Department of Neurology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, Toyota, Japan.
Muscle Nerve. 2023 Aug;68(2):149-156. doi: 10.1002/mus.27824. Epub 2023 Apr 6.
INTRODUCTION/AIMS: In amyotrophic lateral sclerosis (ALS), the impact of motor neuron dysfunction on the motor unit (MU) firing pattern remains to be elucidated. The aim of this study was to clarify the characteristics of the MU firing rate and its association with clinical factors in ALS patients using high-density surface electromyography (HDSEMG) and MU decomposition analysis.
Nineteen ALS patients and 20 controls prospectively underwent HDSEMG recording of the vastus lateralis muscle during ramp-up (30% of maximum voluntary contraction) and sustained (10% of maximal voluntary contraction for 60 seconds) contractions on performing isometric knee extension. After decomposition analysis, instantaneous firing rates (IFRs) of individually identified MUs were calculated. Comparison of IFRs and clinical variables between ALS patients and controls and analysis of the correlation between individual mean IFR and clinical variables in ALS patients were performed.
The number of identified MUs was lower in ALS patients than in controls (P = .017). Mean IFRs of MUs (i.e., mean MU firing rates) were higher in ALS patients than in controls at some force levels on ramp-up contraction (P < .05) and at 50 to 60 seconds during sustained contraction (9.1 [ALS] vs 8.3 [controls] pulses per second; P = .036). There was no correlation between the clinical parameters and mean IFR of each patient.
ALS patients had a higher MU firing rate during muscle contraction at a low force level. Noninvasive assessment of the MU firing rate by HDSEMG can detect a motor neuronal hyperexcitable state in ALS patients.
简介/目的：在肌萎缩侧索硬化症（ALS）中，运动神经元功能障碍对运动单位（MU）放电模式的影响仍有待阐明。本研究旨在使用高密度表面肌电图（HDSEMG）和 MU 分解分析，阐明 ALS 患者 MU 放电率的特征及其与临床因素的关系。
19 名 ALS 患者和 20 名对照者前瞻性地接受了股外侧肌的 HDSEMG 记录，在进行等长膝关节伸展时，进行斜坡上升（最大随意收缩的 30%）和持续收缩（最大随意收缩的 10%，持续 60 秒）。在分解分析后，计算个别识别 MU 的瞬时放电率（IFR）。比较 ALS 患者和对照组的 IFR 和临床变量，并分析 ALS 患者个体平均 IFR 与临床变量之间的相关性。
在 ALS 患者中，识别的 MU 数量低于对照组（P = .017）。在斜坡上升收缩时的某些力水平上（P < .05）和在持续收缩的 50 到 60 秒时（9.1 [ALS] vs 8.3 [对照组] 脉冲/秒；P = .036），MU 的平均 IFR（即 MU 放电率的平均值）在 ALS 患者中高于对照组。临床参数与每位患者的平均 IFR 之间没有相关性。
在低力水平的肌肉收缩期间，ALS 患者的 MU 放电率较高。HDSEMG 对 MU 放电率的非侵入性评估可以检测 ALS 患者运动神经元的过度兴奋状态。
