(Reposted from The ME Association website with permission )
he decision by researchers on the American CFS Name Change Advisory Board (meeting in Florida on 12 January 2007) to agree that a new name should be adopted for chronic fatigue syndrome (CFS) is obviously very welcome. At the same time they have expressed support for the use of the term ME, as myalgic encephalopathy (as this is 'diagnostically accurate') rather than myalgic encephalomyelitis.
This decision has once again opened up the debate over what is the most appropriate term to use to describe the clinical, examination and pathological features of this illness.
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 evidence to demonstrate that the principal pathological feature 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 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 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 material (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 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 psychiatric diagnosis rather than a medical diagnosis.
To provide some clarification, 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 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), nystagmus (involuntary eye movements), tremor, muscle atrophy and weakness, dysequilibrium (and unsteady gait), paraesthesiae (sensory disturbances) , hypothalamic dysfunction, orthostatic intolerance and postural hypotension.
5 More serious neurological symptoms, as described in section 4.2.1.2 of the Chief Medical Officer's report (eg seizures), can also be found in encephalopathies.
6 Mood disturbances can occur.
7 Abnormalities can be found on neuroimaging, spinal fluid examination and electroencephalogra ms - depending on the cause of the encephalopathy.
Examples of well recognised neurological encephalopathies include:
Bovine spongiform encephalopathy ('mad cow disease')
Coxsackie virus encephalopathy
HIV encephalopathy (and AIDS dementia complex)
Hepatitis C encephalopathy
Liver (cirrhotic) encephalopathy
Lyme disease encephalopathy
Mycoplasma encephalopathy
Sarcoid encephalopathy
Wernicke's (thiamine deficiency) encephalopathy
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 (UK)
[Posted in a personal capacity]
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