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What is Myalgic
Encephalomyelitis?
Jed Gallagher
Myalgic Encephalomyelitis (ME) is a chronic disease, acquired during a viral infection, which leaves the
patient with a capacity for physical and mental effort of less than half of their previous capacity, coupled
with numerous impairments to every physiological system of the body (Komaroff 1994). The reduction in the
capacity for physical and mental effort can be as much as 90% in severe cases, leaving the victim totally
bed-bound and reliant on care. Most patients are moderate or mild cases but even this means they spend
most of their time sleeping and resting. Even moderate cases are seriously disabled and unable to work or
study full-time. Mild cases may be able to carry out full-time sedentary work or study but this is only possible
with full domestic support and no other activities; they are forced to spend each evening and weekend
resting and sleeping. For all patients, physically-active time is extremely limited, with the shear effort of
rising, personal hygiene, dressing, feeding, communicating and leaving the house for only short periods taking
up most of their minimal energy - with little left over for personal interests.
The impact of ME on the life of a previously healthy adult is always devastating and the large reduction in the
capacity of all of their physical and mental functions is a truly shocking experience. Patients find great
difficuly in retaining any aspect of their previously healthy lives. Indeed, many victims are completely
unaware of the existence of ME and find it hard to psychologically accept that such a condition could actually
exist. Many state that there is nothing within a healthy persons preconceptions of disease and disability that
could have prepared them for living with ME (Anderson 1997). This is all part of the unique experience of ME
as a medical condition - there is no other disease with this type and level of disability. The cruelty of the
condition is such that, although no physical or mental function is completely lost, the capacity of each
function is so far reduced as to make it useless for day to day activities of living. Patients do not “look” ill but
are actually the most functionally disabled group in any community. Research in the American Journal of
Occupational Therapy has shown that ME patients have very low scores on a whole range of physical and
cognitive testing scales. Short-term memory and concentration difficulties are comparable with mild or
moderate Alzheimers disease (Barrows 1995). Dr Mark Loveless, a north American infectious diseases
physician, who treats HIV/AIDS and ME patients, has testified to the US government that, according to his
clinical research, ME patients feel every day significantly the same as an AIDS patient feels two months
before death. For ME patients, the disabling systemic symtoms and huge reduction in functional capacity
continue for year after year. The reduction in quality of life is enormous. ME patients loose incomes,
marriages, children and friends from their lives; if they are young, they never get a chance to experience
these things in the first place. ME patients just do not have the energy (that is taken for granted in normal
health) to create and maintain normal social and personal relationships.
ME was classified as a neurological disease (G93.3) by the World Health Organisation in 1992 (WHO 1992).
The term was first used in The Lancet in 1956 to describe the condition contracted by 292 hospital staff at
the Royal Free Hospital, London in 1955 (Ramsay 1988). The condition became chronic in around 20% of the
staff. Subsequently, it became apparent that the disease had been known for hundreds of years and had gone
under numerous names (Straus 1991). The consultant in infectious diseases at the Royal Free in 1955 was Dr
Melvin Ramsay - he was the first to define modern diagnostic criteria for the disease (Ramsay 1988). Many
other names are still in use for the condition today; for example, in Japan, it is also known as “the low natural
killer cell syndrome”, refering to one of a number of immunological abnormalities involved.
Encephalomyelitis refers to brain and spinal cord inflammation - producing numerous neurological symptoms
in ME, including a uniquely rapid mental fatigability. However, encephalomyelitis is a common feature of many
neurological diseases. The distinctive feature of ME is that the neurological symptoms are accompanied by a
unique myalgia - muscle pains, tenderness, aches, cramps and, most importanty, rapid muscle fatigability
following trivially minor physical exertion. If the physical exertion is too intense or too prolonged then the
patient is overwhelmed by a post-exertional malaise - an experience of sickness, nausea, dizzyness,
overheating and mental confusion. Most importantly, the muscle fatigue and myalgia increase on the
following day - with full muscle recovery taking anything from 24 hours to a week depending on the initial
exertion (Ramsay 1988).
