Fibromyalgia syndrome (FMS) is a chronic
musculoskeletal disorder and is currently defined as
the presence of both chronic widespread pain (CWP)
and tenderness at multiple anatomical sites.
Additional characteristics of the disorder include,
among others, fatigue, insomnia or nonrefreshing
sleep, diffuse stiffness, and other organic and
psychological features. Confirmation of clinical
diagnosis emphasizes on the presence of tenderness
in 11 out of 18 anatomical points. About 20% of
individuals with CWP suffer from FMS and they are
likely to have higher levels of psychological distress1.