INTRODUCTION
If the cause
of a disease, the way in which it is acquired and the processes by which damage
is caused are known, no definition is needed. To the very few physicians still
practicing today who began seeing patients with this illness some 40 years ago
and who have continued to record and publish their clinical findings throughout,
the current enthusiasm for renaming and reassigning this serious disability to
subgroups of putative and vague “fatigue” entities, must appear more of a
marketing exercise than a rational basis for essential international research.
It was not always so unnecessarily complicated!
MODERN
DESCRIPTIVE OR RESEARCH DEFINITIONS OF ME/CFS
These have
gradually evolved, depending on the technology available throughout the 20th
century:-
1.
A POLIOMYELITIS-LIKE ILLNESS (Descriptive, 1910-1958)
Historically the clinical distinction between ME/CFS and abortive/non paralytic
poliomyelitis has always been blurred. General awareness of a second
polio-like illness was not raised until the early years of this century.
Striking new features of that period were major epidemics of paralytic polio
accompanied sequentially, seasonally and geographically by outbreaks of
“atypical polio”, 38 of which are clearly recorded in medical literature prior
to 1965. At this point, the apparent conquest of the most disabling of all
neurological infections by immunisation led to lack of interest in further
research.
Advantages of
the “polio-like” description – general awareness of the entity by physicians;
information readily available in standard text books and medical journals.
Supportive evidence: (a) a virological distinction between the 2 diseases was
not available until the development of virus culture in 1948. This resulted in
the discovery of some 69 related polio and non-polio enteroviruses. Although
the majority of host/virus contacts produce subclinical infections, these agents
are extremely versatile with a wide range of overlapping tissue affinities.
They are reliably associated with many acute infections of the respiratory and
intestinal tracts; with middle ear, neurological, skin, muscle, throat and
mucous membrane infections; with epidemics of viral meningitis, Bornholm and
Hand Foot and Mouth disease and with chronic sequelae affecting the brain, heart
muscle, the pancreas and other endocrine glands. (b) Serological studies in
Iceland, following the introduction of oral polio vaccine in 1958, indicated
that a 1948 epidemic of Iceland Disease (ME) in the north of the island
effectively blocked a 1957 epidemic of polio type I in the south from spreading
north. At the same time the response to polio type I oral vaccine was standard
in the south but aberrant in patients who suffered from the 1948 epidemic in the
north. This indicated a close relationship between the agents of both diseases
with competition for receptor sites in the bowel and persistence of the 1948
epidemic agent over 7 years.
2.
MYALGIC ENCEPHALOMYELITIS (Descriptive 1958-1988)
In this
halcyon period of increasing co-operation between clinicians and their technical
or laboratory colleagues, ME/CFS research was still determined by the meticulous
observation and examination of patients rather than by non clinical doctors or
scientists working at some distance from patient care. Research into ME/CFS
remained an acceptable subject for MD theses at prestigious Medical Schools.
Such studies by Wallis1.
and by LYLE2.
in 1956 (both of whom were involved in community care) have left us, in the
first instance, with a remarkably accurate description of the disease in adults
and the corresponding variations in children and, in the second case, with the
recorded isolation of ECHO 9 virus (a non-polio enterovirus) from infected
patients. In the same year RAMSAY3. was responsible for the
introduction of the descriptive term “Myalgic encephalomyelitis” (ME) into
medical literature (though some would argue that the virus does not persist and
that “itis” should be changed to “opathy”).
Advantages of
the descriptive name (ME) – With the widespread use of this name in the UK,
Canada, Australasia and elsewhere over the past 40 years, international
collaborative research was simplified and made feasible.
Supportive
Evidence: With the rapid development of technology and access to international
publication, the UK retained its reputation as a leading centre of ME/CFS
research and remained able to report clinical studies backed up by molecular
biology, brain imaging, sophisticated hormonal and other biochemical studies.
At this point, with sound evidence of an infective cause, the way in which such
infection is spread and the pathogenisis of the disease, why were we urged to
adopt the “fatigue definitions” inflicted upon ME/CFS sufferers by USA
scientists?
3. THE FATIGUE STATES (RESEARCH DEFINITIONS 1988-1999)
In those
countries which have adopted mass polio immunisation during the past 30 years,
outbreaks of ME/CFS still continue unabated. Interest in one such epidemic
(Lake Tahoe, Nevada USA 1984) misdiagnosed initially as Epstein-Barr Glandular
Fever – a Herpes virus infection, led a group of non-clinical scientists active
in the field of Herpes virus research and evaluation of drugs, to formulate and
tailor a fitting new research definition (Holmes et al 1988). The exclusion or
downgrading of many characteristic ME/CFS symptoms led to an unreal emphasis on
psychiatric explanations and diminished estimates of the real prevalence.
Attempts to correct this initial “Fatigue” definition in the UK (Sharpe et al
1991) the USA (Fukada et al 1994) and in Australia (Hickie et al 1995) became so
inclusive of a heterogeneous population of sufferers from psychiatric and
miscellaneous non psychiatric states as to elevate the suggested prevalence of
ME/CFS by some 250 times. Major mistakes in these definitions include: (i)
overlooking the distinguishing encephalitic features of ME CFS (ii) elevating
“fatigue” (an inescapable accompaniment of normal human existence and of
cardiovascular, metabolic malignant, psychiatric, neurological and other
disabling conditions) to unreal diagnostic importance among ME/CFS symptoms.
(iii) to
suggest that ME/CFS is merely one subgroup amongst this heterogenous collection
of physiological and pathological states, makes thus making any attempt at
differential diagnosis between them impossibly expensive to pursue. (iv) to
suggest that diagnosis must be delayed for 6 months, vitiates any real attempt
at virus investigation, especially among the young. It has to be remembered
that these “Fatigue” definitions were devised specifically for research, not
clinical purposes; that they exclude variations in children and adolescents and
that scientists in the USA (their main country of origin) are now foremost in
seeking a more descriptive name than that of “Chronic Fatigue” for this
illness!
To Summarise:
I would urge all our colleagues to look again at the literature prior to 1988
before redefining this illness. Meantime, the Ramsay description of myalgic
encephalomyelitis in 1986 (see Appendix A) with slight modifications to
form a short definition 4. still remains a useful guide to
those new to this work.
THE RAMSAY
DEFINITION
“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
enhaustion 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
WHAT IS NEEDED
FOR THE FUTURE?
(1)
A short epidemiological summary
(2)
A working definition suitable for clinicians and researchers
(3)
A modified definition for children and adolescents
References:
1.
WALLIS AL. An investigation into an unusual
disease seen in epidemic and sporadic. Form in a general practice in
Cumberland in 1955 and subsequent years MD Thesis Edinburgh University 1957
2.
LYLE WH. An outbreak of a disease believed to
have been caused by ECHO 9 Virus. Annals of Internal Medicine 1959; 51: 248-269
3.
RAMSAY AM. Encephalomyelitis simulating polio
myelitis. Lancet. 1956;1: 761-766
4.
DOWSETT EG. RAMSAY AM. Myalgic encephalomyelitis
– a persistent enteroviral infection? Post graduate Medical Journal. 1990; 66:
526-530
