title: Use of Clinical and Electrical Myotonia to Differentiate Childhood Myopathies.
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.
authors: Department of Neurology, Mayo Clinic, Rochester, MN, USA Department of Neurology, Boston Children's Hospital, Boston, MA, USA.
authors: Partha S
authors: PS
authors: Ghosh
authors: Department of Neurology, Mayo Clinic, Rochester, MN, USA sorenson.eric@mayo.edu.
authors: Eric J
authors: EJ
authors: Sorenson
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003402:Creatine Kinase / Q000378:metabolism; D003937:Diagnosis, Differential; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000503:physiopathology; D009135:Muscular Diseases / Q000175:diagnosis* / Q000503:physiopathology*; D009222:Myotonia / Q000175:diagnosis / Q000503:physiopathology*; D009431:Neural Conduction; D012189:Retrospective Studies
chemical_list: D003402:Creatine Kinase
keywords: children; electromyography; muscle disorders; myotonia; myotonic discharges