title: Complex regional pain syndrome type I affects brain structure in prefrontal and motor cortex.
abstract: The complex regional pain syndrome (CRPS) is a rare but debilitating pain disorder that mostly occurs after injuries to the upper limb. A number of studies indicated altered brain function in CRPS, whereas possible influences on brain structure remain poorly investigated. We acquired structural magnetic resonance imaging data from CRPS type I patients and applied voxel-by-voxel statistics to compare white and gray matter brain segments of CRPS patients with matched controls. Patients and controls were statistically compared in two different ways: First, we applied a 2-sample ttest to compare whole brain white and gray matter structure between patients and controls. Second, we aimed to assess structural alterations specifically of the primary somatosensory (S1) and motor cortex (M1) contralateral to the CRPS affected side. To this end, MRI scans of patients with left-sided CRPS (and matched controls) were horizontally flipped before preprocessing and region-of-interest-based group comparison. The unpaired ttest of the "non-flipped" data revealed that CRPS patients presented increased gray matter density in the dorsomedial prefrontal cortex. The same test applied to the "flipped" data showed further increases in gray matter density, not in the S1, but in the M1 contralateral to the CRPS-affected limb which were inversely related to decreased white matter density of the internal capsule within the ipsilateral brain hemisphere. The gray-white matter interaction between motor cortex and internal capsule suggests compensatory mechanisms within the central motor system possibly due to motor dysfunction. Altered gray matter structure in dorsomedial prefrontal cortex may occur in response to emotional processes such as pain-related suffering or elevated analgesic top-down control.
authors.affiliation: Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany ; Clinic for Cognitive Neurology, University Hospital Leipzig, Leipzig, Germany.
authors.forename: Burkhard
authors.initials: B
authors.lastname: Pleger
authors.affiliation: Laboratoire de Recherche en Neuroimagerie - LREN, Departement des neurosciences cliniques, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland.
authors.forename: Bogdan
authors.initials: B
authors.lastname: Draganski
authors.affiliation: Department of Neurology, University Hospital Bergmannsheil, Bochum, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Schwenkreis
authors.affiliation: Department of Neurology, University Hospital Bergmannsheil, Bochum, Germany.
authors.forename: Melanie
authors.initials: M
authors.lastname: Lenz
authors.affiliation: Department of Radiology, University Hospital Bergmannsheil, Bochum, Germany.
authors.forename: Volkmar
authors.initials: V
authors.lastname: Nicolas
authors.affiliation: Department of Pain Treatment, University Hospital Bergmannsheil, Bochum, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Maier
authors.affiliation: Department of Neurology, University Hospital Bergmannsheil, Bochum, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Tegenthoff
mesh_terms: D000328:Adult; D001931:Brain Mapping; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000473:pathology* / Q000503:physiopathology; D017397:Prefrontal Cortex / Q000473:pathology* / Q000503:physiopathology; D012019:Reflex Sympathetic Dystrophy / Q000473:pathology* / Q000503:physiopathology