Use of the term myalgic encephalopathy on the new MEA website

October 1, 2010

Medical conditions of uncertain or unknown causation often accumulate a number of names which may or may not appear in WHO ICD10 (World Health Organisation International Classification of Diseases number 10).  This is perfectly understandable given the fact that medical research is continually moving on and producing new information on disease causation and treatment which may, in turn, be relevant to the way in which the disease is named and classified.

ME/CFS is no exception and has been called ‘a disease of many names'.  In America, it is also known as CFIDS (chronic fatigue and immune dysfunction syndrome); in Japan low natural killer cell syndrome; and in France it is sometimes called Spasmophilie.  The  discovery of XMRV, and a possible link to ME/CFS, has also led to the recent proposal that a new name based on XMRV and the associated neuroimmune disorder (ie X-associated neuroimmune disease/XAMD) could/should now be used in those people with ME/CFS who are XMRV+ve..

Historically, I took the view that following publication of the 1996 Royal Colleges Report into ME/CFS, which resulted in a determined effort by some doctors to completely remove the term myalgic encephalomyelitis from UK medical language (and this had already largely occurred at the time as far as international medical publications and research was concerned) that it was time to put forward a new name that would keep the initials ME but could not be criticised as being pathologically inaccurate by doctors – as was/is frequently the case with the encephalomyelitis part of ME.  Hence the introduction of the term myalgic encephalopathy..

Since then, the term myalgic encephalopathy has become accepted by many doctors, as well as the Department of Health and other official bodies in both the UK and overseas.  This initiative has therefore had a degree of success in taking the heat out of the intense medical arguments surrounding the name encephalomyelitis and helped to ensure that ME is still being used, but without hostility, by at least some doctors.

The decision by The ME Association to use the term myalgic encephalopathy in their title and company documents dates back almost ten years .  The decision was fully discussed by our Scientific and Medical Advisory Panel at the time. It was also discussed, debated and voted on by MEA members at an EGM (Extraordinary General Meeting) that was held in London on 14 July 2001. 1274 MEA members voted in favour of using the term myalgic encephalopathy.  43 voted against.

The MEA has not consulted with, or written to the WHO on this proposal and myalgic encephalopathy is not listed in WHO ICD10.  But this does not prevent doctors, people with ME/CFS, or official/government bodies using the term if and wherever they want to .  The MEA and myself use both encephalomyelitis and encephalopathy.  For example, I normally use encephalomyelitis when doing media work and in joint initiatives with other ME/CFS charities but tend to use encephalopathy when speaking to doctors. There is no intention to try and force people or organisations to use this alternative name.  It has just been put forward as a proposal for discussion and a way of allowing doctors to use the term ME when they would otherwise refuse to do so because of the term encephalomyelitis.. But everyone is free to make up their mind on whether and when it would be more helpful to use either option.

I remain open-minded about what may be happening in the central and peripheral nervous system in ME/CFS.  However, I do not believe that there is any robust research evidence, at present, to confirm the use of the term encephalomyelitis – inferring significant and active inflammation involving the brain and spinal cord.  I believe that encephalopathy, meaning a significant abnormality in various aspects of normal brain function, is a more appropriate name to use in our current state of knowledge regarding the neuroscience of ME/CFS..

I am one of a very small number of doctors who is actively trying to resolve the mystery of what is happening to the central and peripheral nervous system in ME/CFS through the use of post-mortem tissue research. To do this I am involved in various aspects of post-mortem tissue research and the MEA is currently raising funds, funding post-mortem research activity, and carrying out a feasibility study – all with the intention of setting up a UK based post-mortem tissue and brain bank. This is now the subject of a paper that is currently being prepared for publication. Some preliminary results from recent post-mortems are also due to be presented at an international research conference later this year.  And while the already reported finding of dorsal root ganglionitis (which can also occur in Sjogren's syndrome and varicella zoster infection) in one ME/CFS post-mortem case is very interesting, it does not equal encephalomyelitis.

If it does turn out that this type of research demonstrates the presence of encephalomyelitis in the brain and spinal cords of people with ME/CFS there will be no need to consider any other name for this illness.

