Severe fatigue that occurs without notable muscle weakness or proven psychologic or physical causes.

Controversy surrounds the etiology. It is thought that psychologic factors may be the cause in some, many, or even all cases. However, CFS is not the same as differentiated typical depression, anxiety, or other psychologic disorders. A chronic viral infection is one etiological hypothesis because many patients identify onset with an event similar to influenza or mononucleosis. The Epstein-Barr virus may be a possible cause, but immunologic evidence of exposure does not appear to be sensitive or specific.

The outstanding symptom is severe fatigue. It generally lasts more than 6 months. It interferes with activities of daily living (ADL), and is often worsened by exertion, exercise, headache, sore throat, and other stresses. Enlarged, painful lymph nodes; sore throat; headache; arthralgias; abdominal pain; muscle pain; low-grade fever; and cognitive difficulty, especially difficulty concentrating and sleeping all may occur as manifestations. Many patients have identified symptom-onset to a viral-like syndrome causing swollen glands, extreme fatigue, fever, and upper respiratory symptoms. Muscle weakness, arthritis, neuropathy, and enlarged organs do not occur.

Because the cause is unknown, diagnostic evaluation procedures are aimed at excluding treatable diseases. A laboratory assessment will probably include complete blood count (CBC), routine chemistries, erythrocyte sedimentation rate (ESR), and thyroid-stimulating hormone. Chest x-ray, and tests for antinuclear antibody, rheumatoid factor, Lyme disease antibody, hepatitis A or B antibodies, and HIV antibody are also considered. Other viral antibody tests will probably not be helpful to determine the diagnosis or cause. If unquestionable depression or severe anxiety is the case, the diagnosis of CFS is not appropriate.

Treatment is directed to each individual case. Antidepressants appear to be the drug of choice for treatment thus far. Up to 80% of patients have reported treatment benefit. Psychological treatment, e.g., individual and group therapy may also be helpful to some patients.

Most patients remain capable of continuing to perform home, work, family, and community activities. However, some feel unable to work, and a small number of individuals need assistance with ADL. The course of illness may lead to isolation, feelings of self pity, and frustration. However, the condition does not appear to progress. Many patients may gradually improve, and a small number recover fully.

1. For Persian Gulf Veterans, this disease shall be granted service connection although not otherwise established as incurred in, or aggravated by service if this condition manifested either during active military, naval, or air service in the Southwest Asia Theater of operations during the Persian Gulf War (PGW), or to a degree of 10 percent or more and by history, physical examination, and laboratory tests cannot be attributed to any known clinical diagnosis. (38 CFR 3.317) The PGW period extends from August 2, 1990, through a date yet to be determined by law or Presidential proclamation.

2. May be entitled to special monthly compensation where the veteran has a single service-connected disability rated as 100% and/or other requirements/qualifications under 38 CFR §3.350 [Special monthly compensation ratings]. Also reference 38 CFR 3.155(d)(2).

3. "For the purpose of evaluating this disability, incapacitation exists only when a licensed physician prescribes bed rest and treatment. " [38 CFR 4.88b Schedule of ratings-systemic diseases].

4. "For VA purposes, the diagnosis of chronic fatigue syndrome requires:

   • new onset of debilitating fatigue severe enough to reduce daily activity to less than 50% of the usual level for at least six months; and

   • the exclusion, by history, physical examination, and laboratory tests, of all other clinical conditions that may produce similar symptoms; and

   • six or more of the following:

     • acute onset of the condition

     • low grade fever

     • sore throat with no secretions (nonexudative pharyngitis)

     • palpable or tender cervical or axillary lymph nodes

     • generalized muscle aches or weakness

     • fatigue lasting 24 hours or longer after exercise

     • headaches [of a type, severity, or pattern that is different from headaches in the pre-morbid state], migratory joint pains, neuropsychologic symptoms

     • migratory joint pains

     • neuropsychological symptoms, and

     • sleep disturbance" [38 CFR §4.88a Chronic fatigue syndrome].