Friday, 12 May 2017

The Ambiguous Term “ME/CFS” Has Become a Problem for Research

12th May is ME Awareness Day

The Ambiguous Term “ME/CFS” Has Become a Problem for Research


JERROLD SPINHIRNE - WEDNESDAY, 10 MAY 2017

For International Awareness Day, May 12, 2017

Increasingly, researchers, doctors, advocates, and patients are using the mixed term “ME/CFS” as if it had some clear, specific meaning and referred to some identifiable disease. In actuality however, the mixed term “ME/CFS” is ambiguous, logically incoherent, and a major impediment for making progress in research of the neurological disease myalgic encephalomyelitis, ME, ICD G93.3. 

Additionally, patients diagnosed with chronic fatigue syndrome, CFS, and not meeting the more specific diagnostic criteria for ME, are also adversely affected by the use of the mixed “ME/CFS” term in research. Non-ME CFS while combined with ME under a single term cannot rationally be researched to identify other coherent patient groups, which could then be renamed and removed from the more encompassing CFS group. This rational strategy for resolving the current impasse in research was called for in the 2011 ME International Consensus Criteria paper, published in the Journal of Internal Medicine, and the 2012 International Consensus Primer, based on the ME-ICC. 

The IC Primer states:

The purpose of diagnosis is to provide clarity. The criterial symptoms, such as the distinctive abnormal responses to exertion can differentiate ME patients from those who are depressed or have other fatiguing conditions. Not only is it common sense to extricate ME patients from the assortment of conditions assembled under the CFS umbrella, it is compliant with the WHO classification rule that a disease cannot be classified under more than one rubric. The panel is not dismissing the broad components of fatiguing illnesses, but rather the ICC are a refinement of patient stratification. As other identifiable patient sets are identified and supported by research, they would then be removed from the broad CFS/CF category.”

The 2011 ME-ICC: 

The 2012 IC Primer: 

Patients can use this convenient guide, prepared by the MEadvocacy organization, to determine if they meet the ICC criteria for ME. 

Understanding the problems created by combining the two disparate terms ME and CFS together as a single mixed diagnosis “ME/CFS” requires an understanding of how the two terms originated.

Myalgic Encephalomyelitis

The term “encephalomyelitis” was used in a 1956 paper by Dr. A. Melvin Ramsay describing an outbreak of infectious disease at the London Royal Free Hospital in 1955, “Encephalomyelitis simulating poliomyelitis,” published in the Lancet. In the same May 26, 1956 issue of the Lancet, an editorial attributed to Dr. E.D. Acheson suggested use of the name “benign myalgic encephalomyelitis.”

The objections to any but a purely descriptive name for a disorder without a known cause or established pathology are obvious. For this reason, the term "benign myalgic encephalomyelitis" may be acceptable. It in no way prejudices the argument for or against a single or related group of causal agents; and it does describe some of the striking features of a syndrome characterized by (1) symptoms and signs of damage to the brain and spinal chord, in a greater or lesser degree; (2) protracted muscle pain with paresis [partial paralysis, muscle weakness] and cramp; (3) emotional disturbances in convalescence; (4) normal C.S.F.; (5) involvement, in some variants, of the reticuloendothelial system [part of the immune response system]; (6) a protracted course with relapses in severe cases; and (7) a relatively benign [death was not immediate] outcome. It remains to identify this syndrome more precisely; but we believe its characteristics are now sufficiently clear to differentiate it from poliomyelitis, epidemic myalgia, glandular fever, the forms of epidemic encephalitis already described, and, need it be said, hysteria.”  

It is important to note that fatigue of any kind is NOT mentioned in this early description of ME, based on the systematic clinical observation of patients with related symptoms identified during outbreaks of disease.

