Faculty of Frontier Engineering, Institute of Science & Engineering, Kanazawa University, Kanazawa, Japan.
Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor, Slovenia.
Clin Neurophysiol. 2022 Oct;142:262-272. doi: 10.1016/j.clinph.2022.06.016. Epub 2022 Jul 16.
The purpose of this study was to detect specific motor unit (MU) abnormalities in people with amyotrophic lateral sclerosis (ALS) compared to controls using high-density surface electromyography (HD-SEMG).
Sixteen people with ALS and 16 control subjects. The participants performed ramp up and sustained contractions at 30% of their maximal voluntary contraction. HD-SEMG signals were recorded in the vastus lateralis muscle and decomposed into individual MU firing behavior using a convolution blind source separation method.
In total, 339 MUs were detected (people with ALS; n = 93, control subjects; n = 246). People with ALS showed significantly higher mean firing rate, recruitment threshold, coefficient of variation of the MU firing rate, MU firing rate at recruitment, and motoneurons excitability than those of control subjects (p < 0.001). The number of MU, MU firing rate, recruitment threshold, and MU firing rate at recruitment were significantly correlated with disease severity (p < 0.001). Multivariable analysis revealed that an increased MU firing rate at recruitment was independently associated with ALS.
These results suggest increased excitability at recruitment, which is consistent with neurodegeneration results in a compensatory increase in MU activity.
Abnormal MU firing behavior provides an important physiological index for understanding the pathophysiology of ALS.
本研究旨在通过高密度表面肌电图（HD-SEMG）检测肌萎缩侧索硬化症（ALS）患者与对照组之间特定运动单位（MU）的异常。
共纳入 16 名 ALS 患者和 16 名对照受试者。参与者以 30%的最大随意收缩力进行斜坡上升和持续收缩。在股外侧肌记录 HD-SEMG 信号，并使用卷积盲源分离方法将其分解为单个 MU 放电行为。
共检测到 339 个 MU（ALS 患者，n=93；对照组，n=246）。与对照组相比，ALS 患者的平均放电率、募集阈值、MU 放电率变异系数、募集时 MU 放电率和运动神经元兴奋性明显更高（p<0.001）。MU 的数量、MU 放电率、募集阈值和募集时 MU 放电率与疾病严重程度显著相关（p<0.001）。多变量分析显示，募集时 MU 放电率增加与 ALS 独立相关。
这些结果表明募集时兴奋性增加，这与神经退行性变导致 MU 活动代偿性增加的结果一致。
异常 MU 放电行为为理解 ALS 的病理生理学提供了重要的生理指标。
