Does Vagus Nerve Stimulation Treat Opioid Withdrawal Symptoms?

Does Vagus Nerve Stimulation Treat Opioid Withdrawal Symptoms?

By In Opioid Addiction, Tools for Recovery
Posted January 27, 2018

In 2016, drug overdose deaths in the United States reached 64,000. This number is greater than the number of Americans killed during the Vietnam War. It’s greater than the peak number of homicides in the U.S., and it’s greater than the number of people killed by the AIDs epidemic at its height.

Of these overdose deaths, 40% can be attributed to prescription opioids. In fact, more than 46 Americans died daily from prescription opioid overdoses in 2016. It’s clear that new solutions must be found to stop this deadly crisis.

One such solution may be vagus nerve stimulation (VNS). In November, the U.S. Food and Drug Administration (FDA) approved an electrical nerve stimulator called the NSS-2 Bridge device to treat opioid withdrawal symptoms.

In this article, we’ll take a closer look at vagus nerve stimulation, the NSS-2 Bridge device, and how this innovation may impact the opioid crisis.

What is the Vagus Nerve?

The vagus nerve is the longest and most complex of the cranial nerves connecting the brain to the body. It runs from the cerebellum and brain stem to the lowest viscera of the abdomen, touching the heart and major organs along the way.

It’s also known as the “wandering nerve” because of the many branches diverging from its two thick stems. The vagus nerve plays a central role in breathing, heart rate, blood pressure, energy levels, digestive functions, mood, learning and memory, and more.

What is Vagus Nerve Stimulation?

Vagus nerve stimulation (VNS) is the process of stimulating the vagus nerve, either manually or electrically.

VNS has already been used to treat conditions such as depression, epilepsy, and inflammation resulting from rheumatoid arthritis. It’s also been explored as a potential treatment for Alzheimer’s, anxiety, PTSD, and migraine headaches.

In most cases, VNS utilizes a device similar to a pacemaker to send pulses of electrical energy to the brain by way of the vagus nerve. This device must be implanted by a neurosurgeon, and the procedure usually lasts no longer than 90 minutes.

The device most recently approved by the FDA, however, is a bit different. The NSS-2 Bridge device is the first VNS device approved for treatment of withdrawal symptoms, and it does not require surgery. (A prescription, however, is necessary.)

It looks like a large hearing aid, and double-sided tape is used to attach it behind the ear. Three electrodes connected to the device are placed on and around the ear.

The device’s battery-powered chip then sends electrical impulses to the vagus nerve, stimulating branches of certain cranial nerves. In particular, it targets the amygdala. The amygdala is rich in opioid receptors, regulates fear, and plays a role in reward-seeking behavior.

How Can VNS Treat Opioid Addiction?

According to the FDA, VNS with the NSS-2 Bridge device can provide relief from opioid withdrawal symptoms.

Opioid withdrawal symptoms are severe and include:

  • Anxiety
  • Insomnia
  • Tremors
  • Excessive sweating
  • Muscle and joint pain
  • Teary eyes and runny nose
  • Abdominal cramps
  • Diarrhea, nausea, and vomiting
  • Rapid heartbeat
  • High blood pressure
  • Dilated pupils with blurry vision

Vagus Nerve Stimulation

These withdrawal symptoms are often a major roadblock for opioid addicts who are trying to stop using. Opioid withdrawal has been compared to a severe case of the flu, often making people believe they’re dying.

“Because of the negative mental, emotional, and physical symptoms related to withdrawal, people are often driven to seek out and use drugs again,” says Dr. Jonathan Harris, the corporate director of neurocognitive services at Caron Treatment Centers.

There are currently three medications available to help treat opioid addiction: buprenorphine, methadone, and naltrexone. The former two are also opioids, but they don’t deliver the same high as drugs like heroin. They’re intended to help patients quit deadlier opioids and gradually quit drugs entirely. But withdrawal symptoms are severe for these treatment drugs as well, and 40-60% of patients relapse after treatment.

It’s also common for patients to have difficulty getting medication-assisted treatment because all opioids must first be flushed from a patient’s system in order to avoid side effects. People often relapse before this goal can be achieved. Many also fear the pain of withdrawal and decide not to seek treatment.

