Fibromyalgia (FM): Definition, Differential Diagnosis, Clinical Contexts and Therapeutic Approaches. The Recent State of the Medical Art and a Possible Key to Etiological Interpretation. A Narrative Review

Fibromyalgia (FM) is a syndrome currently considered idiopathic and multifactorial rheumatic syndrome that causes increased muscle tension, especially during the use of the same muscles. It is characterized by muscle and fibrous tissue (tendons and ligaments) pain of a chronic type associated with stiffness, asthenia (decline in strength with fatigability), cognitive impairment, insomnia or sleep disturbances, and altered sensitivity to stimuli. The etiology is currently unknown. It is under discussion whether to retain it in the definition of the atypical rheumatic syndrome. The hypotheses are oriented according to a multifactorial logic, immunoreumatological in nature with neurological, psychiatric, muscular and metabolic symptoms, although (being a diagnosis by exclusion) it tends to include known phenomena (such as psychiatric symptoms) in a spectrum of heterogeneous symptoms, thus risking diagnostic error, even to accommodate the patient’s needs and wants. This review provides the reader with a comprehensive overview of the disorder, highlighting some aspects that could redefine its clinical framing, thus facilitating a better diagnostic approach to the health problem, from an etiological perspective.