Definitions and aetiology of Myalgic Encephalomyelitis (ME): how the Canadian Consensus 
Clinical Definition of ME Works
 
J. Clin. Pathol. published online 25 Aug 2006; doi:10.1136/jcp.2006.042754
 
Bruce Carruthers
 
 
Abstract
A perspective on the various definitions of ME and the process of discovering its aetiology has
been taken. The importance of clinical guidelines has been emphasised to encourage clinicians to
provide the clear descriptions of their individual patients required for proper clinical activity;
diagnosis, estimation of severity of impact, prognosis, treatment, and rehabilitation. This individual
knowledge is informed by general and (hopefully) publicly confirmed knowledge resulting from
scientific research during the second person interaction which lies at the core of the clinical
encounter. Both types of knowledge are essential.
 
Definitions of a medical disorder must serve two divergent functions; both necessary, yet mutually
exclusive because of their fundamentally different observational contexts - one dealing with groups
of patients who can be approached scientifically and the other with individuals in a clinical context.
Research definitions (1-3) provide researchers with (relatively) homogenous groups of patients to
allow meaningfully isolated and controlled observations as they follow various hypotheses in the
hope of confirming/refuting them. In the context of research all knowledge is under review; both
what is explicitly in doubt and what is supposed to have been confirmed. Thus the observational
context is one of general uncertainty, but grounded in trust that the scientific method can generate
reliable (third-person) knowledge, and one has to start somewhere. As each patient must be
viewed as a member of a selected set, methodologically they cannot be viewed as individuals.
 
At the risk of exhibiting anecdotage , I would like to argue that another context of observation is
critical to the clinical endeavour, one that depends on the anecdotal, viewpoint-including, firstperson
experience of a patient. This is not merely consideration of a list of symptoms. It uses what
is regarded as established third-person medical knowledge (graded into several categories of
certainty/uncertainty), and matches this knowledge with that being provided by the individual
patient, in the certainty of her/his illness experience. These two types of (what is regarded to be)
certain knowledge meet in a second-person interchange between physician and patient involving
the basic clinical activities of individual diagnosis, individual prognosis, individual treatment and
individual prevention (4), also including an assessment of its impact on the patient s individual life
(degree of dis-ease and dis-ability, or deviation from the state of ease and ability which we call
health).
 
The observational context of clinical activity is thus more complex and begins from the first-person
viewpoint generated by the deictic (5,6) co-ordinates of the individual patient, which then meet the
observational and empathic skills of the physician, as well as the generalised third-person coordinates
of established public knowledge backed by various forms of evidence, in the doctor-
patient relationship within a second-person interaction. This knowledge then must be reapplied
within the deictic co-ordinates of the individual patient, viewpoints and all. But this is anecdotal 
certainty, and hence irrelevant to science. But, however anecdotal, this clinical work is essential as
the patient s unique clinical entity must be identified by being observed accurately and adequately
within its proper context. The relevant variables to follow within the entity must be sorted out from
the irrelevant ones, and similarly with those in its background. The symptoms and signs
expressing this dynamic entity must be observed minutely to see how their qualitative and
quantitative changes are developing. Interactions within and without the entity must be observed in
order to find consilient and causal chains to assign symptom priority. The individual effects of
treatments must be observed and such effects may trump the statistical results of evidence based 
treatments within the clinical context.
 
A primary clinical entity cannot be a static object. It is necessarily subjective in part (since it
observes at least itself), and like the primary illness experience that participates in it, is an
undivided, in-dividual, as yet unnamed whole, and of the nature of a real process, not to be
confused with the set of concepts used to name and describe it (see problem of
realism/nominalism(7)). Note that all of these clinical practices depend to a large extent on the
assumption of the accuracy and adequacy of the patient s experience of illness as it unfolds under
the observation of the physician. If the observational discipline of Western painting is based on the
disavowal of deictic reference (8), then it is no wonder that clinical observation skills are
atrophying. But it is the dynamic clinical entity, of necessity both subjective and objective, which
orients the field of clinical activity, if clearly and adequately observed.
 
