Click here to view next page of this article Chronic Fatigue SyndromeFatigue is a common complaint in the general population. Up to one quarter of patients seeking care from their primary care physician acknowledge fatigue as a major problem chronic fatigue syndrome. Fatigue is a common symptom of many acute infectious illnesses, and postinfectious fatigue may persist for weeks after resolution of other acute manifestations of the illness. Persistent fatigue can be a prominent, nonspecific manifestation of chronic conditions or illnesses, including endocrine (eg, hypothyroidism), connective tissue (eg, giant cell arteritis, polymyalgia rheumatica), neoplastic (eg, lymphoma), metabolic (eg, renal or hepatic insufficiency, morbid obesity), hematologic (eg, anemia, preleukemia), psychiatric (eg, depression), neurologic (eg, myasthenia gravis, multiple sclerosis), or chronic infectious (eg, osteomyelitis, endocarditis, toxoplasmosis) disorders. In addition, self-limited exhaustion can occur with unusual physical or emotional stress, generally resolving as the triggering disturbance clears chronic fatigue syndrome. Chronic fatigue syndrome designates an illness of unknown etiology characterized by debilitating fatigue or exhaustion, often of sudden onset, lasting at least 6 months and resulting in substantial (>50%) reduction in premorbid activity and productivity levels. It is often associated with additional symptoms. Physician-based surveillance by the Centers for Disease Control and Prevention in four U.S. urban/suburban sites over a 4-year period demonstrated an overall prevalence of 6.4 cases per 100,000 persons, with rates between 4.0 and 8.7 per 100,000 in the four areas studied. Of patients referred with unexplained, debilitating fatigue or chronic unwellness for at least 6 months, only 23% met Centers for Disease Control and Prevention criteria. Etiology The cause of chronic fatigue syndrome remains unknown. Because onset of chronic fatigue syndrome often occurs with an apparent viral illness, commonly resembling infectious mononucleosis or an influenza-like illness, infectious agents have been studied widely, including Brucella species, enteroviruses, herpes viruses (including Epstein-Barr virus, cytomegalovirus, human herpes virus 6, herpes simplex viruses 1 and 2) and retroviruses (human T-cell lymphoma virus 2). None of these have been implicated convincingly either via primary infection. Psychologic factors have been considered as a cause of chronic fatigue syndrome. Although 50% of patients with chronic fatigue syndrome satisfy criteria of major depression, this does not indicate that psychiatric illness is the explanation for chronic fatigue syndrome because chronic fatigue syndrome and depression share symptoms (fatigue, sleep disturbance, cognitive dysfunction). Depression can result from any chronic, debilitating illness. However, it is possible that premorbid (ie, pre-chronic fatigue syndrome) psychopathology may promote the development of chronic fatigue syndrome. An immunologic cause has been proposed because some studies of immune responses and activation have demonstrated subtle abnormalities in lymphocyte response to mitogens, enhanced activity of proinflammatory cytokines, impaired natural killer cell cytotoxicity, and alteration in proportions of T-lymphocyte subsets. Some investigators have suggested that chronic fatigue syndrome results when a precipitating factor, especially an infectious disease, triggers lymphocyte and cytokine activation. However, the clinical and etiologic significance of these findings is unknown. Other proposed etiologies or factors in patients with chronic fatigue syndrome have included neurally mediated hypotension, primary sleep disorders. Diagnostic Criteria In 1988, the Centers for Disease Control and Prevention proposed a working case definition of chronic fatigue syndrome. In part because of inconsistent adherence to this definition, modifications have been proposed. Centers for Disease Control and Prevention Case Definition of Chronic Fatigue Syndrome* A. Major criteria
B. Minor criteria
Physical Findings
3. Palpable/tender lymph nodes (cervical, axillary) *Chronic fatigue syndrome is diagnosed if patient fulfills both major criteria and (a) at least eight symptom criteria or (b) at least six symptom criteria plus at least two physical criteria. Treatment No specific therapies exist for chronic fatigue syndrome. Treatment is symptomatic, supportive, and psychosocial. Sleep disturbances often respond to treatment with benzodiazepines or Zolpidem for initiation of sleep and reduction of prolonged sleep latency. Tricyclic antidepressants, especially amitriptyline, taken at low doses 2 hours or less before bedtime, are useful for reduction in early awakening. Amitriptyline at low doses may prove helpful in initiating sleep and may improve myalgias as well. Long-acting nonsteroidal antiinflammatory agents may be more effective in treating myalgias and arthralgias, especially with use of a prebedtime dose for nocturnal muscle discomfort. |