The Forward Problem in Electroneurography II: Comparson of Models

We present a comparison of the various model descriptions of the evoked compound action potential (CAP) of a peripheral nerve as have appeared in literature. First, a survey is given of both theoretical and empirical model formulations, concentrating upon the different descriptions of SFAP variation among the active fibers. The relationships between the various model formulations are clarified and the involved assumptions are discussed. Then, using computer calculations of both single fiber and compound action potentials, the differences in signal characteristics as predicted by the different models are studied. It is concluded that the models show distinct differences in the predicted potentials, which are revealed more clearly in near-nerve recordings in pathological nerves. Apart from these differences, however, adequate interpretation of the fiber population-statistics and of volume conductor characteristics prove to be the most essential prerequisites in CAP analysis.