The "Chronic Fatigue Syndrome" is a multifactorial collection of illnesses which are very hard to distinguish from each other, but with fatigue, myalgia, cognitive impairments, and often digestive disturbances in common. The diagnosis is by exclusion of other conditions. This leaves the management. There is , as yet, no single cure. But a staged approach frequently leads to major improvement, if not cure.

http://orthomolecular.org/library/jom/1995/articles/1995-v10n02-p070.shtml