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EMG–EMG coherence in writer's cramp

Authors

  • Carla Cordivari MD,

    1. Department of Clinical Neurophysiology, The National Hospital for Neurology and Neurosurgery, London, United Kingdom
    2. Reta Lila Weston Institute of Neurological Studies, Windeyer Building, University College of London, United Kingdom
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  • Andrew J. Lees MD, FRCP,

    1. Reta Lila Weston Institute of Neurological Studies, Windeyer Building, University College of London, United Kingdom
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  • V. Peter Misra MD,

    1. Department of Clinical Neurophysiology, The National Hospital for Neurology and Neurosurgery, London, United Kingdom
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  • Peter Brown MD

    Corresponding author
    1. Sobell Department of Neurophysiology, Institute of Neurology, London, United Kingdom
    • Sobell Department of Neurophysiology, Institute of Neurology, Queen Square, London WC1N 3BG, United Kingdom
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Abstract

We investigated the extent to which oscillatory drives to muscle, believed to arise mainly from the motor cortex, are exaggerated and/or fail to react normally to peripheral stimulation in writer's cramp. We used the coherence between active forearm flexor and intrinsic hand muscles as our index of such drives before and after digital nerve stimulation of the dominant hand. The results in 8 patients with writer's cramp were compared with those in eight age- and sex-matched healthy subjects. We found no significant difference in either the strength of intermuscular coherence or its modulation by cutaneous stimulation between patients and healthy subjects during voluntary flexion of the wrist and extension–abduction of the fingers. Therefore, we were unable to provide evidence for a pervasive disturbance of oscillatory cortical motor outflow in writer's cramp. © 2002 Movement Disorder Society

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