Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark; UCL Queen Square Institute of Neurology, Queen Square, London, UK.
Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark.
Clin Neurophysiol. 2019 Sep;130(9):1734-1740. doi: 10.1016/j.clinph.2019.05.031. Epub 2019 Jun 22.
MUNIX (motor unit number index), derived from the compound muscle action potential (CMAP) and surface EMG interference pattern (SIP) has become popular as a substitute for motor unit number estimation (MUNE). This study was undertaken to determine why, in recent recordings from amyotrophic lateral sclerosis (ALS) patients and healthy controls, we found that MUNIX values resembled CMAP amplitudes more closely than MUNE values.
The relationship between MUNIX and CMAP and SIP amplitudes was investigated by a theoretical analysis and by reanalysing the data from the previous study.
Theory indicates that when motor unit potentials overlap extensively, information about motor unit size and number is lost, and MUNIX depends only on CMAP area and power. Accordingly, MUNIX values were found to be sensitive to changes in CMAP amplitude but insensitive to changes in SIP amplitude. The reproducibility of MUNIX measurements in healthy controls was found to depend almost entirely on correlation with CMAP properties.
MUNIX gives misleading information about motor unit numbers in healthy controls, and provides little information about loss of motor units in ALS patients beyond that given by simple CMAP amplitude measurements.
MUNIX should not be interpreted as a MUNE method.
MUNIX（运动单位数量指数）源自复合肌肉动作电位（CMAP）和表面肌电图干扰模式（SIP），已成为替代运动单位数量估计（MUNE）的热门方法。本研究旨在确定为什么在最近对肌萎缩侧索硬化症（ALS）患者和健康对照者的记录中，我们发现 MUNIX 值与 CMAP 幅度比 MUNE 值更密切相关。
通过理论分析和重新分析先前研究的数据，研究了 MUNIX 与 CMAP 和 SIP 幅度之间的关系。
理论表明，当运动单位电位广泛重叠时，关于运动单位大小和数量的信息就会丢失，而 MUNIX 仅取决于 CMAP 面积和功率。因此，发现 MUNIX 值对 CMAP 幅度的变化敏感，但对 SIP 幅度的变化不敏感。在健康对照者中，MUNIX 测量的可重复性几乎完全取决于与 CMAP 特性的相关性。
在健康对照者中，MUNIX 提供了有关运动单位数量的误导信息，并且在 ALS 患者中除了简单的 CMAP 幅度测量之外，对运动单位丧失的信息提供很少。
MUNIX 不应被解释为 MUNE 方法。
