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J Child Neurol. 2015 Sep;30(10):1300-6. doi: 10.1177/0883073814559646. Epub 2015 Jan 30.

Use of Clinical and Electrical Myotonia to Differentiate Childhood Myopathies.

Author information

1
Department of Neurology, Mayo Clinic, Rochester, MN, USA Department of Neurology, Boston Children's Hospital, Boston, MA, USA.
2
Department of Neurology, Mayo Clinic, Rochester, MN, USA sorenson.eric@mayo.edu.

Abstract

We retrospectively reviewed 2030 childhood electromyograms performed over an 11-year period (2004-2014). Twenty children (1%) with myotonic discharges were identified and placed into 2 groups. Group A (electrical and clinical myotonia) comprised 9 children (8 with myotonia congenita and 1 with paramyotonia congenita); all of them had diffuse myotonic discharges without clinical weakness or elevated creatine kinase. Group B (electrical myotonia without clinical myotonia) comprised 11 children (4 with inflammatory myopathy; 3, congenital myopathy, 3, muscular dystrophy; and 1, congenital muscular dystrophy). Clinical weakness was demonstrated in all of them and elevated creatine kinase in 6; all had a myopathic electromyogram and scattered myotonic discharges. We conclude that myotonic discharges are a rare but characteristic spontaneous discharge identified during electrodiagnostic studies in children. The presence of electrical and clinical myotonia provides helpful clues to differentiate between various muscle disorders in children.

KEYWORDS:

children; electromyography; muscle disorders; myotonia; myotonic discharges

PMID:
25637645
DOI:
10.1177/0883073814559646
[Indexed for MEDLINE]

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