Chronic Fatigue Syndrome

Chronic fatigue syndrome (CFS) is a complex disease that affects approximately 2 million people in the United States. The United States Public Health Services initially described CFS during an epidemiological study in Los Angeles County during the summer of 1934. Chronic fatigue syndrome, also known as myalgic encephalomyelitis (ME), is a complex, multisystem disease commonly characterized by severe fatigue, cognitive dysfunction, sleep disturbances, autonomic dysfunction, and postexertional malaise, which severely impair activities of daily living. Outcomes are often poor due to delayed or misdiagnosis, inadequate clinician education, clinician bias, and misinformation regarding the diagnosis and treatment of the disease. ME/CFS has been identified as 1 of the 10 chronic overlapping pain conditions by the National Institutes of Health. Patients with chronic overlapping pain conditions often experience nociplastic pain, which arises from altered nociceptive processing in the absence of a clear lesion or disease affecting the somatosensory nervous system, or without actual or threatened tissue damage that would typically activate peripheral nociceptors. Compared to nociceptive or neuropathic pain, nociplastic pain is more frequently associated with central nervous system–related symptoms, including fatigue, cognitive and memory disturbances, depression, and anxiety. CFS presents with fatigue, cognitive dysfunction, and impairment of routine functioning that persists for at least 6 months. CFS is a biological condition, not a psychological disorder, and the exact pathogenesis is not fully understood. Various mechanisms and biochemical changes have been implicated, including immune dysregulation (natural killer cell and T-cell dysfunction, elevated cytokine levels, and autoantibodies), hormonal dysregulation, and response to oxidative stress. Although infectious causes have been proposed, no causal relationship has been identified. Furthermore, patients with CFS can sometimes present to the emergency department with several complex symptoms, such as orthostatic intolerance, postexertional malaise, fatigue, and diarrhea.