An Examination of the Motor Unit Number Index (MUNIX) in muscles paralyzed by spinal cord injury.

Xiaoyan Li, Faezeh Jahanmiri-Nezhad, William Zev Rymer, Ping Zhou
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引用次数: 42

Abstract

The objective of this study was to assess whether there is evidence of motor unit loss in muscles paralyzed by spinal cord injury (SCI), using a measurement called motor unit number index (MUNIX). The MUNIX technique was applied in SCI (n=12) and neurologically intact (n=12) subjects. The maximum M waves and voluntary surface electromyography (EMG) signals at different muscle contraction levels were recorded from the first dorsal interosseous (FDI) muscle in each subject. The MUNIX values were estimated using a mathematical model describing the relation between the surface EMG signal and the ideal motor unit number count derived from the M wave and surface EMG measurements. We recorded a significant decrease in both maximum M wave amplitude and in estimated MUNIX values in paralyzed FDI muscles, as compared with neurologically intact muscles. Across all subjects, the maximum M wave amplitude was 8.3 ± 4.4 mV for the paralyzed muscles and 14.4 ± 2.0 mV for the neurologically intact muscles (p<0.0001). These measurements, when combined with voluntary EMG recordings, resulted in a mean MUNIX value of 112 ± 71 for the paralyzed muscles, much lower than the mean MUNIX value of 228 ± 49 for the neurologically intact muscles (p<0.00001). A motor unit size index was also calculated, using the maximum M wave recording and the MUNIX values. We found that paralyzed muscles showed a mean motor unit size index value of 80.7 ± 17.7 ìV, significantly higher than the mean value of 64.9 ± 10.1 ìV obtained from neurologically intact muscles (p<0.001). The MUNIX method used in this study offers several practical benefits compared with the traditional motor unit number estimation technique because it is noninvasive, induces minimal discomfort due to electrical nerve stimulation, and can be performed quickly. The findings from this study help understand the complicated determinants of SCI induced muscle weakness and provide further evidence of motoneuron degeneration after a spinal injury.

脊髓损伤致瘫痪肌肉运动单位数指数(MUNIX)的研究。
本研究的目的是评估脊髓损伤(SCI)瘫痪的肌肉是否存在运动单元丧失的证据,使用一种称为运动单元数指数(MUNIX)的测量方法。MUNIX技术应用于脊髓损伤(n=12)和神经完整(n=12)受试者。记录每个受试者第一背骨间肌在不同肌肉收缩水平下的最大M波和随意表面肌电(EMG)信号。MUNIX值是用一个数学模型来估计的,该数学模型描述了表面肌电信号与由M波和表面肌电信号测量得出的理想运动单元数之间的关系。我们记录到,与神经完整的肌肉相比,FDI瘫痪肌肉的最大M波振幅和估计的mnunix值都显著下降。在所有受试者中,瘫痪肌肉的最大M波振幅为8.3±4.4 mV,神经完整肌肉的最大M波振幅为14.4±2.0 mV (p
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来源期刊
IEEE Transactions on Information Technology in Biomedicine
IEEE Transactions on Information Technology in Biomedicine 工程技术-计算机:跨学科应用
自引率
0.00%
发文量
1
审稿时长
4.8 months
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