局限性束缩短和束旋转可能与慢性脑卒中幸存者的羽状肌自主产生力量的能力受损有关。
Limited fascicle shortening and fascicle rotation may be associated with impaired voluntary force-generating capacity in pennate muscles of chronic stroke survivors.
机构信息
Shirley Ryan AbilityLab (formerly Rehabilitation Institute of Chicago), Chicago, IL, United States; Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States.
Shirley Ryan AbilityLab (formerly Rehabilitation Institute of Chicago), Chicago, IL, United States; Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States.
出版信息
Clin Biomech (Bristol). 2020 May;75:105007. doi: 10.1016/j.clinbiomech.2020.105007. Epub 2020 Apr 19.
BACKGROUND
Muscle weakness is one of the most common motor impairments after stroke. A variety of progressive muscular changes are reported in chronic stroke survivors, and it is now feasible to consider these changes as an added source of weakness. However, the net contributions of such muscular changes towards muscle weakness have not been fully quantified.
METHODS
Accordingly, this study aims: (1) to compare muscle architecture of the human medial gastrocnemius between paretic and non-paretic sides in seven chronic hemispheric stroke survivors under passive conditions; (2) to characterize fascicle behavior (i.e., fascicle shortening and fascicle rotation) of the muscle during voluntary isometric contractions; and (3) to assess potential associations between muscle architectural parameters and muscle weakness. Muscle architecture of the medial gastrocnemius (including fascicle length, fascicle pennation angle, and muscle thickness) was characterized using B-mode ultrasonography, and fascicle behavior was then quantified as a function of isometric plantarflexion torque normalized to body mass.
FINDINGS
Our experimental results showed that under passive conditions, there was a significant difference in fascicle length and muscle thickness between paretic and non-paretic muscles, but no difference in resting fascicle pennation angle. However, during isometric contraction, both fascicle shortening and fascicle rotation on the paretic side were significantly decreased, compared to the non-paretic side. Moreover, the relative (i.e., paretic/non-paretic) fascicle rotation-shortening ratio (i.e., fascicle rotation per fascicle shortening) was strongly correlated with the relative maximum voluntary isometric plantarflexion torque.
INTERPRETATION
This association implies that such fascicle changes could impair the force-generating capacity of the muscle in chronic stroke survivors.
背景
肌肉无力是中风后最常见的运动障碍之一。慢性中风幸存者报告了多种进行性肌肉变化，现在可以将这些变化视为肌肉无力的另一个来源。然而，这些肌肉变化对肌肉无力的净贡献尚未完全量化。
方法
因此，本研究旨在：（1）在 7 名慢性大脑半球中风幸存者中，在被动条件下比较瘫痪侧和非瘫痪侧内侧腓肠肌的肌肉结构；（2）在等长等速收缩期间，对肌肉的肌束行为（即肌束缩短和肌束旋转）进行特征描述；（3）评估肌肉结构参数与肌肉无力之间的潜在关联。使用 B 型超声对内侧腓肠肌的肌肉结构（包括肌束长度、肌束羽状角和肌肉厚度）进行了特征描述，然后根据肌肉厚度归一化的等长跖屈扭矩对肌束行为进行了量化。
结果
我们的实验结果表明，在被动条件下，瘫痪侧和非瘫痪侧的肌束长度和肌肉厚度存在显著差异，但静息肌束羽状角无差异。然而，在等长收缩期间，与非瘫痪侧相比，瘫痪侧的肌束缩短和肌束旋转均显著减小。此外，相对（即瘫痪/非瘫痪）肌束旋转-缩短比（即肌束旋转除以肌束缩短）与相对最大自主等长跖屈扭矩呈强烈相关。
解释
这种关联意味着这些肌束变化可能会削弱慢性中风幸存者肌肉的产生力量的能力。
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