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At a glance

An acquired clinical syndrome of severe, disabling fatigue of at least 6 months duration that affects both physical and mental functioning and is present at least 50% of the time.


Myalgic Encephalitis; Postviral Fatigue Syndrome; Chronic Fatigue Immune Dysfunction Syndrome; Postural Orthostatic Tachycardia Syndrome.


Estimates range from 3 to 25:10,000 in the general population. It seems to be more common in females and in Caucasians. Females are twice as often affected as males, with the peak occurring between early 20s and mid-40s.

Genetic inheritance

There is no evidence of a genetic basis.


Results of investigations are typically inconclusive. Suggested theories include impaired hypothalamic-pituitary-adrenal interactions and abnormalities of the central and peripheral nervous systems. Another hypothesis is based on impaired inflammatory cytokine production and cellular immunity, which may be linked to the symptoms of Chronic Fatigue Syndrome (CFS) through changes in neurovascular regulation. An association with genetic markers or childhood trauma has also been suggested.


Based on clinical findings and requires the exclusion of other medical and psychiatric disorders, such as endocrinopathies (eg, hypothyroidism, Addison disease), sleep apnea, narcolepsy, severe obesity, major depressive disorder, bipolar affective disorder, schizophrenia, chronic mononucleosis, malignancy, autoimmune disease, subacute infections, alcohol or substance abuse, or reactions to medications. To fulfill the Centers for Disease Control and Prevention (CDC) diagnostic criteria for CFS, a patient must satisfy two criteria. First, the patient must have chronic fatigue for a minimum of 6 months with other medical conditions excluded. Second, the patient must concurrently have four or more of the following: (1) substantial impairment of short-term memory or concentration, (2) sore throat, (3) tender lymph nodes, (4) muscle pain, (5) multi-joint pain without swelling or tenderness, (6) headaches of a new type, pattern, or severity, (7) unrefreshing sleep, and (8) post-exertional malaise lasting more than 6 hours. The symptoms must have persisted or recurred during 6 or more consecutive months of illness and must not have predated the fatigue.

Clinical aspects

As mentioned under “Diagnosis.” Remissions and relapses characterize the clinical course. Orthostatic hypotension consistent with postural orthostatic tachycardia syndrome is described in adolescents with this condition.

Precautions before anesthesia

No specific tests are required. The principal anesthetic concern is that the condition has been misdiagnosed and an unrecognized condition is present (eg, myalgic encephalomyelitis, hypothyroidism).

Anesthetic considerations

General anesthesia, regional, and local anesthesia have been associated with minor adverse effects in these patients. They mainly include mild abnormal cardiovascular responses potentially due to some degree of autonomic dysfunction, query allergy-like symptoms, and potentially exaggerated responses to anesthetic drugs. Other ...

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