What Happens in Vagus: Chronic Pain and Dysautonomia
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=">source</a>">. 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. 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=">Source</a>"> It's also been shown that lower vagus activity can be associated with intensity of symptoms in patients with fibromyalgia. <Source=">Source</a>">
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.
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.