Abnormality of motor cortex excitability in peripherally induced dystonia

Authors

  • Stephan Bohlhalter MD,

    1. Human Motor Control Section, National Institute of Neurological Disorders and Stroke NINDS, NIH, Bethesda, Maryland, USA
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  • Fidias E. Leon-Sarmiento MD, PhD,

    1. Human Motor Control Section, National Institute of Neurological Disorders and Stroke NINDS, NIH, Bethesda, Maryland, USA
    2. Mediciencia Research Group, Universidad Nacional/Clinical Neurology Section, Fundacion Santa Fe, Bogota, Columbia
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  • Mark Hallett MD

    Corresponding author
    1. Human Motor Control Section, National Institute of Neurological Disorders and Stroke NINDS, NIH, Bethesda, Maryland, USA
    • Human Motor Control Section, National Institute of Neurological Disorders and Stroke NINDS, NIH, Bldg. 10, Room 5N226, 10 Center Drive, MSC-1428, Bethesda, MD 20892-1428
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Abstract

It is widely accepted that peripheral trauma such as soft tissue injuries can trigger dystonia, although little is known about the underlying mechanism. Because peripheral injury only rarely appears to elicit dystonia, a predisposing vulnerability in cortical motor areas might play a role. Using single and paired-pulse pulse transcranial magnetic stimulation, we evaluated motor cortex excitability of a hand muscle in a patient with peripherally induced foot dystonia, in her brother with craniocervical dystonia, and in her unaffected sister, and compared their results to those from a group of normal subjects. In the patient with peripherally induced dystonia, we found a paradoxical intracortical facilitation at short interstimulus intervals of 3 and 5 milliseconds, at which regular intracortical inhibition (ICI) occurred in healthy subjects. These findings suggest that the foot dystonia may have been precipitated as the result of a preexisting abnormality of motor cortex excitability. Furthermore, the abnormality of ICI in her brother and sister indicates that altered motor excitability may be a hereditary predisposition. The study demonstrates that the paired-pulse technique is a useful tool to assess individual vulnerability, which can be particularly relevant when the causal association between trauma and dystonia is less evident. © 2007 Movement Disorder Society

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