Questions and Answers
What is neuropraxia?
What is axonotmesis?
The outside of the nerve is intact but the axon and myelin sheath are damaged.
What is neurotmesis?
Type III nerve injury with damage to myelin, axon, and nerve sheath.
What are the different severities of axonotmesis? II = loss of __________ continuity but endoneurium is intact.
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What are the different severities of axonotmesis? III = loss of axonal and __________ continuity but perineurium is intact.
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What are the different severities of axonotmesis? IV = loss of axonal, endoneurium and __________ continuity but the epineurium is intact.
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What are the layers of a nerve?
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In what types of nerve injuries will Tinel's sign be present?
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Study Notes
Seddon Classification of Nerve Injury
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Neuropraxia
- Type I nerve injury characterized by minimal damage.
- Affects myelin without injuring axon or nerve sheath.
- Results in slowed conduction with full recovery expected within hours to months.
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Axonotmesis
- Damage occurs to the axon and myelin sheath while external structures (endoneurium, perineurium, epineurium) remain intact.
- Recovery can be incomplete, taking weeks to months.
- Axon sprouts occur within the nerve sheath during the healing process.
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Neurotmesis
- Type III nerve injury with comprehensive damage including myelin, axon, and nerve sheath.
- Recovery typically requires surgical intervention and may result in permanent paralysis if not treated.
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Severities of Axonotmesis
- Severity II: Loss of axon continuity; endoneurium remains intact.
- Severity III: Loss of both axonal and endoneurium continuity, but perineurium stays intact.
- Severity IV: Loss of axonal, endoneurium, and perineurium continuity while the epineurium is preserved.
- All severities lead to the absence of conduction.
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Layers of a Nerve
- Outermost: Epineurium
- Middle: Perineurium
- Innermost: Endoneurium
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Tinel's Sign
- Present in axonotmesis and neurotmesis injuries.
- Indicates irritation or regeneration of nerves.
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Description
Test your understanding of the Seddon classification system for nerve injuries, including the distinctions between neuropraxia, axonotmesis, and neurotmesis. Learn about the mechanisms of injury and their implications for recovery and treatment.
