title: Diagnostic impact of myotonic discharges in myofibrillar myopathies.
abstract: BACKGROUND
  In patients with myofibrillar myopathies (MFM), myotonic discharges have occasionally been detected by needle electromyography (EMG). Nevertheless, this peculiar type of spontaneous repetitive discharge has not attracted special interest in the genetically heterogeneous MFMs.
  
  
  METHODS
  EMG features were analyzed in 6 patients with genetically confirmed MFM (n = 1 MYOT, n = 1 DES, n = 2 ZASP, n = 2 FLNC).
  
  
  RESULTS
  Fibrillation potentials, positive sharp waves, and myotonic discharges were found in all 6 patients, and complex repetitive discharges were found in 5. Myotonic discharges were detected in approximately 50% of the analyzed muscles independent of the site, including distal (3/6), proximal limb (4/6), and paravertebral muscles (3/6). Clinical myotonia could not be elicited in any patient.
  
  
  CONCLUSIONS
  Myotonic discharges appear to be part of the electrodiagnostic characteristics of myofibrillar myopathy. Along with other appropriate clinical and histological findings, the presence of myotonic discharges supports the diagnosis of myofibrillar myopathy.
authors.affiliation: Department of Neurology, Martin-Luther-University Halle-Wittenberg, Ernst-Grube-Str. 40, D-06120 Halle (Saale), Germany. frank.hanisch@medizin.uni-halle.de
authors.forename: Frank
authors.initials: F
authors.lastname: Hanisch
authors.forename: Torsten
authors.initials: T
authors.lastname: Kraya
authors.forename: Malte
authors.initials: M
authors.lastname: Kornhuber
authors.forename: Stephan
authors.initials: S
authors.lastname: Zierz
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D009202:Cardiomyopathies / Q000473:pathology / Q000503:physiopathology; D004576:Electromyography; D055724:Electrophysiological Phenomena; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000473:pathology / Q000503:physiopathology*; D009136:Muscular Dystrophies / Q000473:pathology / Q000503:physiopathology*; D020914:Myopathies, Structural, Congenital / Q000473:pathology / Q000503:physiopathology*