History of myalgic encephalomyelitis and chronic fatigue syndrome

From MEpedia, a crowd-sourced encyclopedia of ME and CFS science and history
Jump to: navigation, search

Myalgic encephalomyelitis has occurred in both epidemic and sporadic form since at least the 1930s, although is probably much older. The first recorded outbreak of epidemic myalgic encephalomyelitis was in 1934 in Los Angeles and was thought to be an outbreak of atypical polio. After the outbreak in Akureyri, Iceland in 1946, the disease came to be called "Akureyri Disease" or Icelandic disease through much of the 1940s and 1950s. It was named myalgic encephalomyelitis after London's Royal Free Hospital outbreak in 1955. Other names included benign myalgic encephalomyelitis and epidemic neuromyasthenia.

After the Incline Village outbreak in Nevada in 1984, the disease came to be called and redefined as Chronic Fatigue Syndrome. The most recent was putative outbreak was in Arizona in 1996. 

19th century[edit | edit source]

Several descriptions of illness resembling those of chronic fatigue syndrome have been reported for at least two hundred years.[1] In the 19th century, neurologist George Miller Beard popularized the concept of neurasthenia, with symptoms including fatigue, anxiety, headache, impotence, neuralgia and depression.[2] This concept remained popular well into the 20th century, eventually coming to be seen as a behavioral rather than physical condition, with a diagnosis that excluded post-viral syndromes. Neurasthenia has largely been abandoned as a medical diagnosis.[3] The ICD-10 system of the World Health Organization now categorizes neurasthenia under (F48 Other neurotic disorders) which specifically excludes chronic fatigue syndrome.[4]

Epidemic myalgic encephalomyelitis (1930s-1960s)[edit | edit source]


In 1938, Alexander Gilliam described an illness that resembled poliomyelitis, interviewing patients and reviewing records of one of several clusters which had occurred in Los Angeles, United States in 1934.[5] The Los Angeles County Hospital outbreak included all or most of its nurses and doctors.[6] Gilliam called the outbreak "atypical poliomyelitis" and described the symptoms as: rapid muscle weakness, vasomotor instability, clonic twitches and cramps, ataxia, severe pain (usually aggravated by exercise), neck and back stiffness, menstrual disturbance and dominant sensory involvement.

Novices and convent candidates at a Wisconsin convent were diagnosed with "encephalitis" in 1936. Two towns in Switzerland had outbreaks of "abortive poliomyelitis" in 1937, and 73 Swiss soldiers were given the same diagnosis in 1939. Outbreaks in Iceland were called "Akureyri disease" or "simulating poliomyelitis" and were later called "Iceland disease." Eight hundred people in Adelaide, Australia became ill during 1949-1951 with a disease "resembling poliomyelitis." Two smaller clusters in the United States during 1950 were diagnosed as "Epidemic neuromyasthenia" and "resembling Iceland disease simulating acute anterior poliomyelitis." Additional outbreaks of poliomyelitis-like "mystery diseases" occurred from the 1950s through the 1980s, in Denmark, the United States, South Africa, and Australia, among others.[6]

Several outbreaks of a polio-resembling illness occurred in Britain in the 1950s.[7] A 1955 outbreak at the Royal Free Hospital Group was later called Royal Free disease or benign myalgic encephalomyelitis.[8][9] After the Royal Free Hospital outbreak, a disorder with similar symptoms was found among the general population and the epidemic form came to be considered the exception.[10][11] Pathology findings, from both monkeys intentionally infected with biological fluids from patients[12] and from rare human casualties,[13] led to the conclusion that the disorder was caused by inflammation of the brain and the spinal cord, particularly the afferent nerve roots, perhaps with neuroimmune etiology.[14]

Mass hysteria (1960s-1970s)[edit | edit source]

In the 1960s and 1970s, chronic fatigue symptoms were often attributed to chronic brucellosis, but typically people were seen as having psychiatric disorders, in particular depression.[6] Epidemic cases of benign myalgic encephalomyelitis were called mass hysteria by psychiatrists McEvedy and Beard in 1970,[15] provoking criticism in letters to the editor of the British Medical Journal by outbreak researchers, attending physicians, and physicians who fell ill.[16][17][18][19][20][21][22][23][24] The psychiatrists were faulted for not adequately investigating the patients they described,[25] and their conclusions have been refuted.[26][27][28] In 1978 a symposium held at the Royal Society of Medicine (RSM) concluded that epidemic myalgic encephalomyelitis was a distinct disease entity with a clear organic basis.[29]

