Dysautonomia and POTS, 1: Physiology


Dysautonomia and POTS, 1: Physiology

Dizzy when you change positions, slow digestion or even cramps and gut pain, nausea, trembling, heart palpitations, lightheadedness, chronic anxiety, fatigue, brain fog, always too warm or too cold, blurred or tunnel vision, poor sleep, intolerance to exercise, feet turn red or even purple for no apparent reason — these are all possible symptoms of dysautonomia, an imbalance of the involuntary nervous system.

In the body, there are two major divisions of the nervous system: voluntary which makes conscious movement possible, and involuntary (also called autonomic) which controls the non-conscious functions of the body like breathing, heart rate, blood pressure, temperature regulation and some parts of digestion. Two halves of this involuntary/ autonomic nervous system constantly work to keep the body in balance: the sympathetic or “fight or flight” nervous system, and the parasympathetic or “rest and relax” nervous system.  

While there can be many causes for each of the symptoms above (thus making it hard for doctors to come to a diagnosis), dysautonomia symptoms are VERY common in patients with hypermobility spectrum disorder (HSD) and hypermobile Ehlers-Danlos Syndrome (hEDS). And these symptoms can range in severity from mild to disabling.

Sometimes, these symptoms become severe enough that they meet the definition of a syndrome called POTS: postural orthostatic tachycardia syndrome – a very long name which mostly means that the patient’s heart races (100 beats per minute or higher) and they feel worse and worse the longer they stand up including often feeling dizzy or light-headed. POTS can be quite disabling.

POTS is a syndrome, not a specific disease and many disorders with similar symptoms exist.  The diagnostic criteria for POTS however are:

1. An increase in heart rate of 30 beats per minute or more (40 in children) within 10 minutes of changing from lying down to standing.

2. Symptoms worsen when standing and improve with lying down.

3. Symptoms last 6 months or longer.

4. Absence of other causes such as active bleeding, medication reaction or acute dehydration.

Why are dysautonomia and POTS problems for patients with HSD and hEDS? This has to do with the way these inherited connective tissue disorders affect the way the body works. There are three most common types of POTS, that is, three most common physical mechanisms by which the syndrome arises. At times there may be more than one mechanism causing a person’s symptoms.

Neuropathic POTS.

The word neuropathic means a non-specific injury to a nerve. In the case of patients with HSD or hEDS, there can be accumulated damage to the involuntary nerves especially in the lower extremities. This results in less stimulation to the tiny muscles that wrap around the arteries. If those tiny muscles are too relaxed, the blood vessels open up and blood will pool in the legs. There is only so much blood in the body, so when too much blood pools in the legs, there is less for the upper body. When the person tries to stand up, there is too little blood to the brain and sensors in the neck tell the brain that the blood pressure is too low. All of this results in heart racing, dizziness and/or just feeling ill.

Hyperadrenergic POTS.

There are three most common mechanisms for this kind of POTS, but first some background.

The sympathetic nervous system, as we said above, is the “fight or flight” nervous system. The main chemical that serves as a nerve transmitter for the sympathetic nervous system is norepinephrine which is also called adrenaline. When too much of this hormone is in the blood, this is said to be “hyperadrenergic”. Too much norepinephrine throws the body systems out of balance. Specifically, with this kind of POTS, blood pressure levels tend to go too high as well as increased heart rate.

In Central Hyperadrenergic POTS, the sympathetic nervous system is simply too active. The reasons for this can vary. This kind of POTS is thought to be 10% or less of all cases. There may be a genetic link to developing this. In some few cases, there may be an autoimmune condition called Morvan’s syndrome. There are some rare tumor types that produce norepinephrine and which can mimic this kind of POTS. There may be an association with hyperadrenergic POTS and sleep apnea in many patients.

A second type of hyperadrenergic POTS, Norepinephrine Transporter Deficiency, is due to a genetic mutation that causes loss of function of a protein molecule that helps the body to clear away norepinephrine. Body chemicals are produced by cells but also all require some mechanism for elimination. As you might expect, if a transporter molecule needed for elimination of norepinephrine is lacking, too much will build up in the body system. This will cause high blood pressure and high heart rate. While this mutation is relatively rare, Norepinephrine Transporter Deficiency can also be caused by some medications that block the molecule. This can include certain medications used for depression, and also, for attention deficit disorder.

