Combined KHFAC + DC nerve block without onset or reduced nerve conductivity after block

Area of Science:

• Neuroscience
• Biomedical Engineering
• Medical Devices

Background:

• Kilohertz frequency alternating current (KHFAC) offers peripheral nerve block for conditions like pain and spasticity.
• A key limitation of KHFAC is the transient nerve fiber activation during block onset.
• This onset response can cause discomfort or unintended muscle activation.

Purpose of the Study:

• To evaluate the feasibility of using charge balanced direct current (CBDC) to mitigate the KHFAC nerve block onset response.
• To assess if distal CBDC application can prevent or reduce the transient nerve activation.
• To determine the impact of combined KHFAC + CBDC on nerve conductivity.

Main Methods:

• Eight animals were used, with an initial set for feasibility and a second randomized set for comparison.
• KHFAC alone and combined KHFAC + CBDC waveforms were tested.
• Onset response quantified by peak force and force-time integral; nerve conductivity monitored via muscle twitch forces.

Main Results:

• The peak onset force was significantly reduced from 20.73 N (KHFAC alone) to 0.45 N (KHFAC + CBDC).
• The force-time integral decreased from 6.8 Ns to 0.54 Ns.
• No significant changes in nerve conductivity were observed with the combined waveform.

Conclusions:

• Distal CBDC application effectively reduces or eliminates the KHFAC onset response.
• The combined KHFAC + CBDC waveform provides nerve block without compromising nerve conductivity.
• This strategy enhances the safety and tolerability of KHFAC nerve blocks.