Altered motor unit discharge patterns in paretic muscles of stroke survivors assessed using surface electromyography.
Altered motor unit discharge patterns in paretic muscles of stroke survivors assessed using surface electromyography.
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DOI：
10.1088/1741-2560/13/4/046025
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发表时间：
2016-08
影响因子：
4
通讯作者：
Suresh NL
中科院分区：
文献类型：
--
作者：
Hu X;Suresh AK;Rymer WZ;Suresh NL
半脑卒中幸存者经常表现出随意肌激活受损。这些损伤的一个潜在来源可能来自肌肉控制的改变，通过破坏运动单元（MU）放电模式。在这项研究中，我们试图确定与类似的对侧肌肉相比，中风幸存者患侧的MU放电模式是否被改变。使用一种新型的表面肌电（EMG）传感器阵列，结合先进的模板识别软件（dEMG），我们记录了双亲和对侧第一背骨间肌（FDI）的表面肌电信号。当中风幸存者在大力度范围内（最大力度的20%-60%）产生等距食指外展时进行记录。利用dEMG算法，估计每个试验中同时活动的MU的放电率，招募阈值和动作电位振幅。我们的研究结果揭示了近侧FDI肌放电速率模式的显著变化，放电速率与招募力阈值和MU大小的关系不如对侧FDI肌与招募力的关系明显。受影响肌肉的放电率也不像正常肌肉那样随着随意肌收缩的水平而系统地调节。这些放电特性的干扰也与肌肉力量产生的损害密切相关。我们的研究结果提供了强有力的证据，表明脑卒中后麻痹性肌肉的MU放电行为中断，表明脊髓运动神经元池控制的改变可能是中风幸存者肌肉无力的一个因素。
Hemispheric stroke survivors often show impairments in voluntary muscle activation. One potential source of these impairments could come from altered control of muscle, via disrupted motor unit (MU) firing patterns. In this study, we sought to determine whether MU firing patterns are modified on the affected side of stroke survivors, as compared with the analogous contralateral muscle. Using a novel surface electromyogram (EMG) sensor array, coupled with advanced template recognition software (dEMG) we recorded surface EMG signals over the first dorsal interosseous (FDI) muscle on both paretic and contralateral sides. Recordings were made as stroke survivors produced isometric index finger abductions over a large force range (20%–60% of maximum). Utilizing the dEMG algorithm, MU firing rates, recruitment thresholds, and action potential amplitudes were estimated for concurrently active MUs in each trial. Our results reveal significant changes in the firing rate patterns in paretic FDI muscle, in that the discharge rates, characterized in relation to recruitment force threshold and to MU size, were less clearly correlated with recruitment force than in contralateral FDI muscles. Firing rates in the affected muscle also did not modulate systematically with the level of voluntary muscle contraction, as would be expected in intact muscles. These disturbances in firing properties also correlated closely with the impairment of muscle force generation. Our results provide strong evidence of disruptions in MU firing behavior in paretic muscles after a hemispheric stroke, suggesting that modified control of the spinal motoneuron pool could be a contributing factor to muscular weakness in stroke survivors.