Myalgic Encephalomyelitis (ME)

Myalgic Encephalomyelitis is complex, chronic neuroinflammatory illness, which impacts systems throughout the body.


Myalgia = Muscle Pain
Encephalo = Brain
Myelo = Spinal Cord


In the ICD-10, the World Health Organisation has given ME a G93.3 code, as a disorder of the brain, under disorders of the nervous system.


Known as ME in the British Commonwealth countries, the illness has also been referred to as ME/CFS, Chronic Fatigue Syndrome (CFS), Systemic Exertional Intolerance Disease (SEID), or Chronic Fatigue Immune Dysfunction Syndrome (CFIDS) in the United States. The issue of name has been a challenging one, with important ramifications for public perception and disease classification


A debilitating chronic illness, ME can strike suddenly or slowly creep up on adults and children, male and female, often lingering for years.  It can leave its victims unable to work or take care of themselves or their families.  Relentless and relapsing, ME has a devastating impact on the lives of affected individuals.

In a study published in March 2018, Functional Status and Well-Being in People with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Compared with People with Multiple Sclerosis and Healthy Controls, researchers concluded that:


....people with ME/CFS were measurably more disabled than PWMS or HCs in this study population. Furthermore, employment and income data are consistent with loss of functional status. These findings should encourage the health community to recognise the disabling effects of ME/CFS, to advocate for the needs of people with ME/CFS, and to investigate strategies to address the cost of the disease to both individuals and society.


The 2015 Canadian Community Health Survey (CCHS) identified 561,500 adult Canadians with chronic fatigue syndrome, ME, ME/CFS or SEID, as diagnosed by a doctor. This number is a dramatic increase from the 407,600 diagnosed in 2014. This number also does not include children, and does not indicate which diagnostic criteria a doctor has used. Given that many patients are undiagnosed or misdiagnosed, it is difficult to know how reliable the CCHS figures are, however, they are an indication that the illness is very prevalent and on the rise.


The cause of ME is not yet known.  There could be a number of factors which contribute to the onset of the illness, but evidence suggests an immune system dysfunction, possibly triggered by viral infection(s).


The symptoms of ME are similar to the symptoms of several other diseases, including MS. Therefore, it is essential to have a thorough medical examination to rule out other conditions.

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ME can affect every organ and function of the body. Here are some of the major symptoms:

  • Onset of severe, disabling fatigue that is new, persistent or recurrent, and is not alleviated by rest. In ME sufferers, the fatigue is a profound physiological exhaustion.

  • ‘Post Exertion Malaise' (PEM), also known as ‘Post Exertion Neuro-Immune Exhaustion' (PENE), is considered the hallmark symptom of ME. PEM occurs when fatigue and other symptoms worsen as a result of increased activity. The extent of this activity depends on the level of disability, and can involve exercise, socialising, cognitive activity, cleaning, walking, talking for too long, or as little as getting up to go to the bathroom. Patients often refer to a ‘crash’ where they may become immobilized, even bedridden, for extended periods before the fatigue and other symptoms are even partially alleviated. PEM may last from a day or two, to many months.

  • Changes in sleep patterns. People with ME often complain of unrefreshing sleep, and experience disturbances in both quality and quantity of their sleep. Sleep apnea is also often present.

  • ME often causes cognitive function impairments such as short term memory disturbance, confusion and difficulty with thinking and concentration. The abilities to read, write, perform mathematical calculations, and clearly communicate can be affected.

  • Pain is often experienced in the muscles or joints and/or in the onset of headaches of a new type, pattern or severity.


In addition to these major symptoms, people with ME experience, in varying degrees and combinations, a range of other symptoms related to irregularities in the functioning of the neurological, immune and endocrine systems. These can include:

  • problems with balance

  • orthostatic hypotension

  • hormone imbalances

  • chills and/or sweats

  • low grade fever or abnormal body temperature

  • heart rhythm irregularities

  • increased sensitivity to noise, light, odours

  • increased chemical sensitivity

  • gastrointestinal problems such as diarrhea, constipation, irritable bowel symptoms and abdominal pain

  • affective functions (emotions) can be altered and anxiety and mood changes may be severe, unprovoked and inappropriate. Depression may also occur, as a reaction to, rather than as a cause of ME.


Because each person’s experience with ME is unique, individuals exhibit different symptoms at varying intensities. Also, symptoms may wax and wane and change over time, with some diminishing or disappearing altogether while new ones emerge.


It is very important to obtain an early and proper diagnosis. Your doctor will need to rule out all of the other diseases which share the symptoms of ME, and follow the medical protocol in diagnosing the illness. Be sure to describe all of your symptoms so the doctor has as much information as possible, and see your doctor if new symptoms arise. Currently, a diagnosis of ME is based almost entirely on the history that you describe and the findings upon physical examination. There is presently no single laboratory test that can identify ME with certainly, although there are physiological findings that can support the diagnosis. In fact, it may be that you ‘look normal’ and have mostly normal routine bloodwork and lab tests, which can be confusing for practitioners not experienced with ME.


