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Reduced parietal connectivity with a premotor writing area in writer's cramp

Authors

  • Cathérine C.S. Delnooz MD,

    1. Radboud University Nijmegen Medical Centre, Department of Neurology, Donders Institute for Brian, Cognition and Behaviour, Centre for Neuroscience, Nijmegen, The Netherlands
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  • Rick C. Helmich MD, PhD,

    1. Radboud University Nijmegen Medical Centre, Department of Neurology, Donders Institute for Brian, Cognition and Behaviour, Centre for Neuroscience, Nijmegen, The Netherlands
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  • Ivan Toni PhD,

    1. Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, Centre for Cognitive Neuroimaging, Nijmegen, The Netherlands
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  • Bart P.C. van de Warrenburg MD, PhD

    Corresponding author
    1. Radboud University Nijmegen Medical Centre, Department of Neurology, Donders Institute for Brian, Cognition and Behaviour, Centre for Neuroscience, Nijmegen, The Netherlands
    • Department of Neurology, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands
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  • Relevant conflicts of interest/financial disclosures: Nothing to report.

  • Full financial disclosures and author roles may be found in the online version of this article.

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. © 2012 Movement Disorder Society

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