Medical Terminology for Chronic Fatigue Syndrome
The medical term for chronic fatigue syndrome is Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), which is recognized by the World Health Organization as a disorder of the brain classified under ICD code G93.3 as Post Viral Fatigue Syndrome. 1, 2, 3
Official Nomenclature and Classification
ME/CFS is the currently accepted medical terminology that encompasses both the historical term "myalgic encephalomyelitis" and "chronic fatigue syndrome," reflecting the neurological and systemic nature of the disease 4, 5, 3
The condition is officially classified by WHO in the International Classification of Diseases under G93.3 as "Post Viral Fatigue Syndrome" within the chapter on "other disorders of the brain" 3, 6
The American College of Cardiology and other major medical organizations now use ME/CFS as the standard terminology to acknowledge both the neurological components (encephalomyelitis) and the chronic fatigue presentation 1, 2
Related Terminology in Clinical Practice
Chronic Multisymptom Illness (CMI) is an umbrella term used particularly by the VA/DoD that encompasses ME/CFS along with fibromyalgia syndrome and irritable bowel syndrome, recognizing the overlapping symptom patterns 7
Gulf War Illness represents a specific cohort presentation of CMI in military personnel deployed during the Gulf War (1990-1991), though CMI is not unique to veterans 7
The terms are sometimes used interchangeably in clinical settings, though ME/CFS is the more specific diagnostic entity with established criteria requiring profound fatigue lasting ≥6 months, postexertional malaise, unrefreshing sleep, and either cognitive impairment or orthostatic intolerance 1, 2
Important Clinical Context
There is no unique ICD-10 code specifically for CMI, and no universally accepted clinical case definition exists for the broader CMI category, though ME/CFS has more established diagnostic criteria 7
The American College of Cardiology notes that ME/CFS is not comprehensively taught in medical schools, with only 6% of medical schools fully covering ME/CFS across treatment, research, and curricula domains 1
The condition affects an estimated 0.4-1.5% of the worldwide population, predominantly affecting young adults aged 20-45 years with a female to male ratio of 3:1 1, 3, 6