Fact and fallacy in measurement of conduction velocity in motor nerves

Abstract

An assessment of possible sources of error in measurement of conduction velocity in motor nerves is presented. Suitable precautions must be used in studies of human peripheral nerve due to the fact that conduction velocity varies widely with temperature. Many calculations should be employed in standardizing the oscilloscope for a study of muscle response to nerve stimulus. Errors in the measurement of latency can be due to faulty triggering of the oscilloscope, positioning pickup electrode too far from the end-plate zone of the muscle and non-adjusted amplifier gain. It is important that the nerve stimulus is above threshold for all fibers. It must be remembered that the conduction length estimated by surface measurements is only approximate. No borderline values of conduction velocity should be accepted until confirmed by one or more repeat observations with special attention to methodological detail. Anatomically, double innervation is common and there is the possibility of "anastomis" between peripheral nerves to be considered.