RESEARCH ARTICLE Comparison of the Levels of Pro- Inflammatory Cytokines Released in the Vastus Lateralis Muscle of Patients with Fibromyalgia and Healthy Controls during Contractions of the Quadriceps Muscle – A Microdialysis Study

Objective Fibromyalgia is associated with central hyperexcitability, but it is suggested that peripheral input is important to maintain central hyperexcitability. The primary aim was to investigate the levels of pro-inflammatory cytokines released in the vastus lateralis muscle during repet-itive dynamic contractions of the quadriceps muscle in patients with fibromyalgia and healthy controls. Secondarily, to investigate if the levels of pro-inflammatory cytokines were correlated with pain or fatigue during these repetitive dynamic contractions. Material and Methods 32 women with fibromyalgia and 32 healthy women (controls) participated in a 4 hour micro-dialysis session, to sample IL-1β, IL-6, IL-8, and TNF from the most painful point of the vas-tus lateralis muscle before, during and after 20 minutes of repeated dynamic contractions. Pain (visual analogue scale; 0–100) and fatigue Borg’s Rating of Perceived Exertion Scale