What is Chronic Fatigue Syndrome (CFS) / Myalgic Encephalomyelitis (ME)?
The term chronic fatigue syndrome (CFS) is used to describe an illness that is characterised by physical and mental fatigue and fatigability. A characteristic feature is fatigue/malaise that follows minimal exertion. People with CFS often describe the fatigue as being of a type and a scale beyond any other they have experienced. The illness may affect both physical and mental functioning, including cognitive function. Accompanying symptoms may include poor sleep, pain, poor concentration and memory, although this list is not exhaustive.
Chronic fatigue syndrome (CFS) is also known as myalgic encephalomyelitis (ME) and post-viral fatigue syndrome. There is some difference of opinion over whether ME is different from CFS; however, most authorities refer to the condition as CFS/ME.
The symptom of fatigue is a feeling that can sometimes be difficult to describe and to measure. It is a feeling of exceptional or abnormal tiredness or lack of energy in excess of that anticipated in response to current activity. Fatigability in CFS/ME is the overwhelming feeling of exceptional tiredness exacerbated by exertion. CFS/ME is identified by its symptoms and disabling effects, and by excluding other medical conditions that could explain them. There are no confirmatory abnormal findings on physical examination, nor is there any specific investigation such as an abnormal blood test that is diagnostic. This does not mean that CFS/ME is not a real illness, and all medical authorities now accept the illness as being a severe and valid condition.
A consensus definition of CFS/ME has been agreed by international experts for the purposes of research and includes the following -:
A complaint of:
- Persistent or relapsing fatigue for 6 months or more that is:
- Of new or definite onset,
- Not the result of ongoing exertion,
- Not substantially alleviated by rest,
- Results in a substantial reduction in previous levels of occupational, education and social or personal activities.
- Four or more of the following symptoms for 6 months or more
- Impaired short-term memory or concentration,
- Sore throat,
- Tender lymph nodes (neck or armpits),
- Muscle pain,
- Pains in a number of joints (without arthritis),
- New headache,
- Un-refreshing sleep,
- Malaise lasting more than 24 hours after exercise.
- Other physical causes of fatigue such as anaemia, thyroid disease, sleep apnoea, malignancy, liver disease etc. are excluded.
- Major mental health disorders are excluded, although as with other chronic conditions, people with CFS/ME may have conditions such as depression and generalised anxiety disorder occurring at the same time.
A number of other medical conditions such as fibromyalgia, irritable bowel disease and migraine may also occur in people with CFS/ME. These have some symptoms in common with those described in CFS/ME.
