BACKGROUND A proper rehabilitation program targeting gait is mandatory to maintain the quality of life of patients with Myotonic dystrophy type 1 (DM1). Assuming that gait and balance impairment simply depend on the degree of muscle weakness is potentially misleading. In fact, the involvement of the Central Nervous System (CNS) in DM1 pathophysiology calls into account the deterioration of muscle coordination in gait impairment. Our study aimed at demonstrating the presence and role of muscle connectivity deterioration in patients with DM1 by a CNS perspective by investigating signal synergies using a time-frequency spectral coherence and multivariate analyses on lower limb muscles while walking upright. Further, we sought at determining whether muscle networks were abnormal secondarily to the muscle impairment or primarily to CNS damage (as DM1 is a multi-system disorder also involving the CNS). In other words, muscle network deterioration may depend on a weakening in signal synergies (that express the neural drive to muscles deduced from surface electromyography data). METHODS Such an innovative approach to estimate muscle networks and signal synergies was carried out in seven patients with DM1 and ten healthy controls (HC). RESULTS Patients with DM1 showed a commingling of low and high frequencies among muscle at both within- and between-limbs level, a weak direct neural coupling concerning inter-limb coordination, a modest network segregation, high integrative network properties, and an impoverishment in the available signal synergies, as compared to HCs. These network abnormalities were independent from muscle weakness and myotonia. CONCLUSIONS Our results suggest that gait impairment in patients with DM1 depends also on a muscle network deterioration that is secondary to signal synergy deterioration (related to CNS impairment). This suggests that muscle network deterioration may be a primary trait of DM1 rather than a maladaptive mechanism to muscle degeneration. This information may be useful concerning the implementation of proper rehabilitative strategies in patients with DM1. It will be indeed necessary not only addressing muscle weakness but also gait-related muscle connectivity to improve functional ambulation in such patients.

中文翻译：

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为更好地理解强直性肌营养不良症步态障碍的病理生理学铺平道路：一项专注于肌肉网络的试点研究。

背景 针对步态的适当康复计划对于维持强直性肌营养不良 1 型 (DM1) 患者的生活质量是必需的。假设步态和平衡障碍仅仅取决于肌肉无力的程度可能会产生误导。事实上，中枢神经系统 (CNS) 参与 DM1 病理生理学需要考虑步态障碍中肌肉协调性的恶化。我们的研究旨在通过使用时间频谱相干性和直立行走时下肢肌肉的多变量分析来研究信号协同作用，从中枢神经系统的角度证明 DM1 患者肌肉连接性恶化的存在和作用。此外，我们试图确定肌肉网络异常是否继发于肌肉损伤或主要是中枢神经系统损伤（因为 DM1 是一种也涉及中枢神经系统的多系统疾病）。换句话说，肌肉网络的恶化可能取决于信号协同作用（表达从表面肌电图数据推导出来的肌肉神经驱动）的减弱。方法 这种评估肌肉网络和信号协同作用的创新方法在 7 名 DM1 患者和 10 名健康对照 (HC) 中进行。结果 DM1 患者在肢体内和肢体间的肌肉中表现出低频和高频的混合，有关肢体间协调的直接神经耦合较弱，网络分离程度适中，网络集成特性较高，并且神经网络功能贫乏。与 HC 相比，可用的信号协同作用。这些网络异常与肌肉无力和肌强直无关。结论 我们的结果表明，DM1 患者的步态障碍还取决于继发于信号协同恶化（与 CNS 损伤相关）的肌肉网络恶化。这表明肌肉网络退化可能是 DM1 的主要特征，而不是肌肉退化的适应不良机制。该信息对于 DM1 患者实施适当的康复策略可能有用。事实上，不仅需要解决肌肉无力问题，还需要解决与步态相关的肌肉连接性问题，以改善此类患者的功能性行走。