Surface electrode recurrent laryngeal nerve monitoring during thyroid surgery: Normative values

The objective of this study was to determine the normative values for threshold stimulation of the recurrent laryngeal nerve (RLN) using intraoperative neuromonitoring before and after thyroidectomy. Eighty patients with 111 at-risk nerves underwent thyroid surgery by a single surgical team at an academic medical center in central Pennsylvania during this retrospective study. RLN threshold measurements were taken before and after resection to determine the minimum current needed to stimulate the RLN. Risk of paresis was modeled using logistic regression, and risk was quantified using adjusted odds ratios. The results showed the average minimum current required for stimulation of the RLN before resection was 0.50 mA. The average RLN minimum threshold level after resection was 0.47 mA. The average difference in pre- and postresection RLN threshold current was -0.03 mA. The preresection RLN threshold level (P = 0.31), the postresection RLN threshold level (P = 0.82), and the difference in the pre- and postresection RLN threshold level (P = 0.16) all did not have a statistically significant effect on paresis. No other covariates had a significant association with paresis.