title: Evidence of dysfunctional pain inhibition in Fibromyalgia reflected in rACC during provoked pain.
abstract: Over the years, many have viewed Fibromyalgia syndrome (FMS) as a so-called "functional disorder" and patients have experienced a concomitant lack of interest and legitimacy from the medical profession. The symptoms have not been explained by peripheral mechanisms alone nor by specific central nervous system mechanisms. In this study, we objectively evaluated the cerebral response to individually calibrated pain provocations of a pain-free body region (thumbnail). The study comprised 16 female FMS patients and 16 individually age-matched controls. Brain activity was measured using functional magnetic resonance imaging (fMRI) during individually calibrated painful pressures representing 50 mm on a visual analogue scale (VAS) ranging from 0 to 100 mm. Patients exhibited higher sensitivity to pain provocation than controls as they required less pressure to evoke equal pain magnitudes (U(A)=48, p<.002). Despite lower pressures applied in patients at VAS 50 mm, the fMRI-analysis revealed no difference in activity in brain regions relating to attention and affect or regions with sensory projections from the stimulated body area. However, in the primary link in the descending pain regulating system (the rostral anterior cingulate cortex) the patients failed to respond to pain provocation. The attenuated response to pain in this brain region is the first demonstration of a specific brain region where the impairment of pain inhibition in FMS patients is expressed. These results validate previous reports of dysfunctional endogenous pain inhibition in FMS and advance the understanding of the central pathophysiologic mechanisms, providing a new direction for the development of successful treatments in FMS.
authors.affiliation: Stockholm Brain Institute, Osher Center for Integrative Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Karin B
authors.initials: KB
authors.lastname: Jensen
authors.forename: Eva
authors.initials: E
authors.lastname: Kosek
authors.forename: Frank
authors.initials: F
authors.lastname: Petzke
authors.forename: Serena
authors.initials: S
authors.lastname: Carville
authors.forename: Peter
authors.initials: P
authors.lastname: Fransson
authors.forename: Hanke
authors.initials: H
authors.lastname: Marcus
authors.forename: Steven C R
authors.initials: SC
authors.lastname: Williams
authors.forename: Ernest
authors.initials: E
authors.lastname: Choy
authors.forename: Thorsten
authors.initials: T
authors.lastname: Giesecke
authors.forename: Yves
authors.initials: Y
authors.lastname: Mainguy
authors.forename: Richard
authors.initials: R
authors.lastname: Gracely
authors.forename: Martin
authors.initials: M
authors.lastname: Ingvar
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001931:Brain Mapping; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D005356:Fibromyalgia / Q000503:physiopathology*; D006179:Gyrus Cinguli / Q000098:blood supply / Q000503:physiopathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010146:Pain / Q000209:etiology* / Q000473:pathology*; D010147:Pain Measurement; D010812:Physical Stimulation / Q000009:adverse effects*; D055815:Young Adult
chemical_list: D010100:Oxygen