Myalgic Encephalomyelitis (ME)

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Myalgic means muscle pain or tenderness. Encephalomyelitis means inflammation of the brain and spinal cord.

Pronunciation: Myalgic: my-AL-jik
Encephalomyelitis: en-SEF-uh-lo-MY-uh-LY-tis

Myalgic encephalomyelitis and the abbreviation ME are alternate names for chronic fatigue syndrome (CFS). It's common to see the abbreviations combined, as ME/CFS or CFS/ME.

Several countries currently call the condition myalgic encephalomyelitis and it appears to be gaining traction in the U.S.

Some experts use the terms interchangeably, while others consider them separate conditions.

Patients, advocates, and some researchers in the U.S. have pushed for ME/CFS due to the widespread belief that the name "chronic fatigue syndrome" trivializes the condition and leads to misconceptions about it. They hope to eventually drop the "CFS" portion altogether and just use ME.

However, a major report from the Institute of Medicine has called for the name of this condition to be systemic exertion intolerance disease, or SEID. It remains to be seen whether than name will find acceptance.

Critics of the name ME and its variations say that we don't have adequate evidence of inflammation in the brain and spinal cord to re-name the disease for it. However, a small 2014 study did appear to provide some evidence that encephalomyelitis is a feature of the condition. We'll need more research to be certain.


Nakatomi Y, et al. Journal of nuclear medicine. 2014 Jun;55(6):945-50. Neuroinflammation in patients with chronic fatigue syndrome/myalgic encephalmylitis: An 11C-(R)-PK11195 PET study.

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