Chronic fatigue syndrome Health Article

Definition

Chronic fatigue syndrome is a condition of prolonged and severe tiredness or weariness (fatigue) that is not relieved by rest and is not directly caused by other conditions. To be diagnosed with this condition, your tiredness must be severe enough to decrease your ability to participate in ordinary activities by 50%.

See also: Fatigue

Alternative Names

CFS; Fatigue - chronic; Immune dysfunction syndrome

Causes, incidence, and risk factors

The exact cause of chronic fatigue syndrome (CFS) is unknown. Some researchers suspect it may be caused by a virus, such as Epstein-Barr virus or human herpes virus-6 (HHV-6). However, no distinct viral cause has been identified.

Recent studies have shown that chronic fatigue syndrome may be caused by inflammation of pathways in the nervous system, and that this inflammation may be some sort of immune response or process. CFS may occur when a viral illness is complicated by a problem with the body's immune response. Other factors such as age, prior illness, stress, environment, or genetics may also play a role. CFS most commonly occurs in women ages 30 to 50.

The Centers for Disease Control (CDC) describes CFS as a distinct disorder with specific symptoms and physical signs, based on ruling out other possible causes. The number of persons with CFS is unknown.

Symptoms

Symptoms of CFS are similar to those of most common viral infections (muscle aches, headache, and fatigue), often developing within a few hours or days and lasting for 6 months or more.

Main symptoms:

• Fatigue or tiredness, never experienced to this extent before (new onset), lasting at least 6 months and not relieved by bed rest
• Fatigue that is severe enough to restrict activity (serious fatigue develops with less than one-half of the exertion compared to before the illness)

Other symptoms:

• Fatigue lasting more than 24 hours after an amount of exercise that would normally be easily tolerated
• Mild fever (101 degrees F or less)
• Sore throat
• Lymph node tenderness in the neck or armpit
• Muscle weakness, all over or multiple locations, not explained by any known disorder
• Muscle aches (myalgias)
• Feeling unrefreshed after sleeping an adequate amount of time
• Headaches, different from previous headaches in quality, severity, or pattern
• Joint pain, often moving from joint to joint (migratory arthralgias), without joint swelling or redness
• Forgetfulness or other similar symptoms including difficulty concentrating, confusion, or irritability