Redefinitions of ME/CFS – A 20th Century Phenomenon

Purpose: This document critiques the evolving definitions of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) throughout the 20th century. It highlights the impact of shifting terminology on research, diagnosis, and patient care, advocating for a return to descriptive definitions rooted in clinical observations.

Key Points:

1. Historical Definitions of ME/CFS
   • Poliomyelitis-like Illness (1910–1958): ME/CFS was initially described as a polio-like illness, with overlapping symptoms and epidemiological patterns. Advances in virology revealed distinctions between polio and non-polio enteroviruses, linking ME/CFS to persistent viral infections.
   • Myalgic Encephalomyelitis (1958–1988): Dr. Ramsay introduced the term “Myalgic Encephalomyelitis,” emphasizing its neurological and systemic nature. This period saw collaborative research and technological advancements, solidifying ME/CFS as a distinct clinical entity.
2. The Fatigue States (1988–1999)
   • The introduction of “fatigue definitions” by non-clinical researchers shifted focus away from ME/CFS’s neurological features, emphasizing psychiatric explanations.
   • These definitions inflated prevalence estimates and diluted diagnostic criteria, undermining efforts to differentiate ME/CFS from other conditions.
3. Critique of Fatigue Definitions
   • Overlooked encephalitic features of ME/CFS.
   • Elevated fatigue to diagnostic importance, ignoring its ubiquity in other illnesses.
   • Suggested ME/CFS was a subgroup of heterogeneous conditions, complicating differential diagnosis.
   • Delayed diagnosis by requiring symptoms to persist for six months, hindering early intervention.
4. The Ramsay Definition
   • Dr. Ramsay’s 1986 definition remains a valuable guide, describing ME/CFS as a multisystem disease with neurological, musculoskeletal, and endocrine involvement.
   • Key features include post-exertional exhaustion, cognitive dysfunction, and a chronic relapsing course.
5. Recommendations for Future Definitions
   • Develop concise epidemiological summaries.
   • Create working definitions for clinicians and researchers.
   • Modify definitions to address variations in children and adolescents.

Target Audience:

• Healthcare Professionals and Researchers: Clinicians seeking accurate diagnostic criteria for ME/CFS.
• Advocates and Patients: Individuals advocating for recognition of ME/CFS as a distinct neurological illness.
• Policymakers: Decision-makers supporting research and healthcare initiatives for ME/CFS.

Overall Outcome: This document calls for a return to descriptive definitions based on clinical observations, emphasizing the need for clarity and precision in diagnosing and managing ME/CFS.