Acuña Samuel A, Tyler Mitchell E, Thelen Darryl G
Department of Bioengineering, 3298George Mason University, Fairfax, VA, USA.
Center for Adaptive Systems of Brain-Body Interactions, 3298George Mason University, Fairfax, VA, USA.
Neurorehabil Neural Repair. 2022 Apr;36(4-5):317-327. doi: 10.1177/15459683221081064. Epub 2022 Mar 23.
Synergy analysis provides a means of quantifying the complexity of neuromuscular control during gait. Prior studies have shown evidence of reduced neuromuscular complexity during gait in individuals with neurological disorders associated with stroke, cerebral palsy, and Parkinson's disease.
The purpose of this study was to investigate neuromuscular complexity during gait in individuals who experienced a prior traumatic brain injury (TBI) that resulted in chronic balance deficits.
We measured and analyzed lower extremity electromyographic data during treadmill and overground walking for 44 individuals with residual balance deficits from a mild-to-moderate TBI at least 1 year prior. We also tested 20 unimpaired controls as a comparison. Muscle synergies were calculated for each limb using non-negative matrix factorization of the activation patterns for 6 leg muscles. We quantified neuromuscular complexity using Walk-DMC, a normalized metric of the total variance accounted for by a single synergy, in which a Walk-DMC score of 100 represents normal variance accounted for. We compared group average synergy structures and inter-limb similarity using cosine similarity. We also quantified each individual's gait and balance using the Sensory Organization Test, the Dynamic Gait Index, and the Six-Minute Walk Test.
Neuromuscular complexity was diminished for individuals with a prior TBI. Walk-DMC averaged 92.8 ± 12.3 for the TBI group during overground walking, which was significantly less than seen in controls (100.0 ± 10.0). Individuals with a prior TBI exhibited 13% slower overground walking speeds than controls and reduced performance on the Dynamic Gait Index (18.5 ± 4.7 out of 24). However, Walk-DMC measures were insufficient to stratify variations in assessments of gait and balance performance. Group average synergy structures were similar between groups, although there were considerable between-group differences in the inter-limb similarity of the synergy activation vectors.
Individuals with gait and balance deficits due to a prior TBI exhibit evidence of decreased neuromuscular complexity during gait. Our results suggest that individuals with TBI exhibit similar muscle synergy weightings as controls, but altered control of the temporal activation of these muscle weightings.
协同分析提供了一种量化步态中神经肌肉控制复杂性的方法。先前的研究表明，患有与中风、脑瘫和帕金森病相关的神经系统疾病的个体在步态中神经肌肉复杂性降低。
本研究的目的是调查既往有创伤性脑损伤（TBI）并导致慢性平衡缺陷的个体在步态中的神经肌肉复杂性。
我们测量并分析了44名至少在1年前有轻度至中度TBI且存在残余平衡缺陷的个体在跑步机上行走和地面行走时的下肢肌电图数据。我们还测试了20名未受损的对照组作为比较。使用6条腿部肌肉激活模式的非负矩阵分解计算每个肢体的肌肉协同作用。我们使用Walk-DMC量化神经肌肉复杂性，Walk-DMC是一种由单一协同作用解释的总方差的标准化指标，其中Walk-DMC评分为100表示正常方差解释。我们使用余弦相似度比较组平均协同结构和肢体间相似度。我们还使用感觉组织测试、动态步态指数和六分钟步行测试量化每个个体的步态和平衡。
既往有TBI的个体神经肌肉复杂性降低。TBI组在地面行走时Walk-DMC平均为92.8±12.3，显著低于对照组（100.0±10.0）。既往有TBI的个体地面行走速度比对照组慢13%，动态步态指数表现降低（满分24分，得分为18.5±4.7）。然而，Walk-DMC测量不足以区分步态和平衡性能评估中的差异。尽管协同激活向量的肢体间相似度在组间存在相当大的差异，但组平均协同结构在组间相似。
既往有TBI导致步态和平衡缺陷的个体在步态中表现出神经肌肉复杂性降低的证据。我们的结果表明，TBI个体表现出与对照组相似的肌肉协同权重，但这些肌肉权重的时间激活控制发生了改变。
