CMAP DISPERSION, AMPLITUDE DECAY, AND AREA DECAY IN A NORMAL POPULATION

The aim of this investigation was to define the boundaries of compound motor action potential (CMAP) dispersion, amplitude decay, and area d ecay in a control population and determine their dependence on externa l variables such as age and interelectrode distance. Measurements were made from median. ulnar, and common peroneal motor nerves of 110 norm al subjects of ages 15-90 years. Significant differences between nerve s-were found in mean values of each parameter. Dispersion and amplitud e decay increased with the square of age in all three nerves, while ar ea decay increased with age in the median nerve. Dispersion was the ma in cause of amplitude decay. Use of regression equations to predict di spersion and amplitude decay in each nerve significantly tightened con fidence limits and should therefore increase the accuracy of these par ameters in detecting demyelinating pathology in peripheral nerve. (C) 1993 John Wiley & Sons, Inc.