An Analysis of Agreement between MMG vs. EMG Systems for Identification of Nerve Location During Spinal Procedures

Abstract

Neural injury is a major risk of surgical procedures. Traditional surgical exposures emphasize landmark recognition in order to avoid neural injury. As newer MIS techniques develop, neural protection has become an ever-increasing challenge. The utilization of intraoperative neurophysiologic monitoring is becoming a common tool to aid surgeons with neural identification and avoidance. Standard techniques for nerve localization and avoidance employ electromyography (EMG). EMG functions by measuring the electrical activity generated by muscle cells during contraction. This electrical activity is measured and recorded by either surface electrodes or percutaneous needle electrodes. EMG signals are prone to interference, and the analysis of EMG signals is a complex process that is poorly understood by most surgeons, usually requiring specialty training for interpretation. An alternative to EMG, Mechanomyography (MMG), functions by detecting and measuring the motion of contracting muscle using accelerometry. Interpretation of an MMG signal does not require a specialty trained technician or neurologist, it is simply “STOP - the muscle is contracting… a nerve must be nearby” or “GO - no muscle activity detected”.