Chronic Fatigue Syndrome

What Is It?

Chronic fatigue syndrome (CFS) is a controversial and complicated illness that is characterized by at least six months of fatigue (feeling extremely tired or exhausted) that cannot be explained. In many patients with CFS, the disorder begins suddenly, often following a flulike infection or an episode of physical or psychologic trauma, such as surgery, a traumatic accident or the death of a loved one. In other cases, CFS develops gradually.

Currently, the exact cause of chronic fatigue syndrome remains a mystery. Although the illness sometimes occurs after an infection with B. burgdorferi (Lyme disease bacteria) or an episode of infectious mononucleosis, there is no proof that these infections cause CFS. Researchers also have been unable to link CFS to immune-system problems or allergies. So far, the most promising theory describes CFS as a multi-system disorder that disturbs the complex relationship between the hypothalamus (a part of the brain that regulates hormones and vital functions) and the pituitary and adrenal glands. This theory is supported by studies that link CFS to a form of a condition called neurally mediated hypotension, which is abnormally low blood pressure caused by a problem in the nervous system. The most recent studies, however, have found no consistent connection between low blood pressure and chronic fatigue, so the role of brain function and blood-pressure regulation to the condition remains uncertain.

In the United States, federal health authorities estimate that CFS currently affects four to 10 of every 100,000 Americans older than age 18, and women are afflicted twice as often as men. Although the illness is most common in people 25 to 45 years old, CFS can attack people of all age groups, including children.

Most cases of CFS affect isolated individuals. However, at least 30 outbreaks of CFS also have been reported, during which many people in the same area suddenly developed the illness at the same time. Again, despite the larger numbers of patients involved in these outbreaks, health experts have failed to identify a cause for their CFS symptoms.

Symptoms

The most prominent symptom of chronic fatigue syndrome is an unexplained feeling of fatigue, which is not relieved by rest. This fatigue must be severe enough to decrease the activity level at home, work or school. Many physicians look for the fatigue to be severe enough to reduce someone's activity level by 50 percent or more. In addition, to be diagnosed with CFS, patients should have at least four of the following symptoms for at least six months:

• Impaired concentration or short-term memory — severe enough to affect routine activities at home, work, school or social functions
• Sore throat
• Enlarged lymph nodes (swollen glands) in the neck or underarm area