The NSS-2 Bridge device seeks to address these problems and help clear the path to recovery. Patients can use the device for up to five days during the “acute physical withdrawal phase.” Controlling these symptoms may make it easier for patients to stick with a recovery program and regain their sobriety.

Studies have also shown that VNS may reduce drug cravings and drug-seeking behaviors. In January of 2017, researchers at the University of Texas at Dallas School of Behavioral and Brain Sciences discovered that cocaine-addicted rats who were treated with VNS therapy significantly reduced their drug-seeking behaviors.

The researchers explain that VNS therapy helped trigger changes in synaptic plasticity between the rats’ prefrontal cortex and the amygdala. By reducing cravings and encoding new reward behaviors, VNS appeared to facilitate “extinction learning” of the rats’ previous drug-seeking behaviors.

Human studies on this effect haven’t yet been conducted, but it’s a prospect that will likely be explored more in the future.

More Info About the NSS-2 Bridge Device

As mentioned above, patients must have a prescription in order to use the NSS-2 Bridge device. It’s not recommended for patients with hemophilia, cardiac pacemakers, or psoriasis vulgaris. Most doctors charge $600-$1500 to attach it to a patient’s ear.

The device has already garnered attention. A judge in Indiana allows heroin addicts to choose the NSS-2 Bridge device over jail, and state officials in Utah plan to buy 100 devices for inmates. It was even mentioned in Ohio governor John Kasich’s State of the State address.

Does It Really Work?

Of course, the real question is whether or not VNS therapy is truly effective when it comes to treating opioid withdrawal.

The FDA used a single clinical study to approve the NSS-2 Bridge device. 73 patients who were undergoing opioid physical withdrawal used the device for five days, along with any medication needed to treat persistent symptoms such as nausea and vomiting.

Each patient’s clinical opioid withdrawal scale (COWS) was evaluated both before and after treatment. COWS scores range from 0 to over 36. The higher the number, the more severe the withdrawal symptoms feel to the patient.

Before using the device, the average COWS score was 20.1. Within 30 minutes of using the device, all patients experienced at least a 31% reduction in COWS. 88% of patients successfully transitioned to medication assisted therapy (naltrexone, which blocks the brain from craving opioids) after five days using the NSS-2 Bridge device.

The device has received glowing testimonials from recovering addicts who have been sober for months or even a year after using it. Brian Comer, who has been clean for a year, says he felt better within 10 minutes of using the device. He wasn’t hyperventilating anymore and “was able to actually sit.” Within one hour, says Comer, “I noticed almost no symptoms of any withdrawal.”

And Comer has maintained sobriety without ever transitioning to medication-assisted treatment. Comer’s insurance wouldn’t pay for naltrexone. He got one dose for free, then went without it. Comer says, “There’s nothing now that’s holding me back from having a life.”

opioid withdrawal freedom with vagus nerve stimulation

Still, there are skeptics.

Nora Volkow, director of the National Institute on Drug Abuse (NIDA), explains, “The only way that you can determine the extent [to] which this device has potential clinical effects is by doing a randomized controlled trial.”

In this type of trial, patients would be randomly assigned to receive the actual device or a placebo (one that looked like the device but actually did nothing). Without this comparison, it’s impossible to be certain whether the results seen in patients (who report their own COWS scores) are due to the placebo effect.

Additionally, the effects of opioid withdrawal eventually dissipate on their own. This type of study would rule this out at as a possible explanation for the results seen in patients.

Critics also point out that the only study testing the effectiveness of the NSS-2 Bridge device is co-authored by Dr. Arturo Taca Jr., an addiction specialist who pioneered the idea of using the device to treat addiction.

“Because people are desperate, they’re willing to believe anything that anyone promises,” says Volkow. But it remains to be seen if the manufacturer is “generating expectations that are not fulfilled.”


Vagus nerve stimulation has been used to successfully treat depression, epilepsy, and other conditions. Now, researchers believe it can help reduce the pain of opioid withdrawal and put opioid addicts on the path to full recovery.

In particular, the NSS-2 Bridge device has been approved by the FDA for this purpose. It aims to help patients detox in order to transition to medication assisted treatment, particularly with naltrexone, the only approved medication assisted treatment that isn’t also an opioid.

Although initial studies have been promising, more research is needed to be sure that the NSS-2 Bridge device is a truly effective treatment for opioid addiction.

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