Autonomic dysfunction

Dr Alan Hakim, Consultant Rheumatologist & Professor Rodney Grahame, Consultant Rheumatologist, The Hypermobility Unit, Hospital of St John and St Elizabeth, London

Please note: The following text cannot and should not replace advice from the patient's healthcare professional(s). Any person who experiences symptoms or feels that something may be wrong should seek individual, professional help for evaluation and/or treatment. This information is for guidance only and is not intended to provide individual medical advice.

The information included in this sheet relates to hypermobile Ehlers-Danlos syndrome (hEDS) and the hypermobility spectrum disorders (HSD) only.

The autonomic nervous system (ANS) is responsible for controlling blood pressure, fluid and salt balance in blood and body tissues, visceral (e.g. heart, lung, kidney, bowel) function and body temperature. Individuals with hypermobile Ehlers-Danlos syndrome (hEDS) can suffer with symptoms that appear to be related to abnormal function of the ANS; the term autonomic dysfunction is used. In particular they may suffer from problems related to heart rhythm and blood pressure. Similar problems are found in fibromyalgia and chronic fatigue syndrome. How chronic widespread pain, fatigue and autonomic dysfunction are linked is a question open to research. Potential mechanisms include the interactions of hormones and other chemicals in pain centres and autonomic centres of the brain and spinal cord, and the impact of physical de-conditioning (e.g. of muscles, heart) that occurs as a consequence of widespread pain and reduced activity.

 

Symptoms

Many of the common symptoms reported relate to changes in posture. They occur when changing from a lying or sitting to a standing position, and are relieved by sitting or lying down. These include:

  • Fast heart rate (palpitations)
  • Dizziness
  • Light-headedness
  • Blurring of vision
  • Loss of concentration
  • Fear of or actual ‘blacking out’
  • Swelling in the legs after standing for only relatively short periods of time (e.g. 30 mins)

Individuals often also notice associated tiredness, tremor, sweating, anxiety and clumsiness at the same time. The symptoms are often more sudden or more severe if:

  • Dehydrated
  • Anaemic (low red cell blood count)
  • In a hot environment
  • After exercise
  • After alcohol or caffeine
  • During other illness
  • After long periods of rest

Other symptoms may NOT be related to sudden changes in posture. These include:

  • Tiring easily
  • Reduced concentration
  • Inability to exercise
  • Intolerance of hot or cold environments
  • Anxiety
  • Excessive sweating
  • Muscle and joint pain
  • Bowel dysfunction – akin to irritable bowel syndrome

Many different types of medications can also cause these kinds of symptoms, particularly related to their effects on blood pressure control when changing posture. The more common ones include:

  • Water tablets (diuretics like furosemide)
  • Blood pressure medications (beta blockers, nitrates, calcium channel blockers like amlodipine, ACE-inhibitors such as enalapril)
  • Painkillers (morphine and other opiate drugs, gabapentin)
  • Antidepressants (tricyclics like amitriptyline)

 

Heart and blood pressure (cardiovascular) autonomic dysfunction

There are three typical conditions described: orthostatic hypotension (OH), orthostatic intolerance (OI), and postural tachycardia syndrome (PoTS). These can be diagnosed in a clinic, without the need for complex tests, if the following are identified:

  • Orthostatic hypotension – a rapid drop in blood pressure by more than 20 systolic /10 diastolic mmHg from that when sitting that occurs within 3 minutes of standing.
  • Orthostatic intolerance – the same degree of blood pressure drop as above but over a more protracted period of time, e.g. 5–10 minutes, and symptoms relieved on lying down.
  • Postural orthostatic tachycardia – a greater than 30 beat-per-minute rise in the pulse on standing or a count greater than 120 beats per minute after 10 minutes with no other known cause.

Other tests that can be done simply in a clinic with the right equipment include an ECG (electrocardiogram) heart trace, measure of heart rate changes with deep breathing and the Valsalva manoeuvre (where one takes a deep breath in, holds the breath, and forces the pressure up inside the lungs and abdomen (as if straining on the toilet!)), and measuring the effect on pulse and blood pressure of sustained forceful handgrip. Even mental arithmetic testing can activate an over-sensitive autonomic nervous system (though this may of course be ‘nerves’ if your maths is weak!)

