Myalgic Encephalomyelitis / Chronic Fatigue Syndrome (ME/CFS) and Fibromyalgia Syndrome  (FMS)

ME/CFS and FMS are complex illnesses that can be debilitating.  There is a wide overlap of symptoms in ME/CFS and FMS.  Many believe that they are variants of the same or similar disease process or pathogenesis.  ME/CFS and FMS are distinguished from one another on the basis of symptom balance.  ME/CFS patients have greater post-exertional malaise and/or fatigue, more severe fatigue, cognitive dysfunction, and  immune dysfunction.  FMS patients have greater pain and musculoskeletal dysfunction. 

Although ME/CFS and FMS share a number of symptoms, ME/CFS is commonly triggered by a viral infection, whereas FMS is commonly triggered by a physical trauma, most often involving the spine.   ME/CFS can be distinguished from FMS patients by the confirmed breakdown of one of the body's antiviral defense pathways.  It is interesting that if a patient meets both the criteria for ME/CFS and FMS, her/his test results will be that of  an ME/CFS patient.

While approximately 75% of ME/CFS patients also meet the criteria for FMS, only a relatively small number of FMS patient meet the criteria for ME/CFS.  This is reflected in the much higher prevalence of FMS.  Approximately 422 per 100,000 or 0.42% of adults meet the criteria for ME/CFS,  whereas 3 - 10 % (depending on the study)  of the adult population have FMS.