CHRONIC FATIGUE: NEW INSIGHTS, OLD MYSTERIES.

Chronic fatigue syndrome (CFS) continues to inspire interest and controversy. The Centers for Disease Control and Prevention recently updated the case definition (Ann Intern Med 1994; 121:953), drawing 65,000 requests for reprints. The definition includes symptoms only, which illustrates the controversy: like similar syndromes before it, such as neurasthenia and myalgic encephalomyelitis, CFS has no proven etiology or pathogenetic fingerprint. Moreover, its symptoms, including fatigue itself, overlap those of psychiatric syndromes. CFS is more than normal fatigue. It is defined as a new, severe fatigue that significantly interferes with a person's life, is not relieved by rest, and is accompanied by other chronic symptoms: sore throat, tender lymph nodes, myalgias, arthralgias, malaise after exertion, new headaches, unrefreshing sleep, and impaired memory or concentration. While fatigue in general is very common, only an estimated 1.8 to 6.3 percent of U.S. adults have debilitating chronic fatigue lasting at least …