Simulation of nerve block by high-frequency sinusoidal electrical current based on the Hodgkin-Huxley model

Nerve conduction block induced by high-frequency sinusoidal electrical current was simulated using a lumped circuit model of the unmyelinated axon based on Hodgkin-Huxley equations. Axons of different diameters (1-20 /spl mu/m) can be blocked when the stimulation frequency is above 4 kHz. At higher frequency, a higher stimulation intensity is needed to block nerve conduction. Larger diameter axons have a lower threshold intensity for conduction block. High-frequency sinusoidal electrical currents are less effective in blocking nerve conduction than biphasic square pulses of the same frequency. The activation of potassium channels, rather than inactivation of sodium channels, is the possible mechanism underlying the nerve conduction block of the unmyelinated axon induced by high-frequency biphasic (sinusoidal or square pulse) stimulation. This simulation study, which provides more information about the axonal conduction block induced by high-frequency sinusoidal currents, can guide future animal experiments, as well as optimize stimulation waveforms for electrical nerve block in possible clinical applications.