Type 2 nerve injury is characterized by what?

• A. Conduction Block
• B. Neurotmesis
• C. Axonotmesis
• D. Demyelination

Answer: (C)

The main idea is how nerve injuries differ based on what happens to the axon and its supporting connective tissue. Type II nerve injury is axonotmesis: the axon and its myelin are damaged and distal to the injury we see Wallerian degeneration, but the surrounding connective tissue scaffold (the endoneurium) remains intact. Because that intact scaffold guides regenerating axons, there is potential for real recovery as the axon regrows along the original pathway, roughly a few millimeters per day, with Schwann cells helping steer the process.

This differs from conduction block (neurapraxia), where the axon remains intact and the problem is a transient loss of conduction due to demyelination or other factors, with little to no axonal damage. Demyelination itself is not a separate injury type; it underpins conduction block in neurapraxia. Neurotmesis, on the other hand, is a complete severance with loss of the nerve fibers and supporting structures, leaving little chance for spontaneous recovery without surgical repair.