Fibromyalgia comorbidity in primary headaches.

Fibromyalgia syndrome (FMS) is a chronic pain condition of unknown aetiology characterized by diffuse pain and tenderness at tender points. The aim of the study was to assess the prevalence and clinical features of FMS in the different forms of primary headaches, in a tertiary headache centre. Primary headache patients (n = 217) were selected and submitted to the Total Tenderness Score, anxiety and depression scales, Migraine Disability Assessment, allodynia questionnaire, Short Form 36 Health Survey and the Medical Outcomes Study-Sleep Scale. In patients with FMS, the Multidimensional Assessment of Fatigue, the Pain Visual Analog Scale, the Manual Tender Point Survey and the Fibromyalgia Impact Questionnaire were employed. FMS was present in 36.4% of patients and prevailed significantly in tension-type headache and in patients with higher headache frequency. Headache frequency, pericranial muscle tenderness, anxiety and sleep inadequacy were especially associated with FMS comorbidity. In the FMS patients, fatigue and pain at tender points were significantly correlated with headache frequency. FMS seems increasingly prevalent with increased headache frequency, for the facilitation of central sensitization phenomena favoured by anxiety and sleep disturbances.