It is very difficult to diagnose chronic fatigue syndrome. Even experts do not have a clear definition of what chronic fatigue actually is, or what mechanisms in the brain or nervous system are responsible for it. The best diagnostic approach is to determine whether the patient matches the criteria for CFS and rule out other possible causes of symptoms.
Criteria for Chronic Fatigue Syndrome
In May 2006, the Centers for Disease Control and Prevention (CDC) released a revised definition for Chronic Fatigue Syndrome based on a consensus of many of the leading CFS researchers and doctors (including input from patient group representatives). In the revised definition, chronic fatigue syndrome is considered a subset of chronic fatigue, a broader category defined as unexplained fatigue that lasts for 6 months or longer. Chronic fatigue is considered a subset of prolonged fatigue, which is defined as fatigue that lasts for 1 month or more.
Unexplained chronic fatigue can be classified as CFS if the patient meets the following criteria:
- Unexplained persistent or relapsing chronic fatigue that is either new or that started at a definite period of time; is not the result of ongoing exertion; is not substantially relieved by rest; and significantly reduces activities such as work, education, and social life.
- Also, four or more of the following symptoms, which must have continued or recurred during 6 or more consecutive months of illness and must not have started before the fatigue:
- Significant impairment in short-term memory or concentration
- Sore throat
- Tender lymph nodes
- Muscle pain
- Joint pain without swelling or redness
- Headaches of a new type, pattern, or severity
- Unrefreshing sleep
- Malaise that lasts for more than 24 hours after exertion
In 2007, the British National Institute for Health and Clinical Excellence (NICE) released new guidelines for the diagnosis and management of CFS in adults and children. According to these guidelines, CFS may be diagnosed if the person has disabling fatigue that starts suddenly, lasts a long time, keeps coming back, and can't be explained by another condition.
People with CFS also can have the following symptoms:
Review Date: 01/10/2011
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.