Department of Neurology, Teikyo University School of Medicine, Tokyo, Japan.
Department of Clinical Neurophysiology, Institute of Neuroscience, Uppsala University, Uppsala, Sweden.
Muscle Nerve. 2020 Dec;62(6):735-741. doi: 10.1002/mus.27072. Epub 2020 Sep 29.
Size index (SI) is a motor unit potential (MUP) parameter in concentric needle electromyography calculated from amplitude and area/amplitude, which can sensitively discriminate between control and neurogenic MUPs. In this study, we investigated the application of SI to myogenic MUPs based on expanded data.
MUPs were collected from the biceps brachii (BB) and tibialis anterior (TA) muscles. Muscles showing unequivocal neurogenic or myogenic changes by visual inspection were selected for patients. In addition to the original SI, a revised SI (rSI) was defined using the logarithmic scale for area/amplitude. The coefficient for area/amplitude was varied and that achieving the best sensitivity both for BB and TA was selected.
Analyzed were 1619, 340, and 498 MUPs from the BB of 26, 10, and 14 subjects (control, neurogenic, and myogenic), respectively, and 1245, 536, and 473 MUPs from the TA of 23, 18, and 13 subjects (control, neurogenic, and myogenic), respectively. For neurogenic MUPs, the original SI and the newly defined rSIn were similarly sensitive (82.1% and 81.8% sensitivity for SI and rSIn, respectively, for BB, and 68.1% and 69.6% for TA), and were more sensitive than area (72.6% for BB and 57.6% for TA), the most sensitive parameter among conventional ones. For myogenic MUPs, the sensitivity of rSIm was 9.0% for BB and 24.5% for TA, which was not significantly different from duration (7.4% for BB and 21.8% for TA), the most sensitive parameter among conventional ones.
SI, rSIn, and rSIm are promising as new MUP parameters.
大小指数（SI）是一种在同心针肌电图中从幅度和面积/幅度计算得出的运动单位电位（MUP）参数，它可以灵敏地区分控制和神经源性 MUP。在这项研究中，我们基于扩展数据研究了 SI 在肌源性 MUP 中的应用。
从肱二头肌（BB）和胫骨前肌（TA）中采集 MUP。选择通过视觉检查显示出明确神经源性或肌源性变化的肌肉进行患者检查。除了原始 SI 外，还使用对数标度定义了一个修正的 SI（rSI）。对面积/幅度的系数进行了变化，并选择了对 BB 和 TA 都具有最佳灵敏度的系数。
分析了 26 名、10 名和 14 名受试者的 BB 中的 1619、340 和 498 个 MUP（分别为对照、神经源性和肌源性），以及 23 名、18 名和 13 名受试者的 TA 中的 1245、536 和 473 个 MUP（分别为对照、神经源性和肌源性）。对于神经源性 MUP，原始 SI 和新定义的 rSIn 具有相似的灵敏度（SI 和 rSIn 的灵敏度分别为 82.1%和 81.8%，对于 BB，68.1%和 69.6%对于 TA），并且比面积（BB 为 72.6%，TA 为 57.6%）更敏感，面积是常规参数中最敏感的参数。对于肌源性 MUP，rSIm 的灵敏度在 BB 中为 9.0%，在 TA 中为 24.5%，与传统参数中最敏感的参数——持续时间（BB 中为 7.4%，TA 中为 21.8%）没有显著差异。
SI、rSIn 和 rSIm 是很有前途的新 MUP 参数。
