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24 Cards in this Set
- Front
- Back
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Describe neuropraxia
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Conduction block (injury to themyelin) without wallerian
degeneration Axons intact |
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Describe axonotmesis.
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Conduction block (injuiy to axons and myelin) with wallerian
degeneration (distal) Axon, myelin degenerate Endoneural tubes remain |
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Describe neurotmesis.
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All layers disrupted
Wallerian degeneration occurs Requires surgery |
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What degree of nerve injury has the most variable extent of recovery?
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Axonotmesis
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What microstructural change occurs when a nerve is elongated by at least 8%?
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Decreased microcirculation
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At what degree of stretch do nerve ischemia and axonal loss occur?
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15% stretch
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What electromyograph (EMG) findings are consistent with denervation?
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Fibrillations
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How long after injury are they generally seen?
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2 to 4 weeks
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What EMG finding is consistent with reinnewation?
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Polyphasic potentials
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What is the most important prognostic factor for recovery after periphera nerve injury?
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Degree of injury
Distance of injury from motor endplates |
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What is the general rule for the rate of nerve regeneration in children?
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3 to 5 mm/day
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What is the rate of regeneration in adults?
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1 mm/day
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What is the best clinical indication of nerve regeneration?
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Advancing Tinel’s sign
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Are distal or proximal peripheral nerve injuries generally better prognostically?
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Distal injuries have better prognoses than proximal
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What key consideration must be kept in mind during attempted nerve repair?
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Avoid tension
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What is the time limit beyond which delayed repair is unlikely to be successful?
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18 months, because of irreversible motor endplate demise
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With chronic compression, is sensory or motor function affected first?
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Sensory function is lost first
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What electrodiagnostic studydemonstrates changes first: EMG or nerve conduction velocity (NCV)?
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NCV (sensory latency) changes seen before EMG
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What is the order of sensory functional loss with chronic compression?
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Threshold functions are lost first
Then static two-point discrimination Moving two-point discrimination Moving touch Pain Pressure Total anesthesia results |
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What tests are most sensitive for the presence of compressive neuropathy?
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Threshold tests
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What are some examples of threshold tests?
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Semmes monofilament (slow adapting fibers)
Vibration (quick adapting) |
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What is the key Semmes monofilament number for the hand?
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2.83 mm
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What is the key Semmes monotilament number for the foot?
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5.07 mm
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What are some examples of density tests?
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Static two-point discrimination (slow adapting fibers)
Moving two-point discrimination (quick adapting) |
