Original Article

Cold extends electromyography distinction between ion channel mutations causing myotonia

  1. Emmanuel Fournier MD, PhD1,2,3,4,5,*,
  2. Karine Viala MD1,2,
  3. Hélène Gervais MD6,
  4. Damien Sternberg MD, PhD7,
  5. Marianne Arzel-Hézode MD1,2,3,4,
  6. Pascal Laforêt MD3,5,
  7. Bruno Eymard MD3,5,
  8. Nacira Tabti MD, PhD8,
  9. Jean-Claude Willer MD, PhD1,2,
  10. Christophe Vial MD6,
  11. Bertrand Fontaine MD, PhD2,4,8

Article first published online: 19 JUN 2006

DOI: 10.1002/ana.20905

Issue

Annals of Neurology

Annals of Neurology

Volume 60, Issue 3, pages 356–365, September 2006

Additional Information

How to Cite

Fournier, E., Viala, K., Gervais, H., Sternberg, D., Arzel-Hézode, M., Laforêt, P., Eymard, B., Tabti, N., Willer, J.-C., Vial, C. and Fontaine, B. (2006), Cold extends electromyography distinction between ion channel mutations causing myotonia. Ann Neurol., 60: 356–365. doi: 10.1002/ana.20905

Author Information

  1. 1

    Fédération de Neurophysiologie Clinique, Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Université Pierre et Marie Curie, Paris

  2. 2

    Fédération des Maladies du Système Nerveux, Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Université Pierre et Marie Curie, Paris

  3. 3

    Institute of Myology, Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Université Pierre et Marie Curie, Paris

  4. 4

    Centre de référence des canalopathies musculaires, Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Université Pierre et Marie Curie, Paris

  5. 5

    Centre de réference des maladies neuromusculaires, Groupe Hospitalier Pitié-Salpétrière, Assistance Publique-Hôpitaux de Paris

  6. 6

    Service d'Électromyographie, Hôpital Neurologique Pierre Wertheimer, Lyon

  7. 7

    Department of Biochemistry, Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris

  8. 8

    Institut National de la Sante et de la Recherche Médicale UMR546, Paris, France

*Département de Physiologie, Faculté de Médecine Pitié-Salpêtrière, 91 Bd de l'Hôpital, 75651 Paris Cedex 13, France

Publication History

  1. Issue published online: 18 SEP 2006
  2. Article first published online: 19 JUN 2006
  3. Manuscript Accepted: 28 APR 2006
  4. Manuscript Revised: 20 APR 2006
  5. Manuscript Received: 17 JAN 2006

SEARCH

SEARCH BY CITATION

ARTICLE TOOLS

View Full Article with Supporting Information (HTML) Get PDF (477K)

Abstract

Objective

Myotonias are inherited disorders of the skeletal muscle excitability. Nondystrophic forms are caused by mutations in genes coding for the muscle chloride or sodium channel. Myotonia is either relieved or worsened by repeated exercise and can merge into flaccid weakness during exposure to cold, according to causal mutations. We designed an easy electromyography (EMG) protocol combining repeated short exercise and cold as provocative tests to discriminate groups of mutations.

Methods

Surface-recorded compound muscle action potential was used to monitor muscle electrical activity. The protocol was applied on 31 unaffected control subjects and on a large population of 54 patients with chloride or sodium channel mutations known to cause the different forms of myotonia.

Results

In patients, repeated short exercise test at room temperature disclosed three distinct abnormal patterns of compound muscle action potential changes (I-III), which matched the clinical symptoms. Combining repeated exercise with cold exposure clarified the EMG patterns in a way that enabled a clear correlation between the electrophysiological and genetic defects.

Interpretation

We hypothesize that segregation of mutations into the different EMG patterns depended on the underlying pathophysiological mechanisms. Results allow us to suggest EMG guidelines for the molecular diagnosis, which can be used in clinical practice. Ann Neurol 2006

View Full Article with Supporting Information (HTML) Get PDF (477K)