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Understanding Myalgic Encephalomyelitis (M.E.)


If a patient or a family member has tried to search the internet for an understanding of Myalgic Encephalomyelitis (M.E.), or so-called “Chronic Fatigue Syndrome” (CFS, currently being called “ME/CFS”), they will have been overwhelmed by the multitude of technical descriptions and the numerous overlapping medical conditions. There have been many attempts to define CFS, some of them described in our 1992 book ‘The Clinical and Scientific Basis of ME and CFS’. M.E. and ME/CFS represent a complex, multi-system group of afflictions, adversely affecting the brain, heart, neuro-endocrine, immune and circulatory systems in our bodies, but, crucially, M.E. is a distinct illness, while both CFS and ME/CFS are umbrella terms for a group of symptoms common to many illnesses and conditions. This has led to M.E. symptoms being confused with the symptoms for neurasthenia, multiple chemical sensitivities, fibromyalgia syndrome, chronic mononucleosis, and much more.

The US Centers for Disease Control and Prevention (CDC) first defined CFS, with great emphasis on the word “fatigue”, in 1988. This definition, referred to as “Holmes”, was later replaced by the 1994 ”Fukuda”, then by the 2005 “Reeves”, and most recently by the 2015 IOM (Institutes of Medicine) report, still emphasizing fatigue. Definitions have also included the 1991 UK ”Oxford” report and the more well-known 2003 Canadian Consensus Criteria (CCC), that talks of M.E. and CFS as though they were the same illness. They are not. The CCC was updated and replaced in 2011 by the International Consensus Criteria (ICC) which insisted that CFS should not be considered a diagnostic entity and that M.E. is a specific diagnosis requiring thorough patient history, examination, and testing. Unfortunately the CDC did not accept or adopt the ICC, written by 26 experts in the field, and instead commissioned its own group with limited access to M.E. information, to create their vague 2015 IOM report, minimizing the disease yet again. This is the report most widely used and accepted throughout the world today (2022). [except of course for those countries and organizations that still use only “CFS”, or worse, also classify this “CFS” as a psychiatric condition, using euphemistic terms like Central Sensitisation Syndrome or Functional Neurological Disorder.] 

The position of Nightingale Research Foundation is that the IOM does NOT describe or define M.E., and that the ICC, while far superior to the IOM, is still not specific enough. 
In creating the Nightingale Definition, we have studied decades of clinical evidence, and followed up on the work of Dr. Melvin Ramsay (case descriptions published 1981 and 1988), Dr. Elizabeth Dowsett, Dr. John Richardson, and others who closely studied M.E. patients and M.E. outbreaks over several decades.

M.E. has a clearly defined disease process, while CFS by definition has always been a syndrome. In light of this state of affairs, the Nightingale Research Foundation created its 2007 Definition of M.E. and updated it in 2016. Our Nightingale Definition of M.E. is located on our website under "Publications" and is available as a free download in English, French, Norwegian, and Danish.

The Complexities of Diagnosis 

In 2003, Dr. Byron Hyde completed a chapter for L. A. Jason, P. A. Fennell and R. R. Taylor for their book Handbook of Chronic Fatigue Syndrome, John Wiley and Sons Inc., Hoboken N.J., titled “The Complexities of Diagnosis”1, Chapter 3. This chapter includes the following definition of CFS: 

“The physician and patient alike should remember that CFS is not a disease. It is a chronic fatigue state where the one essential characteristic of M.E. is acquired Central Nervous System (CNS) dysfunction, that of CFS is primarily chronic fatigue. By assumption, this CFS fatigue can be acquired abruptly or gradually. Secondary symptoms and signs were then added to this primary fatigue anomaly. None of these secondary symptoms is individually essential for the definition and few are scientifically testable. Despite the list of signs and symptoms and test exclusions in these definitions, patients who conform to any of the CDC, Oxford, Australian and Canadian CFS definitions may still have an undiagnosed major illness, certain of which are potentially treatable. Although the authors of these definitions have repeatedly stated that they are defining a syndrome and not a specific disease, patient, physician, and insurer alike have tended to treat this syndrome as a specific disease or illness, with at times a potentially specific treatment and a specific outcome. This has resulted in much confusion, and many physicians are now diagnosing CFS as though it were a specific illness. They either refer the patient to pharmaceutical, psychiatric, psychological, or social treatment or simply say: “you have CFS and nothing can be done about it”. The CFS definitions have another curiosity. If in any CFS patient, any major organ or system injury or disease is discovered, the patient is removed from the definition. The CFS definitions were written in such a manner that CFS becomes like a desert mirage: The closer you approach, the faster it disappears and the more problematic it becomes.”

Definition Essentials 

Some of the definition essentials required to accurately diagnose either M.E. or CFS, or any chronically ill patients group, include: 

  • A working case clinical definition must be short, clear and testable.

  • Patients and their illness or illnesses must be part of an integrated system. Neither the patients’ patho-physiology nor their illness can be understood without a concise knowledge of their integrated pathophysiological systems.

  • A statistically significant group of patients who have M.E. and CFS type illnesses must be subjected to a complete personal and family history to map the genetic and historical causes of their illnesses. 

  • Accordingly, the patient’s illness can only be understood if a complete total body mapping is performed on all systems and organs. The mammalian and animal bodies are an integrated physiological mechanism and when one major system change occurs, many physiological systems are liable to shift. 

  • In the past it has been facile to pose psychiatric diagnoses on M.E. and CFS patients since psychiatric diagnoses cannot be subjected to scientific examination. Psychiatrists rarely actually examine patients and almost never do an integrated patho-physiological patient investigation of the patient’s organs and systems. Nor have most psychiatrists been of any help in diagnosing M.E. and CFS patients except to the insurance industry. In the more than 70 years since the first major M.E. and CFS epidemic struck the Los Angeles County General Hospital in 1934, no psychiatric treatment has proven significantly effective in treating the M.E. and CFS group of patients and restoring them to health. This is understandable since neither represents a psychiatric disorder. 

  • Effective treatment of the M.E. and CFS group of patients depends upon precisely defining the organ and system pathologies and learning how to treat these patho-physiological conditions. 

  • M.E. and the CFS group of illnesses are chronic illnesses. For too long physicians have been considering chronic diseases and chronically ill patients as they would acute short-term illnesses. We believe this is an error and we direct those interested to our chapter on diagnosis. Relatively young chronically ill patients, often do not have a disease process, they often have many disease processes.

Definition of Myalgic Encephalomyelitis (M.E.)

Nightingale is pleased to offer the definition of Myalgic Encephalomyelitis in a downloadable PDF format for free in the following translations:

If you would prefer a hard copy of one of the definitions the fee is $30 within North America. Delivery is by mail.  Please contact our office for further information.

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