Clinical and Pathophysiological Aspects of Chronic Fatigue Syndrome

SUMMARY

Prolonged fatigue is a common complaint in the community and is usually transitory. If fatigue continues for more than six months, is disabling, and is accompanied by other constitutional and neuropsychological symptoms, then a diagnosis of Chronic Fatigue Syndrome [CFS] should be considered, according to the Centers for Disease Control case definition [1994]. Actually, the diagnosis of CFS is only a clinical diagnosis, since laboratory tests are only useful to identify and/or exclude alternative diseases with a well defined etiology, which may explain the same symptoms. The CFS onset is explained by different etiopathogenetic hypotheses: toxic exposure well documented in some cases [e.g., ciguatera poisoning, workers exposure to solvents and other chemicals], infectious agents [e.g., Epstein-Barr virus and other herpesviruses, coxsackievirus, etc.], immunologic factors [CFS = Chronic Fatigue Immune Dysfunction Syndrome-CFIDS], neuroendocrine alterations [significant dysfunction of hypothalamic pituitary adrenal axis has been observed in CFS patients]. Also the psychiatric hypothesis is still credited by CFS researchers. However, a concurrent diagnosis of major depression should exclude a diagnosis of CFS according to the last case definition. Furthermore the depressive syndrome often observed in CFS patients is often secondary to the malaise and disability. Although the various pathogenetic hypotheses are not necessarily in contrast, it seems more likely that CFS is a heterogeneous disease, probably multifactorial, or that CFS includes different pathologies which manifest with the same symptoms. Among the several questions which are still unexplained there is one of remarkable importance about the pathogenetic substrate of CFS symptoms and particularly of “fatigue.” Furthermore, it is still unclear whether the fatigue or the other neuromuscular symptoms [e.g., myalgia] have a central or a peripheral origin. Most of the alterations described so far in CFS point out a clinical and a functional impairment of the central nervous system. However, our own observations at the Reference Center for CFS Study of Chieti University indicate the existence of peripheral alterations [neuromuscular] and this supports the theory about a heterogeneity of the CFSs.

KEYWORDS:

• Chronic fatigue syndrome
• fibromyalgia
• fatigue
• myalgia
• muscle