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Showing posts with label EMG. Show all posts
Showing posts with label EMG. Show all posts

Myotonic discharges and its EMG significance

Generator :  of Myotonic discharges  is Muscle membrane
Sound : It is identified by the Diving Bonder / motorcycle rewing sound while doing EMG
Firing pattern: Myotonic discharges  has Waxing and waning firing pattern
What are the conditions where you see Myotonic discharges?
1.Myotonic discharges in  neurogenic disorders
  • Chronic or longstanding axonal peripheral neuropathies (foot/distal muscles)
  • Chronic or old, severe radiculopathies
Usually long, change of firing rate (waxing/waning) is slow
Increase in firing rate  can distinguishes it from a rapidly waning fibrillation potential
2.Myotonic discharges – along with clinical myotonia
  • Myotonic dystrophy   
         Type 1
         Type 2
In this condition Myotonia less prominent with repetitive contraction
  • Myotonia congenita
  • Paramyotonia congenita-In this condition Myotonia increase following repetitive contraction
3.Myotonic discharges without clinical Myotonia
  •  Hyperkalemic periodic paralysis
  •  Emery-Dreifuss muscular dystrophy
Infrequently in:
  • Inflammatory myopathies
  • Medication induced (statins)