Updated 22 May 2015

Myalgic Encephalomyelitis (ME)

ME is a complex disorder characterised by severe fatigue.


Alternative names

chronic fatigue syndrome; postviral fatigue syndrome; chronic fatigue immune dysfunction syndrome (CFIDS)

What is myalgic encephalomyelitis (ME)?

Myalgic encephalomyelitis (ME) is a complex disorder, characterised by severe disabling fatigue that does not improve with bed-rest and may worsen with physical or mental activity. People with ME function at a significantly lower level of activity than before the onset of the condition.

In the 1980s, ME was referred to as "yuppie flu", because those who consulted doctors for chronic fatigue were mainly people in their thirties and forties with high incomes and education levels. Since then, doctors have seen the syndrome in people of all ages, socio-economic levels and ethnic backgrounds.

Some members of the public and medical community remain unaware or unconvinced of the syndrome's existence as a genuine illness, although acceptance is slowly growing. The scepticism arises partly because no cause has been discovered for ME, there is no specific test or clinical sign to aid diagnosis, and many people do not keep abreast of recent research, which, in general, increasingly legitimises the disease.

The US Centre for Disease Control and Prevention (CDC) listed ME as a disease entity in 1988.

What causes ME?

The cause of ME is not yet known. Several possible causes have been proposed, including:
  • Iron deficiency anaemia (iron-poor blood)
  • Low blood sugar (hypoglycaemia)
  • Allergies to environmental agents e.g. pollutants
  • Immune system dysfunction
  • Systemic (i.e. affecting the whole body) infections. ME was thought to be caused by a virus infection, most probably the Epstein-Barr virus. It is now generally accepted, however, that ME is not caused by any single recognised infectious agent. The illness seems to prompt a chronic immune reaction in the body, but this may be a dysfunction of the immune system itself, rather than a response to an infection.
  • HPA (hypothalamic-pituitary-adrenal) dysfunction: a brain disorder resulting in abnormal levels of hormones produced by the hypothalamus, pituitary or adrenal glands, which affect the stress response system in the body. People with ME often appear to be hypersensitive to stress.
  • Mild, chronic low blood pressure (hypotension)
  • Systemic yeast infection (candidiasis)
  • Nutritional deficiencies

ME has been previously linked to depression, because the two conditions have similar symptoms. However, recent research indicates that ME is not depression: levels of the hormone cortisol are not elevated in ME patients as they are in those with depression. Also, unlike the typical person with depression, ME patients tend to overestimate their abilities, retain a strong interest in life, and respond poorly to exercise. People with ME can get "secondary depression" as a result of the negative impact of chronic fatigue on their lives.

There are several other conditions with symptoms and patterns so similar to ME that some researchers suspect there is a common causative mechanism involved, possibly HPA dysfunction. Minor variations in such a dysfunction might produce various similar illnesses such as ME, fibromyalgia, multiple chemical sensitivities and Gulf War Syndrome.

It is possible that ME has multiple causes. Infectious agents might play a contributory role.

Additionally co-factors (such as genetic predisposition, stress, environment, gender, age and prior illness) may be important in the development and course of the illness.

ME may be latent and is then "triggered" by some stressful event. Some people first experience symptoms of ME following an infection (such as 'flu), head injury, surgery or excessive antibiotic use. High-stress events usually worsen symptoms once the illness has already developed.

Who gets ME and who is at risk?

Because the cause of ME is unknown, researchers have yet to determine definite risk factors for the disease.

As there is no specific laboratory test or clinical sign for ME, it is difficult to ascertain how many people it affects. The prevalence of the disease is estimated at approximately 0.5 - 1.5% of the population.

Doctors diagnose ME two to four times more often in women than in men, but gender is not a proven risk factor. It is unclear whether ME affects women more frequently or if women simply report the symptoms more often than men do.

Some studies indicate that ME is more common among higher socio-economic groups, but it may be because only those with access to medical care get counted in such studies, resulting in a bias with regards to income and race.

Although ME is most common in people 25 to 45, it can affect people of all ages.

Symptoms and signs of ME

ME exhibits symptoms similar to most common viral infections. Unlike 'flu symptoms, however, which usually subside within a few days or weeks, ME symptoms either persist or come and go frequently, often with no clear pattern, for months or years. The mean duration of illness is 16 months, with some cases reporting illness persisting for 13 years (or even longer).

ME can start during or shortly after a period of illness or severe stress, or develop gradually without any clear starting point.

The main symptom is persistent fatigue. The CDC criteria for ME are as follows:

  • Severe unexplained fatigue for over six months that is
    • of a new or definite onset
    • not due to continuing exertion
    • not resolved by rest
    • functionally impairing
  • The presence of four or more of the following new symptoms:
    • Impaired memory or concentration
    • Sore throat
    • Tender lymph nodes
    • Muscle pain
    • Pain in several joints
    • Headache of a new type, pattern or severity
    • Sleep disturbance: difficulty falling asleep, frequent waking or waking unrefreshed
    • Exhaustion, lasting more than 24 hours, after normal exercise or exertion.

People with ME also commonly report various additional symptoms to those mentioned above.

How is ME diagnosed?

ME is difficult to diagnose because it has some of the same symptoms as many other diseases, symptoms vary considerably among different individuals, and there is no laboratory procedure to confirm its presence.

A diagnosis of ME is based on exclusion: your doctor must first rule out any other condition that could be causing the fatigue and related symptoms.

