Chronic Fatigue Syndrome/Myalgic Encephalomyelitis

Chronic Fatigue Syndrome/Myalgic Encephalomyelitis

National Organization for Rare Disorders, Inc.


It is possible that the main title of the report Chronic Fatigue Syndrome/Myalgic Encephalomyelitis is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.


  • Akureyri Disease
  • Benign Myalgic Encephalomyelitis
  • Epidemic Myalgic Encephalomyelitis
  • Epidemic Neuromyasthenia
  • Iceland Disease
  • Raphe Nucleus Encephalopathy
  • Royal Free Disease
  • Tapanui Flu
  • ME
  • CFS

Disorder Subdivisions

  • None

General Discussion

Until the late 1980s, myalgic encephalomyelitis was thought to be a distinct, infectious disorder affecting the central, peripheral and autonomic nervous systems and the muscles. Its major symptom was fatigue to the point of extended periods of exhaustion. A group of experts studying the Epstein-Barr virus first published strict criteria for the symptoms and physical signs of chronic fatigue syndrome in 1988. This case definition was further refined in 1994.

The Fact Sheet for CFS published by the National Institutes of Allergy and Infectious Diseases of the National Institutes of Health states that "[T]oday, CFS is also known as myalgic encephalomyelitis, postviral fatigue syndrome, and chronic fatigue and immune dysfunction syndrome." ME/CFS is now recognized as part of a range of illnesses that have fatigue as a major symptom.

ME/CFS is not rare. The CDC estimates that there are as many as 500,000 persons in the United States who have CFS-like symptoms. However, the disorder remains debilitating, complex and mysterious in origin, natural history, understanding and treatment.


Usually, the signs and symptoms of CFS/ME appear after a period of time in which the individual has experienced a cold, bronchial distress, hepatitis or intestinal discomfort. Sometimes, the symptoms appear after a bout of fatiguing infectious mononucleosis. In each case, the major symptom is the sudden onset and persistence of profound fatigue. Frequently, patients describe the onset as coming after a period of intense stress.

The fatigue may last for weeks or may come and go over a period of many months. In addition to fatigue, symptoms may include headache, tender lymph nodes, muscle and joint pain, and difficulty in concentrating.


The exact cause of chronic fatigue syndrome/myalgic encephalomyelitis is not known. Researchers believe the disorder may be caused by a viral infection in association with an immune system abnormality. At one time, the Epstein-Barr virus was thought to be implicated in this disorder. However, scientists find high concentrations of Epstein-Barr antibodies (disease-fighting proteins created by the immune system in response to the presence of the virus) in some healthy people, as well as in some people with CFS/ME.

It remains unclear whether the disorder is related to some other virus, one or more environmental pollutants, immune system collapse, or one or more genetic abnormalities. The immune system fails in this disorder, but the cause of the failure is not yet clear.

Affected Populations

Myalgic encephalomyelitis appears to affect adults almost exclusively, and it occurs up to three times more often in females than in males.

Standard Therapies


A diagnosis of chronic fatigue syndrome is made when a patient has severe and chronic fatigue for at least six months with other medical conditions having been excluded by clinical diagnosis. Also, four or more of the following should be present for a diagnosis: substantial reduction in short-term memory or concentration; sore throat; tender lymph nodes; muscle pain; multi-joint pain without swelling or redness; headaches of a new type, pattern, or severity; unrefreshing sleep; and feelings of dissatisfaction or depression lasting for 24 hours or more after exercise or exertion. These symptoms must be present or have recurred for six or more consecutive months, and must not have been evident prior to the onset of fatigue.


Treatment is aimed at relieving the more obvious symptoms and restoring the patient to some level of pre-existing function and well-being. Since the cause of CFS/ME is not known and the course of its development is also unknown, all treatments should be considered cautiously. Most physicians combine some of the treatment options listed below.

Pharmacologic Therapies

Caution and care are necessary in the use of drugs to relieve the symptoms of a chronic disorder whose cause is not known. Patients with diagnosed CFS may be particularly susceptible to drugs affecting the nervous system.

Nonsteroid antiinflammatory drugs may be used to relieve pain. They are generally safe when used as directed but can cause side effects.

Low-dose tricyclic antidepressants have been prescribed to reduce pain and improve sleep. Use of these drugs may also cause adverse side effects of which the patient and physician must be aware.

Other antidepressants including the serotonin reuptake inhibitors have been prescribed in doses lower than those offered to depressed patients. These drugs also must be monitored for adverse side effects.