If your doctor is not knowledgeable about ME, you may wish to share with them the Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Clinical Case Definition and Guidelines for Medical Practitioners.

See more at:


Dr. Alison Bested is a Canadian Haematological Pathologist, who has focused her practice on patients with complex chronic diseases, in particular ME and FM.


Dr. Bested developed the Functional Capacity Scale, which incorporates energy rating, symptom severity, and activity level, to measure a patient's functional capacity (or impairment).


Dr. Bested was one of the contributors towards the 2003 Canadian Consensus Criteria, the most stringent diagnostic criteria for ME/CFS to that time, and the foundation for criteria which followed. She also co-authored the Hope and Help for Chronic Fatigue Syndrome and Fibromyalgia along with Alan Logan ND, and lawyer Russ Howe. She is now currently practicing with Dr. Nancy Klimas at the Insitute for Neuroimmune Medicine in Fort Lauderdale, USA.


There is, as yet, no cure or universal treatment for ME; there is only individual treatment for specific symptoms. However, there are some steps that you can take which may help:

  • Aggressive Rest, especially in the early stages and during relapses, is the one therapy universally agreed upon as key in the management of ME;

  • Pacing, which means staying within your ‘energy envelope’ by managing your activities as best you can to avoid the push-crash cycle of relapsing symptoms;

  • Some Minimal Exercise is encouraged, but always stay within your energy limits, even it means only gentle stretching and very short walks, if possible;

  • A Healthy Diet seems to help some patients. Since some people develop food sensitivities, it may be helpful to experiment with diet to discover which are better tolerated and which should be avoided;

  • Work with your Medical Professional to obtain appropriate medical support for sleep disturbances, unmanageable pain, reactive depression, any nutritional and hormonal deficiencies, and/or to assist you with lifestyle changes needed to manage a chronic illness;

  • Join a Support Group to relieve the isolation and loneliness which ME can create, and to learn more about the illness and how others cope with it.


Above all, when you are feeling a bit better, avoid the temptation to catch up with unfinished tasks as this is likely to cause a relapse. Slowly build up your activity levels gradually and listen to your body when it tells you to rest. It is crucial to recognize your limits and not push beyond them.



1. Learn as much as you can about ME from a local support group, your community library, and searching on-line.  Please refer to our resources for a list of books and websites on ME;​


2. Try to pace and not over-commit yourself.  Listen to what your body tells you it can and cannot do;


3. Keep a journal of your symptoms, activities, feelings and medical history (i.e. appointments and tests).  Record what makes you feel better and what makes you feel worse.  This will help monitor the course of your ME for yourself and your doctor(s).  It will also make you more aware of your capabilities and limitations;


4. Join a local ME or chronic illness support group.  Please refer to our Support Group link for more information on finding a group in your area.  Groups can help you understand and cope with your illness, and they provide an outlet for concerns and fears.  They are also a valuable source of information;


5. Find a knowledgeable, understanding physician for diagnosis and ongoing treatment.  New symptoms should be thoroughly investigated to exclude other illnesses.  Your doctor can prescribe medications which may relieve some of your symptoms.  Adjunctive and/or alternative therapies many also be of value.

There is a severe shortage of doctors who are familiar with the illness, or who will even take patients seriously. So when you can't find a doctor who is knowledgeable, take a printed copy of the information on our section "What to Take To your Doctor".



Below are great videos which you can watch and share with your family and health care providers:

The Bateman Horne Center has launched their new six part series of online classes for ME and FM patients. 


Thanks so much to Dr. Lucinda Bateman for all her incredible work and generous contributions to the ME and FM communities. Patients around the world - including Canada! - benefit from her efforts and the knowledge she shares.


Videos will drop on the following dates:


9 November Getting the Right Diagnosis

16 November Activity Intolerance and Post-Exertional Malaise (PEM)

23 November Restorative Sleep

30 November Chronic Widespread Pain

7 December Cognitive Impairment

14 December Orthostatic Intolerance (OI) Syndromes

Watch Jennifer Brea's award winning feature documentary "Unrest" now available on

Jennifer Brea is about to marry the love of her life when she’s struck down by a fever that leaves her bedridden. When doctors tell her “it’s all in her head,” she turns her camera on herself and her community as she looks for answers and fights for a cure.

"riveting......equal parts medical mystery, science lesson, political advocacy primer and even a love story." The San Francisco Chronicle

After Unrest: is a short documentary about Myalgic Encephalomyelitis (also known as ME/CFS or chronic fatigue syndrome) created by Australian ME patient, Ketra Wooding. This documentary tells Ketra’s story, and includes talks by health care professionals that have helped Ketra with her illness. It touches on current research and also features Australian patients, their stories and perspectives on this all too common disease. It provides a toolbox of information to help practitioners, patients and families alike.

