From: A Connolly
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Myotonia: Features
- Repetitive spontaneous discharge of: Muscle fiber
- Firing rate, general: 20 to 150 Hz
- Morphology of individual potentials: Positive wave or Brief spike
- Differences from fibrillations
- Waxing & Waning: Varied frequency & amplitude
- Amplitude: May vary up to 10 fold
- Frequency: Often decreasing with time: 50 Hz → 10 Hz
- Duration of runs of myotonic repetitive discharges
- Myotonic runs: Longer in Myotonic dystrophy than in
Myotonia congenita
- Myotonic dystrophy: Many runs > 2 sec & longest 30 sec
- Myotonia congenita: Most runs < 1 sec & longest is 10 sec
- Stimulus
- Mechanical or Electrical
- May be spontaneous
- Myotonia: Disorders
- Typical
- Myotonic dystrophies: 1; 2
- Myotonia congenita
- Paramyotonia
- Other disorders
- Acid maltase deficiency
- Immune myopathies
- Myotubular myopathies
- Hyperkalemic pedriodic paralysis
- Denervation: Brief run; Not predominant wave form
- Temperature sensitivity
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