title: Intrinsic brain connectivity in fibromyalgia is associated with chronic pain intensity.
abstract: OBJECTIVE
  Fibromyalgia (FM) is considered to be the prototypical central chronic pain syndrome and is associated with widespread pain that fluctuates spontaneously. Multiple studies have demonstrated altered brain activity in these patients. The objective of this study was to investigate the degree of connectivity between multiple brain networks in patients with FM, as well as how activity in these networks correlates with the level of spontaneous pain.
  
  
  METHODS
  Resting-state functional magnetic resonance imaging (FMRI) data from 18 patients with FM and 18 age-matched healthy control subjects were analyzed using dual-regression independent components analysis, which is a data-driven approach for the identification of independent brain networks. Intrinsic, or resting-state, connectivity was evaluated in multiple brain networks: the default mode network (DMN), the executive attention network (EAN), and the medial visual network (MVN), with the MVN serving as a negative control. Spontaneous pain levels were also analyzed for covariance with intrinsic connectivity.
  
  
  RESULTS
  Patients with FM had greater connectivity within the DMN and right EAN (corrected P [P(corr)] < 0.05 versus controls), and greater connectivity between the DMN and the insular cortex, which is a brain region known to process evoked pain. Furthermore, greater intensity of spontaneous pain at the time of the FMRI scan correlated with greater intrinsic connectivity between the insula and both the DMN and right EAN (P(corr) < 0.05).
  
  
  CONCLUSIONS
  These findings indicate that resting brain activity within multiple networks is associated with spontaneous clinical pain in patients with FM. These findings may also have broader implications for how subjective experiences such as pain arise from a complex interplay among multiple brain networks.
authors.affiliation: Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, 149 Thirteenth Street #2301, Charlestown, MA 02129, USA. vitaly@nmr.mgh.harvard.edu
authors.forename: Vitaly
authors.initials: V
authors.lastname: Napadow
authors.forename: Lauren
authors.initials: L
authors.lastname: LaCount
authors.forename: Kyungmo
authors.initials: K
authors.lastname: Park
authors.forename: Sawsan
authors.initials: S
authors.lastname: As-Sanie
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Clauw
authors.forename: Richard E
authors.initials: RE
authors.lastname: Harris
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D002908:Chronic Disease; D005260:Female; D005356:Fibromyalgia / Q000503:physiopathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D009415:Nerve Net / Q000503:physiopathology*; D010146:Pain / Q000503:physiopathology*; D010147:Pain Measurement; D012044:Regression Analysis; D012720:Severity of Illness Index