Nerve injury classification

In the second degree the axon is damaged, but the surrounding connecting tissue remains intact – axonotmesis.

In 1943, Seddon described three basic types of nerve injury:[2] Neurapraxia is a temporary interruption of conduction without loss of axonal continuity.

[3] Neurapraxia involves a physiologic block of nerve conduction in the affected axons.

Other characteristics: Axonotmesis involves loss of relative axon continuity and myelin covering, but preservation of the connective tissue framework (including encapsulating tissue, the epineurium and perineurium).

In fourth-degree injury, only the epineurium remain intact, requiring surgical repair.