Definition
Chronic fatigue syndrome or Myalgic Encephalomyelitis (ME) is diagnosed when an individual feels tired most of the time, the tiredness usually being worsened by exertion. Other symptoms such as generalised muscle pains, difficulty in mental concentration and painful lymph glands are common.
Strictly defined, these symptoms should have lasted at least six months and other conditions excluded before a firm diagnosis can be made.
Incidence
As this is not a notifiable disease, who gets CFS and when is not precisely known. The illness usually strikes between the ages of ten and forty the average lying between twenty five and thirty. Girls and young women are affected about three times as often as males. The diagnosis is certainly made more often in people from the middle class though it is possible that this is only because they are more likely to demand a medical ‘label’ for their symptoms.
Siblings may be affected but I would estimate that this applies to less than 10% of cases. The condition is particularly common in certain occupational groups such as teachers but overall it is thought to affect about 1% of the population of England and Wales.
It is widely assumed that it is a modern phenomenon but it is clear from biographies and contemporary novels that this is not so. I suspect that Florence Nightingale was a sufferer, with periodic flare-ups through most of her nine decades. However, because CFS does not shorten life, estimates of incidence in the past are even less certain than those of today.
Causes
In a minority of cases there is a definite diagnosis of a virus infection at the outset and fatigue continues after the other features have subsided. Glandular fever is by far the commonest such trigger but this may only be because few other viruses of adolescence or young adult life are diagnosed with certainty.
What is clear is that in the vast majority of cases the fatigue persists long after there is any evidence of continued multiplication of the virus. Some studies have suggested that there may be a persistent gut infection with an enterovirus but, if so, then there is no evidence that the virus is damaging the host’s cells or stimulating an inflammatory reaction to them.
This lack of any obvious damage to cells underlies the futile “is it physical or psychological?” questions which side-track so many people from coping with their symptoms and getting on with their lives. Without understanding the cause, prevention is difficult. It seems reasonable to advise everybody to minimise stress in their lives and to learn how to manage what is unavoidable. Setting realistic targets is sensible advice for everyone but whether this could actually prevent some cases or merely allows people to cope better with its effects is hard to say.
Signs & Symptoms
Fatigue is present most of the time, often on waking from sleep and is felt throughout the body, though the legs often seem to be particularly targeted. The fatigue is often accompanied by pain in the fatigued muscles and headaches are common. Some people complain that if certain points over muscles are pressed they experience excruciating pain.
Feverishness is commonly felt, often at the same time as pain from lymph glands in the neck. However the body temperature should not exceed 37.5° and glands are rarely enlarged to more than 1/2cm in diameter. If they are regularly found to be much larger the diagnosis should be questioned.
Most people with CFS have trouble with sleep. Some have difficulty getting off, others wake in the early hours and this is sometimes a pointer to co-existing depressive illness. Most sleep for long periods at night, and may have an overwhelming need to sleep in the day as well. Characteristically, they wake feeling unrefreshed.
Written by Medpages Editorial Team
Last Editorial Review: 21/1/2010