Acheson, writing later in a 1959 paper based on clinical observations made during 14 related outbreaks of disease, again did not mention fatigue of any kind as a commonly observed or diagnostically useful symptom:

"All the outbreaks shared the following characteristics: (1) headache; (2) myalgia; (3) paresis [muscle weakness, partial paralysis]; (4) symptoms or signs other than paresis suggestive of damage to the brain, spinal cord or peripheral nerves; (5) mental symptoms; (6) low or absent fever in most cases; (7) no mortality. In addition, (1) a higher attack frequency in women; (2) a predominantly normal cerebrospinal fluid, and (3) relapses have occurred in almost all outbreaks. In eleven of the fourteen epidemics symptoms which suggest activity of the disease have persisted for months or years in a few cases, and in eight instances there was an apparent predilection for the nursing or medical professions. Lymphadenopathy was a feature in four outbreaks.

Neither does Dr. Melvin Ramsay in his 1986 case definition of ME mention fatigue of any kind:

A syndrome initiated by a virus infection, commonly in the form of a respiratory or gastrointestinal illness with significant headache, malaise and dizziness sometimes accompanied by lymphadenopathy or rash. Insidious or more dramatic onsets following neurological, cardiac or endocrine disability are also recognised. Characteristic features include:

(1) A multisystem disease, primarily neurological with variable involvement of liver, cardiac and skeletal muscle, lymphoid and endocrine organs.

(2) Neurological disturbance – an unpredictable state of central nervous system exhaustion following mental or physical exertion which may be delayed and require several days for recovery; an unique neuro-endocrine profile which differs from depression in that the hypothalamic/pituitary/adrenal response to stress is deficient; dysfunction of the autonomic and sensory nervous systems; cognitive problems.

(3) Musculo-skeletal dysfunction in a proportion of patients (related to sensory disturbance or to the late metabolic and auto immune effects of infection)

(4) A characteristically chronic relapsing course." 

In the last paper published by Ramsay in 1990, and with Dr. Elizabeth Dowsett, this was the ME research case definition they used:

"We adopted the following clinical criteria for investigation of ME: a syndrome commonly initiated by respiratory and/or gastro-intestinal infection but an insidious or more dramatic onset following neurological, cardiac or endocrine disability occurs. The pathognomonic features are: a complaint of general or local muscular fatigue following minimal exertion with prolonged recovery time; neurological disturbance, especially of cognitive, autonomic and sensory functions; variable involvement of cardiac and other systems; a prolonged relapsing course."

The symptom of post-exertional muscle fatigue used here is very different from the symptom of perceived general fatigue, the subjective feeling of tiredness, that is used as the basis for making a CFS diagnosis. Muscle fatigue can be objectively measured. Perceived, general fatigue can only be evaluated by psychometric questionnaires – an important distinction. 

People with ME may experience episodes of profound fatigue, but many people with ME do not have a feeling of persistent, chronic fatigue. Dr. Elizabeth Dowsett said in an 1992 interview:

"One of the most striking features of ME is that the patient is not tired all the time! Extreme and sudden variability of energy levels both within and between episodes of illness differentiate this syndrome from other diseases associated with fatigue. One can only deplore the current fashion in the United States as well as the United Kingdom to redefine and rename a disability which has been clearly described in the literature for at least 100 years."

"There is nothing to be said in favour of the American acronym CFIDS (chronic fatigue immune deficiency syndrome) with its connotation of a primary immune dysfunction. The term 'chronic fatigue syndrome' recently adopted in this country also is nonspecific and non-descriptive because most of the definition is based on a vast number of exclusions (some of which, for example, endocrine disturbance, are actually found in ME)."

"'Post-viral fatigue syndrome', another British name, describes one essential feature (the association of the illness with viral infection) but gives the impression that the infection was antecedent rather than, as we now know, persistent. I prefer to use the more specific term 'myalgic encephalomyelitis' as it emphasizes the essential encephalitic component of the illness, the muscle pain, and the close clinical and epidemiological similarity to poliomyelitis." 


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