Health and Environmental Illness

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ME/CFS Definition and Description

ME/CFS is not a vague or poorly defined complaint. It is well defined by the Canadian Clinical Case Definition.

Canadian Clinical Case Definition

Myalgic Encephalomyelitis/ Chronic Fatigue Syndrome: Clinical Working Case Definition, Diagnostic and Treatment Protocols (PDF)
Journal of Chronic Fatigue Syndrome, Vol. 11(1) 2003)

The Diagnostic Criteria for ME/CFS from the Canadian Consensus Document

Canadian Expert Consensus Panel Clinical Case Definition for ME/CFS

Founding Principles and M.E. Society Definitional Framework--Discussion
by Maryann Spurgin, PhD, Myalgic Encephalomyelitis Society of America

The Myalgic Encephalomyelitis Society of America states, "The defining characteristic is exercise intolerance, post-exertional muscle weakness, generalized weakness, faintness, and pain; and post-exertional relapsing of symptoms."

The Society suggests specific descriptive terminology instead of the vague word "fatigue":

"There are more specific ways of describing the symptoms, such as dramatic loss of muscle power after exercise, delayed recovery of muscle function, orthostatic faintness, cardiac output problems, and other more specific terminology than 'fatigue.'...The defining characteristics of M.E./CFS can be easily outlined without reference to 'fatigue.' What all patients must an abnormal muscle metabolism--a delayed or impaired recovery of muscle function after exercise, which patients experience as paralytic muscle weakness and pain, not 'fatigue.'"

The enormous amount of medical research already done on ME/CFS includes studies on "cardiac disease, circulatory disease, dysautonomia and endocrine disorders, abnormal muscle metabolism, mitochondrial disease, immune disease, viral and bacterial disease, orthostatic problems, cardiac output problems, etc."

International Consensus Criteria

International Consensus Criteria (PDF)


Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness
Committee on the Diagnostic Criteria for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome; Board on the Health of Select Populations; Institute of Medicine

Further Description

Ten Discoveries About the Biology of CFS
by Dr. Anthony Komaroff, MD

Some of the Abnormalities that Have Been Demonstrated in ME/CFS (PDF)
by Eileen Marshall and Margaret Williams, March 31, 2006

Dr. Paul Cheney, MD, believes that CFS progresses through three phases: a post-viral or otherwise induced RNase L activity (an immune activation); xenobiotic toxicity from damage to enzyme systems; and hypothalamic injury and genetic changes.

The Three Phases of CFS: Dr. Paul Cheney's Theory
by Carol Sieverling

Lecture by Paul Cheney, MD, PhD, February 1999
Notes by Sue Bailey

Definition Wars

Unfortunately, the 1994 case definition developed by the CDC, which ignored the previous textbook definition of the existing disorder of Myalgic Encephalomyelitis, has served only to obfuscate and confuse. The Discussion in the CDC's Complete Text of Revised Case Definition, formerly posted on the CDC website, actually stated, "We dropped all physical signs from our inclusion criteria." Consequently, as Maryann Spurgin writes in the Founding Principles linked above, "These criteria...are too broad to define any disease."

Comparison of the Canadian Consensus Document with the CDC's Case Definition
by Mary Schweitzer, PhD

A Medical Morass? (PDF)
by Margaret Williams

Presentation to the Chronic Fatigue Syndrome Advisory Committee, U.S. Dept. of Health and Human Services, May 17, 2007
by Mary M. Schweitzer, PhD
By using vague, non-specific criteria, the CDC has been able to incorrectly maintain that there are no tests or treatments for ME/CFS. Mary Schweitzer describes the consequences of this stand and argues persuasively and logically for the use of tests and treatments.

Incredibly, the CDC promoted a new empirical definition, which abandons all attempts at diagnosis and instead administers the MOS 36-item short-form health survey, the twenty-item Multidimensional Fatigue Inventory, and the nineteen-symptom Symptom Inventory. Unlike the Canadian Case Definition referenced above, the empirical definition is based upon what are essentially short psychological tests. It promises only further obfuscation, confusion, and the distortion of medical research results.

Defining Chronic Fatigue Syndrome (ME/CFS)
by Cort Johnson, Phoenix Rising

Updated 1/29/2017