ME and CFS are complex conditions that vary in degrees of disablement through a spectrum. Whether a patient is mildly, moderately or severely affected, these illnesses create intense suffering. ME and CFS are classified as neurological illnesses in the World Health Organisation’s ICD-10. (Parkinson’s Disease and Multiple Sclerosis are other examples of neurological illnesses).

The 2011 Myalgic Encephalomyelitis: International Consensus Criteria state that ME is a complex disease involving profound central nervous system dysregulation, immune system dysfunction, cardiovascular and respiratory abnormalities, neuro-cognitive impairment, sleep disturbance, pain, motor disturbances, gastro-intestinal and genitor-urinary impairments. The cardinal sign is a pathological exhaustion after minimal physical or cognitive activity (referred to as PENE – post-exertional neuro-immune exhaustion).

The Australian 2002 Chronic Fatigue Syndrome Clinical Practice Guidelines state that CFS is characterised by clinically evaluated, unexplained, persistent fatigue for six months or more; along with at least four symptoms of: impaired short term memory or concentration, sore throat, tender lymph nodes, muscle and joint pain, headaches, unrefreshing sleep, and post-exertional malaise lasting more than 24 hours.

The illnesses Myalgic Encephalomyelitis and Chronic Fatigue Syndrome are not to be confused with the simple symptom ‘chronic fatigue’ – which is a symptom that many people experience in association with a large variety of health issues.