The third type of hyperadrenergic POTS is not directly related to norepinephrine. Mast Cell Activation Syndrome (MCAS) is another common set of problems which may arise with patients with hypermobility or hypermobile Ehlers-Danlos Syndrome. MCAS will be the topic of future blog posts, but for now, a quick summary is to say that mast cells are important sentinels in the body which will release inflammatory chemicals in the body as part of its defense system. These can become over sensitive and too quick to release their chemicals. Some of the inflammatory chemicals, histamine for example, when excessive, can create POTS symptoms especially high heart rate and high blood pressure in some patients.


Hypovolemia means low blood volume – too little of the fluid part of the blood, plasma. Some patients with hypovolemic POTS may be low by as much as 13%. While the mechanism that causes this is known, how that the mechanism gets out of balance is not well understood.

The kidneys are the chief organ of the body responsible to regulate how much fluid the body holds on to and how much the body eliminates. There is an important system of hormones given off by the kidneys called the “renin-angiotensin-aldosterone system”. In many people with HSD or hEDS, this system is thrown out of balance causing the kidneys to eliminate too many minerals (electrolytes) and with them too much fluid leaving the person chronically dehydrated.

Which type do you have? Reviewing, in general terms, all of the types of POTS described here result in high heart rates and feelings of dizziness or illness when the person stands for a period of time. In Neuropathic and Hypovolemic POTS, the blood pressure tends to fall. In the different types of hyperadrenergic POTS, not only does heart rate go up with standing, or activity, so does the blood pressure.

The basic diagnostic test for POTS is called a tilt table test. The patient is asked to lie down on a flat tiltable table and their heart rate, blood pressure and symptoms are recorded. Then the table is tilted up by degrees until the patient is standing and changes in heart rate, blood pressure and any symptoms are closely monitored. A similar type of test, the “Standing Test”, can be done in the office for diagnosis by a physician or screening by a therapist. These tests will identify POTS but may not give enough guidance about which type of POTS to guide prescription of medications if needed.

While there are a number of primary care physicians who have educated themselves about POTS and it’s management, treatment is often done by specialists, especially autonomic neurologists (a very hard to find sub-specialty) or more commonly by a cardiologist.

In the next blog post, we will look at how the different kinds of POTS are managed including both conservative (non-drug) treatments and some general principles of how physicians manage with drugs too.

Until then, cheers!


Zeborah Dazzle, PT, WWF

Spokes-Zebra and Patient Educator for Good Health Physical Therapy and Wellness.

Thanks to Dr. Mark Melecki, PT for his assistance in preparing this blog. (It is very challenging to type with hooves rather than fingers. Thanks Mark.)


  1. Raj, S., Postural Tachycardia Syndrome (POTS), Circulation. 2013; 127: 2336-2342
  2. Olshansky, B., et. al., Postural Orthostatic Tachycardia Syndrome (POTS): A Critical Assessment. Prog Cardiovasc Dis., 2020; 63(3): 263-270.
  3. Walker, A., The Trifecta Passport, US: Kindle Direct Publishing, c. 2021, ISBN 978-1-7337117-2-2

Taming the Zebra Excerpt 4

Website: tamingthezebra.org

Mailing List: https://www.tamingthezebra.org/join-the-email-list

Excerpt from: Taming the Zebra – It’s Much More than Hypermobility: The Definitive Physical Therapy Guide to Managing HSD/EDS, Volume 1 Systemic Issues and General Approach 

(Due out Winter of 2023)

