Hong Yoon No G, Roh Jinsook
Department of Biomedical Engineering, University of Houston, Houston, TX, United States.
Front Neurol. 2023 Sep 22;14:1280276. doi: 10.3389/fneur.2023.1280276. eCollection 2023.
Stroke survivors have challenges appropriately coordinating the multiple muscles, resulting in a deficit in motor control. Therefore, comprehending the mechanism underlying abnormal intermuscular coordination becomes crucial in developing effective rehabilitation strategies. Quantitative analyses have been employed at pairwise or multi-dimensional levels to understand the underlying mechanism of abnormal intermuscular coordination and its relationship to motor impairment. However, how alterations in individual muscle activation contribute to abnormal intermuscular coordination, motor impairment, and motor performance remains unclear. Thus, we investigated the alterations in the preferred direction of individual muscles after stroke and their relationship with stroke-induced changes in intermuscular coordination, clinical motor impairment, and qualities of motor performance during isometric force generation in the upper extremity.
Twenty-four stroke survivors and six age-matched controls were recruited and performed isometric force target matches while recording electromyographic signals from eight upper limb muscles. We determined the preferred activation direction of each muscle, evaluated abnormal intermuscular coordination through a muscle synergy analysis, assessed motor impairment using upper extremity Fugl-Meyer Assessment scores, and examined motor performance characteristics defined by force trajectory features.
The post-stroke alterations in the preferred direction of the brachioradialis, anterior, middle, and posterior deltoid were correlated with the motor impairment level and attributed to the changes in muscle synergy characteristics. Only alterations in the preferred direction of the brachioradialis and posterior deltoid activation in forward-backward and upward-downward axes were associated with the qualities of isometric force generation, respectively.
These findings imply that alterations in the preferred direction of individual muscle activation contribute to various aspects of motor deficit following stroke. This insight may serve as a foundation for the development of innovative stroke neurorehabilitation approaches that take into account specific attributes of individual muscle activation, including their preferred activation direction.
中风幸存者在协调多块肌肉时面临挑战，导致运动控制能力不足。因此，了解异常肌间协调背后的机制对于制定有效的康复策略至关重要。已采用成对或多维度水平的定量分析来理解异常肌间协调的潜在机制及其与运动障碍的关系。然而，个体肌肉激活的改变如何导致异常肌间协调、运动障碍和运动表现仍不清楚。因此，我们研究了中风后个体肌肉首选激活方向的改变及其与上肢等长力产生过程中肌间协调的中风诱导变化、临床运动障碍和运动表现质量的关系。
招募了24名中风幸存者和6名年龄匹配的对照组，在记录来自八块上肢肌肉的肌电信号的同时进行等长力目标匹配。我们确定了每块肌肉的首选激活方向，通过肌肉协同分析评估异常肌间协调，使用上肢Fugl-Meyer评估评分评估运动障碍，并检查由力轨迹特征定义的运动表现特征。
中风后肱桡肌、三角肌前束、中束和后束的首选方向改变与运动障碍水平相关，并归因于肌肉协同特征的变化。只有肱桡肌和三角肌后束在前后和上下轴上的首选激活方向改变分别与等长力产生的质量相关。
这些发现表明，个体肌肉激活首选方向的改变导致中风后运动缺陷的各个方面。这一见解可为开发创新的中风神经康复方法提供基础，该方法考虑到个体肌肉激活的特定属性，包括其首选激活方向。
