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Abstract
Objective: To determine open-label, pilot study whether ranolazine could improve signs and symptoms of myotonia and muscle stiffness in patients with myotonia congenita (MC).
Methods: Thirteen participants were assessed at baseline and 2, 4, and 5 weeks. Ranolazine was started after baseline assessment (500 mg twice daily), increased as tolerated after week 2 (1,000 mg twice daily), and maintained until week 4. Outcomes included change from baseline to week 4 in self-reported severity of symptoms (stiffness, weakness, and pain), Timed Up and Go (TUG), hand grip and eyelid myotonia, and myotonia on EMG.
Results: Self-reported severity of stiffness (p < 0.0001) and weakness (p < 0.01) was significantly improved compared with baseline. TUG and grip myotonia times were reduced (p = 0.03, p = 0.01). EMG of the abductor digiti minimi and tibialis anterior showed significantly reduced myotonia duration (p < 0.001, p < 0.01) at week 4. No participant discontinued ranolazine because of side effects.
Conclusions: Ranolazine appeared to be well tolerated over a period of 4 weeks in individuals with MC, and ranolazine resulted in improvement of signs and symptoms of muscle stiffness. The findings of this study suggest that ranolazine should be investigated in a larger controlled study.
Classification of evidence: This study provides Class IV evidence that ranolazine improves myotonia in myotonia congenita.
GLOSSARY
- ADM=
- abductor digiti minimi;
- MC=
- myotonia congenita;
- NDM=
- nondystrophic myotonic disorder;
- TA=
- tibialis anterior;
- TUG=
- Timed Up and Go
Footnotes
Go to Neurology.org for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
Supplemental data at Neurology.org
- Received December 17, 2016.
- Accepted in final form May 18, 2017.
- © 2017 American Academy of Neurology
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