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Involuntary painful muscle contractions in Satoyoshi syndrome: A surface electromyographic study

Authors

  • Gea Drost MD,

    Corresponding author
    1. Department of Clinical Neurophysiology, Institute of Neurology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
    2. Neuromuscular Centre Nijmegen, Institute of Neurology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
    • Radboud University Nijmegen Medical Centre, Institute of Neurology, P.O. Box 9101, 6500 HB, Nijmegen, the Netherlands
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  • Aad Verrips MD, PhD,

    1. Canisius Wilhelmina Hospital, Nijmegen, The Netherlands
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  • Baziel G.M. van Engelen MD, PhD,

    1. Neuromuscular Centre Nijmegen, Institute of Neurology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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  • Dick F. Stegeman PhD,

    1. Department of Clinical Neurophysiology, Institute of Neurology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
    2. Neuromuscular Centre Nijmegen, Institute of Neurology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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  • Machiel J. Zwarts MD, PhD

    1. Department of Clinical Neurophysiology, Institute of Neurology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
    2. Neuromuscular Centre Nijmegen, Institute of Neurology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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Abstract

We report a child with Satoyoshi syndrome manifested by involuntary painful muscle contractions and alopecia. Although an autoimmune origin of Satoyoshi syndrome seems likely, its exact etiology remains as yet unknown, as is the origin of the involuntary contractions. To gain a better understanding of the electrophysiological characteristics of the involuntary contractions, we performed a surface electromyographic (EMG) study. We investigated muscle contractions in the legs using two noninvasive techniques: high-density surface EMG (HD-sEMG) recordings on one muscle, and polymyographic surface EMG (sEMG) recordings on various muscles. During the involuntary contractions, HD-sEMG showed a fourfold increase in amplitude compared to maximal voluntary contractions. These high potentials were widely distributed across the whole muscle and showed a pronounced oscillatory behavior with a frequency around 45 Hz. Polymyographic sEMG revealed that the involuntary contractions often occur simultaneously in various muscles or showed a switch of activity from one muscle to another. These findings point to hyperactivity or a disinhibition at the alpha motor neuron level, originating probably at that level, although a central origin cannot be excluded. © 2006 Movement Disorder Society

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