If such clarity and adequacy are not achieved, several types of smudging may result. In other
words, if the generalisations from the medical model are too generic, they have no chance of
adequately meeting the patients illness experience, and much relevant data may be overlooked
and/or misinterpreted. Thus the move from a more specific clinical concept such as ME or
Fibromyalgia to a more generic concept such as Chronic Fatigue Syndrome or Chronic Pain
Syndrome entails missing a lot of the information that makes the syndrome as a name match the
syndrome as an experience. The syndrome as an experience is a coherent entity whose parts run
together as a process - as the word syndrome indicates etymologically - and whose causal
interactions are sensed directly in the mode of causal efficacy (9). This entity arises against a
background which is treated as a nonentity for the purposes of the observation. Thus the attempt
to organise clinical activity around a nonentity, such as in Somatization Disorder and Munchausen
Syndrome(10,11), where diagnosis depends on the absence of an entity, may interfere with proper
clinical activity by importing a misplaced forensic attitude towards a patient s illness experience,
discounting or distorting its relevance. The move towards ignoring the distinctions between primary
and secondary which designate sensed causal directions within a clinical entity, whether applied to
depression, anxiety, infection or fibromyalgia, add to the confusion and impede the elucidation of a
properly dynamic clinical entity. The widespread use of the holistic biopsychosocial model of
disease(12-14) without any distinction between a clinical entity and its background encourages the
drowning of clinical entities by risk factors which can proliferate endlessly in a nominalist fury
without orientation as to their state of relevance or lack thereof with respect to a real entity (7).
 
The Canadian consensus case definition and diagnostic protocol for ME (15) has been influenced
by the clinical method of Sydenham (16), which is to provide a fuller and richer framework to fit the
patient's illness experience into a framework that is specific and complete enough to match the
patient's experience, yet consonant with the large body of public and confirmed results that have
been obtained by the research activity stimulated by earlier definitions. It tries to be more adequate
to the clinical activity that each patient's unique clinical situation demands. It facilitates a precise
and adequate observation of the unique clinical entity arising in a patient in contrast to its
contextual background. This is necessary to orient clinical activities, to guide the quantification of
the events, both syndromal and contextual, which may be of particular relevance, as well as
sorting out their causal direction and priority. It tries to remain close enough to be adequate to the
illness experience of the patient and thus invariant to the changes in interpretation of this
experience as science evolves over the years (16). Unless a disease entity is eliminated by better
understanding and better technology, it will continue to require clinical attention, whatever we
hypothesize its natural kind to be.
 
To improve clinical observation, the Canadian definition and diagnostic protocol lays out a number
of regions of patho-physiological dysfunction, as necessary components of the syndrome of ME,
but the particular expression of symptoms within each region is contingent between individuals,
and their specific pattern is left open to be decided by clinical observation of the individual and
later diagnostic classification. These component regions include fatigue, which must be severe
and prolonged and of a certain dynamic pattern (delayed, prolonged reactive), and significant
dysfunction must be observed in the following realms - sleep, pain, neurological/cognitive, and at
least one of the following 3 realms - autonomic nervous system, neuroendocrine, and immune
system. This approach facilitates the identification of the patient s individual clinical entity or
syndrome, how its parts fit together and interact, as well as its impact on the patient s life - seen as
dis-ability and dis-ease - and leading to a more accurate and adequate diagnosis. It allows
estimates of the clinical course and prognosis, decisions regarding treatment, estimation of the
treatment effects, and search for successful preventive and rehabilitative strategies. With its
flexible combination of necessary and optional features, the definition allows the diagnosis to fit the
patient rather than the other way around (as with Procrustes, an innkeeper from Greek mythology
who stretched the guests to fit his bed!).
 
The possible aetiology of ME is under scientific observation. This is done by experiment and by
controlled observation. Many observers are following various lines of investigation and observation
as to the aetiology of ME, which we are all following with interest.
 
