Abnormality of motor cortex excitability in peripherally induced dystonia

Mov Disord. 2007 Jun 15;22(8):1186-9. doi: 10.1002/mds.21424.


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.

Publication types

  • Case Reports
  • Research Support, N.I.H., Intramural

MeSH terms

  • Arousal / physiology*
  • Dystonia / diagnosis
  • Dystonia / physiopathology*
  • Dystonia / therapy
  • Evoked Potentials, Motor / physiology
  • Female
  • Hand / innervation
  • Hand / physiopathology
  • Humans
  • Male
  • Middle Aged
  • Motor Cortex / physiopathology*
  • Muscle, Skeletal / innervation
  • Muscle, Skeletal / physiopathology
  • Transcranial Magnetic Stimulation