SUMMARY
Chronic fatigue syndrome (CFS), popularly known in Europe as myalgic encephalomyelitis (ME), is a common but not a new illness. CFS/ME was classified as a neurological disease by the World Health Organisation in 1993. Neurological dysfunction is considered the principal mechanism of both physical and mental fatigue in this condition. This article reviews the neurological symptoms of the epidemic and sporadic forms of the illness. Paroxysmal changes in the severity of symptoms (fatigue and neuropsychiatric) are the hallmark features in the natural history of this disease. Ion channel abnormality leading to neuronal instability in selective anatomical pathways (basal ganglia circuitry) is proposed as the possible mechanism of fluctuating fatigue and related symptoms in CFS.