Investigational Therapies

The Centers for Disease Control and Prevention (CDC) have released a report on the experimental use of a synthetic, immune system modifier, Ampligen, which yielded modest improvement among CFS patients. Further study is needed of this investigational therapy for chronic fatigue syndrome. The drug is expensive and not reimbursable through health insurance. Adverse side effects have not yet been well defined.

The same CDC report suggests that the experimental use of gamma globulin, corticosteroids and dehydroepiandrosterone were either ineffective or provided temporary relief of symptoms for one month or less.

Research is underway to determine if a Coxsackie B virus associated with stress and amino acid (tryptophan) deficiencies may be implicated in onset of myalgic encephalomyelitis. When the disorder is better understood, scientists may be able to determine a better course of treatment or possibly some method of prevention.

Information on current clinical trials is posted on the Internet at All studies receiving U.S. Government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222

TTY: (866) 411-1010


For information about clinical trials sponsored by private sources, contact:



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Fauci AS, Braunwald E, Isselbacher KJ, et al., eds. Harrison's Principles of Internal Medicine. 14th ed.McGraw-Hill Companies. New York, NY; 1998:2483.


Natelson BH, Lange G. A status report on chronic fatigue syndrome. Environ Health Perspect. 2002;110 Suppl 4:673-77.

Pall MI, Satterle JD. Elevated nitric oxide/peroxynitrite mechanism for the common etiology of multiple chemical sensitivity, chronic fatigue syndrome, and posttraumatic stress disorder. Ann N Y Acad Sci. 2001;933:323-29.

Patarca I. Cytokines and chronic fatigue syndrome. Ann N Y Acad Sci. 2001;933:185-200.

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Buskila D, Press J. Neuroendocrine mechanisms in fibromyalgia-chronic fatigue. Best Pract Res Clin Rheumatol. 2001;15:747-58.

Whiting P, Bagnall AM, Sowden AJ, et al. Interventions for the treatment and management of chronic fatigue syndrome: a systematic review. JAMA. 2001;286:1360-68.


Mayo Clinic. Chronic fatigue syndrome. 2001:9pp.

NIAID (National Institute of Allergy and Infectious Diseases) Fact Sheet. Chronic Fatigue Syndrome. 2002:5pp.

Myalgic Encephalomyelitis. 1999:8pp.

Basic Introduction to CFS(ME) - (layman's version). 1999:8pp.

Myalgic Encephalomyelitis. BBC News. 1998:3pp.


Hyde B. Nightingale Research Foundation. The clinical and scientific basis of myalgic encephalomyelitis/chronic fatigue syndrome. nd. 2pp.

Contact a Family. Myalgic Encephalomyelitis. 2001:5pp.

The Myalgic Encephalomyelitis Association of Ontario. About M.E./C.F.S. nd. 2pp.


National Chronic Fatigue Syndrome & Fibromyalgia Association

P.O. Box 18426

Kansas City, MO 64133


Tel: (816)737-1343

Fax: (816)524-6782



ME Association

7 Apollo Office Court

Radclive Road


Bucks, MK18 4DF

United Kingdom

Tel: 01280818964



Centers for Disease Control and Prevention

1600 Clifton Road NE

Atlanta, GA 30333

Tel: (404)639-3534

Tel: (800)232-4636

TDD: (888)232-6348



NIH/National Institute of Allergy and Infectious Diseases

Office of Communications and Government Relations

6610 Rockledge Drive, MSC 6612

Bethesda, MD 20892-6612

Tel: (301)496-5717

Fax: (301)402-3573

Tel: (866)284-4107

TDD: (800)877-8339



CFIDS Association of America

PO Box 220398

Charlotte, NC 28222-0398


Tel: (704)365-2343

Fax: (704)365-9755

Tel: (800)442-3437



MAME, Inc. (Mothers Against Myalgic Encephalomyelitis)

1 Orne Square

Salem, MA 01970


Tel: (978)744-8293

Fax: (978)744-2027



National CFIDS Foundation, Inc.

103 Aletha Road

Needham, MA 02492-3931

Tel: (781)449-3535

Fax: (781)449-8606




P.O. Box 9204

Bardonia, NY 10954

Tel: (914)648-9197

Fax: (845)215-0041



Genetic and Rare Diseases (GARD) Information Center

PO Box 8126

Gaithersburg, MD 20898-8126

Tel: (301)251-4925

Fax: (301)251-4911

Tel: (888)205-2311

TDD: (888)205-3223


ME Research UK

The Gateway

North Methven Street

Perth, PH1 5PP

United Kingdom

Tel: 01738451234



For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders, Inc.® (NORD). Cigna members can access the complete report by logging into For non-Cigna members, a copy of the complete report can be obtained for a small fee by visiting the NORD website. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational treatments (if available), and references from medical literature. For a full-text version of this topic, see

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