative flexible nasendoscopy. The primary outcome was RLNP rate. We analysed potential associated factors including age, sex, operative time, surgical indication, pathology, American Society of Anaesthesiologists Physical Status, Mallampati scores, body mass index, intubation grade, TT size and specimen weight. The independent risk factors were identified by logistic regression analysis. Results: Overall, RLNP occurred in 83 patients (8.3%) of which one was permanent (0.1%). On univariate analysis, RLNP was associated with male sex (P = 0.02), and duration of surgery (P = 0.002). On multivariate analysis, both male sex (P = 0.047) and duration of surgery (P = 0.04) remained significant. Further, factors postulated to cause intralaryngeal compression of the RLN, including TT size, body mass index, intubation grade and Mallampati score, were not significantly associated with RLNP. Conclusion: Our study showed a RLNP rate of 8.3%, and associations with longer operative duration, and male sex. Potential intralaryngeal factors were not identified.