Autonomic Nervous System (ANS) Dysfunction in Long Covid and in ME/CFS

March 1, 2021

Dr Charles Shepherd, Hon. Medical Adviser, ME Association

A new review paper in the Journal of the Royal College of Physicians is devoted to the presence of ANS dysfunction in Long Covid:

Much of the background and management information is also relevant to ANS dysfunction in ME/CFS. Apart from the section on activity management and exercise.

“‘Post-acute COVID’ (known colloquially as ‘long COVID’) is emerging as a prevalent syndrome.

“It encompasses a plethora of debilitating symptoms (including breathlessness, chest pain, palpitations, and orthostatic intolerance) which can last for weeks or more following mild illness.

“We describe a series of individuals with symptoms of ‘long COVID’, and we posit that this condition may be related to a virus- or immune-mediated disruption of the autonomic nervous system resulting in orthostatic intolerance syndromes.

“We suggest that all physicians should be equipped to recognise such cases, appreciate the symptom burden and provide supportive management…”

Autonomic dysfunction in ‘long COVID’: rationale, physiology, and management strategies


One of the important clinical and neurological overlaps between ME/CFS and Long Covid is the presence of what is called autonomic nervous system (ANS) dysfunction, also known as dysautonomia.

Symptoms – Orthostatic Intolerance

From control systems in the brain, the ANS sends out messages to the heart, bowel, and bladder to basically either speed them up or slow them down through what are known as the sympathetic and parasympathetic nervous systems.

In relation to the cardiovascular system, the ANS plays a very important part in altering heart rate and blood pressure when changes take place in posture from lying or sitting to standing.

The aim is to make sure that when we move from lying or sitting to standing, there are rapid compensatory mechanisms in place to ensure that as well as approx. 750 millilitres (mls) of blood heading south in the body there is still enough blood being pumped north to the brain.

When this vital neurological/cardiovascular control system becomes defective, people will experience problems when standing up and/or maintaining an upright posture – known as orthostatic intolerance (OI).

OI is a common and often overlooked symptom of ME/CFS. If the blood pressure falls too much during a change in posture from lying to standing this is known as orthostatic hypotension.

Postural Orthostatic Tachycardia Syndrome (PoTS)

Both conditions can cause dizziness, light-headedness, blurred vision, mental confusion, nausea and feeling faint, or even fainting.

In the pulse rate rises excessively when moving from lying to standing this is known as postural orthostatic tachycardia syndrome (PoTS).

All three of these important aspects of ANS dysfunction occur in both ME/CFS and in Long Covid.

Screening tests

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