Which injury is defined by complete nerve division with endoneurial disruption?

• A. Neuropraxia
• B. Neurotmesis
• C. Axonotmesis
• D. Demyelinating neuropathy

Answer: (B)

Neural injuries are graded by how much of the nerve’s structure is damaged, which also guides healing chances. When a nerve is completely divided and the endoneurial tubes are torn, the supporting scaffolding that guides regenerating fibers is lost, so spontaneous reinnervation is unlikely and surgical repair is typically needed. This pattern defines neurotmesis, the most severe category, where the axon, myelin, and all connective tissue layers (including the endoneurium) are disrupted. By contrast, neuropraxia is a temporary conduction block with intact axons; axonotmesis involves axonal disruption with preserved endoneurial tubes that can guide regrowth, albeit with distal Wallerian degeneration. Endoneurial disruption specifically marks neurotmesis.