The disorder we call chronic fatigue syndrome (CFS) does not appear to be new. It is a condition in which is characterized by muscle pain and weakness, with extreme fatigue that is prolonged after events such as exercise. It is usually coupled with symptoms associated with infection, such as sore throat, mild fever and enlarged tender lymph nodes.
The cause of CFS is controversial. Psychological factors may be the cause in some; however, chronic fatigue syndrome appears to be distinct from typical depression, anxiety, or other psychological disorders. A chronic viral infection has been proposed because many patients relate onset to an event similar to influenza or mononucleosis. Epstein-Barr virus is a possible cause, but the markers of exposure to the virus are not sensitive to show a specific causation.
The prevalence is impossible to state with precision, varying from 7 to 38 cases/100,000 population. This variation may be due to differences in psychologic or genetic makeup, social acceptability, or exposure to an infectious or toxic agent or to differences in diagnosing. Women are affected 1.3 to 1.7 times more often than men. Chronic Fatigue Syndrome primarily afflicts Caucasian women between the ages 25 and 45.
Allergic reactions have also been proposed as the aetiology; about 65% of patients complain of previous allergies, and for them, the rate of cutaneous reactivity to inhalants or foods is 25 to 50% higher than that in the general population.
Typically, CFS arises suddenly in a previously active individual. An otherwise unremarkable flu-like illness or some other acute stress leaves unbearable exhaustion in its wake. Other symptoms, such as headache, sore throat, tender lymph nodes, muscle and joint aches, and frequent feverishness, lead to the belief that an infection persists, and medical attention is sought. Over several weeks, despite reassurances that nothing serious is wrong, the symptoms persist and other features of the syndrome become evident—disturbed sleep, difficulty in concentration, and depression.
Many patients report that diverse complaints are linked—that during periods of greatest fatigue they perceive the most pain and difficulty with concentration. Patients also commonly assert that excessive physical or emotional stress may exacerbate their symptoms.
Symptoms of CFS
The main symptom is severe fatigue, generally longer than 6 months, which impairs daily life and is often made worse by exertion, exercise, headache, sore throat, and other stresses. It may be accompanied by enlarged, painful lymph nodes; sore throat; headache; joint pain; abdominal pain; muscle pain; low-grade fever; and cognitive difficulty, especially difficulty concentrating and sleeping. Many patients relate symptom onset to a viral-like syndrome, with swollen glands, extreme fatigue, fever, and upper respiratory symptoms.
Mild to moderate depression is present in half to two-thirds of people. Much of this depression may be reactive to the health situation, but its prevalence exceeds that seen in other chronic medical illnesses.