title: Altered resting-state functional connectivity in complex regional pain syndrome.
abstract: This study explored the functional connectivity between brain regions implicated in the default mode network, the sensorimotor cortex (S1/M1), and the intraparietal sulcus (IPS/MIP) at rest in patients with complex regional pain syndrome. It also investigated how possible alterations are associated with neuropathic pain. Our group used functional magnetic resonance imaging to investigate functional brain connectivity in 12 complex regional pain syndrome patients in comparison with that in 12 age- and sex-matched healthy controls. Data were analyzed using a seed voxel correlation analysis and an independent component analysis. An analysis of covariance was employed to relate alterations in functional connectivity with clinical symptoms. We found significantly greater reductions in functional default mode network connectivity in patients compared to controls. The functional connectivity maps of S1/M1 and IPS/MIP in patients revealed greater and more diffuse connectivity with other brain regions, mainly with the cingulate cortex, precuneus, thalamus, and prefrontal cortex. In contrast, controls showed greater intraregional connectivity within S1/M1 and IPS/MIP. Furthermore, there was a trend for correlation between alterations in functional connectivity and intensity of neuropathic pain. In our findings, patients with complex regional pain syndrome have substantial spatial alterations in the functional connectivity between brain regions implicated in the resting-state default mode network, S1/M1, and IPS/MIP; these alterations show a trend of correlation with neuropathic pain intensity.
  
  
  CONCLUSIONS
  This article presents spatial alterations in the functional resting-state connectivity of complex regional pain syndrome patients. Our results add further insight into the disease states of CRPS and into the functional architecture of the resting state brains of pain patients in general.
authors.affiliation: Department of Neurology, University Hospital Erlangen, Erlangen, Germany; Department of Physiology and Pathophysiology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Bolwerk
authors.forename: Frank
authors.initials: F
authors.lastname: Seifert
authors.forename: Christian
authors.initials: C
authors.lastname: Maihöfner
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001342:Autonomic Nervous System Diseases / Q000503:physiopathology; D020918:Complex Regional Pain Syndromes / Q000503:physiopathology*; D003627:Data Interpretation, Statistical; D017352:Echo-Planar Imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology; D009415:Nerve Net / Q000503:physiopathology*; D009437:Neuralgia / Q000503:physiopathology; D010147:Pain Measurement; D010296:Parietal Lobe / Q000503:physiopathology*; D013003:Somatosensory Cortex / Q000503:physiopathology; D055815:Young Adult
keywords: Complex regional pain syndrome; default mode network; functional magnetic resonance imaging; resting state; sensorimotor cortex