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What Happens in Vagus: Chronic Pain and Dysautonomia

I’ve been doing a lot of reading lately about the vagus nerve and the autonomic nervous system. We’ve been super fortunate to work with a handful of patients with POTS in the past 6 months with some really great and surprising results from taking a cervical and vestibular approach to care, and it’s driven me to learn more about this unconscious super system in the body.

While dysautonomia is considered a rare problem, there are actually certain types of patients that have a higher risk of having dysautonomia as a co-morbid condition. This includes neurodegenerative disorders like multiple sclerosis and Parkinson’s Disease, but the ground I want to cover is something that affects people as an invisible illness.

Today we’re going to breakdown the relationship between chronic pain and the vagus nerve.

Fibromyalgia, Chronic Fatigue, and Dysautonomia

Fibromyalgia and chronic fatigue syndrome (aka myalgic encephalomyelitis) are 2 conditions that are frequently associated with each other. Estimates as high as 75% of of fibromyalgia patients report fatigue as a major symptom and 20% of chronic fatigue patients also report having widespread body pain [source].

What’s unique about these disorders is that they both show an unusually high amount of dysautonomia compared to the general population. A review in the Journal of Clinical Rheumatology showed that patients with fibromyalgia frequently show scores reflecting autonomic dysfunction along with non-pain symptoms like light-headedness on standing (orthostatic intolerance), digestive complaints, excess sweating, and fatigue.

It’s also been reported in the Journal of Internal Medicine that patients with chronic fatigue syndrome frequently have postural orthostatic tachycardia syndrome (POTS) enough to classify the POTS patients as a distinct subgroup of chronic fatigue.

So why is chronic pain associated with this breakdown of the autonomic nervous system?

What Happens in Vagus….

The nervous system is classified into different branches. For ease of understanding, you have one branch that controls all of your muscles like your biceps, triceps, and quads called the somatic nervous system. You also have another branch that controls your organ systems called the autonomic nervous system.

The autonomic nervous system is further divided into the sympathetic nervous system and the parasympathetic nervous system. The sympathetic system is the one that causes the things you feel when you get stressed out. Rapid heart beat, sweating, high blood pressure, along with increased blood flow to your muscles. It helps you prepare to fight or escape danger. The sympathetic system is primarily driven by a bundle of nerves called the sympathetic chain.

The parasympathetic does the opposite. It forces you to breathe slowly, digest, breathe slowly, and think about reproducing. The parasympathetic system is mainly driven by your vagus nerve.

The Vagus Nerve has a direct connection to most of your body’s internal organ systems

These systems generally work in opposition to each other to set the tone for how your body is going to operate.

The vagus nerve is an special and unique nerve that travels from your brainstem into the bulk of your internal organ systems. It gives the brain a direct line of communication with your organ systems because your body generally wants to spend most of it’s time being parasympathetic. 

Why?

Because when your body is more parasympathetic it is able to breath easier, digest better, engage in sexual intercourse, sleep, and heal from injury.

The sympathetic system is designed to help you survive from an imminent threat, but your parasympathetic system is there to ensure that you can adequately heal and recover from that threat.

The more active the Vagus nerve is, the more likely your body is able to heal and recover. This isn’t just some pleasant billboard sticker either. Research has shown that increased parasympathetic activity is associated with higher survival heart disease and cancer. It’s also associated with improved recovery and decreased injury in athletes.

Most importantly for the patient in chronic pain, lower vagus nerve activity was associated with chronic pain compared to healthy controls. [Source] It’s also been shown that lower vagus activity can be associated with intensity of symptoms in patients with fibromyalgia. [Source]

Weak Vagus and Chronic Stress

Vagal activity is measured using something called heart rate variability (HRV). Many years ago, you could only measure heart rate variability from electrocardiograms (EKG) and measuring the distance between each heart beat. Today, there is no shortage of computer and even smart phone applications that have brought HRV to a wide audience.

In general terms, the higher your HRV is over time, the higher your vagal or parasympathetic activity. The lower your HRV is over time, the higher your stress or sympathetic activity.

If your body is in a chronically high state of stress, then it is going to:

  • Decrease blood flow to your organs
  • Increase exposure to your stress hormones (adrenaline and noradrenaline)
  • Decrease your stores of serotonin (feel good neurotransmitter)
  • Increase your blood sugar (diabetes)
  • Increase your blood pressure
  • Decrease your immune system
  • Decrease tissue healing

Why? Because if your brain thinks that it is in danger from attack, then it does not care about healing and immune function. It is strictly concerned about getting you out of danger.

When you have low HRV and high sympathetic activity, your body is at a distinct disadvantage when it comes to healing and resilience. While low HRV isn’t necessarily the cause of heart disease, cancer, fibromyalgia, or chronic fatigue, but if you have a low HRV then your body’s ability to adapt and overcome these conditions is compromised.

