Next Article in Journal
Hypertension Assessment via ECG and PPG Signals: An Evaluation Using MIMIC Database
Previous Article in Journal
Circulating Tumor Cells for the Management of Renal Cell Carcinoma
Article Menu
Issue 3 (September) cover image

Export Article

Open AccessHypothesis
Diagnostics 2018, 8(3), 64;

Myalgic Encephalomyelitis (ME) or What? An Operational Definition

ME-de-Patiënten Foundation, Zonnedauw 15, 1906 HB Limmen, The Netherlands
Received: 3 August 2018 / Revised: 4 September 2018 / Accepted: 6 September 2018 / Published: 8 September 2018
Full-Text   |   PDF [880 KB, uploaded 10 September 2018]   |  


Myalgic encephalomyelitis (ME), identified as a new clinical entity with distinctive features in 1956, was originally considered as a neuromuscular disease. In 1988 the Centers for Disease Control and Prevention introduced the ill-defined concept of chronic fatigue syndrome (CFS). As predicted, CFS, unjustly considered to be a synonym for ME, pushed ME to the background. To develop effective therapies for of ME and CFS, it is essential to investigate patients with ME specifically. For that reason, an operational definition of ME is indispensable. This article proposes an operational definition based on the most recent formal definitions and symptoms observed in ME. ME is a multi-systemic illness, which (1) often has a sudden onset, in most cases a respiratory and/or gastro-intestinal infection, but a gradual or more dramatic onset is also possible; (2) has an epidemic and an endemic form; (3) has an unique clinical pattern deviating from other post-viral states; (4) is distinguished by muscle fatigability/prolonged muscle weakness after trivial exertion; (5) is accompanied by symptoms relating to neurological disturbance, especially of cognitive, autonomic, and sensory functions; (6) can be accompanied by symptoms associated with cardiac and other systems; (7) is characterized by fluctuation of symptoms (within and between “episodes”); (8) has a prolonged relapsing course; and (9) has a tendency to become chronic. In conclusion, a discriminative definition for ME contains four mandatory elements: (1) muscle fatigability/post-exertional muscle weakness lasting for days; (2) operational criteria for “neurological disturbance, especially of cognitive, autonomic and sensory functions”; (3) fluctuation of symptoms; and (4) a prolonged relapsing course. This tentative definition of ME justifies the qualification “neuromuscular disease”.
View Full-Text
Keywords: myalgic encephalomyelitis; chronic fatigue syndrome; diagnosis; neuromuscular; neurological disorders myalgic encephalomyelitis; chronic fatigue syndrome; diagnosis; neuromuscular; neurological disorders

Graphical abstract

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

Share & Cite This Article

MDPI and ACS Style

Twisk, F. Myalgic Encephalomyelitis (ME) or What? An Operational Definition. Diagnostics 2018, 8, 64.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Diagnostics EISSN 2075-4418 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top