Chronic fatigue syndrome (1980s & 1990s)[edit | edit source]

The illness gained national attention in the United States when the popular magazine Hippocrates ran a cover story of an epidemic at Lake Tahoe, Nevada, in the mid-1980s.[30] The designation Chronic Epstein-Barr Virus was in use in the U.S.,[31][32] but the magazine used the term "Raggedy Ann Syndrome" to note the fatigue and loss of muscle power patients felt.[33]

Researchers investigating the Lake Tahoe cluster did not find evidence that EBV was involved, and they proposed the name chronic fatigue syndrome, describing the main symptom of the illness.[34][35] They published the first working case definition for CFS in 1988.[36] Research increased considerably, and more so after the criteria were relaxed in 1994.[37]

In 1990, researchers presented evidence they found DNA sequences very similar to the human HTLV-II retrovirus in some CFS patients, at a conference in Kyoto, Japan.[38][39] Their study was later published in the Proceedings of the National Academy of Sciences.[40] A reporter on Prime Time Live stated the announcement made headlines all over the world.[41] The CDC first ignored their findings then later conducted a study and published a paper that refuted the hypothesis.[42]

In the United Kingdom, the Chief Medical Officer Kenneth Calman requested a report from the medical Royal Colleges in 1996. This led to the publication of a joint report in which the term "chronic fatigue syndrome" was found to be most representative.[43] This was followed in 2002 by a further report by the new CMO, Liam Donaldson.[44]

The U.S. Centers for Disease Control & Prevention (CDC) recognized CFS as a serious illness, and launched a campaign in June 2006 to raise public and medical awareness about it.[45][46]

XMRV[edit | edit source]

A 2009 study published in the journal Science reported an association between a retrovirus xenotropic murine leukemia virus-related virus (XMRV) and CFS. The editors of Science subsequently attached an "Editorial Expression of Concern" to the report to the effect that the validity of the study "is now seriously in question,"[47] and in September 2011, the authors published a "Partial Retraction" of their 2009 findings;[48] this was followed by a full retraction by the magazine’s Editor in Chief, after the authors failed to agree on a full retraction statement.[49] Also in September 2011, the Blood XMRV Scientific Research Working Group published a report, which concluded "that currently available XMRV/P-MLV assays, including the assays employed by the three participating laboratories that previously reported positive results on samples from CFS patients and controls, cannot reproducibly detect direct virus markers (RNA, DNA, or culture) or specific antibodies in blood samples from subjects previously characterized as XMRV/P-MLV positive (all but one with a diagnosis of CFS) or healthy blood donors."[50] In December 2011, the Proceedings of the National Academy of Sciences published a similar retraction for an August 2010 paper.[51] Some members of the patient community, who had viewed the XMRV findings as a source of hope for a possible cure, initially reacted negatively when the papers were called into question. One UK researcher reported verbal abuse after publishing an early paper indicating that the XMRV studies were flawed.[52]

Institute of Medicine Report[edit | edit source]


February 15, 2015, The National Academy of Medicine (known as the Institute of Medicine or IOM until June 2015) published a report on ME/CFS, Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness[53] proposing a new name – systemic exertion intolerance disease – and a new diagnostic criteria. It has since influenced government policy and healthcare for the disease in the United States and around the world.[54][55][56][57]

The proposed name proved to be highly unpopular and has not been widely adopted by government agencies or researchers and proposed criteria captured an overlapping but different subset of patients than stricter criteria like the International Consensus Criteria or the Canadian Consensus Criteria. Despite some positive impacts, its recommendations have remained controversial among many patients and advocacy groups.

