Temporary persistence of conduction block after prolonged kilohertz frequency alternating current on rat sciatic...

Area of Science:

• Neuroscience
• Biomedical Engineering
• Electrophysiology

Background:

• Kilohertz frequency alternating current (KHFAC) can induce rapid nerve conduction block.
• Nerve conduction recovers after KHFAC cessation, typically within seconds to minutes.
• The effects of repeated and prolonged KHFAC application on nerve recovery are not fully understood.

Purpose of the Study:

• To investigate the impact of cumulative KHFAC application duration on nerve conduction recovery.
• To assess the reversibility of nerve conduction block induced by KHFAC.
• To evaluate the potential for a carry-over block effect for sustained nerve modulation.

Main Methods:

• Rat sciatic nerves were subjected to varying durations of KHFAC using bipolar platinum electrodes.
• Nerve conduction was monitored by measuring peak Gastrocnemius muscle force.
• The ratio of muscle forces evoked by proximal (PS) and distal (DS) stimulation quantified nerve conduction patency through the block zone.

Main Results:

• Conduction recovery time was significantly influenced by the cumulative duration of KHFAC exposure.
• Full recovery to pre-block muscle force levels occurred after KHFAC application under 15 minutes.
• Significant but near-complete recovery was observed after cumulative stimulus durations of 50 ± 20 minutes, with a biphasic recovery pattern (fast and slow phases).
• No permanent nerve conduction block was detected in any experimental condition.

Conclusions:

• The cumulative duration of KHFAC application critically affects nerve conduction recovery.
• A carry-over block effect exists, suggesting potential for non-continuous KHFAC application to achieve sustained peripheral nerve block.