Motor Activated Auricular Vagus Nerve Stimulation as a Potential Neuromodulation Approach for Post-Stroke Motor...

Area of Science:

• Neuroscience
• Rehabilitation Medicine
• Biomedical Engineering

Background:

• Implanted vagus nerve stimulation (VNS) enhances post-stroke motor rehabilitation.
• Transcutaneous auricular vagus nerve stimulation (taVNS) offers a non-invasive alternative to VNS.
• taVNS may replicate the benefits of implanted VNS for stroke recovery.

Purpose of the Study:

• To evaluate if taVNS paired with motor rehabilitation improves post-stroke motor function.
• To determine the significance of movement synchronization in taVNS therapy.
• To assess the impact of stimulation amount on rehabilitation outcomes.

Main Methods:

• A randomized, double-blind pilot trial was conducted with 20 stroke survivors.
• A novel closed-loop system, motor activated auricular vagus nerve stimulation (MAAVNS), was developed.
• Participants received either MAAVNS or active unpaired taVNS during task-specific training over 4 weeks.

Main Results:

• Both MAAVNS and unpaired taVNS groups showed improvements in upper extremity motor function (Fugl-Meyer Assessment).
• MAAVNS exhibited a larger effect size (Cohen's d=0.63) compared to unpaired taVNS (Cohen's d=0.30).
• MAAVNS participants received significantly fewer stimulation pulses than the unpaired group.

Conclusions:

• Stimulation timing, specifically pairing taVNS with movements, appears crucial for enhanced motor recovery.
• The MAAVNS approach demonstrates comparable effect sizes to implanted VNS.
• This study supports the potential of synchronized taVNS for improving upper limb function after stroke.