Table 3.

Seddon and Sunderland nerve injury classifications.

Criteria	Seddon Classification	Sunderland Classification	Description
Grade 1	Neuropraxia	First-degree (Grade 1)	Temporary conduction block, no axonal disruption. Recovery is usually complete within weeks to months.
Grade 2	Axonotmesis	Second-degree (Grade 2)	Axonal disruption without injury to the surrounding connective tissue. Wallerian degeneration occurs distal to the injury. Full recovery possible but may take months.
Grade 3	Axonotmesis	Third-degree (Grade 3)	Axonal disruption with partial injury to the endoneurium. Wallerian degeneration occurs, and recovery is incomplete without surgical intervention.
Grade 4	-	Fourth-degree (Grade 4)	Axonal disruption with damage to the endoneurium and perineurium. Recovery is unlikely without surgical repair.
Grade 5	Neurotmesis	Fifth-degree (Grade 5)	Complete transection of the nerve with loss of continuity. Requires surgical repair; recovery may be incomplete even with surgery.