Research Article

Electrophysiological features of myoclonus-dystonia†

  1. Jie-Yuan Li MD1,2,3,
  2. Danny I. Cunic PhD1,
  3. Guillermo Paradiso MD1,
  4. Carolyn Gunraj MHSc1,
  5. Pramod K. Pal MD1,
  6. Anthony E. Lang MD, FRCPC1,
  7. Robert Chen MBBChir, MSc, FRCPC1,*

Article first published online: 29 AUG 2008

DOI: 10.1002/mds.22273

Issue

Movement Disorders

Movement Disorders

Volume 23, Issue 14, pages 2055–2061, 30 October 2008

Additional Information

How to Cite

Li, J.-Y., Cunic, D. I., Paradiso, G., Gunraj, C., Pal, P. K., Lang, A. E. and Chen, R. (2008), Electrophysiological features of myoclonus-dystonia. Mov. Disord., 23: 2055–2061. doi: 10.1002/mds.22273

Author Information

  1. 1

    Division of Neurology, Department of Medicine and Toronto Western Research Institute, University of Toronto, Toronto, Ontario, Canada

  2. 2

    Division of Neurology, Department of Internal Medicine, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan

  3. 3

    Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan

*Toronto Western Hospital, 7MC411, 399 Bathurst Street, Toronto, Ontario, Canada M5T 2S8

  1. †

    Potential conflict of interest: None reported.

Publication History

  1. Issue published online: 27 OCT 2008
  2. Article first published online: 29 AUG 2008
  3. Manuscript Accepted: 17 JUL 2008
  4. Manuscript Revised: 16 JUN 2008
  5. Manuscript Received: 7 DEC 2007

Funded by

  • Canadian Institutes of Health Research. Grant Number: MOP15128
  • Elizabeth Barford Fellowship in Neurology

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Keywords:

  • myoclonus;
  • dystonia;
  • physiology;
  • transcranial magnetic stimulation;
  • cortical inhibition

Abstract

Inherited myoclonus-dystonia (M-D) is an autosomal dominant disorder characterized by myoclonus and dystonia that often improves with alcohol. To examine the electrophysiologic characteristics of M-D, we studied 6 patients from 4 different families and 9 age-matched healthy subjects. Neurophysiological studies performed include electromyography (EMG)-electroencephalography (EEG) polygraphy, jerk-locked back-averaged EEG, somatosensory evoked potentials (SEP), long-latency reflex (LLR) to median and digital nerve stimulation, and transcranial magnetic stimulation studies with short-interval intracortical inhibition (SICI), intracortical facilitation (ICF), and long-interval intracortical inhibition (LICI). All 6 patients showed myoclonus and dystonia on clinical examination and EMG testing. The EMG burst durations ranged from 30.4 to 750.6 milliseconds (mean, 101.5 milliseconds). Jerk-locked back-averaged EEG failed to reveal any preceding cortical correlates. Median nerve SEP revealed no giant potential. No patients had exaggerated LLR to median or digital nerve stimulation. There was no significant difference in SICI, ICF, and LICI between M-D patients and normal subjects. Myoclonus in inherited M-D is likely of subcortical origin. Normal intracortical inhibition and facilitation suggest that the GABAergic circuits in the motor cortex are largely intact and that the mechanisms of myoclonus and dystonia are different from those for cortical myoclonus and other dystonic disorders. © 2008 Movement Disorder Society

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