Active Nerve Injuries

Question 1

Neurapraxia

Answer 1

• Mildest form of injury
• Atonal continuity preserved
• Nerve conduction is preserved proximal and distal to the lesion
• Symptoms include pain, minimal muscle atrophy, numbness or greater loss of motor and sensory function, diminished proprioception
• Recovery is rapid and complete and will occur within 4-6 weeks
• Pressure injuries are the most common

Question 2

Axonotmesis

Answer 2

• A more severe grade of injury to a peripheral nerve
• Reversible injury to damaged fibers since they maintain an anatomical relationship to each other
• Damage occurs to the axons with preservation of the supporting structures
• Distal Wallerian degeneration can occur
• The nerve can regenerate distal to the site of the lesion at a rate of one millimeter per day
• Recovery is spontaneous and varies from spotty to no recovery; surgery may be required for repair.
• Traction, compression, and crush injuries are the most common.

Question 3

Neurotmesis

Answer 3

• The most severe grade of injury to a peripheral nerve
• Axon, myelin, connective tissue components are all damaged or transected
• Irreversible injury; no possibility of regeneration
• Flaccid paralysis and wasting of muscles occur; total loss of sensation to area supplied by the nerve.
• All motor and sensory loss distal to the lesion becomes permanently impaired
• No spontaneous recovery; with surgical reattachment, potential regenerating axons may grow at one millimeter per day with proximal covers first; sensory recovery occurs sooner than motor fibers.