See also[edit | edit source]

References[edit | edit source]

  1. Lorusso, Lorenzo; Mikhaylova, Svetlana V.; Capelli, Enrica; Ferrari, Daniela; Ngonga, Gaelle K.; Ricevuti, Giovanni (Feb 2009). "Immunological aspects of chronic fatigue syndrome". Autoimmunity Reviews. 8 (4): 287–291. doi:10.1016/j.autrev.2008.08.003. ISSN 1873-0183. PMID 18801465. 
  2. Beard, George Miller (1869). "Neurasthenia, or nervous exhaustion". The Boston Medical and Surgical Journal. 3 (18): 217–221. 
  3. Evengård, B.; Schacterle, R. S.; Komaroff, A. L. (Nov 1999). "Chronic fatigue syndrome: new insights and old ignorance". Journal of Internal Medicine. 246 (5): 455–469. ISSN 0954-6820. PMID 10583715. 
  4. "ICD-10, Chapter V Mental and behavioural disorders (F00-F99)". WHO International. 2007. 
  5. Gilliam, AG (1938). "Epidemiological study on an epidemic, diagnosed as poliomyelitis, occurring among the personnel of Los Angeles County General Hospital during the summer of 1934,". United States Treasury Department Public Health Service Public Health Bulletin. Washington, DC: United States Government Printing Office. 240: 1–90. 
  6. 6.06.16.2 Patarca-Montero, Roberto (2004). Medical Etiology, Assessment, and Treatment of Chronic Fatigue and Malaise. Haworth Press. pp. 6–7. ISBN 0-7890-2196-X. 
  7. Ramsay, A. Melvin (1986). Postviral Fatigue Syndrome. The saga of Royal Free disease. London: Gower. ISBN 0-906923-96-4. 
  8. "An outbreak of encephalomyelitis in the Royal Free Hospital Group, London, in 1955". Br Med J. 2 (5050): 895–904. 1957. doi:10.1136/bmj.2.5050.895. PMC 1962472Freely accessible. PMID 13472002. 
  9. "A new clinical entity?". Lancet. 270 (6926): 789–90. 1956. doi:10.1016/S0140-6736(56)91252-1. PMID 13320887. 
  10. Wojcik, Wojtek; Armstrong, David; Kanaan, Richard (June 2011). "Chronic fatigue syndrome: labels, meanings and consequences" (PDF). Journal of Psychosomatic Research. 70 (6): 500–504. doi:10.1016/j.jpsychores.2011.02.002. ISSN 1879-1360. PMID 21624573. 
  11. Dawson, J (Feb 7, 1987). "Royal Free disease: perplexity continues" (PDF). British Medical Journal (Clinical research ed.). 294 (6568): 327–328. ISSN 0267-0623. PMC 1245346Freely accessible. PMID 3028544. 
  12. Pellew, RA; Miles, JA (September 1955). "Further investigations on a disease resembling poliomyelitis seen in Adelaide". Med. J. Aust. 2 (13): 480–2. PMID 13272481. 
  13. Wallis, AL (1957). "An investigation into an unusual illness seen in epidemic and sporadic form in a general practice in Cumberland in 1955 and subsequent years" (M.D. Thesis). University of Edinburgh. 
  14. Richardson, J (2002). "Myalgic encephalomyelitis: guidelines for doctors" (PDF). Journal of Chronic Fatigue Syndrome. 10 (1): 65–80. doi:10.1300/j092v10n01_06. 
  15. McEvedy, CP; Beard, AW (1970). "Concept of Benign Myalgic Encephalomyelitis". British Medical Journal. 1 (5687): 11–5. doi:10.1136/bmj.1.5687.11. PMC 1700895Freely accessible. PMID 5411596. 
  16. Scott, BD (Jan 1970). "Epidemic malaise". Br Med J. 1 (5689): 170–175. doi:10.1136/bmj.1.111.170. PMC 1699088Freely accessible. PMID 5370039. 
  17. Compston, N. D.; Dimsdale, H. E.; Ramsay, A. M.; Richardson, A. T. (Feb 1970). "Epidemic malaise". Br Med J. 1 (5692): 362–363. doi:10.1136/bmj.1.5692.362-a. PMC 1699022Freely accessible. 
  18. Acheson, E. D. (Feb 1970). "Epidemic Malaise". Br Med J. 1 (5692): 363–4. doi:10.1136/bmj.1.5692.363-b. PMC 1698971Freely accessible. 
  19. Gosling, PH (Feb 1970). "Epidemic malaise". Br Med J. 1 (5694): 499–500. doi:10.1136/bmj.1.5694.499-b. PMC 1699452Freely accessible. PMID 5435167. 
  20. Burke, GJ (Feb 1970). "Epidemic malaise". Br Med J. 1 (5694): 500. doi:10.1136/bmj.1.5694.500. PMC 1699458Freely accessible. PMID 5435168. 
