1. EMG indicates what?
    physiological state of the muscle, which is affected by the motor nerve axons
  2. proteins and muscle stability?
    • AHC and motor nerve cells give nutrients and stability to muscle fibers. Proteins are provided by axoplasmic flow to the muscle.
    • If you restrict/reduce
    • flow of proteins and you’ll get decline in muscle stability
  3. causes of muscle membrane instability
    compression, denervation, axonal degen, spinal shock
  4. 4 contraindications to EMG
    • Blood clotting disorders
    • Lymph node resections in that extremity
    • Lymphedma
    • Immune-compromised pts at high risk for infection
  5. precautions to EMG
    • Indwelling pacemaker, deep brain stimulator, or other indwelling device
    • Chest wall and abs needle insertions
    • PTs in ICUs, CCUs
  6. 5 normal EMG waveforms seen at rest
    • insertional activity
    • fasciculations (if in only 1-2 muscles)
    • nerve potential
    • end plate noise
    • a few MUs (just indicates muscle isn't fully relaxed)
  7. what is this insertional activity you tell me is normal when seen at rest?
    non-specific, can't be individually id'd, happens when needle pierces muscle membrane, lasts up to 300 ms after insertion
  8. fasciculation potentials
    • look like normal MU, but rate/freq is irregular and they're invol
    • can be caused by fatigue
  9. nerve potential seen at rest, why?
    touched an axon with the needle tip
  10. end plate noise seen at rest, what is it?
    • when tip of needle is near an end plate, base line will be elevated. sounds like a conch shell.
    • Due to a small quanta of ACh being released into NMJ
  11. normal duration of MUAP
    long duration
    • 7-12 ms
    • more than 12
  12. normal amplitude of MUAP
    5 mv or less

    patho ones are usually 2 mv or less, with "short amplitude" at less than 100 uV
  13. normal phases of MUAP
  14. 3 components of a motor unit
    • AHC,
    • nerve axon,
    • all muscle fibers innervated by that AHC
  15. waveform produced by each depol = summation of ___
    all the muscle fibers in the MU
  16. single unit interference pattern on max effort indicates ...
    • severe loss of MUs
    • severe neuropathy

    baseline is apparent between each spike, and the spikes are relatively short – this indicates minimal effort (or if seen with max effort, indicates above problem)
  17. incomplete interference pattern on max effort indicates ...
    • major loss of MUs
    • partial neuropathy 

    more MUs are firing than in SUIP, some MUAPs have merged visually due to simultaneous recruitment. BUT, baseline is still visible. This is normal at a low effort = 3+ to 4- MMT. If this is max effort, it's the above trouble.
  18. complete interference pattern on max effort indicates...
    • good
    • but, if it occurs on early effort with low amplitude, indicates myopathy
  19. complete interference pattern early with low amplitude indicates...
    myopathy (like polio -- so watch out for over exercising and exhausting these pts)
  20. complete interference pattern represents what percent of max effort?

    so, CIP doesn’t indicate full innervation, just that failure to get this indicates significant loss.

    This wave has no visible baseline, it’s crowded with peaks.

    (In myopathy/polio you’ll see CIP on early effort bc of reduced force production in each motor unit. So, they’ll recruit a greater number of MUs for ADL, leaving fewer MUs on reserve for prolonged/vigorous activities. SOOO, watch out for over-exercising these pts, as they’ll get to overuse weakness pretty fast.)
  21. 5 names of patho wave forms
    • increased insertional activity
    • fibrilation potentials
    • positive sharp waves
    • fasciculation potentials
    • high frequency discharges
  22. increased insertional activity -- looks like what? indicates what?
    prolonged unidentified discharges after insertion or movement.

    Indicates muscle membrane instability.

    Difficult to interpret if they’re the only finding at rest along with normal MUs.
  23. fibrilation potentials and positive sharp waves indicate what?
    muscle membrane instability (usually as a result of nerve damage or myopathy)
  24. fibrilation potentials - describe
    • low then high peak, the squiggles at baseline
    • seen at rest due to invol discharge of individ muscle fibers
    • not a type of motor unit
  25. positive sharp waves, describe
    • downward peak followed by squiggles
    • not a type of MU
  26. fasciculation potentials (normal if there are just a few, problematic if there are more) - indicate what if there are more?
    AHC or nerve axon instability/irritability

    they're irregular discharges of the MU, not under vol control
  27. high freq discharges aka myotonic or bizarre discharges - describe
    prolonged continuous discharges at rest
  28. high freq discharges at rest indicate ..5..
    • myotonia
    • chronic myopathy
    • neuropathy
    • radiculopathy
    • AHC disease
  29. 3 patho waveforms seen due to muscle membrane instability
    • increased insertional activity
    • fibrilation potentials
    • pos sharp waves
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