Other conditions that can cause fatigue include:

  • Hormonal disorders, such as hypothyroidism (low levels of thyroid hormones)
  • Sleep apnoea and narcolepsy
  • Respiratory problems e.g. asthma, tuberculosis
  • Heart disease e.g. heart failure
  • Uncontrolled diabetes
  • Reactions to certain medications
  • Cancer
  • Major depressive disorder or other psychiatric disorders such as schizophrenia, dementia, eating disorders or bipolar affective disorders
  • Alcohol or drug abuse
  • Severe obesity
  • Recovering from a viral illness, such as glandular fever
  • Anaemia
  • Sub-acute infections
  • Chronic mononucleosis
  • Autoimmune disease

Certain other diseases, many of which have similar symptoms to ME, cannot be confirmed by laboratory tests or observable clinical signs. These include anxiety disorders, depressive disorders, fibromyalgia and multiple chemical sensitivity disorder.

Your doctor will obtain a detailed medical history and perform a thorough physical examination. Initial testing should include a mental status examination, which typically involves a brief discussion or oral test. Standard laboratory tests should be performed to help identify other possible causes of illness. If test results suggest an alternative cause for the symptoms, additional tests may be performed to confirm that diagnosis.

When other diseases or conditions are ruled out, your doctor may then determine if your illness meets the diagnostic criteria for ME, as laid down by the International Chronic Fatigue Syndrome Study Group:

  • Unexplained, persistent or relapsing chronic fatigue is present for six months or more that; is of new or definite onset (i.e. has not been lifelong); is not the result of ongoing exertion; is not substantially alleviated by rest; and results in substantial reduction in previous levels of activities.
  • At least four of the eight primary symptoms (See Symptoms and signs) are also present. Symptoms must have persisted or recurred during six or more consecutive months and must not have predated the fatigue.

How is ME treated?

There is no specific treatment for ME. In general, treatment aims to relieve symptoms, using a combination of the following:
  • Lifestyle changes. Your doctor will likely advise you to avoid excessive physical and psychological stress, and to slow down in general.
  • Exercise. You may be encouraged, often with the help of a physical therapist, to follow an exercise programme in which physical activity is gradually and carefully increased up to your tolerance level. This can help prevent or decrease muscle weakness caused by prolonged inactivity, and can improve your energy level.
  • Treatment of psychiatric problems. Problems often related to ME, such as depression and anxiety, can be treated with medication and/or behaviour therapy, which teaches you helpful responses to difficult situations and symptoms.
  • Medication for specific symptoms:
    • People with ME often benefit from antidepressants, which, apart from improving mood, may help control pain and improve sleep.
    • Analgesics and antipyretics or anti-inflammatory drugs such as paracetamol and ibuprofen.
    • Antihistamines such as loratadine, and decongestants that contain pseudoephedrine may relieve allergy-like symptoms.

You may need to try several drugs before finding one that is effective and can be tolerated. Some medications can cause adverse reactions or side-effects that are worse than the original symptoms. ME patients tend to be unusually sensitive to drugs and must take doses that are less than standard doses. Consult your doctor before starting any treatment for ME.

Home treatment

Learning how to manage fatigue and other symptoms can help you improve your level of functioning and quality of life. Aim to maintain general good health as follows:
  • Reduce stress and pace yourself. Avoid overexertion and emotional stress. Allow yourself regular relaxation time. Try to stick to your previous routine as much as possible; people who remain active tend to do better. Keep your activity on an even level. Plan activities to take advantage of times when you feel better.
  • Get enough sleep. Allot sufficient time for sleep, and practise good sleep habits such as going to bed and getting up at the same time each day.
  • Exercise regularly. Appropriate regular exercise often improves symptoms. Stretching, good posture and relaxation exercises are also often helpful.
  • Eat a balanced diet. Also, avoid any foods that seem to worsen symptoms. Many people with ME have food sensitivities; common "problem" food products include caffeine, alcohol, sugar and artificial sweeteners. Dietary supplements may be helpful, but some supplements and herbal preparations can have potentially harmful side-effects and may interfere with prescription medications. Consult your doctor before using any unprescribed remedy.
  • Stop smoking.
  • Counselling and support can help you and those close to you manage the limitations and frustrations of ME. Consider joining a support group for people with ME.

What is the outcome of ME?

The course of ME varies from person to person. Most people experience their most severe symptoms within the first one to two months of illness, followed by gradual improvement. ME often follows a cyclical course, alternating between periods of illness and relative well being.

The degree of severity differs widely among different people, and also varies over time for the same patient. Severity can range from becoming unusually fatigued following stressful events, to being bedridden and completely disabled.

The long-term outlook is unpredictable. The actual percentage of patients who recover is unknown. Some people recover completely after about a year; for others, recovery takes several years. Some people recover to the point that they can resume work and other activities, but continue to experience periodic symptoms. Other people grow progressively worse, and a few become incapacitated.

Possible complications of ME include:

  • Social isolation due to being too fatigued to take part in activities with others.
  • Lifestyle restrictions.
  • Depression, related to symptoms, lack of diagnosis or uncertainty about the condition's long-term outcome.
  • Medication side-effects.
  • Physical effects of lack of activity e.g. becoming overweight.

When to call the doctor

See your doctor if you have fatigue that is excessive (i.e. it is severe enough to prevent you from fully performing your normal activities) and persists for several weeks.

It is important to ensure that no other medical problems exist, which could be cured by the right treatment.

Try to find a health practitioner who is familiar with ME. A good source of advice for identifying a suitable local doctor is through support groups.

Can ME be prevented?

Because the cause of ME is unknown, there is as yet no known way to prevent the condition.

(Reviewed by Dr Felix Potocnik)


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