Systematic review and meta-analysis on intra-operative neuro-monitoring in high-risk thyroidectomy

Abstract

Introduction: Use of intra-operative neuro-monitoring (IONM) during high-risk thyroidectomy has been suggested to decrease the rate of recurrent laryngeal nerve (RLN) palsy. However, current evidences were mixed and there was no large-scale study concluding its benefit. We evaluated the role of IONM in reducing RLN palsy during high-risk thyroidectomy and identified which high-risk subgroup would be most benefited.

Methods: A systemic review was performed to identify studies comparing the use of IONM and visual identification of RLN alone (VA) during high-risk thyroidectomy, namely re-operation, thyroidectomy for malignancy, thyrotoxicosis or retrosternal goitre. Rate of RLN palsy was presented in terms of number of nerve-at-risk (NAR). Meta-analysis on overall high-risk thyroidectomy and subgroups were performed using fixed or random-effects model.

Results: Ten articles were eligible for final analysis. There were 4460 NARs in VA group and 6155 NARs in IONM group. Comparing to VA, IONM had lower rate of overall [4.5% vs. 2.5%, Odd ratio (OR): 1.40, 95% confidence interval (CI): 1.12-1.79, p = 0.003] and temporary [3.9% vs. 2.4%; OR: 1.47, 95% CI: 1.07-2.00, p = 0.016] RLN palsy in overall high-risk thyroidectomies. On subgroup analysis, although numbers of NARs were less than minimal numbers required for a statistical powered study (2.1%-72.7%), use of IONM decreased the rate of overall RLN palsy during re-operation (7.6% vs. 4.5%, OR: 1.32, p = 0.021) and temporary RLN palsy during thyroidectomy for malignancy (3.1% vs. 1.6%, OR: 1.90, p = 0.026). Use of IONM tended to have a lower rate of overall RLN palsy during thyroidectomy for malignancy than VA alone. (3.5% vs. 2.1%, p = 0.050).

Conclusions: Selective use of IONM during high-risk thyroidectomy decreased the rate of overall RLN palsy. IONM should be applied during re-operative thyroidectomy and thyroidectomy for malignancy.

Keywords: Intra-operative neuro-monitoring; Re-operation; Recurrent laryngeal nerve palsy; Thyroid cancer; Thyroidectomy.