Rhee E K, England J D, Sumner A J
Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia.
Ann Neurol. 1990 Aug;28(2):146-56. doi: 10.1002/ana.410280206.
A reduction in compound muscle action potential (CMAP) amplitude and area following proximal versus distal stimulation is the accepted clinical hallmark of conduction block; however, quantitative criteria for determining conduction block remain ambiguous. In this study, digitized records of individual motor unit action potentials (MUAPs) elicited by incremental stimulation in vivo were arithmetically combined in a computer simulation of CMAP generation. Through simulation of possible phase interaction patterns of individual MUAPs, we have shown that abnormal temporal dispersion alone can produce reductions in CMAP area of up to 50%, values that are commonly thought to represent conduction block. Furthermore, by simulating conduction block without excessive temporal dispersion in defined subpopulations of axons, we have demonstrated the importance of the fastest conducting (largest MUAP) axons in determining CMAP amplitude and area. In conclusion, measurements of CMAP amplitude and area in determining conduction block may be misleading if there is significant abnormal temporal dispersion, and quantitation of the degree of conduction block is difficult without knowledge of which subpopulations of axons are affected.
近端刺激与远端刺激相比，复合肌肉动作电位（CMAP）幅度和面积减小是公认的传导阻滞临床特征；然而，确定传导阻滞的定量标准仍不明确。在本研究中，通过体内递增刺激引出的单个运动单位动作电位（MUAP）的数字化记录，在CMAP产生的计算机模拟中进行算术组合。通过模拟单个MUAP可能的相位相互作用模式，我们已经表明，单独的异常时间离散可导致CMAP面积减少高达50%，而这些值通常被认为代表传导阻滞。此外，通过在定义的轴突亚群中模拟无过度时间离散的传导阻滞，我们已经证明了传导速度最快（MUAP最大）的轴突在确定CMAP幅度和面积方面的重要性。总之，如果存在显著的异常时间离散，在确定传导阻滞时测量CMAP幅度和面积可能会产生误导，并且在不知道哪些轴突亚群受到影响的情况下，很难对传导阻滞程度进行定量。
