See Appendix for CINCH group participants.
A quantitative measure of handgrip myotonia in non-dystrophic myotonia†
Article first published online: 13 SEP 2012
Copyright © 2012 Wiley Periodicals, Inc.
Muscle & Nerve
Volume 46, Issue 4, pages 482–489, October 2012
How to Cite
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. and and the CINCH Consortium (2012), A quantitative measure of handgrip myotonia in non-dystrophic myotonia. Muscle Nerve, 46: 482–489. doi: 10.1002/mus.23402
Disclosure: The contents of this study are solely the responsibility of the authors and do not necessarily represent the official views of the National Center for Research Resources, Office of Rare Diseases Research, or National Institutes of Health.
- Issue published online: 13 SEP 2012
- Article first published online: 13 SEP 2012
- Accepted manuscript online: 5 APR 2012 04:51AM EST
- Manuscript Accepted: 30 MAR 2012
- National Center for Research Resources
- National Institutes of Health. Grant Number: U54 NS059065-05S1
- University of Kansas Medical Center. Grant Number: CTSA Grant UL1 RR 033179 NCRR/NIH
- University of Rochester. Grant Number: CTSA Grant UL1 RR 024160 NCRR/NIH
- University of Texas Southwestern. Grant Number: CTSA Grant UL1 RR 024982 NCRR/NIH
- Brian Bundy's contribution. Grant Number: NCRR (RR019259)
- ion channel mutation;
- muscle disease;
- natural history;
- non-dystrophic myotonia
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. Muscle Nerve 46: 482–489, 2012