title: Reduced parietal connectivity with a premotor writing area in writer's cramp.
abstract: Writer's cramp is a task-specific form of dystonia with symptoms characterized by abnormal movements and postures of the hand and arm evident only during writing. Its pathophysiology has been related to faulty sensorimotor integration, abnormal sensory processing, and impaired motor planning. Its symptoms might appear when the computational load of writing pushes a tonically altered circuit outside its operational range. Using resting-state fMRI, we tested whether writer's cramp patients have altered intrinsic functional connectivity in the premotor-parietal circuit. Sixteen patients with right-sided writer's cramp and 19 control subjects were studied. We show that writer's cramp patients have reduced connectivity between the superior parietal lobule and a dorsal precentral region that controls writing movements. This difference between patients and controls occurred in the absence of writing and only in the hemisphere contralateral to the affected hand. This finding adds a novel element to the pathophysiological substrate for writer's cramp, namely, task-independent alterations within a writing-related circuit.
authors.affiliation: Radboud University Nijmegen Medical Centre, Department of Neurology, Donders Institute for Brian, Cognition and Behaviour, Centre for Neuroscience, Nijmegen, The Netherlands.
authors.forename: Cathérine C S
authors.initials: CC
authors.lastname: Delnooz
authors.forename: Rick C
authors.initials: RC
authors.lastname: Helmich
authors.forename: Ivan
authors.initials: I
authors.lastname: Toni
authors.forename: Bart P C
authors.initials: BP
authors.lastname: van de Warrenburg
mesh_terms: D000328:Adult; D000368:Aged; D001931:Brain Mapping; D004421:Dystonia / Q000503:physiopathology; D020821:Dystonic Disorders / Q000473:pathology* / Q000503:physiopathology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000098:blood supply / Q000473:pathology*; D009434:Neural Pathways / Q000098:blood supply / Q000473:pathology*; D010100:Oxygen / Q000097:blood; D010296:Parietal Lobe / Q000098:blood supply / Q000473:pathology*
chemical_list: D010100:Oxygen