Thyroid surgery outcomes in a 4-year series with intraoperative neuromonitoring: a retrospective cohort study.

Background: Meticulous surgical technique is essential for safe thyroid surgery, with high-volume surgeons experiencing the lowest complication rates. Intraoperative neuromonitoring (IONM) is increasingly adopted in high-volume centers to enhance outcomes and reduce complications. The aim of this study is to evaluate surgery outcomes during IONM introduction in daily practice.

Methods: This retrospective cohort study evaluated morbidity associated with the introduction of IONM by analysing all consecutive thyroid surgeries performed between 2019 and 2022 at Hospital da Luz Lisboa. Patient demographics, clinical characteristics, and surgery-related data were collected. Primary outcomes were recurrent laryngeal nerve (RLN) palsy and annual progression of IONM use. Secondary outcomes included hypoparathyroidism and surgical complications.

Results: A total of 502 patients (98 men and 404 women, with mean ages of 54.9 and 52.6 years, respectively) underwent either lobectomy or total thyroidectomy (TT), involving 719 RLNs at risk (RLNAR). A transient palsy rate of 0.56% and a definitive palsy rate of 0.28% were identified, with no associated risk factors. In the IONM group (n=237), transient RLN palsy occurred in 0.81% of patients, with no definitive palsy cases. IONM use increased from 35.9% in 2019 to 73.2% in 2022 (P<0.001). Permanent hypoparathyroidism occurred in 0.39% of patients. No cervical hematoma or surgical site infection was observed.

Conclusions: The progressive implementation of IONM in thyroid surgery, alongside increasing case complexity and annual surgical volume, may support RLN preservation and reduce morbidity, while enabling gradual skill acquisition. Routine IONM use should be considered to improve patient outcomes, particularly in complex thyroid procedures.