Chapter 15 - Degree of Pathology

Summary

Slowed conduction in a demyelinated nerve is proportional to the degree of pathology. More severe pathology leads to conduction block and ultimately to degeneration of the nerve. Degeneration causes the amplitudes of the action potentials, sensory nerve action potentials (SNAPs) or compound muscle action potentials (CMAPs), to be reduced. Unfortunately, the positively skewed distribution of these severely limits their clinical usefulness in assessing the degree of pathology. The demonstration of unstable nascent potentials can be a useful sign that motor nerve regeneration is occurring but, in general, the contribution of electrophysiological techniques to the monitoring of peripheral nerve degeneration is disappointing.