Card Set Information

2011-04-18 00:48:55

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  1. ENMG
    electroneuromyography consists of the observation, analysis, and interpretation of the bioelectrical activity of muscle and nerve in response to volitional activation or electrical stimulation
  2. SNAP
    • sensory nerve action potential
    • b/c sensory nerves contain some of the large axons and are most vulnerable to neuropathies, abnormalities in the SNAP are often the first indication of pathology
    • sensory latency is usually the only finding reported
  3. CMAP
    • compound motor action potential
    • is defined as the sum of electrical activity of all of the muscle fibers in the region of the recording electrode that are innervated by the nerve being stimulated
    • biphasic in nature
  4. upward deflection
    downward deflection
    • is considered negative
    • is considered positive
  5. electrodes
    • stimulating, recording, reference, and ground
    • needle (generally recording only)
    • surface can be all 4
  6. latency
    • time from the application of the stimulus until a response is recorded (initial negative deflection)
    • is measured in msec and is the time the action potential takes to travel down the nerve, cross the neuromuscular junction, and initiate the muscle action potential
  7. latency is directly related to
    electrode placement
  8. latency measures and possible interpretations
    • normal- normal or partial axon loss or partial conduction block
    • prolonged- focal demylenation
    • absent- complete axon loss or complete conduction block
  9. prolonged or absent latencies
    occur with acute or chronic compressive lesions also certain diseases that disrupt the myelin
  10. amplitude
    • how big a response is from the baseline to the (-) peak
    • total number of muscle fibers innervated by the nerve that is being stimulated
    • is measured in uV
    • no change in amplitude with changes in distance of electrodes
  11. reductions in amplitude
    occur in wallerian degeneration lesions such as lacerations, traction injuries, infarctions, significant compression, or carcinoma infiltrations and axonal degeneration lesions associated with some metabolic diseases also occur moderate and severe myelinopathies
  12. results of amplitude measures and possible interpretations
    • normal- normal or focal demyelination
    • reduced- partial axon loss or partial conduction block
    • absent- complete conduction block or complete axon loss
  13. duration
    • measured in msec
    • function of the different speeds of the axons stimulated
    • time period that begins with the initial negative deflection and ends when that deflection returns to baseline
  14. increase in duration
    diseases that disrupt the axon or myelin
  15. neuropraxia lesions
    • focal demyelination
    • partial conduction block
    • complete conduction block
  16. axonotmesis and neurotmesis
    • partial axon loss
    • complete axon loss
  17. sensory testing orthodromic
    stimulate distal record proximal
  18. sensory testing antidromic
    stimulate proximal record distal
  19. motor testing
    • helps define where the lesion could be
    • inc intensity and amplitude
    • amplitude inc can only inc so high