Symptoms of CFS
People with chronic fatigue syndrome (CFS) always have disabling fatigue. The fatigue in CFS is not due to any particular medical problem such as muscle or thyroid gland disease. It is not the ordinary type of fatigue which is brought on by severe effort and not substantially relieved by rest.
Other symptoms commonly associated with fatigue in CFS include chronic widespread pain, headaches and sleep disturbance. Patients also often report proneness to infections and sore throats.
Associated conditions
The symptoms of CFS overlap with those of fibromyalgia, where the main symptom is pain and discomfort in the muscles and joints, together with fatigue and sleep disturbance. Many patients diagnosed with CFS could equally well be diagnosed with fibromyalgia, and the reverse is also true, so that some doctors believe that it might be better to regard the two conditions as on a continuum, rather than being two entirely separate conditions.
Another condition often associated with CFS is irritable bowel syndrome, in which the main symptoms are abdominal discomfort and erratic bowel function.
The link between CFS, fibromyalgia and irritable bowel syndrome is that none are due to diseased organs. They are among the medical conditions which are abnormalities in the body’s function rather than in its structure.
How common is CFS, and what sort of people are affected?
CFS can affect people of any age. Women are more often affected than men.
Widely differing estimates have been given for the frequency of CFS in the population – from 1% to 8%. One reason for this is that it is difficult to define the symptoms precisely, and the distinction between CFS and other conditions such as fibromyalgia is dubious. Community surveys have shown that the main symptoms of CFS are experienced by people from many different cultural backgrounds in many parts of the world. However, only a minority of people with such symptoms presents to a doctor. Surveys have shown that people from deprived backgrounds are less likely to seek medical help.
What causes CFS?
It is often said that the cause of CFS is a mystery. This is an exaggeration. A lot of research evidence and knowledge has been accumulated about the physical and psychological changes which are found in people with CFS. Complex combinations of factors lead to the symptoms and disabilities experienced by individuals and their families.
As with many chronic conditions, it is useful to consider three ways in which symptoms can be caused: these are predisposing factors (for example genetics), precipitating factors (triggers to the onset of chronic problems) and perpetuating factors, which can lead to symptoms remaining for long periods even when the other factors are no longer operating.
Predisposing factors
We know that female gender is a predisposing factor although the reasons for this are unclear. There is some evidence suggesting that people may inherit genes which predispose them to developing conditions such as CFS. This is true of many chronic diseases. By and large, genes only contribute to the possibility of illnesses rather than guaranteeing that a person with the relevant genes will be affected. Some people think that certain personality types are more prone to CFS – traits such as perfectionism have been suggested. One can imagine how these traits might be inherited, but the evidence on this point is weak.
Precipitating (trigger) factors: Is CFS caused by a virus?
We know that the symptoms of CFS can be triggered by certain viruses - the best known of these is Epstein Barr virus which causes infectious mononucleosis (glandular fever). Cytomegalovirus infection can cause a similar syndrome. In most patients who have post-viral fatigue, the symptoms do not become chronic but improve in a few weeks or at most a few months. In some people, a viral infection may be a trigger, but viral infection always leaves antibodies in the blood and research evidence shows conclusively that no single virus is responsible for all cases of CFS.
Another possible precipitating factor is psychological stress and many patients feel that their initial symptoms were brought on either during a period of stress or, equally often, some time afterwards as a delayed reaction. There is not much research evidence concerning this important issue. Since many people suffer from stress, it is difficult to draw conclusions from individual cases.
Perpetuating factors
There is a lot of research evidence on factors liable to cause the symptoms of CFS to persist. First there are physical factors. Some of these are obvious: disturbed sleep can be due to a multiplicity of environmental and psychological factors, and poor sleep undoubtedly contributes to daytime fatigue. Excessive daytime sleeping sets up a vicious circle whereby the quality of night-time sleep is reduced.
Poor diet or obesity can also have effects on physical stamina, as can lack of physical exercise. People with fatigue inevitably have more difficulty in maintaining fitness, and this in its turn contributes to fatigue and associated symptoms such as pain. Resting for long periods causes muscle wasting and reduces stamina.
In addition to physical factors, psychological processes are also often perpetuating factors. Misleading ideas and feelings can cause people to be increasingly restricted in their physical activity. There are different theories about how such psychological processes operate but we know that they are important through the fact that psychologically-based treatments such as cognitive behavioural therapy can be useful for people with CFS.
Diagnosing CFS
There are no blood tests, x-rays or scans which can diagnose CFS, although certain tests which can be done by GPs are invaluable guides to alternative causes of fatigue.
Diagnosis of CFS is made largely from the history: some symptoms are characteristic of the syndrome, others are unusual; some symptoms can identify alternative diagnoses such as depression, or they may suggest a primary sleep disorder. Obstructive sleep apnoea causes daytime sleepiness which can be mistaken for CFS. The typical patient with obstructive sleep apnoea is overweight, snores heavily at night and has periods during which breathing is interrupted during sleep.
Along with the history, physical examination is important where symptoms raise the possibility of alternative medical causes of fatigue - for example arthritis. The patients who are probably most likely to be misdiagnosed are those whose previous health has been good and in whom fatigue is a new and recent symptom, and it is important that they are examined and investigated.
If there is a specific medical or psychiatric cause for fatigue, abnormalities on routine history taking or on physical examination will often raise a doctor’s suspicions of a diagnosis other than CFS. Many alternative diagnoses can be excluded decisively if clinical assessment shows no abnormalities.
A small number of blood tests and a routine urine test will screen for relevant conditions. If the results of any of these are abnormal, further tests may be necessary.
A note on terminology: Why doctors are sometimes reluctant to call CFS "ME"...
The term ‘ME’ is not favoured by doctors because it is misleading from the medical point of view . ME stands for ‘myalgic’, meaning muscle pain, and ‘encephalomyelitis’, meaning inflammation of the brain and spinal cord, or alternatively ‘encephalopathy’, meaning disease of the brain. There is almost no evidence to suggest that chronic fatigue syndrome involves inflammation in the nervous system or disease in the brain.
Professor Chris Ward
March 23, 2007