There are some problems. A hypothesis is a cognitive structure necessary to organise one's
experimental efforts. When rigorously tested independently and often enough, your hypothesis can
be regarded as tentatively confirmed. But within the context of research, you should work to
disprove your hypothesis. As noted by Sydenham (16), to arrange reality to save it can cause
much error. I quote In writing the history of a disease, every philosophical hypothesis whatsoever,
that has previously occupied the mind of the author, should lie in abeyance. This being done, the
clear and natural phenomena of the disease should be noted - these and these only. They should
be noted accurately, and in all their minuteness;......No man can state the errors that have been
occasioned by these physiological hypotheses. Writers, whose minds have taken a false colour
under their influence, have saddled diseases with phenomena which existed in their own brains
only; but which would have been clear and visible to the whole world had the assumed hypotheses
been true. 
 
The opposite problem of importing a context of doubt into the clinical arena, which is heavily
dependant on deictic certainties, can result in the disruption of the second person clinical
observation structure and subsequent clinical practices, as observed with the smudge diagnoses
mentioned earlier.
 
The problem of cultivating a holistic view without adequately structuring the field with a proper
clinical entity can lead to great confusions of relevance, where contextual and syndromal features
are confounded with no way of clinically quantifying their relative impacts. Choose the right kind of
entity or you may end up only considering background factors with no clinical entity left that they
are the background of - see the fate of the Cheshire cat in Alice in Wonderland, where the cat
fades, leaving only the smile! (17)
 
References
1.Holmes GP, Kaplan JE, Gantz NM, et al. Chronic fatigue syndrome: a working case definition.
Ann Intern Med. 1988;108(3):387-9.
2.Sharpe MC, Archard LC, Banatvala JE, et al. A report - chronic fatigue syndrome: guidelines for
research. J R Soc Med. 1991;84(2):118-21.
3.Fukuda K, Straus SE, Hickie I, Sharpe MC, Dobbins JG, Komaroff A. The chronic fatigue
syndrome: a comprehensive approach to its definition and study. International Chronic Fatigue
Syndrome Study Group. Ann Intern Med. 1994 Dec 15;121(12):953-9.
4.McDermott W. Evaluating the Physician and His Technology. In Doing Better and Feeling
Worse: Health in the United States , ed, Knowles JH. Norton, New York, 1977, pp.142-156.
5.Tallis R. The Raymond Tallis Reader. Ed, Grant M. Palgrave Macmillan, New York, 2000.
6.Bryson N. Vision and Painting. Yale University Press, New Haven, 1983, p.87.
7.Hacking I. The Social Construction of What? Harvard University Press, Cambridge, 1999, pp.80-
84; 96-99; 174; 205-6.
8.Bryson N. Vision and Painting. Yale University Press, New Haven, 1983, p.89.
9.Whitehead AN. Symbolism. Capricorn Books, New York, 1927, pp.30-59.
10. Hollifield, MA. Somatoform Disorders. In: Kaplan and Sadock s Comprehensive Textbook of
Psychiatry. Eds. Sadock BJ and Sadock VA, 8th ed. Baltimore: Lippincott, Williams and Wilkins,
2004, pp.1800-1828.
11. Wang D, Nadiga DN and Jenson, JJ. Factitious Disorders. In: Kaplan and Sadock s
Comprehensive Textbook of Psychiatry. Eds. Sadock BJ and Sadock VA, 8th ed. Baltimore:
Lippincott, Williams and Wilkins, 2004, pp.1829-1843.
12. Engel GL. The clinical application of the biopsychosocial model. Am J Psychiatry
1980;137:535-44.
13.Dilts SL. Models of the Mind. Brunner Routledge, Philadelphia, 2000.pp13-16.
14.Wessely S, Hotopf M, Sharpe MC. Chronic Fatigue and its Syndromes. Oxford University
Press, Oxford, 1998, pp.363-5.
15.Carruthers BM, Jain AK, De Meirleir KL, et al. Myalgic encephalomyelitis / Chronic Fatigue
Syndrome: clinical working case definition, diagnostic and treatment protocols. Journal of Chronic
Fatigue Syndrome 2003;11:7-115.
16.Sydenham T. Medical observations concerning the history and the cure of acute diseases.
Preface to the 3rd edition, section 9, p14. (First Edition, 1676, The works of Thomas Sydenham,
MD. Classics of Medicine Library, 1979).
17.Carroll L. Alice in Wonderland. Collins, London, undated, pp.67-80.