  21. Hopkins, EJ (Feb 1970). "Epidemic malaise". Br Med J. 1 (5694): 500–1. doi:10.1136/bmj.1.5694.500-a. PMC 1699426Freely accessible. PMID 5435169. 
  22. Galpine, JF (Feb 1970). "Epidemic malaise". Br Med J. 1 (5694): 501. doi:10.1136/bmj.1.5694.501. PMC 1699416Freely accessible. PMID 5435170. 
  23. Poskanzer, DC (May 1970). "Epidemic malaise". Br Med J. 2 (5706): 420–1. doi:10.1136/bmj.2.5706.420-b. PMC 1700311Freely accessible. PMID 5420612. 
  24. Parish, JG (Jul 1970). "Epidemic malaise". Br Med J. 3 (5713): 47–8. doi:10.1136/bmj.3.5713.47-c. PMC 1700986Freely accessible. PMID 4316803. 
  25. Hooper, M. (May 2007). "Myalgic encephalomyelitis: a review with emphasis on key findings in biomedical research". Journal of Clinical Pathology. 60 (5): 466–471. doi:10.1136/jcp.2006.042408. ISSN 0021-9746. PMC 1994528Freely accessible. PMID 16935967. 
  26. Evangard, B; Schacterie, RS; Komaroff, AL (Nov 1999). "Chronic fatigue syndrome: new insights and old ignorance". Journal of Internal Medicine. 246 (5): 455–469. doi:10.1046/j.1365-2796.1999.00513.x. PMID 10583715. 
  27. David, AS; Wessely, S; Pelosi, AJ (Mar 1988). "Postviral fatigue syndrome: time for a new approach". Br Med J (Clin Res Ed). 296 (6623): 696–9. doi:10.1136/bmj.296.6623.696. PMC 2545306Freely accessible. PMID 3128374. 
  28. Stricklin A, Sewell M, Austad C (Jan 1990). "Objective measurement of personality variables in epidemic neuromyasthenia patients". S. Afr. Med. J. 77 (1): 31–4. PMID 2294610. 
  29. "Epidemic myalgic encephalomyelitis". Br Med J. 1 (6125): 1436–7. Jun 3, 1978. doi:10.1136/bmj.1.2791.1436-a. PMC 1604957Freely accessible. PMID 647324. 
  30. Johnson, Hillary (1996). Osler's Web: inside the labyrinth of the chronic fatigue syndrome epidemic. New York: Penguin Books. p. 24. ISBN 0-595-34874-2. 
  31. Jones, J. F.; Ray, C. G.; Minnich, L. L.; Hicks, M. J.; Kibler, R.; Lucas, D. O. (Jan 1985). "Evidence for active Epstein-Barr virus infection in patients with persistent, unexplained illnesses: elevated anti-early antigen antibodies". Annals of Internal Medicine. 102 (1): 1–7. ISSN 0003-4819. PMID 2578266. 
  32. Straus, Stephen E. (Jan 1, 1985). "Persisting Illness and Fatigue in Adults with Evidence of Epstein-Barr Virus Infection". Annals of Internal Medicine. 102 (1): 7. doi:10.7326/0003-4819-102-1-7. ISSN 0003-4819. 
  33. Day, W (1987). "Raggedy Ann syndrome". Hippocrates: July/August, cover story. 
  34. Sharpe, Michael; Campling, Frankie (2000). Chronic Fatigue Syndrome (CFS/ME): TheFacts. Oxford: Oxford Press. pp. 14, 15. ISBN 0-19-263049-0. Retrieved Apr 2, 2008. 
  35. Packard RM, Berkelman RL, Brown PJ, Frumkin H (2004). Emerging Illnesses and Society. JHU Press. ISBN 0-8018-7942-6. 
  36. Holmes, Gary P.; Kaplan, Jonathan E.; Gantz, Nelson M.; Komaroff, Anthony L.; Schonberger, Lawrence B.; Straus, Stephen E.; Jones, James F.; Dubois, Richard E.; Cunningham-Rundles, Charlotte; Pahwa, Savita; Tosato, Giovanna; Zegans, Leonard S.; Purtilo, David T.; Brown, Nathaniel; Schooley, Robert; Brus, Irena (Mar 1, 1988). "Chronic Fatigue Syndrome: A Working Case Definition". Annals of Internal Medicine. 108 (3): 387. doi:10.7326/0003-4819-108-3-387. ISSN 0003-4819. 
  37. Fukuda, Keiji; Straus, Stephen E.; Hickie, Ian; Sharpe, Michael C.; Dobbins, James G.; Komaroff, Anthony; International Chronic Fatigue Syndrome Study Group (Dec 15, 1994). "The Chronic Fatigue Syndrome: A Comprehensive Approach to Its Definition and Study". Annals of Internal Medicine. 121 (12): 953. doi:10.7326/0003-4819-121-12-199412150-00009. ISSN 0003-4819. 
  38. Palca, J (Sep 14, 1990). "Does a retrovirus explain fatigue syndrome puzzle?". Science. 249 (4974): 1240–12. doi:10.1126/science.2399461. PMID 2399461. 
  39. Altman, Lawrence K. (Sep 5, 1990). "Virus found that may be linked to a debilitating fatigue ailment". The New York Times. Retrieved Feb 24, 2009. 