The neurological symptoms are accompanied by a large number of endocrine and immune abnormalities these are sub-clinical and so not indicative of any other specific disease. The number of related symptoms is
so great - around 100 - that the existence of the disease can appear unbelievable to medical doctors too, so
patients are often accused of being hypochondriacs. ME is not a common condition but neither is it rare - best
estimates put the prevalence at around 1 per 1000 of population (Hyde 1992). It affects all socio-economic
classes and ethnicities. However, female patients outnumber male patients by around three to one. In this
respect, ME is similar to many auto-immune diseases which disproportionately affect females because of
female hormonal susceptibility to developing these conditions (Komaroff 1994). This also means that ME is
actually a rare condition in males: around 1 per 4000.
This unknown existence of ME has been compounded by the lack of scientific understanding of both etiology
and pathophysiology. The viral trigger is generally agreed but there is no agreement as to whether the
disease is the result of an ongoing infection by some unidentified or undiscovered micro-organism. Tarello
(2001) has recently found the CO2-dependent small-colony variant (SCV) of staphylococcus aureus in the
blood of human and animal CFS patients. This SCV is not detectable by currrent automated blood culture
tests. Or, whether it represents viral damage. Or, whether it is the manifestation of virus-induced adaptations
to still fully-functioning physiological systems (Gallagher 1996). In fact, the physiological mechanism which
is able to account for the symptoms of ME has only recently been discovered - neuroimmunomodulation (NIM).
NIM research has demonstrated that the three physiological control systems of the body - nervous, immune
and endocrine systems - are not, as previously thought, discrete and independent but rather acting as a single
system by forming an interdependent network. Without NIM, it has not been possible to scientifically
understand how a viral trigger could cause and sustain such widespread physiological disruption in the ME
patient (Kavelaars 2000).
In 1993, the medical advisors to the UK ME patient organisations collaborated on a new set of diagnostic
criteria, based on Ramsays work, to be known as the London criteria (Tyrell 1994):
1) Exercise-induced fatigue precipitated by trivially small exertion (physical or mental) relative to the patients
previous exercise intolerance.
2) Impairment of short-term memory and loss of powers of concentration, usually coupled with other
neurological and psychological disturbances such as emotional lability, nominal dysphasia, disturbed sleep
patterns, dysequilibrium or tinnitus.
3) Fluctuation of symptoms, usually precipitated by either physical or mental exercise.
4) These symptoms should have been present for at least six months and should be ongoing.
Criteria number 1 identifies ME as a unique and specifically identifiable disease. Many diseases produce
“chronic” fatigue in their victims. The intensity of the “chronic” fatigue afflicting each patient varies, as in ME,
from mild, to moderate, to severe. So, if a person suffers with “chronic” fatigue, it does not actually diagnose
ME. (Still, the intensity of the “chronic” fatigue in severe ME cases is such, that it could only be ME, or the last
few days of life of an AIDS patient, or someone with a severe phobia who is imitating illness). The key
differentiating point for ME is that the “chronic” fatigue of ME is significantly exacerbated by trivial physical
and mental exertion. So, in ME, the intensity of the “chronic” fatigue experienced is not static; it always
increases greatly with only trivial exertion. No other “chronic” fatigue-inducing condition has this “trivial
exertion” feature, including all psychiatric and psychological disorders; it must be present for a diagnosis of
ME.
