TUESDAY, May 27, 2025 (HealthDay News) — “It’s easier to put your elbow in your ear” is a time-tested way to describe the impossibility of any given task.

But the route to easing knee pain might indeed wend through the ear, a new study says.

Stimulating the vagus nerve through the ear improved knee pain for some patients, according to early trial results published recently in the journal Osteoarthritis and Cartilage Open.

The vagus nerve plays an important role in the parasympathetic nervous system, which controls the body’s ability to rest and digest, researchers said. It is countered by the sympathetic nervous system, which manages the “fight-or-flight” response.

“The current evidence suggests that individuals with osteoarthritis knee pain have an imbalance of sympathetic versus parasympathetic activity in the body, which can cause pain,” said lead researcher Kosaku Aoyagi, an assistant professor of physical therapy and movement sciences at the University of Texas at El Paso.

“By stimulating the vagus nerve, we hypothesized that our treatment may rectify this imbalance,” Aoyagi said in a news release.

For the small-scale trial, researchers recruited 30 patients with knee pain and treated them with a transcutaneous auricular vagus nerve stimulation (tVNS) device for an hour.

The device rests on the ear and sends electrical pulses to the branch of the vagus nerve that runs through the ear. It’s already approved by the U.S. Food and Drug Administration to treat conditions like epilepsy and depression, researchers noted.

Overall, 11 of the 30 participants felt a noticeable improvement in their knee pain following the treatment, results show.

These findings are solid enough to prompt a larger follow-up clinical trial, in which some people will get vagal nerve treatment while others get a placebo, Aoyagi said.

“Dr. Aoyagi’s research on knee osteoarthritis is an innovative step in identifying a treatment that successfully reduces knee pain,” Stacy Wagovich, interim dean of the University of Texas at El Paso College of Health Science, said in a news release.

“With future, large-scale studies, his team’s work has the potential to greatly improve treatment options available for knee osteoarthritis,” added Wagovich, who was not involved in the research.

More information

The Cleveland Clinic has more on the vagus nerve, while the University of Maryland has more on transcutaneous vagus nerve stimulation.

SOURCE: University of Texas at El Paso, news release, May 22, 2025