More information on the post-mortem research that is being funded and carried out by the MEA Ramsay Research Fund can be found on the MEA website:

More information on the use of the term encephalopathy:

The reason why so many clinicians and researchers now either refuse, or are extremely reluctant to use the term ME – as myalgic encephalomyelitis –  is due to the continuing lack of sound research evidence to demonstrate that the principle pathological feature in ME/CFS is a widespread inflammatory change taking place within the brain (ie encephalitis) and the spinal cord (ie myelitis).  And while there is undoubtedly some evidence of past or present inflammatory changes (+/- immune system dysregulation) within the central nervous system taking place in some people with ME/CFS (mainly in research defined CFS cases) this is not the sort of evidence that would confirm a clinical or pathological diagnosis of encephalomyelitis to a neurologist.

Evidence of past or present inflammation within the CNS can have a number of explanations and care needs to be taken to avoid drawing conclusions from existing research studies  (the results of neuroimaging studies in people with research defined CFS in particular) that cannot be justified on scientific grounds.  Adopting this approach is also likely to be counter-productive when it comes to challenging medical opinion on the issue of nomenclature.

Consequently, some doctors, including myself, have proposed that the term encephalopathy should replace encephalomyelitis (as the E in ME) on the grounds that encephalopathy is a far more appropriate description of the neurological symptoms, signs and investigative abnormalities (neuroimaging and neuroendocrine in particular) that have been described in the literature.

Encephalopathy is also a term that doctors cannot simply dismiss on the grounds that it is pathologically inaccurate in relation to ME (or research defined cases of CFS).

There does, however, continue to be considerable confusion over what an encephalopathy is with some people claiming, quite wrongly, that it is a relatively benign psychiatric diagnosis rather than a serious medical diagnosis with neurological symptoms and complications.

To provide some clarification, some of the key features of an encephalopathy (all of which are consistent with ME/research defined CFS) are listed below:

1  A significant and sometimes diffuse disorder of the brain that can involve both changes to structure and function.

2  A permanent or reversible neurological disorder than can be caused by infections (viral, bacterial, prion), metabolic or mitochondrial dysfunction, exposure to toxins (eg drugs, chemicals, pesticides), lack of oxygen or blood supply to the brain.

3  A disorder that commonly produces serious disturbances in cognitive function – involving memory, concentration etc.

4  Other neurological symptoms that can be found in an encephalopathy include myoclonus (twitching of muscles or muscle groups), poor co-ordination of limb movements, nystagmus (involuntary eye movements), tremor, muscle atrophy and weakness, dysequilibrium and unsteady gait, paraesthesiae (sensory disturbances), hypothalamic dysfunction and heat intolerance, orthostatic intolerance and postural hypotension.

5  More serious neurological symptoms, as described in section of the Chief Medical Officer's report into ME/CFS  (eg seizures), can also be found in encephalopathies.

6  Mood disturbances can occur – as they sometimes do in ME/CFS.

7  Objective abnormalities can be found on neuroimaging, spinal fluid examination and electroencephalograms – depending on the cause of the encephalopathy.

8  Some encephalopathies are fatal.

Examples of some well recognised encephalopathies include:

Bovine spongiform encephalopathy (‘mad cow disease')

Coxsackie virus encephalopathy

Diabetic encephalopathy

Enteroviral encephalopathy

Glycine encephalopathy – a paediatric metabolic encephalopathy

Hashimoto's encephalopathy – associated with Hashimoto's thyroiditis

HIV encephalopathy (and AIDS dementia complex)

Hepatitis C encephalopathy

HHV-6 encephalopathy

HTLV encephalopathy

Hypoxic ischaemic encephalopathy – from decreased oxygenation to the brain

Liver (cirrhotic) encephalopathy – from advanced cirrhosis of the liver

Lyme disease encephalopathy

Mitochondrial encephalopathy (and MELAS) – involving damage to mitochondrial DNA

Mycoplasma encephalopathy

Sarcoid encephalopathy

Toxic encephalopathy – often leading to permanent brain damage

Uraemic encephalopathy –  build up of toxins in renal failure

Wernicke's (thiamine deficiency) encephalopathy

These are all very serious medical conditions with neurological complications and symptoms.  They are not psychiatric conditions and they are not treated with psychiatric interventions.

This is an important debate and I am pleased that it is now taking place in America as well as here in the UK.

Dr Charles Shepherd
Hon Medical Adviser, ME Association

1 thought on “Use of the term myalgic encephalopathy on the new MEA website”

  1. I run a weekly enquiry on Pubmed using the term, “Chronic Fatigue Syndrome”. Is this wrong? It does seem to be the most generally used terminology and does not produce false positives. I do not see the point of using a nomenclature which is not generaly accepted by researchers.

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