Vagus Nerve Stimulation in Clinical Practice
The vagus nerve originates in the medulla and is the longest cranial nerve in the human body. It has bidirectional motor and sensory functions that influence many organ systems and regions within the body. Because it is a main component of the parasympathetic nervous system, it is often associated with stress response and mood.
“The vagus nerve is responsible for not only sensing stress but also affecting many of the symptoms of stress,” explained integrative medicine physician Jeff Hardin, MD. “In the worst-case scenario, patients can have a myriad of symptoms from stress such as heart palpitations, arrhythmias, dyspepsia, ulcers, and others that are mediated via the vagus nerve.”
While research shows that vagus nerve activation can help reduce acute stress responses, it has further applications in clinical practice.
“Vagus nerve stimulation has traditionally been used for seizure disorders and treatment-resistant depression,” said Hardin. “In the emergency department, we maximally stimulate the vagus nerve via several techniques in order to convert patients out of supra-ventricular tachycardia.”
Research has established a strong link between vagus nerve activity and the heart, making it a potential intervention for cardiovascular disorders such as cardiac arrest, acute myocardial infarction, and stroke.
A 2023 systematic review featured in the Journal of Clinical Medicine also demonstrated that vagus nerve stimulation has cardioprotective effects. In that review, the researchers analyzed data from 35 different clinical studies and consistently found that vagus nerve stimulation modulated heart dynamics, inflammatory response, and cellular components.
Vagus nerve stimulation can also help with brain function. A 2019 review found that vagus nerve stimulation is a potent promoter of synaptic brain plasticity. That same review found that vagus nerve stimulation enhanced memory and reduced anxiety.
As Hardin mentioned previously, vagus nerve stimulation can help with depression, especially treatment-resistant depression. The United States Food and Drug Administration (FDA) has approved vagus nerve stimulation via a surgically implanted device through a procedure known as vagotomy for the treatment of depression.
A 2022 clinical trial found that vagus nerve stimulation improved overall mood, with the researchers concluding that it could be a useful add-on strategy to current mood-enhancing behavioral interventions.
Other Health Effects
In vivo and preclinical research also indicates that vagus nerve stimulation can be used to treat a variety of inflammatory disorders, including rheumatoid arthritis, diabetes, traumatic brain injury, and others, as well as pain control in cases of fibromyalgia and migraines.
“Vagotomy used to be the treatment for peptic ulcers before the age of acid reduction therapies and is now being investigated for weight loss,” said Hardin. “Irritable bowel syndrome is probably also mediated in part via the vagus nerve.”
Non-invasive Vagus Nerve Stimulation
Of course, integrative practitioners prefer to utilize the least invasive and more natural strategies possible before resorting to pharmaceuticals or surgery. Fortunately, there are many options for clinicians to consider beginning with breathwork.
“The best way I have found to stimulate the vagus nerve is via breathing techniques,” said Hardin. “My favorite is the one taught by my teacher Andrew Weil, MD, which is known as 4-7-8 breathing.”
With the 4-7-8 breathing technique, the patient breathes in for a count of four, holds for a count of seven, and breathes out for a count of eight. Research shows that 4-7-8 breathing, in particular, can help improve heart rate variability and blood pressure. Slowing down the breath and controlled breathing have been shown to have many positive psycho-physiological effects on the brain and body.
In addition to 4-7-8 breathing and other breathing techniques, meditation can also help stimulate vagus nerve activity. “Most forms of meditation and breath work positively influence health via the vagus nerve,” said Hardin. “Many of the biofeedback techniques, such as Heart Math, entrain the parasympathetic nervous system over the sympathetic nervous system. I have also found that auricular acupuncture is extremely effective.”
Cold plunging and exposure to cold have also become popular ways to stimulate the vagus nerve; however, research is limited. A randomized controlled trial from 2018 found that cold stimulation at the lateral neck area resulted in higher heart rate variability and lower heart rate compared to the control group. A 2008 study found that cold exposure lowered sympathetic activity while increasing parasympathetic activity.
Effective Integrative Strategy
A growing amount of research indicates that vagus nerve stimulation is an effective strategy for stress management, heart health, mood enhancement, and more. Teaching patients to utilize non-invasive methods to stimulate vagus nerve activity is worth considering.
"I believe that our modern life overstimulates our sympathetic nervous system, and reducing this effect by increasing parasympathetic tone can be helpful,” said Hardin.