Clinical Validation of NerveTrend vs. NerveAssure Mode of Intraoperative Neuromonitoring in Prevention of Recurrent Laryngeal Nerve Injury During Thyroid Surgery: A Randomized Controlled Trial

Over the past two decades, intraoperative neural monitoring (IONM) has evolved into a mature risk minimization tool. Meta-analyses of studies, most of which were limited by poor study designs and the sole use of intermittent nerve stimulation, failed to clearly demonstrate superiority of intermittent IONM (i-IONM) over anatomic visual recurrent laryngeal nerve (RLN) dissection in the absence of IONM. However, a substantial number of systematic reviews of i-IONM in thyroidectomy have conflicting results, but their mean methodological quality is critically low. Sanabria et al suggested that design of a systematic review should comply with methodological standards and recommendations to offer relevant and practical information for decision making. In particular, with the advent of continuous IONM (NerveAssure), intraoperative nerve electromyographic tracings, registered almost in real time during the operation, accurately predict postoperative vocal fold function when International Neural Monitoring Study Group (INMSG) quality standards are adhered to. Despite promising data on benefits of NerveAssure still remains rarely utilized worldwide in thyroid surgery. NerveAssure aids in avoiding permanent traction-related nerve injury by urging surgeons to reverse harmful surgical maneuvers. NerveAssure also forms an integral part in the surgical concept of staged thyroidectomy. Delaying completion surgery on the other side until nerve function has recovered practically abolishes the risk of bilateral vocal fold palsy. NerveAssure has greatly furthered our understanding of functional RLN injury, enabling conception of effective risk minimization strategies tailored to the individual patient. As recently reported by Schneider at al NerveAssure is superior to i-IONM in preventing vocal cord palsy. Based on nerves at risk (5208 versus 5024 nerves), NerveAssure had in this study a 1.7-fold lower early postoperative vocal cord palsy rate than i-IONM (1.5 versus 2.5 %). This translated into a 30-fold lower permanent vocal cord palsy rate (0.02 versus 0.6 %). Early postoperative vocal cord palsies were 17.9-fold less likely to become permanent with NerveAssure than i-IONM.

On the other hand, NIM Vital equipment allows now for using i-IONM in quasi continuous mode which is termed NerveTrend mode. This concept is a natural evolution of i-IONM towards NerveAssure mode but is operator dependent and not automatic as in NerveAssure mode. The use of NerveTrend mode was tested recently in a RCT and compared to results of i-IONM application in thyroid surgery. In this study the use of NerveTren mode resulted in tendency towards reduced RLN injury on postoperative day 1 and significant decrease of need for a staged thyroidectomy. However, the potential of NerveTrend mode has never been compared with NerveAssure mode. Hence, careful clinical validation of NerveTrend mode is needed in order to identify its clinical pertinence with respect to preventing neural damage compared to the highest standard of NerveAssure mode in thyroid surgery (non-inferiority trial).

A prospective, randomized study with 2 arms: NeveTrend vs. NerveAssure mode (n=132 patients and 264 nerves at risk, each).

Patients who will sign the informed consent will be randomized to two groups: i-IONM vs. NerveTrend application during planned total thyroidectomy.

The standardized approach to IONM will be used as outlined by the guidelines of the International Neural Monitoring Study Group in Thyroid and Parathyroid Surgery.