High-frequency nerve conduction block.

High frequency alternating current waveforms have been shown to produce a rapidly reversible nerve block in animal models, but the parameters and mechanism of this block are not well understood. A frog sciatic nerve/gastrocnemius muscle preparation was used to examine the parameters for nerve conduction block in vivo. A complete and reversible nerve block was achieved in all preparations. The results indicate that a 100% block of motor activity can be accomplished with a variety of waveform parameters, including sinusoidal and rectangular waveforms at frequencies from 2 kHz to 20 kHz. The most efficient waveform for conduction block was a 3-5 kHz constant-current biphasic sinusoid. It was demonstrated that the block is not produced indirectly through fatigue.