Q&A: Practical Applications of Vagus Nerve Stimulation in Clinical Practice

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In his 2024 Integrative Healthcare Symposium presentation, Navaz Habib, DC, APMCP, AcuP, discussed the mechanisms of vagus nerve stimulation and its potential for treating inflammatory conditions.

We interviewed Dr. Habib in a podcast episode leading up to the symposium about his experiences with the therapy in his patient practice, how to measure vagus nerve function, and the different forms of vagus nerve stimulation.

Integrative Practitioner: This is a very general question, but can you tell me what the vagus nerve is and what happens when it doesn't function correctly?

Navaz Habib, DC, AFMCP, AcuP: The vagus nerve is our tenth cranial nerve. We call it the vagus nerve, but really, it's a pair of nerves that extend out from our brainstem and go down through the neck. To some extent, the vagus nerve innervates essentially every internal organ within our body. About 20 percent of signals go down from the brain to the organs via the vagus nerve, while 80 percent of the information comes from the organs sending status updates to the brain. 

This two-way communication pathway allows us to truly understand what's happening internally within each organ from a functional perspective. It allows us to know the state of inflammation that's present in each of the organs. So, we're looking at the overall function and the status of immune system activity because we want to control how much inflammation is present in the organs. 

Suppose there's a threat to that organ's survival or function. In that case, we absolutely require an inflammatory process to remediate that issue, where if we don't have this signal coming down from the brain via the vagus nerve, we will not be able to modulate that inflammatory control. 

The system that runs through the vagus nerve is called the cholinergic anti-inflammatory pathway. Over the last couple of decades, a ton of research has shown the importance of vagus nerve function, showing that when it’s dysfunctional, the control of inflammation is heavily limited. If the vagus nerve is not functioning properly, we won't be able to keep inflammation as an acute response, which allows for the chronicity or the long-term nature of inflammation to continue.

Integrative Practitioner: How do you measure vagus nerve function in clinical practice? And what kind of patient are you choosing to measure it in?

Dr. Habib: I work with patients remotely, so I can't do in-office tests. The good thing is we live in a time when everybody has tools and devices to measure stress. Wearable devices are the prime way we learn about the amount of stress somebody's under, the challenges their body is experiencing, and the response their body is creating to those stressors. Wearable devices are truly the tool I use more often than anything else to help me understand what's happening in the vagus nerve and the body regarding balance and stress. 

The specific marker I'm looking for is heart rate variability (HRV). I've had my Aura Ring for about five years and have tons of data from that. But people are choosing to wear Apple, Fitbit, and Garmin watches, all of which give us a ton of data as well. What's great about this data is that it's not secluded from when they're in the clinic with us; we're getting real-time information from their everyday lives. For me, there’s no question that wearable devices, particularly looking at heart rate variability, are going to be my top tools for identifying vagus nerve function. 

Integrative Practitioner: Can you tell me about vagus nerve stimulation and how it can help improve health outcomes?

Dr. Habib: For the last 25 to 30 years, we've become more aware of this nerve's importance as the controlling mechanism of inflammation. So, Kevin Tracey, MD, and his colleagues at the Feinstein Institute found that when the vagus nerve was cut, our ability to control inflammation was significantly reduced. And then, when the vagus nerve was stimulated, initially using something like electricity, they realized they could modulate and increase its function. And then they obviously did a ton more work to figure out the particular parameters to stimulate it.

If we look back at traditional practices, we see the use of breath. Breathing is extremely important and the strongest way anybody can manage their body’s stress. When we breathe effectively, we use our diaphragm, so our belly should protrude in and out, expanding with the inhale and decreasing with the exhale. That's an ideal form of breathing, but a lot of us, probably around 60 percent, breathe primarily with our chests. That's a sign that we’re under stress, a signal for our body to physiologically shift towards being in the sympathetic state, to push the accelerator. So, with all my patients, I have them put a hand on their chest and a hand on their belly and take three deep breaths. We'll check to see if there is more motion occurring at the chest or the belly.

When focusing on breathing form, it’s not just about diaphragmatic breathing. Diaphragmatic breathing is huge, but we want that breathing to be through the nose. So nasal breathing over mouth breathing. We want the breath to be diaphragmatic in nature, so it's going into the belly, and we want to be slow. The rate of breath is very important here. Ideally, we want to breathe into our belly with an inhale that's relatively short and an exhale that's relatively long. 

When we exhale, we're actually sending a signal to slow everything down. You'll notice this with athletes. For example, a pitcher on the mound, throwing a baseball, will often take a deep breath, and when exhaling, as he calms everything down, he'll throw the pitch. At the same time, the batter takes a breath, gets ready, exhales, and then swings. So, that exhale puts us into a state where we're more cognitively capable, our parasympathetic nervous system is more ready, and we're more resilient to whatever challenge we face. And the control of that is done through the breath. If we’re looking to create real changes by stimulating the vagus nerve, breathing is the tool we can utilize anytime. 

Over the last twenty years or so, there's also been a ton of research and several new devices and tools created to help support patients dealing with vagus nerve dysfunction. Today, noninvasive devices, like a handheld device that you put directly over the area where the vagus nerve is, are being used to effectively stimulate the vagus nerve. When we put the electrical device on the carotid artery and increase the intensity, we see fMRI studies showing very clearly that we can activate the nuclei. 

What we have is an electrical stimulation that creates a signaling process along the vagus nerve that allows us to have greater vagus nerve activity and control. This then creates a controlling mechanism for inflammation throughout the entire body. And it's accelerating the process by which we can support our patients. We're helping them shift from a state where they're constantly pushing on the accelerator with worn out brakes, to a state of healing. We’re helping to rebuild that brake light and get it working more effectively. 

With vagus nerve stimulation, we aren’t claiming to cure any particular condition; rather, we're helping to create a shift to a parasympathetic state where healing can occur. It's a guiding tool to help us approach the health of our patients from a state-based manner.

Editor's Note: This interview was edited and condensed.