It is essential to understand that trivial physical and mental exertion in ME is an absolute concept in relation
to the exertion capacities of a healthy person but that it is relative to the severity of “chronic” fatigue in a
particular case of ME; that is, relative to whether they are a mild, moderate or severe ME case. As I have said,
a mild case of ME may be capable of six or seven hours of sedentary mental exertion (with minimal physical
exertion) for four or five days each week. But, they will literally do nothing else but rest and sleep during the
rest of the time. This is clearly trivial exertion to a healthy person but if the mild ME case does anything more
than this, then they will find themselves unable to work at all. In a severe ME case, the level of “chronic”
fatigue is so intense that they spend 90% of every day sleeping and resting in bed. In this case, the amount of
exertion deemed trivial is much less than in a mild case. The capacity for physical exertion will be almost
zero and mental exertion may stretch to half an hour of reading or television. (In fact, in most severe ME
cases, sensitivity to light is so great that anything involving lighting is actually precluded). So, for
understanding ME, it is absolutely essential to appreciate that a patient can be afflicted by different levels of
“chronic” fatigue, roughly divided into mild, moderate or severe cases. And, that the capacity for physical and
mental exertion in each type of case is trivial in comparison to normal health, but it is relative to the type of
ME case.
Criteria number 2 indicates that specific and measurable neurological deficits must be present for a diagnosis
of ME. The two key deficits are short-term memory and concentration difficulties; again, these are
exacerbated by trivially small amounts of mental and physical exertion. Although these deficits do not affect
a patients intelligence or intellect, even intelligent ME patients are often perceived as “slow” or “not all
there”. Again, the severity of these deficits is relative to the severity of the ME case. Due to the emotional
lability and depression in ME, patients can often exhibit inappropriate behaviour and “strange” moods in
social situations.
Criteria number 3 is essential for understanding that reduced capacity for physical and mental exertion in ME
are interdependent. This means that physical exertion will also increase mental fatigue and vice versa. So,
physical exertion will precipitate subsequent difficulty in thinking and thinking will precipitate a draining of
physical energy. For this reason, highly intelligent ME patients learn to keep their physical exertion to an
absolute minimum to extract maximum mental capacity. This behaviour will also reduce the effects of
short-term memory and concentration difficulties.
Also, criteria number 3 is essential for understanding how patients live and cope with ME on a day to day
basis and over longer periods of time. Moderately and mildly-affected ME patients learn to keep their physical
and mental activity for each day within a daily limit. They learn not to walk too far, stand for too long, read or
write for too long, or physically exert themselves too much. They get the balance right between physical and
mental activities. They get lots of sleep and rest. By doing this, it means they will be able to do the same
small levels of activity the following day. (In a similar way to healthy people taking for granted that they can
do a whole day of activity and then get up the next day and do it all again; maybe with a Sunday morning in
bed.) ME patients may be seen out and about attending to their chores and errands on a daily basis but this is
all they will be doing during that day. Yet, because they are restricted by capacity to function rather than loss
of function, it gives the impression that they are fit and well and living a normal life.
If an mild/moderate ME case does not pace themselves and keep their activities within their daily limit then
their reduced capacity for effort is lost altogether the following day; this loss can continue for up to a week
depending on the duration and intensity of the activity. They find that they are too weak to get out of bed for
days, sleeping each day through, suffering with muscle aches and pains, blinding headaches, blurred vision,
and a light aversion which means they are not even able to watch television without overwhelming nausea.
Still, if anybody saw their increased activity of the previous day, they would appear to be perfectly healthy. All
ME patients are faced with this dilemma of just how much activity to do each day against such a wide
fluctuation in symptoms.
Pacing of activity over the longer term is an even more important aspect of living and coping with ME. For
example, a moderately affected ME patient may find that they think they have no choice financially but to
work full-time; even when such daily activity is way beyond what they can cope with on a daily basis. They
then find themselves in constant pain, constantly in a state of confusion, applying minimum effort to all work
tasks, sleeping every spare minute of the day. They will often manage to do this for one, two or three years.
Then, they find that their ME significantly worsens and they become a severe case. They spend 90% of the
day in bed and literally crawl to use the bathroom; this is the importance of long term pacing with ME. They
may stay like this for two years with full-time care required. Again, we can see how the severity of symptoms
of ME can fluctuate; this time over longer periods. A person with moderate ME, for example, often exhibits a
pattern where they have much greater levels of activity in some years as compared to other years.