I’ll put that in bold text because that’s an important distinction:

When you have low HRV and high sympathetic activity, your body is at a distinct disadvantage when it comes to healing and resilience. While low HRV isn’t necessarily the cause of heart disease, cancer, fibromyalgia, or chronic fatigue, but if you have a low HRV then your body’s ability to adapt and overcome these conditions is compromised.

Bringing Vagus Back

There was an interesting study published in 2014 that used strength exercise as a treatment for patients with fibromyalgia. The study showed that patients with Fibromyalgia had significant improvements in pain and quality of life through a regiment of strength training, but no significant changes in HRV. The study was surprising, because exercise is one of the best, easiest, and cheapest ways you can improve your HRV, but the biggest surprise was in the conclusion. The study concluded that strength training was an effective therapy for patients with fibromyalgia, which is absolutely true, but also said that changing the autonomic nervous system is not a goal worth achieving in patients with fibromyalgia.

Knowing what you know now about the autonomic nervous system, it seems like a rational and reasonable goal for any patient because improving the autonomic nervous system improves the health and survival of patients regardless of what condition they have.

The best part is that vagal tone can be improved using non-invasive methods that include cardiovascular exercise, resistance exercise, breathing exercise, mindfulness training, non-invasive vagal nerve stimulation, and yes even upper cervical chiropractic.

By taking the focus away from just addressing the pain, and making the focus of care on the autonomic nervous system, it gives us the ability to affect the person as a whole, instead of just addressing a symptom. By taking people away from their condition, and returning them to their bodies.

 

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Dysautonomia – A possible cause of post-concussion syndrome

Dysautonomia and PCS

With concussion being a dominant topic in sports medicine, we have seen a large spike in research dollars being spent to study the effects of brain injury. Despite our increased knowledge, when someone has concussion symptoms for longer than 30 days, there still isn’t great consensus as to why these people develop persistent symptoms and what is causing it to happen.

The symptoms of post-concussion syndrome (PCS) are what make the illness difficult to understand. The primary symptoms of PCS include:

  • Persistent headache
  • Dizziness
  • Loss of balance
  • Difficulty with concentration/brain fog
  • Nausea
  • Impaired or slow cognitive activity

The symptoms are vague and non-specific. In medicine, there’s a tendency and a desire to have a condition be linked to one very specific piece of anatomy. That way you can treat the diseased organ and cure the illness.

The reality is that a head injury is likely disrupting multiple body parts simultaneously. The higher centers of the brain aren’t the only things that get scrambled during a concussion. A concussion is likely damaging multiple areas in the brain along with the inner ear organs, the neck, the jaw, and the eyes.

Since every head injury is unique in terms of velocity, direction, and magnitude, it means that each person’s head injury is likely to impact their anatomy in individual ways. This is where you can have a lot of variation in how someone with post-concussion syndrome looks symptomatically.

Another struggle is that different body parts can create similar symptoms. An injury to the neck can cause a feeling of vertigo just like an injury to an inner ear organ. An injury to the neck can also cause headaches symptoms just like the eyes or the vessels in the brain.

Some doctors are looking at another potential cause of persistent concussive symptoms called dysautonomia.

Dysautonomia – A Fight Between 2 Super Systems

Dysautonomia is a condition where the brain loses normal control of the internal organ systems of your body. Dysautonomia can show up in organs like the digestive system, bladder, glands, and pupils. Classically, these disorders show up in the cardiovascular system by affecting your heart rate and blood pressure.

Autonomic Nerveous System Chart

The autonomic nervous system is compromised in patients with dysautonomia

The most common disorders linked to dysautonomia are:

  • Multiple sclerosis
  • Fibromyalgia
  • Postural Orthostatic Tachycardia Syndrome (POTS) – an illness characterized by rapid heart beat to 150-200 bpm at rest
  • Neurocardiogenic syncope – a disorder characterized by unpredictable fainting attacks.

When people have these disorders then the broken function of the nervous system causes people to feel dizzy, in a fog, extremely fatigued, light headed, and anxious. When you read those symptoms on paper (or screen) it doesn’t sound like much, but the way those symptoms persist can drive someone mad.

People don’t just have a brain fog, they are scared and frustrated that their brain won’t allow them to focus and accomplish a task.

People don’t just have fatigue, they have an inability to socialize and be effective at work and at home because of exhaustion.

People don’t just have dizziness, they are worried about driving and being in open spaces because their body is betraying them.

People don’t just have a rapid heart beat, they have fear and anxiety that this next attack could put them in the emergency room.

Having dysautonomia whether it’s an illness on it’s own like POTS, or part of another illness like MS can make life much harder and depressing, because treatment for the illness is really limited.

