Gao Farong, Cao Yueying, Zhang Chuan, Zhang Yingchun
School of Automation, Artificial Intelligence Institute, Hangzhou Dianzi University, Hangzhou, China.
Department of Biomedical Engineering, University of Houston, Houston, TX, United States.
Front Neurol. 2020 Mar 17;11:191. doi: 10.3389/fneur.2020.00191. eCollection 2020.
Motor Unit Number Index (MUNIX) is a technique that provides a susceptive biomarker for monitoring innervation conditions in patients with neurodegenerative diseases. A satisfactory repeatability is essential for the interpretation of MUNIX results. This study aims to examine the effect of channel number and location on the repeatability of MUNIX. In this study, 128 channels of high-density surface electromyography (EMG) signals were recorded from the biceps brachii muscles of eight healthy participants, at 10, 20, 30, 40, 50, 60, 70, 80, and 100% of maximal voluntary contraction. The repeatability was defined by the coefficient of variation (CV) of MUNIX estimated from three experiment trials. Single-channel MUNIX (sMUNIX) was calculated on a channel-specific basis and a multi-channel MUNIX (mMUNIX) approach as the weighted average of multiple sMUNIX results. Results have shown (1) significantly improved repeatability with the proposed mMUNIX approach; (2) a higher variability of sMUNIX when the recording channel is positioned away from the innervation zone. Our results have demonstrated that (1) increasing the number of EMG channels and (2) placing recording channels close to the innervation zone (IZ) are effective methods to improve the repeatability of MUNIX. This study investigated two potential causes of MUNIX variations and provided novel perspectives to improve the repeatability, using high-density surface EMG. The mMUNIX technique proposed can serve as a promising tool for reliable neurodegeneration evaluation.
运动单位数量指数（MUNIX）是一种可为监测神经退行性疾病患者的神经支配状况提供敏感生物标志物的技术。MUNIX结果的解读需要令人满意的重复性。本研究旨在探讨通道数量和位置对MUNIX重复性的影响。在本研究中，从八名健康参与者的肱二头肌记录了128通道的高密度表面肌电图（EMG）信号，记录时的肌肉收缩强度分别为最大自主收缩的10%、20%、30%、40%、50%、60%、70%、80%和100%。重复性由三次实验测得的MUNIX变异系数（CV）定义。单通道MUNIX（sMUNIX）是基于特定通道计算得出的，多通道MUNIX（mMUNIX）方法则是多个sMUNIX结果的加权平均值。结果表明：（1）所提出的mMUNIX方法可显著提高重复性；（2）当记录通道远离神经支配区时，sMUNIX的变异性更高。我们的结果表明，（1）增加EMG通道数量和（2）将记录通道放置在靠近神经支配区（IZ）的位置是提高MUNIX重复性的有效方法。本研究调查了MUNIX变异的两个潜在原因，并利用高密度表面EMG提供了提高重复性的新视角。所提出的mMUNIX技术可作为一种有前景的工具用于可靠的神经退行性评估。