Carte Blanche Report on ME/CFS


For an excellent, comprehensive report on ME, watch the "Millions Missing" report on Carte Blanche Blanche South Africa's M-Net pay-channel’s flagship magazine and actuality programme, 20 Feb 2017.

Includes interviews with patients, Ron Davis, David Tuller.

Pain BC logo.png
Pain BC Podcast
Understanding Myalgic Encephalomyelitis: Context and Lived Experiences


Pain BC’s Sim Jhutti interviews four thoughtful and knowledgeable British Columbia patients – Serena, Kati, Meagan and Marcel - each living with differing levels of ME, and Elizabeth Sanchez, President / Program Director of the ME/FM Society of BC.



The Canadian Consensus Criteria Documents

In 2003 Health Canada, in cooperation with the National MEFM Action Network, convened an expert panel to develop and publish a Canadian clinical case definition for the diagnosis and treatment of Myalgic Encephalomyelitis / Chronic Fatigue Syndrome.  The resulting full document was peer reviewed and published as:

Myalgic Encephalomelitis/Chronic Fatigue Syndrome: Clinical Working Case Definition, Diagnostic and Treatment Protocols – A Consensus Document
Bruce M Carruthers, Anil Kumar Jain, Kenny L De Meirleir, Daniel L Peterson, Nancy G Klimas, A Martin Lerner, Alison C Bested, Pierre Flor-Henry, Pradip Joshi, AC Peter Powles, Jeffrey A Sharkey, Marjorie I van de Sande, Journal of Chronic Fatigue Syndrome 11(1):7-115, 2003

In 2005, a summary of the above full definition was published to assist physicians in applying the protocols to clinical practice. The summary is available as:

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Clinical Case Definition and Guidelines for Medical Practitioners.  An Overview of the Consensus Document.  Bruce M Carruthers, Marjorie I van de Sande 2005/2006  ISBN: 0-9739335-0-X

The Canadian Consensus Criteria are internationally recognised, used in clinical and research settings. It has become the basis for most criteria which followed.

The International Consensus Criteria

The International Consensus Criteria build on the Canadian Consensus documents, setting up specific criteria for the diagnosis of Myalgic Encephalomyelitis, and describing Post Exertional Neuroimmune Exhaustion (also known as post exertional malaise) in greater detail thatn the earlier criteria.

Myalgic Encephalomyelitis – Adult & Paediatric: International Consensus Primer for Medical Practitioners, 2012, International Consensus Panel, Editors: Bruce M. Carruthers, MD, CM, FRACP(C), Marjorie I. van de Sande, B Ed

Myalgic Encephalomyelitis: International Consensus Criteria, 2011, International Consensus Panel, Editors: Bruce M. Carruthers, MD, CM, FRACP(C), Marjorie I. van de Sande, B Ed

Primer for Young People

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Diagnosis and Management in Young People: A Primer (2017) Rowe, P. C., Underhill, R. A., Friedman, K. J., Gurwitt, A., Medow, M. S., Schwartz, M. S., . . . Rowe, K. S. Frontiers in Pediatrics, 5(121). doi: 10.3389/fped.2017.00121


Institute of Medicine - Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness

by The National Academies of Science Engineering Medicine |

"The Department of Health and Human Services (HHS), the National Institutes of Health, the Agency for Healthcare Research and Quality, the Centers for Disease Control and Prevention, the Food and Drug Administration, and the Social Security Administration asked the Institute of Medicine (IOM) to convene an expert committee to examine the evidence base for ME/CFS. In Beyond Myal­gic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness, the committee proposes new diagnostic criteria that will facilitate timely diagnosis and care and enhance understanding among health care providers and the public."  In this consensus document, the Institute of Medicine reviews the main studies done on ME/CFS, concluding that it is a real and often severely disabling illness, at the core of which is exertion intolerance. The document suggests a new name - Systemic Exertion Intolerance Disease (SEID) - with four main symptoms noted for diagnosis. It differs from the above criteria in classifying a number of formerly exclusionary conditions as  comorbidities rather than exclusions.  Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness, 2015, Ellen Wright Clayton, Chair Committee on the Diagnostic Criteria for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Comparison of Canadian Consensus Criteria and SEID

The BC Women's Hospital's Complex Chronic Diseases Program has created this clear document which compares the CCC and SEID:

Demystifying the Diagnostic Criteria for ME and Related Disease, by Jaime Seltzer, Director of Scientific and Medical Outreach, #MEAction.

Included in this comprehensive article is a detailed Criteria Comparison Chart


The Nightingale Research Foundation Definition of Myalgic Encephalomyelitis (M.E.)

by Byron M. Hyde, M.D. |

The information in this document explains how physicians can diagnose clinically & test scientifically for Myalgic Encephalomyelitis (M.E.).



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