Differentiate axonotmesis and neurotmesis in peripheral nerve injury and typical prognosis.

• A. Axonotmesis: complete transection with tissue disruption; Wallerian degeneration is absent; Neurotmesis: axon intact and regenerates rapidly.
• B. Axonotmesis: axon damaged with intact connective tissue; Wallerian degeneration; potential regeneration; Neurotmesis: complete transection with disrupted connective tissue; poor prognosis without surgical repair.
• C. Both injuries regenerate quickly without intervention.
• D. Axonotmesis has a poorer prognosis than neurotmesis.

Answer: (B)

In this topic, the amount of structural disruption in a peripheral nerve determines whether regeneration can occur. In axonotmesis, the axon is damaged but the surrounding connective tissue scaffolding (such as the endoneurium) remains intact. This preserved framework allows regenerating axons to grow along the original pathway, with Wallerian degeneration occurring distal to the injury. Because the pathway is preserved, recovery is possible over time, though it depends on how far the target has to be reached. In neurotmesis, the nerve is completely transected and the connective tissue structures are disrupted, so there’s no intact track for guided regrowth; spontaneous recovery is unlikely without surgical repair and tends to have a poor prognosis.

So the best description is that axonotmesis involves axonal damage with intact connective tissue and Wallerian degeneration, offering potential regeneration, whereas neurotmesis is a complete transection with disrupted connective tissue and a poor prognosis without surgical repair.