Ear-based nerve stimulation may boost hand rehab in people with MS

Scientists at the University of Colorado are testing an experimental approach for multiple sclerosis (MS) that uses electrical stimulation of the vagus nerve to potentially boost the brain’s ability to rewire itself and make rehabilitation more effective.

The trial (NCT06641271) is enrolling by invitation at the Clinical Translational Research Center at CU Anschutz in Aurora, Colorado. It is expected to enroll about 70 adults with relapsing-remitting MS who have problems with hand and arm movement.

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How ear-based VNS will be tested

For the first four weeks of the trial, participants will come to the clinic three times per week and perform a hand movement task for about 30 minutes. Some will receive the experimental electrical stimulation through an earbud-like device positioned in the ear, while others will receive sham stimulation.

Participants will then return for follow-up visits at two, three, and six months. Those who complete all study visits will receive up to $275 for their time.

MS is an inflammatory disease of the brain and spinal cord that damages the myelin sheath — the fatty covering around nerve fibers that helps electrical signals travel along nerves. Current MS treatments can slow disease progression by reducing inflammation, but no treatment has been proven to restore lost myelin.

The vagus nerve is a major nerve that runs from the brain to many internal organs and helps control automatic body functions. Vagus nerve stimulation (VNS) uses gentle electrical pulses to stimulate this nerve.

Studies in people with stroke have shown greater improvements in motor function when VNS is paired with physical therapy than with physical therapy alone. The findings suggest VNS may promote neuroplasticity — the brain’s ability to adapt by forming or reorganizing connections.

Animal studies suggest VNS may support myelin repair

To understand whether VNS could also help people with MS, Cristin Welle, PhD, a professor at the University of Colorado, and her team tested the approach in animal models. VNS increased the number of new myelin-making cells, and brain images suggested that regenerated myelin was returning to areas where it had previously been lost.

“No one has really established a link between neuromodulation (such as VNS) and improved myelin before,” Welle said in a university news story.

For stroke rehabilitation, VNS is usually delivered using a device surgically implanted in the chest. The MS trial is testing a less invasive approach that delivers stimulation through the ear.

“There’s a small branch of the vagus nerve in the ear, which is a crazy little biological anomaly, but it’s there,” Welle said. She explained that the nerve can be stimulated from the surface of the ear.

The study will primarily assess the safety and tolerability of the approach, while also measuring its effects on motor function and disability. Researchers ultimately hope to develop an at-home system that uses the ear-stimulation technology.

Welle said medications do not always provide a good solution for neurologic injuries and generally are not targeted to specific areas of the brain.

“But with neuromodulation, you can target your treatment to the parts of the brain that really need that extra support. So it creates this very precise therapy that is meant to drive plasticity in the context of regaining motor function,” Welle said. “From a big-picture perspective, what’s exciting to me about vagus nerve stimulation is that it’s kind of harnessing the body’s own ability to repair. Rather than creating an artificial condition, it’s just helping the body to use its own repair processes.”