Under the most widely used case definition, a diagnosis of chronic fatigue syndrome requires six months of unexplained fatigue as well as four of eight other persistent symptoms: impaired memory and concentration, sore throat, tender lymph nodes, muscle pain, joint pain, headaches, disturbed sleeping patterns and post-exercise malaise.
It is combined with four or more of the eight specified accompanying symptoms: headache, muscle pain, joint pain, sore throat, tender lymph nodes, impaired memory or concentration, unrefreshing sleep, and malaise after exertion [ 1].
Chronic fatigue syndrome or myalgic encephalomyelitis (CFS/ME) is most commonly characterized by fatigue lasting more than 6 months accompanied by symptoms such as muscle and joint pain, sore throat, tender lymph nodes, and cognitive difficulties.
Five of the eight CFS-defining symptoms reflect pain (headaches of a new type, pattern, or severity, muscle pain, and multi-joint pain without swelling or redness, sore throat, tender cervical/axillary lymph nodes).
Data included age, sex, disease duration, number of fulfilled Yamaguchi disease criteria, immunological profile, systemic symptoms (fever, rash, lymphadenopathy, hepatosplenomegaly, serositis, sore throat), tender joint count, swollen joint count, haematological profile, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), liver enzymes, and serum ferritin levels during follow up.
CDC criteria also require that patients present with at least four of eight named symptoms (subjective memory impairment, sore throat, tender lymph nodes, muscle pain, joint pain, headaches, unrefreshing sleep and postexertional malaise), whereas NICE criteria include these symptoms (plus flu-like symptoms, dizziness, nausea and palpitations) for guidance only.
CFS was defined according to CDC Centers for Disease Control and Preventionn) criteria [ 1], and included a case-defining fatigue associated with at least four of the following ancillary symptoms: impaired short-term memory or concentration, sore throat, tender lymphadenopathy, muscle pain, joint pain, headaches of a new type, sleep disturbance and post-exercise malaise [ 1].
In brief, criteria for CFS-like illness included chronic fatigue that was not alleviated by rest, and was accompanied by at least 4 of 8 symptoms (unusual post-exertion fatigue, impaired memory/concentration, unrefreshing sleep, headache, muscle pain, joint pain, sore throat, tender lymph nodes).