Post-Concussion Syndrome and Dysautonomia

Going back to post-concussion syndrome, we discussed how the illness can be extremely frustrating because doctors and scientists have had a hard time coming to a consensus as to where the symptoms are coming from.

Some doctors and scientists are presenting an interesting theory that cases of post-concussion syndrome may be a manifestation of dysautonomia.

One of the first studies to look at this phenomenon was done in 2016 on young patients with persistent concussion symptoms. The study involved a test called the head-upright table tilt test. You can check out the full study here:

Orthostatic intolerance and autonomic dysfunction in youth with persistent postconcussive symptoms: a head-upright table tilt study

Image credit to Stickman Communications

Image credit to Stickman Communications

This test is used to diagnose feinting conditions but is also a hallmark test for POTS. The study showed that 24 out of 34 PCS patients had findings on the test indicating a form of dysautonomia. 10 Patients had syncope while 14 patients had POTS.

Even more interesting was that when the patients with POTS stopped having PCS symptoms, they also stopped having a reaction to the table tilt test when re-examined.

Another 2016 study showed that patients who have a history of concussion show a decreased ability to modulate their heart rate and blood pressure at rest indicating a loss of autonomic control. This was happening in patients without any overt signs or symptoms of dysautonomia.

Valsalva maneuver unveils central baroreflex dysfunction with altered blood pressure control in persons with a history of mild traumatic brain injury

Then you also have a wide range of studies looking at how concussion can impact your heart rate variability which is an increasingly utilized biomarker for autonomic nervous system activity.

HRV Studies

A dysautonomic theory of post-concussion syndrome can also help explain some of the unusual symptoms that may arise after a head injury. While it’s easy to understand how a PCS patient can have persistent headache and dizziness, there are a lot of people who will have a concussion or whiplash and start developing persistent gut issues and sensitivities to foods. Dysautonomia as a culprit helps to make better sense of this phenomenon.

What Does This Mean for Treatment?

Dysautonomia is a condition that is not well recognized by many physicians and there aren’t many choices for effective treatment options. In dysautonomia, the brain is having a terribly hard time making sense of its environment.

There’s some interesting work going on utilizing balance and vestibular exercises and graded cardiovascular exercise to help the brain recover from injury, but I’ll cover that on another day. Today I want to talk about the veins in your neck.

Dr. Michael Arata is an interventional radiology specialist in Southern California. I heard him speak at a conference in 2015 where he talked about the effect that the veins in your neck could have on your autonomic nervous system. It’s been an interesting and controversial theory that has been tied to illnesses like multiple sclerosis where dysautonomia is a hallmark of the illness. When the large veins in the neck become narrowed or occluded, it can cause abnormal fluid movement in the brain leading to venous reflux, congestion, and neuroinflammation in the brain.

Dr. Arata even published 2 studies that demonstrating that a procedure that uses a balloon to open these veins was able to create changes in the autonomic function of patients with multiple sclerosis including heart rate variability and blood pressure control.

Transvascular autonomic modulation: a modified balloon angioplasty technique for the treatment of autonomic dysfunction in multiple sclerosis patients.

Blood pressure normalization post-jugular venous balloon angioplasty

But that wasn’t the most interesting part of his presentation. During his talk, he talked about the concept of the atlas vertebra creating compression on these vascular structures. He even used an imaging technique called a venogram to show this happening in his patients:

Dr. Arata shows images of a venagram to show how atlas rotation can disrupt the internal jugular vein

Dr. Arata shows images of a venagram to show how atlas rotation can disrupt the internal jugular vein

It’s because of this phenomenon that Dr. Arata actually refers some of his patients for upper cervical correction so that they can influence this part of the autonomic nervous system.

If dysautonomia is a primary symptom generator in PCS patients, then the impact from a potential neurovascular insult like an craniocervical displacement should be considered especially considering the mechanism of injury includes a blunt force to the head.

An Personalized Approach to Post-Concussion Syndrome

Patients with post-concussion syndrome with signs of dysautonomia likely have multiple systems that must be addressed to regain normal functionality. In addition to dysfunction in multiple systems is the idea that each person will have a varying tolerance to different therapies.

In truth, no single therapy is likely to fix someone with persistent post-concussive symptoms and dysautonomia. These patients need to improve their tolerance to exercise with gradual increased load (especially if they’re an athlete). They also need vestibular rehabilitation so that their brain can move the head and eyes normally again. There’s no disputing the necessity and usefulness of those treatment strategies.

However, if we are concerned about the chronic effects of head injury and the ability to improve fluid movement through the brain, then we have to consider the impact that trauma has on the structural alignment of the neck and the neuroinflammatory consequences that these injuries can leave behind.

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