  40. DeFreitas, E; Hilliard, B; Cheney, PR; Bell, DS; Kiggundu, E; Sankey, D; Wroblewska, Z; Palladino, M; Woodward, JP (April 1991). "Retroviral sequences related to human T-lymphotropic virus type II in patients with chronic fatigue immune dysfunction syndrome". Proc. Natl. Acad. Sci. U.S.A. 88 (7): 2922–6. doi:10.1073/pnas.88.7.2922. PMC 51352Freely accessible. PMID 1672770. 
  41. "CFS and the CDC's Failure to Respond: Primetime Live (1996)". YouTube. 1996. Retrieved Dec 19, 2018. 
  42. "Inability of retroviral tests to identify persons with chronic fatigue syndrome, 1992". Morbidity and Mortality Weekly Report. U.S. Centers for Disease Control and Prevention. 42 (10): 183, 189–90. March 1993. PMID 8446093. Retrieved Feb 23, 2009. 
  43. Chronic fatigue syndrome: Report of a joint working group of the Royal Colleges of Physicians, Psychiatrists and General Practitioners. London, UK: Royal College of Physicians of London. 1996. ISBN 1-86016-046-8. 
  44. CFS/ME Working Group (2002). "A report of the CFS/ME working group: report to the chief medical officer of an independent working group". London: Department of Health. 
  45. "Chronic fatigue syndrome basic facts". CDC.gov. Centers for Disease Control and Prevention. May 9, 2006. Retrieved Feb 7, 2008. 
  46. "Address at CFS awareness campaign launch". CDC.gov. Jun 7, 2008. 
  47. Alberts, Bruce (2011). "Editorial Expression of Concern". Science. 333 (6038): 35. doi:10.1126/science.1208542. PMID 21628391. 
  48. Mikovits, Judy A.; Dean, Michael; Gold, Bert; Petrow-Sadowski, Cari; Bagni, Rachel K.; Ruscetti, Sandra K.; Peterson, Daniel L.; Hagen, Kathryn S.; Pfost, Max A. (Oct 14, 2011). "Partial Retraction". Science. 334 (6053): 176–176. doi:10.1126/science.1212182. ISSN 1095-9203. PMID 21998366. 
  49. Alberts, Bruce (2011). "Retraction". Science. 334 (6063): 1636. doi:10.1126/science.334.6063.1636-a. PMID 22194552. 
  50. Simmons, Graham; Glynn, Simone A.; Komaroff, Anthony L.; Mikovits, Judy A.; Tobler, Leslie H.; Hackett, John; Tang, Ning; Switzer, William M.; Heneine, Walid (Nov 11, 2011). "Failure to Confirm XMRV/MLVs in the Blood of Patients with Chronic Fatigue Syndrome: A Multi-Laboratory Study". Science. 334 (6057): 814–817. doi:10.1126/science.1213841. ISSN 0036-8075. PMC 3299483Freely accessible. PMID 21940862. 
  51. Sciences, National Academy of (Jan 3, 2012). "Retraction for Lo et al., Detection of MLV-related virus gene sequences in blood of patients with chronic fatigue syndrome and healthy blood donors". Proceedings of the National Academy of Sciences. 109 (1): 346–346. doi:10.1073/pnas.1119641109. ISSN 1091-6490. PMC 3252929Freely accessible. PMID 22203980. 
  52. "Chronic fatigue syndrome researchers face death threats from militants". The Guardian. Aug 21, 2011. Retrieved Feb 2, 2014. 
  53. Committee on the Diagnostic Criteria for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome; Board on the Health of Select Populations; Institute of Medicine (2015). Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness. The National Academies Collection: Reports funded by National Institutes of Health. Washington (DC): National Academies Press (US). ISBN 9780309316897. PMID 25695122. 
  54. NHMRC. "Myalgic Encephalomyelitis and Chronic Fatigue Syndrome". www.nhmrc.gov.au. Retrieved Jul 23, 2019. 
  55. Gezondheidsraad (2018). "Kernadvies ME/CVS" (PDF). 
  56. Maxmen, Amy (Jan 3, 2018). "A reboot for chronic fatigue syndrome research". Nature. 553: 14. doi:10.1038/d41586-017-08965-0. 
  57. Twisk, Frank (Jun 2018). "Dutch Health Council Advisory Report on Myalgic Encephalomyelitis and Chronic Fatigue Syndrome: Taking the Wrong Turn". Diagnostics. 8 (2): 34. doi:10.3390/diagnostics8020034. 

