This study presents single-fiber electromyography (EMG) analysis for assessment of paretic muscle changes after stroke. Single-fiber action potentials (SFAPs) were recorded from the first dorsal interosseous (FDI) muscle bilaterally in 12 individuals with hemiparetic stroke. The SFAP parameters, including the negative peak duration and the peak-peak amplitude, were measured and further used to estimate muscle fiber diameter through a model based on the quadratic function. The SFAP parameters, fiber density, and muscle fiber diameter derived from the model were compared between the paretic and contralateral muscles. The results show that SFAPs recorded from the paretic muscle had significantly smaller negative peak duration than that from the contralateral muscle. As a result, the derived muscle fiber diameter of the paretic muscle was significantly smaller than that of the contralateral muscle. The fiber density of the paretic muscle was significantly higher than that of the contralateral muscle. These results provide further evidence of remodeled motor units after stroke and suggest that paretic muscle weakness can be due to both complex central and peripheral neuromuscular alterations.

中文翻译：

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单纤维肌电图检查中风后肌纤维直径和密度的变化

本研究提出了单纤维肌电图 (EMG) 分析，用于评估中风后的麻痹性肌肉变化。在 12 名偏瘫性卒中患者的双侧第一背侧骨间 (FDI) 肌肉中记录了单纤维动作电位 (SFAP)。测量 SFAP 参数，包括负峰持续时间和峰峰幅度，并通过基于二次函数的模型进一步用于估计肌纤维直径。比较了麻痹肌肉和对侧肌肉的 SFAP 参数、纤维密度和模型得出的肌纤维直径。结果表明，从麻痹肌肉记录的 SFAP 的负峰值持续时间明显小于对侧肌肉的负峰值持续时间。因此，麻痹肌的衍生肌纤维直径明显小于对侧肌。麻痹肌纤维密度明显高于对侧肌纤维密度。这些结果提供了中风后运动单位重塑的进一步证据，并表明麻痹性肌无力可能是由于复杂的中枢和外周神经肌肉改变。