Myalgic encephalomyelitis/chronic fatigue syndrome
Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a serious long-term illness. People with ME/CFS experience a profound fatigue that does not go away with rest, sleep issues and problems with memory or concentration. They are able to do much less than before they became ill. Further common symptoms include dizziness, nausea and pain.[3] The hallmark symptom is a worsening of the illness which starts hours to days after minor physical or mental activity. This "crash" can last less than a day to several months.[10]
Not to be confused with chronic fatigue, a symptom experienced in many chronic illnesses, including idiopathic chronic fatigue.Myalgic encephalomyelitis/chronic fatigue syndrome
Post-viral fatigue syndrome (PVFS), systemic exertion intolerance disease (SEID)[1]: 20
Rheumatology, rehabilitation medicine, endocrinology, infectious disease, neurology, immunology, general practice, paediatrics, other specialists in ME/CFS[2]: 58
Worsening of symptoms with activity, long-term fatigue, sleep problems, others[3]
Peaks at 10–19 and 30–39 years old[4]
Long-term[5]
Unknown[6]
Being female, family history, viral infections[6]
Based on symptoms[7]
About 0.17% to 0.89% (pre-pandemic)[9]
The cause of the disease is unknown.[11] ME/CFS often starts after an infection, such as mononucleosis.[12] ME/CFS can run in families, but no genes that contribute to ME/CFS have been found.[13] ME/CFS is associated with changes in the nervous and immune systems, as well as in energy production.[14] Diagnosis is based on symptoms because no diagnostic test is available.[7]
The illness can improve or worsen over time, but full recovery is uncommon.[12] No therapies or medications are approved to treat the condition and management is aimed at relieving symptoms.[2]: 29 Pacing one's activities can help avoid flare-ups and counselling may help in coping with the illness.[8] Before the COVID-19 pandemic, ME/CFS affected roughly one in every 150 people, although estimates varied widely.[9] However, many people with long COVID fit ME/CFS diagnostic criteria.[15] ME/CFS occurs more often in women than in men. It most commonly affects adults between ages 40 and 60 but can occur at other ages, including childhood.[16]
ME/CFS has a large social and economic impact. About a quarter of individuals are severely affected and unable to leave their bed or home.[10]: 3 The disease can be socially isolating.[17] People with ME/CFS often face stigma in healthcare settings and care is complicated by controversies around the cause and treatments of the illness.[18] Doctors may be unfamiliar with ME/CFS, as it is often not fully covered in medical school.[15] Historical research funding for ME/CFS has been far below that of diseases with comparable impact.[19]
Classification[edit]
ME/CFS has been classified as a neurological disease by the World Health Organization (WHO) since 1969, initially under the name benign myalgic encephalomyelitis.[20] In the WHO's most recent classification, the ICD-11, both chronic fatigue syndrome and myalgic encephalomyelitis are named under post-viral fatigue syndrome, classified under other disorders of the nervous system.[21]
The cause of the illness is unknown and the classification is based on symptoms which indicate a central role of the nervous system.[22] Alternatively, based on abnormalities in immune cells, ME/CFS may better fit into a classification of a neuroimmune condition.[23]
Some people with post-acute infection syndrome (PAIS) meet the criteria of ME/CFS. PAISs such as long COVID and post-treatment Lyme disease syndrome share many symptoms with ME/CFS and are suspected to have a similar cause. The term post-infectious fatigue syndrome describes severe fatigue after an infection, often with additional signs and symptoms. It was initially considered a subset of chronic fatigue syndrome with a documented triggering infection. There is no agreement on which conditions the term should encompass.[24]
ME/CFS often leads to serious disability, but the degree varies considerably.[11] ME/CFS is generally classified into four categories of illness severity:[2]: 8 [28]: 10
Roughly a quarter of those living with ME/CFS fall into the mild category, and half fall into the moderate or moderate-to-severe categories.[6] The final quarter falls into the severe or very severe category.[10]: 3 Severity may change over time. Symptoms might get worse, improve or the illness may go into remission for a period.[11] People who feel better for a period may overextend their activities, triggering PEM and a worsening of symptoms.[26]
Those with severe and very severe ME/CFS experience more extreme and diverse symptoms. They may face severe weakness and be unable to move at times.[29] They can lose the ability to speak, swallow, or communicate completely due to cognitive issues. They can further experience severe pain and hypersensitivities to touch, light, sound, and smells.[2]: 50 Exposure can lead to an increase in symptoms, in particular pain. The activities that can trigger PEM in the severely ill are very minor, such as sitting or going to the toilet.[29]
People with ME/CFS have decreased quality of life according to the SF-36 questionnaire, especially in the domains of physical and social functioning, general health, and vitality. However, their emotional functioning and mental health are not much lower than healthy controls.[30] Functional impairment can be greater than multiple sclerosis, heart disease, or lung cancer.[12] Fewer than 50% of people with ME/CFS are employed, and 19% have a full-time job.[9]
Prognosis[edit]
Information on the prognosis of ME/CFS is limited. Complete recovery, partial improvement, and worsening are all possible,[11] but full recovery is uncommon.[10]: 11 Symptoms generally fluctuate over days, weeks, or longer periods, and some people may experience periods of remission. Overall, many will have to adjust to life with ME/CFS.[2]: 20
An early diagnosis may improve care and prognosis.[25] Factors that may make the disease worse over days, but also over longer time periods, are physical and mental exertion, a new infection, sleep deprivation, and emotional stress.[10]: 11 Some people who improve need to manage their activities in order to prevent relapse.[11] Children and teenagers are more likely to recover or improve than adults.[11][2]: 20 For instance, a study in Australia among 6- to 18-year-olds found that two-thirds reported recovery after ten years, and that the typical duration of illness was five years.[10]: 11
The effect of ME/CFS on life expectancy is poorly studied, and the evidence is mixed. One large retrospective study on the topic found no increase in all-cause mortality due to ME/CFS. Death from suicide was, however, significantly higher among those with ME/CFS.[28]: 59 In extreme cases, people can die from the illness.[57]