Myalgic encephalomyelitis (ME) - A disease often marked by neurological symptoms, but fatigue is sometimes a symptom as well. Some diagnostic criteria distinguish it from chronic fatigue syndrome, while other diagnostic criteria consider it to be a synonym for chronic fatigue syndrome. A defining characteristic of ME is post-exertional malaise (PEM), or post-exertional neuroimmune exhaustion (PENE), which is a notable exacerbation of symptoms brought on by small exertions. PEM can last for days or weeks. Symptoms can include cognitive impairments, muscle pain (myalgia), trouble remaining upright (orthostatic intolerance), sleep abnormalities, and gastro-intestinal impairments, among others. An estimated 25% of those suffering from ME are housebound or bedbound. The World Health Organization (WHO) classifies ME as a neurological disease.

Antibody - Antibodies or immunoglobulin refers to any of a large number of specific proteins produced by B cells that act against an antigen in an immune response.

ME/CFS - An acronym that combines myalgic encephalomyelitis with chronic fatigue syndrome. Sometimes they are combined because people have trouble distinguishing one from the other. Sometimes they are combined because people see them as synonyms of each other.

Myalgic encephalomyelitis (ME) - A disease often marked by neurological symptoms, but fatigue is sometimes a symptom as well. Some diagnostic criteria distinguish it from chronic fatigue syndrome, while other diagnostic criteria consider it to be a synonym for chronic fatigue syndrome. A defining characteristic of ME is post-exertional malaise (PEM), or post-exertional neuroimmune exhaustion (PENE), which is a notable exacerbation of symptoms brought on by small exertions. PEM can last for days or weeks. Symptoms can include cognitive impairments, muscle pain (myalgia), trouble remaining upright (orthostatic intolerance), sleep abnormalities, and gastro-intestinal impairments, among others. An estimated 25% of those suffering from ME are housebound or bedbound. The World Health Organization (WHO) classifies ME as a neurological disease.

World Health Organization (WHO) - "A specialized agency of the United Nations that is concerned with public health. It was established on 7 April 1948, and is headquartered in Geneva, Switzerland. The WHO is a member of the United Nations Development Group. Its predecessor, the Health Organization, was an agency of the League of Nations." The International Statistical Classification of Diseases and Related Health Problems (ICD) is maintained by WHO.

Myalgic encephalomyelitis (ME) - A disease often marked by neurological symptoms, but fatigue is sometimes a symptom as well. Some diagnostic criteria distinguish it from chronic fatigue syndrome, while other diagnostic criteria consider it to be a synonym for chronic fatigue syndrome. A defining characteristic of ME is post-exertional malaise (PEM), or post-exertional neuroimmune exhaustion (PENE), which is a notable exacerbation of symptoms brought on by small exertions. PEM can last for days or weeks. Symptoms can include cognitive impairments, muscle pain (myalgia), trouble remaining upright (orthostatic intolerance), sleep abnormalities, and gastro-intestinal impairments, among others. An estimated 25% of those suffering from ME are housebound or bedbound. The World Health Organization (WHO) classifies ME as a neurological disease.

The information provided at this site is not intended to diagnose or treat any illness.
From MEpedia, a crowd-sourced encyclopedia of ME and CFS science and history.