|
Chronic fatigue syndrome is the current name for a disease that has been described for three centuries. It is characterized by a debilitating fatigue and a variety of other physical, constitutional, and neuropsychological complaints. Certain individuals, who were labeled in the past with diagnoses such as the vapors, neurasthenia, effort syndrome, hyperventilation syndrome, chronic brucellosis, epidemic neuromyasthenia, myalgic encephalomyelitis, hypoglycemia, multiple chemical sensitivity syndrome, chronic candidiasis, chronic mononucleosis, chronic Epstein-Barr virus infection, and post-viral fatigue syndrome, probably had what we now call chronic fatigue syndrome.(1) The diversity of names is a reflection of the number and controversy of theories of the disease's etiology. Whatever the cause, there seems to be several common themes that occur. It is often postinfectious, it is associated with immunological disturbances, and it is frequently accompanied by depression.
Currently, the lymphotropic herpes viruses, retroviruses, and enteroviruses are being studied as potential etiologic agents. Multiple factors that have led investigators to believe one or more of these viruses causes chronic fatigue syndrome. Chronic fatigue can be precipitated by a variety of acute infections, and some of these organisms have the ability to persist in humans, causing chronic illness. Also, titers to many infectious agents are elevated in patients with chronic fatigue syndrome (most herpes viruses, measles virus, rubella virus, and coxsackie virus B). Experience suggests that, while viruses may precipitate the syndrome, it is unlikely that they contribute to its long-term features. There have been several immunologic disturbances reported in patients with chronic fatigue syndrome; however, none of them appear in all patients, nor have any been correlated with the severity of the illness. An immune disturbance of some type is in line with a favored theory that at least some of the symptoms result from excessive cytokine release.(2)
An interesting finding that has been observed in controlled studies in recent years is that patients with chronic fatigue syndrome have a reduced production of corticotropin-releasing hormone in the hypothalamus.(3) This causes a mean serum cortisol that is lower than in control patients, and a correspondingly high level of adrenocorticotropic hormone (ACTH). Hypothetically, these endocrine abnormalities could contribute to the mood and impaired energy level of patients. It is unclear what significance this finding may have in determining the cause of this syndrome. It does, however, further indicate the complex nature of the illness.
Some clinicians propose that chronic fatigue syndrome is primarily a psychiatric disorder, and that various immune and neuroendocrine disturbances arise secondarily. This has been proposed because mild to moderate depression is evident in approximately two-thirds of patients. While this may be primarily a reactive depression, the percentage exceeds that of other chronic illnesses.
Cases in childhood and middle age have been described; however, the greatest frequency of cases occurs in people aged 25 to 45, and women develop chronic fatigue syndrome approximately twice as often as men. There has been no infectious or environmental causes identified; however, throughout history, there have been sporadic occurrences of “outbreaks” in specific geographical areas. A few examples are Los Angeles County Hospital in 1934; in Akureyri, Iceland, in 1948; in the Royal Free Hospital in London, in 1955; in Punta Gorda, Florida in 1956; and in Incline Village, Nevada, and surrounding communities in 1985.
The typical case of chronic fatigue syndrome arises suddenly, in a previously active individual. Usually the patient can describe an otherwise unremarkable flu-like illness or stressful occurrence as the triggering event. Pati
|
