Effects of treatment of peripheral pain generators in fibromyalgia patients.

Fibromyalgia syndrome (FS) frequently co-occurs with regional pain disorders. This study evaluated how these disorders contribute to FS, by assessing effects of local active vs placebo treatment of muscle/joint pain sources on FS symptoms. Female patients with (1) FS+myofascial pain syndromes from trigger points (n=68), or (2) FS+joint pain (n=56) underwent evaluation of myofascial/joint symptoms [number/intensity of pain episodes, pressure pain thresholds at trigger/joint site, paracetamol consumption] and FS symptoms [pain intensity, pressure pain thresholds at tender points, pressure and electrical pain thresholds in skin, subcutis and muscle in a non-painful site]. Patients of both protocols were randomly assigned to two groups [34 each for (1); 28 each for (2)] to receive active or placebo local TrP or joint treatment [injection/hydroelectrophoresis] on days 1 and 4. Evaluations were repeated on days 4 and 8. After therapy, in active--but not placebo-treated-- groups: number and intensity of myofascial/joint episodes and paracetamol consumption decreased and pressure thresholds at trigger/joint increased (p<0.001); FS pain intensity decreased and all thresholds increased progressively in tender points and the non-painful site (p<0.0001). At day 8, all placebo-treated patients requested active local therapy (days 8 and 11) vs only three patients under active treatment. At a 3-week follow-up, FS pain was still lower than basis in patients not undergoing further therapy and had decreased in those undergoing active therapy from day 8 (p<0.0001). Localized muscle/joint pains impact significantly on FS, probably through increased central sensitization by the peripheral input; their systematic identification and treatment are recommended in fibromyalgia.