SOMATOSENSORY CONDUCTION VELOCITY DISTRIBUTION OF MEDIAN NERVE MIDDLE PALMAR DIGITAL COMPONENT

Abstract

Collision technique is one of the methods used to obtain the relative number of fibers in a nerve bundle. In 25 normal subjects, the right median nerve has been concurrently stimulated at proximal (elbow) and distal (wrist) locations, and the resultant compound action potentials (CAP) were recorded at the middle finger via ring electrodes. The delay between the two stimuli (Inter Stimulus Interval; ISI), beginning from 7 ms, has been decreased in 0.1 ms steps, until the CAPs, elicited by proximal stimulation, totally disappeared. The obtained data have been transferred to computer medium for further analysis. In this procedure, areas under proximal CAPs have been obtained for each ISI value. Using these areas, the relative numbers of fibers (%) belonging to the middle proper palmar digital (MPPD) component of sensory median nerve have been derived. The mean conduction velocities in MPPD component of sensory median nerve ranged from 40 m/s to 68 m/s. In the histogram,a large amount of heaping of the relative number of fibers has been observed in 48-59 m/s conduction velocity interval with the ratio of 64%, although there has been a 21% group having 43-47 ms conduction velocity. These results can be a guide to future studies concerning basic and clinical nerve conduction studies