Names of myalgic encephalomyelitis and chronic fatigue syndrome

The name myalgic encephalomyelitis was coined by Dr. Melvin Ramsay following the 1955 Royal Free Hospital outbreak and is a portmanteau of several of the key signs and symptoms of the disease: myalgic (muscle pain), encephalo (brain), myel (spinal cord), itis (inflammation).

Several other names have been used or proposed throughout the history of the disease, including atypical polio, Icelandic disease, benign myalgic encephalomyelitis, epidemic neuromyasthenia, chronic fatigue syndrome, and systemic exertion intolerance disease. This has lead to much confusion as a variety of names have been used at different times to describe discrete outbreaks, a wider and potentially more heterogenous population of sporadic cases, and with a wide variety of case definitions.

A survey by The MEAction Network in 2016 found that the majority of patients prefer the name myalgic encephalomyelitis to other names including chronic fatigue syndrome. Most government agencies and researchers around the world use the term ME/CFS.

Criterion defining ME, CFS, and ME/CFS
Patients that meet the International Consensus Criteria (ICC) defining ME are usually more severely impaired than patients that meet the Canadian Consensus Criteria (CCC) defining ME/CFS, or the minimum symptoms defined in the criteria for patients with Systemic Exertion Intolerance Disease (SEID) which also defines ME/CFS. Researchers believe all patients meeting these criteria, including Fukuda criteria defining CFS, are experiencing brain inflammation.