Abstract Journal Endocrine Surgery

Purpose: Injuries of the recurrent laryngeal nerve (RLN) during thyroidectomy, although uncommon, can lead to major morbidity.Transection and permanent RLN injury are rare, however temporary neuropraxia and loss of signal (LOS) during intraoperative neuro-monitoring (IONM) are seen more frequently.The aims of this study were to identify factors associated with type I (segmental) and II (global) LOS of the RLN during thyroid surgery and to analyse time to recovery of vocal fold function.Methodology: This retrospective cohort observational study included 3806 patients (2924 female, 76.8%; 882 male, 23.2%) who underwent hemi-or total thyroidectomy in a tertiary referral centre in the period January 2015-March 2021.Intermittent IONM was used routinely in all thyroid procedures studied.Regression analyses were used to determine factors associated with loss of signal and subsequent time to recovery.Results: RLN LOS occurred in 161 (4.5%) patients and 167 of (2.7%) of 5983 nerves at risk during surgery.The rate of Type I LOS and Type II LOS per nerve at risk was 1.4% and 1.3% respectively.Thyroid malignancy, retrosternal goitre and Graves disease were associated with a significantly higher rate of LOS (P < 0.01).The time to recovery was reduced for those who had a Type II LOS (median 4 weeks) compared to those who had a Type I LOS (median 8 weeks; P = 0.04).Female sex and increasing age were each independently associated with a longer duration to return of vocal fold function.Conclusion: Thyroid malignancy, Graves disease and retrosternal goitre are associated with an increased risk of LOS in thyroid surgery.The time to recovery of RLN function is significantly reduced for patients who experience a Type II LOS.