Dysautonomia, HSD/EDS and the GI System

The GI system has just as many nerves as the spinal cord. The patient and practitioner cannot overlook the Autonomic Nervous System (ANS) when dealing with gut issues. They are one in the same. The GI system’s nerve supply is primarily the ANS. The Vagal Nerve (or Vagus nerve) part of the ANS, innervates the digestive tract from the esophagus to the splenic flexure of the colon. The sacral parasympathetic nucleus (another part of the ANS) innervates the colon and rectum. When someone has low Vagal tone, or a dysfunctioning ANS, this will impair GI motility. Dysfunction of the Vagus nerve can cause poor mobility in the esophagus as well, causing difficulty swallowing (see figure 6.7). A well functioning Vagus nerve also may help reduce inflammation in the gut as low tone in this nerve is associated with higher levels of inflammation within the body. The GI system and the ANS can be a chicken-or-egg scenario when symptoms occur. Knowing the answer to which came first may not be as important for some as addressing both systems to reduce symptoms. Exploring that complex question can be very helpful in regards to long term care and control of health.

Conditions to Investigate with Difficulty Swallowing
DysautonomiaEsophageal dysfunction (structural or functional)Local nerve irritation to the throat musculatureUpper cervical instabilityEagle SyndromeUpper thoracic or cervical spine involvement

Figure 6.7 Difficulty swallowing can be due to a number of conditions. These should be explored with the patient to avoid missing a condition that will require a referral to a specialist.

Episodes of Dysautonomia may also be triggered by events that happen in the gut. We see this with gastric dumping. For someone with impaired motility/movement of the food through the GI system, one will lose the rhythmical small contractions, and the stomach may dump its contents rapidly into the small intestine. With this, the food is not fully broken down, and one is left with larger particles than the small intestine is used to taking care of, along with a larger portion of food at one time that can cause some stretching of the small intestine. When the small intestine registers this stretch occurring in the organ, the nerves try to increase its response to help move the food through the area and this can cause local pain to the small intestine. Along with a physical pain response, the body releases additional hormones along with shifting the blood flow back to the GI system to assist with this “emergency” of a dumping response. When the blood flow is adjusted to the system, this begins to trigger a shift in the Sympathetic Nervous System and may cause an overall systemic autonomic response as the body struggles to find balance again (see Figure 6.8).

Figure 6.8 Dumping Syndrome is a reaction of the ANS seen in those with Dysautonomia and/or motility issues in the gut.

Early or late dumping responses may occur within the same patient. Early dumping is an ANS response from the reaction that occurs within 30 minutes of eating because the small intestine is being stretched, there is an increase in hormone release, and the ANS overcompensates to assist in the event. This can be seen in the GI system as malnutrition in protein energy and manifest in the rest of the body as the following:

  • Heart palpitations
  • Tachycardia (increased heart rate)
  • Feeling the need to lie down after meals
  • Flushing or paleness
  • Sweating
  • Lightheadedness
  • Drop in blood pressure
  • Headaches
  • Possible fainting
  • Feeling full soon into eating
  • Stomach pain
  • Nausea
  • Abdominal area cramping
  • Bloating
  • Rumbling/gurgling in the GI system after eating

Late dumping can be seen one to three hours after eating a meal. This can be from an increase in the hormones secreted into the GI system, chronic GI inflammation, Dysautonomia, or a history of Diabetes. Symptoms include:

  • Sweating
  • Faintness
  • Decreased concentration, brain fog
  • Varying levels of consciousness

Late dumping is less common than early dumping. An individual can have both early and late dumping occur with meals. Specific meal strategies can be found later in this GI management section. Treatments for the ANS can be found later in this book (Chapter 16). Both are recommended in combination as treatment strategies when dumping is suspected.

Basics of EDS Part 4

Hello, Zeborah Dazzle, PT, WWF here. I am the spokes-zebra and patient educator for Good Health Physical Therapy and Wellness. As some of you know, while I am a physical therapist who treats all kinds of problems, including all kinds of bone and muscle problems, my special interest is hypermobile Ehlers-Danlos Syndrome (hEDS) and Hypermobility Spectrum Disorder (HSD). Sometimes it is wise to pause and go back to basics. That is what I will focus on with this post.

How are the laxities caused by HSD and hEDS Treated?

