Prospective evaluation of the utility of routine neuromonitoring for an established thyroid surgical practice

The use of routine intraoperative neuromonitoring (IONM) is controversial in thyroid surgery. Guidelines have been published to standardize IONM. This study examines the impact of routine IONM on a high-volume thyroid surgeon.

A prospective study was conducted using IONM between May 2013 and December 2014. Demographics, type of operation, pathology, recurrent laryngeal nerve (RLN) and external branch of the superior laryngeal nerve (EBSLN) visualization and sub-type classification, cricothyroid or cricopharyngeal twitch/electrode depolarization were obtained, and complications were recorded. Outcomes were compared with 500 thyroidectomies performed by the same surgeon without neuromonitoring.

Two hundred and ninety-nine total thyroidectomies and 191 hemithyroidectomies were performed with IONM resulting in 789 RLN and 789 EBSLN at risk of injury. Demographics, indication, pathology and complications were similar between the two groups. IONM provided additional information for 58 RLN dissections (7.4%) stratifying surgical decision-making. Loss of signal was detected in 1.8% of nerves at risk. IONM assisted in identification of 109 (13.8%, P < 0.0001) EBSLN, including a 15.8% improvement in identifying type 2b EBSLN. Utility of IONM was not predicted by surgery indication; however, multinodular goitre was a significant predictor of IONM assisted identification of type 2b EBSLN (OR = 2.24, P = 0.01).

Routine IONM provides intraoperative information to a high-volume thyroid surgeon regarding the recurrent and external nerves over and above direct visualization alone, and its utility could not be predicted by operative indication.