Beware this common medical device scam: ‘There is no way to know’

They’ve got some nerve!

Vagus nerve stimulators are making waves as a potential way to relax, sleep better and improve gut health.

But an expert on the vagus nerve warns that noninvasive VNS devices may not deliver as promised.

“There is no evidence that using these devices to deliver electricity into the ear or skin of the neck is actually stimulating the vagus nerve,” Dr. Kevin J. Tracey, president and CEO of Northwell Health’s Feinstein Institutes for Medical Research, told The Post.

Tracey — who wrote the new book, “The Great Nerve,” and is often called the “founding father” of bioelectronic medicine — cuts through the noise of vagus nerve therapy to distinguish the beneficial from the buzz.

What is the vagus nerve?

The vagus nerve is a complex network of over 200,000 fibers that acts as an information superhighway between the brain and major organs.

It’s a paired structure — think two thumbs or two kidneys — with one on each side of your brainstem at about the level of your ears, descending through the neck and chest to reach the heart, lungs and gastrointestinal tract.

It regulates essential bodily functions like heart rate, breathing and digestion.

“The vagus nerve is the 10th cranial nerve and the longest nerve in your body,” Tracey said. “It is also the only nerve that would cause death if cut on both sides.”

How can you stimulate the vagus nerve?

Deep breathing, gargling, humming, singing and cold water immersion are commonly suggested ways to stimulate the nerve, but Tracey cautions that “the scientific understanding and proof for most of these suggestions are lacking.”

“Humming might stimulate a few hundred fibers connected to your voice box, but these aren’t the same fibers that go to your heart or regulate inflammation,” he added.

Tracey does support implantable VNS devices that the Food and Drug Administration (FDA) has approved for the treatment of epilepsy, depression and stroke rehabilitation.

A pulse generator, similar to a pacemaker, is implanted in the chest, and a wire connects it to the vagus nerve in the neck. A doctor programs the equipment to deliver electrical stimulation at set intervals.

The noninvasive stimulators, meanwhile, are designed to be placed on the ear or neck to send the impulses.

Tracey compared these devices to TENS units, which have been used for decades to deliver electricity through the skin to stimulate nerves and relieve pain.

He noted that small clinical trials suggest at-home VNS may ease headaches, back pain and anxiety, but there’s a lack of large, well-controlled, randomized clinical trials to support these claims.

“There is no way to know whether the TENS unit is stimulating a branch of the vagus nerve or stimulating many other nerves as well,” Tracey said.

“Stimulating a small number of fibers in the neck or ear is quite different from stimulating the vagus nerve itself as occurs by implanting an FDA-approved device.”

What conditions does VNS target?

“It is likely that the first conditions to be treated by vagus nerve stimulation will be rheumatoid arthritis, inflammatory bowel disease and multiple sclerosis, but rheumatoid arthritis is likely to be the first indication in the US,” Tracey said.

Rheumatoid arthritis is a chronic autoimmune disease that causes joint inflammation and pain. VNS can help by signaling the brain to tamp down inflammation.

VNS is also being explored for longevity. World-famous biohacker Bryan Johnson, 47, said he applies electrical impulses to his ear “at the first potential signs of sickness,” such as a sudden drop in heart rate variability.

Vagus nerve dysfunction can cause heart rate and blood pressure changes, digestive issues like nausea and bloating, fainting episodes, difficulty swallowing and chronic inflammation.

“If increased vagus nerve activity decreases chronic inflammation, it’s reasonable to suggest it might improve health span and quality of life as people age,” Tracey mused. “These ideas are being studied in laboratories and clinical trials worldwide.”

Before purchasing a VNS device

Tracey recommends consulting with a physician before using a TENS unit or similar gadget to make sure you don’t have cardiac, neurological or other risks. And buyers should beware.

“Calling a TENS unit a ‘vagus nerve stimulator’ does not mean the unit is actually stimulating the vagus nerve. It may or may not be,” Tracey said.

“It is not a requirement for marketing such devices that the name of the device has been proved to correspond to what is actually happening.”