As we discussed in our last post, many of the effects of HSD and hEDS are on skin and joint laxity. While lax skin may not cause a lot of pain, lax joints often do. Medical doctors that we work with frequently rely on two approaches to help patients with these diagnoses: medications or supplements to help manage pain and physical therapy.

In physical therapy, while there are many variations on how we do this, our approach overall is to seek to restore balance within the body. More specifically what that means is to help get the joints back in a normal alignment, assure that the tissues are in balance around the joints allowing normal movement and strengthening to help keep the joints strong and stable.

We rely on both exercise and manual therapy to achieve strong, stable balanced joints and movement. Oh, and since our job as physical therapists is to help people to move and function better, we also bring in a lot of teaching: how to protect joints; tips and tricks for conservative management of pain; and how to recenter a joint which has gone out.

As we have also already discussed, the symptoms for both HSD and hEDS are on a spectrum, with some people having very few and some being challenged by a great deal of debility. So too then, restoring strength and balance around the joints for some patients is a quick, easy process, and for some a slow and gradual journey toward health.

This said though, we strongly believe in the potential of all of our patients to achieve a higher level of function.

How are the associated problems of dysautonomia/ POTS and mast cell activation treated?

Accompanying HSD and hEDS, for most patients, are isolated symptoms or full syndromes involving the involuntary nervous system, and/ or mast cells. As we have discussed, an imbalance of the involuntary nervous system is called a dysautonomia; this imbalance can reach the level of a syndrome known as POTS (postural orthostatic tachycardia syndrome). Most patients with HSD or hEDS have at least a symptom or two of dysautonomia. Mast cells are front line sentinels in the tissues of the body monitoring for wounds, foreign bodies, and infections. When they are triggered by a trauma or a foreign invader, they release chemicals called mediators which cause inflammation. Connective tissue disorders can set both the involuntary nervous system and the mast cells on edge, so they are more easily triggered.

Both dysautonomia/ POTS syndrome and mast cell imbalance (called mast cell activation syndrome) have treatment approaches which involve conservative interventions as well as drug-based treatments.

Overall, the conservative approaches for dysautonomia/ POTS involve methods to: help keep the blood from pooling in the legs which causes dizziness, blood pressure drop and rapid heartbeat; emphasis on hydration with extra electrolytes since patients with dysautonomia frequently do not absorb and retain electrolytes well; and finally, gradual progression of exercise. If conservative measures alone do not restore balance, cardiac medications may be prescribed usually to help support blood pressure and/ or to moderate heart rate. There are several medical specialties skilled in managing POTS. Many of our patients have worked successfully with cardiologists, heart doctors.

The conservative approach for Mast Cell Activation Syndrome (MCAS), is first to identify factors which lead to flare ups. Sensitized mast cells may be easily triggered to release their inflammatory chemicals by both emotional and environmental causes. While the list of common triggers is long, each patient’s particular triggers are unique to them. These can include, strong emotions, stress, excessive heat or cold, molds, pollution, specific chemicals, and very often specific foods. Patients very often already know what kind of weather, or chemicals or foods make them feel bad. For some patients, additional testing for sensitivities or elimination diets may be helpful. When additional help is needed to identify triggers, working with a functional medicine physician and/ or a naturopathic physician can be very helpful.

There are a number of supplements which can be helpful with MCAS and medications too. The focus of treatment are supplements or medications which make the mast cells less likely to release inflammatory chemicals or which reduce the amount released. Many of the medications used for this purpose have been in use for many years and are over the counter. Regardless, it is important to work with a physician to find the right supplements, medications, and dosages. Most of our patients work quite successfully with their primary care physician for this.

In coming blog posts, we will look more in depth at POTS and MCAS and we will discuss a topic requested by our office staff – insurance benefits and helping the helpers help you.

Until then, Cheers! Zebbie

P.S. More information is available at the Ehlers-Danlos Society website. I particularly like this downloadable PDF overview: https://ehlers-danlos.com/wp-content/uploads/EDS_Awareness_2017_v3_img_2021.pdf

Thanks to Dr. Mark Melecki, PT for his assistance in writing this blog. (It is very challenging to type with hooves rather than fingers. Thanks Mark.)