A quantitative measure of handgrip myotonia in non-dystrophic myotonia

Jeffrey M. Statland, Brian N. Bundy, Yunxia Wang, Jaya R. Trivedi, Dipa Raja Rayan, Laura Herbelin, Merideth Donlan, Rhonda McLin, Katy J. Eichinger, Karen Findlater, Liz Dewar, Shree Pandya, William B. Martens, Shannon L. Venance, Emma Matthews, Anthony A. Amato, Michael G. Hanna, Robert C. Griggs, Richard J. Barohn

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

Introduction: Non-dystrophic myotonia (NDM) is characterized by myotonia without muscle wasting. A standardized quantitative myotonia assessment (QMA) is important for clinical trials. Methods: Myotonia was assessed in 91 individuals enrolled in a natural history study using a commercially available computerized handgrip myometer and automated software. Average peak force and 90% to 5% relaxation times were compared with historical normal controls studied with identical methods. Results: Thirty subjects had chloride channel mutations, 31 had sodium channel mutations, 6 had DM2 mutations, and 24 had no identified mutation. Chloride channel mutations were associated with prolonged first handgrip relaxation times and warm-up on subsequent handgrips. Sodium channel mutations were associated with prolonged first handgrip relaxation times and paradoxical myotonia or warm-up, depending on underlying mutations. DM2 subjects had normal relaxation times but decreased peak force. Sample size estimates are provided for clinical trial planning. Conclusion: QMA is an automated, non-invasive technique for evaluating myotonia in NDM.

Original languageEnglish (US)
Pages (from-to)482-489
Number of pages8
JournalMuscle and Nerve
Volume46
Issue number4
DOIs
StatePublished - Oct 1 2012

Keywords

  • Ion channel mutation
  • Muscle disease
  • Myotonia
  • Natural history
  • Non-dystrophic myotonia

ASJC Scopus subject areas

  • Physiology
  • Clinical Neurology
  • Cellular and Molecular Neuroscience
  • Physiology (medical)

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    Statland, J. M., Bundy, B. N., Wang, Y., Trivedi, J. R., Raja Rayan, D., Herbelin, L., Donlan, M., McLin, R., Eichinger, K. J., Findlater, K., Dewar, L., Pandya, S., Martens, W. B., Venance, S. L., Matthews, E., Amato, A. A., Hanna, M. G., Griggs, R. C., & Barohn, R. J. (2012). A quantitative measure of handgrip myotonia in non-dystrophic myotonia. Muscle and Nerve, 46(4), 482-489. https://doi.org/10.1002/mus.23402