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Cerebellar stimulation fails to modulate motor cortex plasticity in writing dystonia

Authors

  • Anna Sadnicka MD,

    1. Shared first authorship, London, United Kingdom
    2. Sobell Department of Motor Neuroscience and Movement Disorders, University College London, London, United Kingdom
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  • Masashi Hamada MD, PhD,

    1. Shared first authorship, London, United Kingdom
    2. Sobell Department of Motor Neuroscience and Movement Disorders, University College London, London, United Kingdom
    3. Department of Neurology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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  • Kailash P. Bhatia MD, FRCP,

    1. Sobell Department of Motor Neuroscience and Movement Disorders, University College London, London, United Kingdom
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  • John C. Rothwell PhD,

    1. Sobell Department of Motor Neuroscience and Movement Disorders, University College London, London, United Kingdom
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  • Mark J. Edwards MD, PhD

    Corresponding author
    1. Sobell Department of Motor Neuroscience and Movement Disorders, University College London, London, United Kingdom
    • Correspondence to: Dr Mark Edwards, Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, Box 146, National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, United Kingdom, E-mail: m.j.edwards@ucl.ac.uk

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  • Funding agencies: This study was supported by grants from the Guarantors of Brain Clinical Fellowship Scheme (AS) and the Japan Society for the Promotion of Science Postdoctoral Fellowships for Research Abroad (MH).

  • 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

Background

Primary dystonia is characterized neurophysiologically by reduced inhibitory mechanisms and abnormal regulation of plasticity responses. The potential of anodal cerebellar transcranial direct current stimulation as a therapeutic tool in writing dystonia was examined, after the observation that cerebellar stimulation reduces responses to an associative plasticity protocol in healthy subjects.

Methods

Ten patients with writing dystonia completed a two-part study (sham and anodal) in which cerebellar stimulation was given simultaneously with paired associative stimulation. Electrophysiological and clinical parameters were measured before and after stimulation.

Results

Clinical symptoms were unchanged by cerebellar stimulation. Patients exhibited much variability in the size and direction of their plasticity responses. Excessive or topographically abnormal plasticity responses were not observed. In the subgroup of patients with facilitatory responses to paired associative stimulation in the sham condition, anodal cerebellar stimulation retained its ability to reduce the magnitude of plasticity response.

Conclusions

Our limited understanding of intersubject variability of plasticity responses in writing dystonia currently undermines cerebellar stimulation as a novel treatment in this subset of dystonia. Cerebellar stimulation may be beneficial in other neurological disorders with consistently exaggerated plasticity. © 2014 International Parkinson and Movement Disorder Society

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