We just saw that some Japanese ME/CFS researchers believe they may have developed an objective test to measure post-exertional fatigue. Heart rate variability tests indicated that fatigue after a cognitive test is associated with reduced parasympathetic nervous system (PNS or ‘rest and digest’ system) functioning and increased sympathetic nervous system (SNS or ‘fight or flight’ system) functioning.
Heart rate and heart rate variability studies in Chronic Fatigue Syndrome and Fibromyalgia suggest that difficult cognitive tests aren’t needed to put them in a similar state – their ‘fight or flight’ system is up, and their ‘rest and digest’ system is down – all the time.
These two branches of the autonomic nervous system operate in a ying-yang fashion; when one is up the other is down. In the human body the default is to have the SNS on. Since the PNS is the only thing that can turn the SNS off, unless it does so, it will be on all the time. That suggests that the PNS, not the SNS, may be the problem in ME/CFS and that finding a way to boost it up could be helpful.
Since an over-active SNS has been associated with poor sleep, cognitive decline, inflammation, and increased pain and could play a role in many other symptoms in Chronic Fatigue Syndrome and Fibromyalgia, turning it down could be quite helpful.
That brings us to the vagus nerve. Since the vagus nerve controls parasympathetic nervous system functioning in the body, boosting the activity of the vagus nerve should increase PNS functioning and reduce the SNS activity that’s of concern in ME/CFS and FM.
The medical community knows how to do this. In fact it’s been resetting the ANS by stimulating the vagus nerve in thousands upon thousands of patients for the last decade or so. The problem is that it involves the surgical implantation of an electrode and a generator in the neck region. It’s been effective in about 50,000 people with treatment-resistant epilepsy and has been approved for treatment-resistant depression as well. It’s been trialed in heart failure, inflammation, Alzheimer’s disease, chronic pain, and tinnitus, but the surgical requirement has meant, despite the benefits it could bring to a wide variety of disorders, vagus nerve stimulation (VNS) has not been widely used.
That may be about to change. If a new advance works out, vagus nerve stimulation may be available to many.
It turns out that electrical stimulation of the branch of the vagus nerve that ends up at the ear (yes, the ear) may end up having the same effect. In fact applying electrodes to the surface of the ear might be able – at least for awhile – to reset the whole darn autonomic nervous system. It doesn’t require surgery, or painful side-effects. It simply requires sitting in a chair feeling a tingling sensation in your ear for about ten minutes. It’s about the most unintrusive therapy one can imagine.
(Non-invasive Vagus Nerve Stimulation in Healthy Humans Reduces Sympathetic Nerve Activity; Jennifer A. Clancy a, David A. Mary a, Klaus K. Witte a, John P. Greenwood a, Susan A. Deuchars b, Jim Deuchars b,* Brain Stimulation xxx (2014) 1e7)
In this study researchers from the University of Leeds in the UK, in a process called transcutaneous vagus nerve stimulation (vTNS), applied an electrode to the surface of the ear to stimulate the vagus nerve in healthy controls. They hoped to electrically put the body into rest and digest mode.
First the participants were asked to lie down while their autonomic nervous system activity was tracked. Then surface electrodes from a TENS unit were applied. The TENS unit was turned on in one group and not the other. Heart rate variability tests and muscle sympathetic nerve activity (MSNA) indicated if the status of their autonomic nervous systems changed.
The electro-acupuncture-like treatment of the ear actually worked. The low frequency aspect of the heart rate variability measure increased in the treatment group (but not in the control group) indicating that the activity of the fight or flight system (SNS) had been reduced while the activity of the rest and digest system (PNS) had increased. A fifty percent decrease in muscle sympathetic nerve activity in the leg indicated the reduced SNS activity was large and far-reaching extending to the muscles in the limbs.
Much work needs to be done to validate this approach in disease. Some other studies using different techniques or smaller sample sizes have not had significantly positive results, but one study using electroneurostimulation of the ear in coronary artery disease had impressive results. After four days of fifteen minutes of tVNS their angina at rest had stopped and they were taken off vasodilators. After seven days their exercise intolerance had decreased enough and they were able to climb 5-7 flights of stairs without suffering from angina.
Because tVNS simply turns down the SNS (instead of addressing why it’s increased) it’s not a cure. Three weeks after the tVNS sessions stopped the coronary artery patients’ relief ended.
If used regularly, though, it’s possible it could improve sleep, cognitive functioning, and perhaps even exercise tolerance. As an adjunct therapy that reduces the ‘load’ in ME/CFS – thus assisting other treatments’ effectiveness – it could be very valuable.
The Vagus Nerve Redux
The vagus nerve is a big deal in more ways than one. Not only is it responsible for telling the ‘fight/flight response’ to go to sleep, it’s also the conduit through which most of the body’s immune signals get to the brain and through which the brain’s immune signals pass through to the body.
The anti-cholinergic functions of the vagus nerve make it a key part of the anti-inflammatory response. Low PNS activity is associated with increased inflammation, making it no surprise that reduced PNS activity is common in cardiovascular disorders.
An over-active sympathetic nervous system, for instance, is believed to skew the immune response in the Th2 direction resulting in increased antibody production and decreased protection against intracellular pathogens. Turning the SNS down could then improve antiviral defenses and reduce autoimmune processes.
Chronic Fatigue Syndrome and Fibromyalgia
It bears noting that the general type of ANS dysfunction found in ME/CFS – increased sympathetic nervous system and decreased parasympathetic nervous system activation – is also found in a variety of chronic disorders. (One wonders if a base state of dysfunction (low HRV) is present that gets translated into different configurations in different disorders. The very complex ANS system provides many opportunities for different things to go wrong.)
From an increased heart rate while asleep, to the pounding hearts in POTS patients when they try to stand, to low blood volume, to blood vessel constrictions in the brain, to increased nerve fibers in the hands and more -there appears to be a lot going on with the autonomic nervous systems in ME/CFS and/or Fibromyalgia. There may be no telling what a treatment designed to broadly reduce SNS functioning would have on individual ME/CFS or FM patients, but to all appearances it’s trending in the right direction.
It’s clear that reducing sympathetic nervous system activity is simply good for one’s general health. Decreased heart rate variability is associated with an increased risk of death — not just in people with cardiovascular disorders, but in the general population as well.
Insurance companies surely won’t be paying for tVNS in ME/CFS at this point, but with low HRV well documented in ME/CFS, one wonders why they wouldn’t do so as this technology becomes better validated (as hopefully it will.) The next step for these researchers is testing the device in heart failure patients.
Much remains to be done before electrically stimulating vagus nerve endings becomes the du jour treatment for disorders involving the sympathetic nervous system. Some studies have not been successful. It’s not clear how long the boost to the ‘rest and digest’ system lasts either. It is, however, a non-invasive approach that does not appear to cause side effects and which may, this study suggests, have far-reaching effects on the autonomic nervous system.
The Mind/Body Approach to Vagus Nerve Stimulation
You may not need a prescription drug, an electrical implant, or even an electrode taped to your ear to reduce your SNS and boost your PNS activity. Mind/body techniques that induce the relaxation response such as Qigong, meditation, yoga and others appear to be able, over time, to affect autonomic nervous system functioning in some people.
Next up we hear from an experienced meditator who abandoned her meditation practice when she came down with ME/CFS but then later picked it up again and experienced significant benefits.
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