Schneider J, Silny J, Rau G
Helmholtz-Institute for Biomedical Engineering, Aachen, Germany.
IEEE Trans Biomed Eng. 1991 Sep;38(9):851-60. doi: 10.1109/10.83605.
The determination of conduction velocity in the muscle fibers of single motor units from noninvasive recordings of single motor unit action potentials can be improved by the method of spatially filtering multielectrode EMG. The use of this conduction velocity as a diagnostic tool requires a high reliability of the detected values. However, experiments did reveal that the measured conduction velocity values showed remarkably high fluctuations depending on the recording site along the muscle fibers which could not be attributed to the influence of the endplate and tendon region. The present work examines the hypothesis that the observed fluctuations in propagation velocity were caused by electrically inhomogeneous tissue, regions of different electrical conductivity which are located between the excited muscle fibers and the recording electrodes and which cause a deformation of the extracellular electric current field. The investigation was performed by means of a physical model as well as by finite element model calculations. In both models single, simple shaped (cylindrical) inhomogeneity regions with a conductivity of 0.1 to 10 times that of the surrounding medium and diameters ranging between 1.6 and 2.7 mm were placed between excitation sources and recording site. The results indicate that the observed conduction velocity fluctuations of up to some 10% can be well attributed to inhomogeneity effects of the tissue conductivity. Based on these results, one may look for signal processing methods to cut down such fluctuations in conduction velocity measurements.
通过空间滤波多电极肌电图方法，可以改进从单运动单位动作电位的非侵入性记录中确定单个运动单位肌纤维的传导速度。将这种传导速度用作诊断工具需要检测值具有高度可靠性。然而，实验确实表明，所测量的传导速度值显示出明显的高波动，这取决于沿肌纤维的记录部位，而这不能归因于终板和肌腱区域的影响。本研究探讨了以下假设：观察到的传播速度波动是由电不均匀组织引起的，即位于兴奋的肌纤维和记录电极之间的具有不同电导率的区域，这些区域会导致细胞外电流场变形。研究通过物理模型以及有限元模型计算进行。在这两种模型中，在激发源和记录部位之间放置了单个简单形状（圆柱形）的不均匀区域，其电导率为周围介质的0.1至10倍，直径在1.6至2.7毫米之间。结果表明，观察到的高达约10%的传导速度波动可以很好地归因于组织电导率的不均匀性效应。基于这些结果，可以寻找信号处理方法来减少传导速度测量中的此类波动。
