Seddon's Classification Scheme for Peripheral Nerve Injury

Seddon's Classification Scheme for Peripheral Nerve Injury

• Seddon's classification scheme describes three types of nerve injury: neurapraxia, axonotmesis, and neurotmesis, based on severity of tissue injury, prognosis, and time for recovery.
• Neurapraxia is the mildest type, referring to a block to conduction of nerve impulses without disruption of the axon or perineurium.
• In neurapraxia, nerve fibers are unable to conduct an action potential despite axonal continuity, with complete return of sensation or function expected within hours, days, weeks, or up to a few months.
• Axonotmesis refers to loss of axonal continuity without associated disruption of the fascicular connective tissue elements, commonly seen in crush injuries.
• In axonotmesis, the axon and its myelin sheath are broken, yet the surrounding connective tissue framework remains partially or fully intact.
• Neurotmesis describes the most severe injury type, with disruption of the entire nerve and severe disruption of the connective tissue components of the nerve trunk, resulting in compromised sensory and functional recovery.
• Examples of neurotmesis include sharp injury, some traction injuries, or injection of noxious drugs, with extremely poor prognosis for spontaneous recovery without surgical intervention.

Sunderland's Classification Scheme

• Sunderland's classification scheme further stratifies Seddon's three injury types into five categories according to severity of the injury.
• First-degree injury is equivalent to Seddon's neurapraxia.
• Second, third, and fourth-degree injuries are equivalent to Seddon's axonotmesis, differing in degree of mesenchymal damage to the nerve.
• Fifth-degree injury is equivalent to Seddon's neurotmesis.

Importance of Anatomy and Classification in Peripheral Nerve Injury

• Traumatic peripheral nerve injuries are a challenge to clinicians, requiring a thorough understanding of anatomy, pathophysiology of nerve injury, and reconstructive options.
• Seddon's and Sunderland's classification schemes help clinicians and neuroscientists in further studies on management and treatment of peripheral nerve injuries.