 

Laboratory investigation of cardiovascular autonomic dysfunction

Complex symptoms that are not easily identified by clinical tests or seem not to respond to simple treatments require further investigation. The common tests used include:

  • Head-up tilt: This tends to be used to study causes of blackouts (syncope). After resting flat for 30 minutes on a specially designed bed, the bed is tilted upright to about 60–80° from horizontal. The normal body response would be an increase in heart rate by about 10–15 beats per minute, a rise in diastolic pressure (the lower figure of the blood pressure, i.e. 80 if the bp was recorded as 120/80) by approximately 10 mmHg, and virtually no change in systolic pressure (the upper figure of the blood pressure recording). If the test reproduces the patient’s symptoms it is considered positive, even if there is no actual blackout or changes akin to OH or PoTS as described above.
  • Heart rate variability analysis: These tests are based on the fact that heart rate is modulated by impulses from two types of autonomic nerves and chemicals. These are the ‘sympathetic’ and ‘parasympathetic’ branches of the ANS. The tests can be done during a head-up tilt test. Different responses to the heart rate and nature of the heart’s electrical signals can inform the autonomics expert of either sympathetic or parasympathetic dysfunction, which can help in determining next steps in treatment.
  • Other screening tests: Food ingestion can sometimes trigger low blood pressure (postprandial hypotension). Again using the head-up tilt table, the cardiovascular responses to a balanced liquid meal can be measured, responses are measured while lying down before the meal and on tilt test 45 minutes later. Responses to hot and cold can also be tested.

Finally, it may be necessary to take blood tests that measure catecholamine levels (sympathetic and parasympathetic chemicals).

 

Treatment of OH and PoTS

The symptoms can often be successfully managed with the simple remedies of increasing water and salt intake, and support stockings. Exercise to improve muscle re-conditioning and heart condition is also important.

Medications:

Different classes of drugs do different things to help the symptoms of OH and PoTS. These are best prescribed by an expert and after more detailed testing as to the cause of the autonomic dysfunction.

They may have the effect of:

  • Increasing the blood flow /  total amount of fluids in the circulation (e.g. fludrocortisone and clonidine)
  • Cause blood vessel constriction – reducing the capacity or space of the circulation giving an effect similar to increasing the fluid / blood volume (e.g. midodrine, Ritalin)
  • Blocking certain ANS chemicals (beta blockers, disopyramide, ACE-inhibitors)

 

Bowel symptoms and autonomic dysfunction

People with OH / PoTS often express concern over bowel symptoms that are labelled “irritable bowel”. These include bloating, pain and hard stools fluctuating with diarrhoea. In the majority of cases, a cause for these symptoms is not found following investigations such as upper and lower bowel endoscopy (camera tests) and dynamic bowel tests using things like barium X-ray and CT scanning. The term functional gastro-intestinal disorder (FGID) is used to describe this situation when no abnormality can be found.

It has been suggested that some individuals may have autonomic dysfunction of the bowel as a consequence of imbalance or over-sensitivity to the same chemicals that are associated with pain and autonomic dysfunction in the brain and the heart. Changing the effect of these chemicals in the bowel may be one way in which classes of drugs like anti-depressants help reduce the symptoms of irritable bowel. The more common treatments for irritable bowel syndrome may be of benefit. These include:

  • Fibre: There are two main types of fibre – soluble fibre (dissolves in water) and insoluble fibre. More soluble fibre is the current advice. It can be found in powder form in pharmacies and health food stores and sourced from oat, ispaghula (psyllium), nut and seed including linseed oil (good for bloating). Limit insoluble fibre intake, e.g. reduce corn and limit fresh fruit to three portions (about 80g each) per day. Fibre helps bulk up faeces (stool), encourages retention of water in faeces and thus better transit through the bowel whilst also reducing the risk of constipation.
  • Have regular meals and take time to eat at a leisurely pace.
  • Drink at least eight cups of fluid per day, especially water or other non-caffeinated drinks.
  • Restrict tea, coffee, fizzy drinks and alcohol to a minimum.
  • Diarrhoea can be triggered by the artificial sweetener sorbitol often found in sugar-free foods, sweets and drinks.
  • A dietician may be able to advise on an exclusion diet if there appears to be an intolerance to certain food products such as dairy, refined sugar / flour or certain vegetables such as onions.
  • Probiotics – these are nutritional supplements that contain good gut bacteria that may not be present in healthy quantities. When levels are low, it allows ‘bad’ bacteria the opportunity to flourish, often leading to bloating. Probiotic bacteria are found in dairy products, i.e. milk drinks, yoghurt, cheese and ice creams, often advertised in food stores as containing ‘live’ bacteria or ‘cultures’.
  • Antispasmodic medicines – the most common ones to be prescribed are mebeverine, hyoscine and peppermint oil.
  • Anti-diarrhoeal drugs – loperamide is the most commonly used.
  • Clinical psychology – anxiety and stress can often be the trigger for IBS.

Peer reviewed by: Dr Hanadi Kazkaz, Consultant Rheumatologist, University College London Hospital

Date of last review: 01/03/2015

Date of next review: 01/03/2018

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