The association between nerve conduction velocity and the compound action potential amplitude during ischemic blocking.

It is not known in detail how the compound sensory nerve action potential amplitude and conduction velocity are associated in nerve ischemia or in other conditions like carpal tunnel syndrome. Ischemia was produced by inflating a tourniquet around the upper arm in five healthy subjects. When median sensory nerve conduction velocities and action potential amplitudes were recorded from the third digit, they decreased in parallel, thereby resembling the blocking process during wrist flexion in healthy subjects. The area under the action potential decreased earlier with longer distances during the ischemic blocking process. A theoretical model is presented in which the area under the compound nerve action potential is determined by the probability for the single fibre action potential to propagate through the internodal distance. This in turn is associated with the internodal conduction time.