Simulation analysis of conduction block in myelinated axons induced by high-frequency biphasic rectangular pulses.

Nerve conduction block induced by high-frequency biphasic rectangular pulses was analyzed using a lumped circuit model of the myelinated axon based on Frankenhaeuser-Huxley (FH) equations. At the temperature of 37 degrees C, axons of different diameters (2-20 microm) can be blocked completely at supra-threshold intensities when the stimulation frequency is above 10 kHz. However, at stimulation frequencies between 6 kHz and 9 kHz, both nerve block and repetitive firing of action potentials can be observed at different stimulation intensities. When the stimulation frequency is below 6 kHz, nerve block does not occur regardless of stimulation intensity. Larger diameter axons have a lower threshold intensity to induce conduction block. When temperature is reduced from 37 degrees C to 20 degrees C, the lowest frequency to completely block large axons (diameters 10-20 microm) decreased from 8 kHz to 4 kHz. This simulation study can guide future animal experiments as well as optimize stimulation waveforms for electrical nerve block in clinical applications.