The utility of intraoperative nerve monitoring during thyroid surgery

Damage to the recurrent laryngeal nerve (RLN) can lead to vocal cord paralysis, resulting in hoarseness, aspiration, stridor, and respiratory distress. The purpose of this study was to examine the impact of intraoperative nerve monitoring (IONM) on RLN injury during thyroidectomy when it is used as an adjunct to confirm the functional integrity of the RLN during delineation of its anatomic course after it has been visually identified.

A retrospective cohort study was performed comparing the rate of RLN injury in patients undergoing thyroidectomy with IONM, which was implemented in 2012, to patients who underwent thyroidectomy without IONM during the 3-year period immediately before IONM. Secondary analysis was performed to determine if there was a relationship between RLN injury and patient age, sex, substernal extension, central neck dissection, prior neck surgery, nodule size, gland weight, or pathology.

A total of 627 patients underwent thyroidectomy, 315 with IONM and 312 without IONM. Of the 531 nerves at risk in the cohort with IONM, 4 (0.75%) were injured compared to 3 (0.58%) among the 517 nerves at risk in the cohort without IONM (P > 0.05). No secondary factor had a significant impact on RLN injury.

The use of IONM had no impact on the rate of permanent RLN injury during thyroidectomy. Because of the low rate of RLN injury, a much larger sample size is needed to determine if IONM will a valuable adjunct in thyroid surgery, especially in specific high-risk subgroups.