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Thalamic neuronal and EMG activity in psychogenic dystonia compared with organic dystonia

Authors

  • Kazutaka Kobayashi MD PhD,

    1. Department of Neurosurgery, Johns Hopkins Hospital, Baltimore, Maryland, USA
    2. Department of Neurological Surgery, Nihon University School of Medicine, Tokyo, Japan
    3. Division of Applied Systems Neuroscience, Department of Advanced Medical Science, Nihon University School of Medicine, Tokyo, Japan
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  • Anthony E. Lang MD, FRCPC,

    1. Division of Neurology, University Health Network and University of Toronto, Toronto, Ontario, Canada
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  • Mark Hallett MD,

    1. Human Motor Control Section, NINDS, NIH, Bethesda, Maryland, USA
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  • Frederick A. Lenz MD, PhD, FRCSC

    Corresponding author
    1. Department of Neurosurgery, Johns Hopkins Hospital, Baltimore, Maryland, USA
    • Department of Neurosurgery, Johns Hopkins Hospital, Meyer Building 8-181, 600 North Wolfe Street, Baltimore, MD 21287-7713, USA

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  • Relevant conflict of interest/financial disclosures: Nothing to report. This work was supported by the National Institutes of Health—National Institute of Neurological Disorders and Stroke Intramural and Extramural Programs (RO1 NS38493 and ROL NS40059 to F.A.L.).

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

Abstract

Background:

This is a retrospective analysis of thalamic neuronal and electromyogram activities between subjects with organic dystonia and a subject with psychogenic dystonia in whom a thalamotomy was carried out before the diagnosis of psychogenic dystonia was made.

Results:

The signal-to-noise ratio in the lowest frequency band (dystonia frequency < 0.76 Hz) in the electromyogram was not significantly different by diagnosis or muscle. The coherence at dystonia frequency for wrist flexors X biceps electromyograms was significantly higher in organic dystonia, whereas the phase was not apparently different from zero for either diagnosis. In a thalamic pallidal relay nucleus (ventral oral posterior), neuronal firing rates were not apparently different between psychogenic and organic dystonia. The neuronal signal-to-noise ratio in ventral oral posterior was significantly higher in organic dystonia than in psychogenic dystonia, whereas both were greater than in controls with chronic pain. Spike X electromyogram coherence apparently was not different between psychogenic and organic dystonia. The proportion of thalamic cells responding to joint movements was higher in the cerebellar relay nucleus (ventral intermediate) of psychogenic dystonia than in organic dystonia.

Conclusions:

These results suggest that some features, such as firing rates and thalamic reorganization, are similar in psychogenic and organic dystonia. Other features differ, such as the coherence between the electromyograms from different muscles and the thalamic neuronal signal-to-noise ratio, which may reflect pathophysiological factors in organic dystonia. © 2011 Movement Disorder Society

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