Decrease in nerve temperature: a model for increased temporal dispersion.
A decrease in nerve temperature causes a proportional decrease in conduction velocity which, in percentage terms, is equal for all nerve fibers. The absolute decrease in conduction velocity is larger for faster conducting nerve fibers. This results in a compression and a shift to lower values of the conduction velocity distribution and an increase in temporal dispersion. The purpose of this study was to determine if these effects could be detected by a combination of two collision techniques designed to obtain the motor conduction velocity distribution and refractory period distribution. In 12 healthy volunteers we measured the conduction velocity distribution in the median nerve at nerve temperatures of 25 and 40 degrees C. The results showed that our method could detect the predicted changes in conduction velocity distribution and temporal dispersion. We conclude that temperature change is a model that can be used to study temporal dispersion. This may be a first step towards distinguishing between the effects of conduction block and (abnormal) temporal dispersion in demyelinated nerve fibers.