Development of a Novel Intraoperative Neuromonitoring System Using an Accelerometer Sensor in Thyroid Surgery: A Porcine Model Study

Abstract

Objectives. The sensitivity and positive predictive value of widely used intraoperative neuromonitoring (IONM) using electromyography (EMG) of the vocalis muscle in thyroid surgery are controversial. Thus, we developed a novel IONM system with an accelerometer sensor that uses the piezoelectric effect instead of EMG to detect laryngeal twitching. The objective of this study was to evaluate the feasibility and safety of this novel IONM system during thyroid surgery in a porcine model. Methods.We developed an accelerometer sensor that uses the piezoelectric effect to measure laryngeal twitching in three dimensions. This novel accelerometer sensor was placed in the anterior neck skin (transcutaneous) or postcricoid area. Stimulus thresholds, amplitude, and latency of laryngeal twitching measured using the accelerometer sensor were compared to those measured through EMG of the vocalis muscle.Results. The amplitudes of the accelerometer sensor at the anterior neck and postcricoid area were significantly lower than those of EMG because of differences in the measurement method used to evaluate laryngeal movement. However, no significant differences in stimulus thresholds between the EMG endotracheal tube and transcutaneous or postcricoid accelerometer sensors were observed. Conclusion.Accelerometer sensors located at the anterior neck or postcricoid area were able to identify laryngeal twitching. The stimulus intensity measured with these sensors was equivalent to that from conventional vocalis EMG. Our novel IONM system with an accelerometer sensor that checks changes in surface acceleration can be an alternative to EMG of the vocalis muscle for IONM in the future.

Application of Novel Intraoperative Neuromonitoring System Using an Endotracheal Tube With Pressure Sensor During Thyroid Surgery: A Porcine Model Study

“…A previous study has reported that the pressure sensor has the same stimulus threshold as EMG in rabbits [27]. An accelerometer sensor placed in anterior neck skin and the posterior cricoid also has the same stimulus threshold as EMG in pigs [36]. These reports have suggested that the accuracy of the pressure sensor to identify laryngeal muscle twitching to assess RLN status is likely to be very similar to that of EMG.…”

Application of an Intraoperative Neuromonitoring System Using a Surface Pressure Sensor in Parotid Surgery: A Rabbit Model Study

“…A piezoelectric pressure sensor was modified to measure changes in skin surface pressure and to identify facial muscle movement [ 12 , 22 ]. The objective of the present study was to determine the feasibility and reliability of FNM using a surface pressure sensor in a rabbit model.…”

A New Era of Intraoperative Neuromonitoring: Beyond the Electromyography Endotracheal Tube During Thyroid Surgery

“…If either electrode has poor contact, accurate EMG measurements cannot be made. Therefore, instead of evaluating muscle movements using EMG, novel IONM systems that mea- [11,12]. In the future, these sensors can be further developed into skin adhesive sensors or endotracheal tube-attached sensors.…”

“…If either electrode has poor contact, accurate EMG measurements cannot be made. Therefore, instead of evaluating muscle movements using EMG, novel IONM systems that measure muscle movements with a new single sensor, such as a surface pressure sensor or an accelerometer based on a piezo-electric sensor, have been introduced [ 11 , 12 ]. In the future, these sensors can be further developed into skin adhesive sensors or endotracheal tube-attached sensors.…”