As well as the four primary diagnostic criteria for ME, there is the additional presence of a large number
(around 100) of secondary autonomic (nervous), immune and endocrine symptoms which are interpreted
within the context of the presence of the primary criteria. Although all of these secondary symtoms are not
experienced by all patients - there are a large number which are common to most patients. Many of these
symtoms have been scientifically investigated and all have been found to have an objective physiological
basis. These include disabling hypersensitivity of the senses (light, sound, pain, odours, tastes), rapid
dehydration (thirst) with increased urination, intense fatigue-headaches, disabling intolerance of drugs
(alcohol, caffeine, medications, anaesthetics), feeling faint with prolonged standing or climbing stairs,
insomnia, daytime sleeping, and rapid postural discomfort when sitting. The full list is too numerous to list
here. Also, provided the four primary criteria for ME are met, a pyschiatric diagnosis (such as clinical
depression), does not exclude a diagnosis of ME. The four primary diagnostic criteria of ME differentiate ME
from all psychiatric disorders. Indeed, many ME patients understandably develop a depressive disorder
related to the devastating effects ME has on their lives.
Since 1988, the most common term used in the medical literature for reporting scientific research into ME has
been Chronic Fatigue Syndrome (CFS). Although the term ME was, until recently, recognised by the legal and
social security systems in the USA, north American medical scientists were not happy with the accuracy of
the term and decided to formulate their own definition and name for research purposes (Holmes 1988). As
such, this definition has many flaws when used for clinical diagnosis. The definition was last updated in 1994
but both the definition and the name are currently being revised (Fukada 1994). The term CFS has also been
adopted by the majority of medical scientists outside the USA to report their ME research. However, both the
term CFS and its definition have not been accepted by ME patients and those doctors who work closely with
them. US patient groups use the term Chronic Fatigue and Immune Deficiency Sydrome (CFIDS) - this term
can also be found in the medical literature. This is an attempt to give CFS the same legitimacy as ME as a
distinct clinical entity within the USA.
There are two main objections to the term CFS which have a bearing on how research references on ME are
interpreted and understood. Firstly, although the phrase “chronic fatigue” correctly identifies the central
disabling symptom of ME, it does not actually distinguish this “chronic fatigue” from the fatigue experienced
in normal health and as part of numerous other physiological, psychological and psychiatric conditions (unlike
the ME criteria). This, in turn, only increases the scepticism that ME is not a distinct and unique disease
entity and so not open to scientific investigation. Secondly, although CFS automatically excludes all known
physical conditions, it is too broadly defined to identify those patients with ME against those experiencing
chronic fatigue specifically due to psychiatric and psychological conditions. (CFS is considered to be an
“unbrella diagnosis” by the global ME community - sheltering many other conditions as well as ME). Estimates
of the prevalence of CFS have produced rates as high as 3 per 100 of population - or 30 times the actual
prevalence of ME. This has has led many psychiatrists to understand ME as being a psychiatric disorder and a
failure to recognise ME as a distinct physiological entity. However, such caution generally only applies when
reading research references purporting to investigate possible psychological and psychiatric causes of ME.
The now very large number of research papers demonstrating numerous physiological dysfunctions in CFS
can mostly be understood as referring to ME. The term CFS, and its diagnostic criteria, has now been
acknowledged as a mistake by the US medical research community who defined it and it is due to be replaced
in the near future. However, the US psychiatric lobby is very influential within the US CFS medical research
community and it is unlikely that they will finally recognise ME and bring the USA in line with the rest of the
world. Even so, US patient groups are now moving towards replacing their current term, CFIDS, with ME.
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Copyright: Jed Gallagher 2001. No copying of this work, in any media, without permission from the author.