Classification of Nerve Injuries

In 1951, Sunderland expanded Seddon’s classification to five degrees of peripheral nerve injury.

First-degree (Class I)

Seddon’s neurapraxia and first-degree are the same.

Second-degree (Class II)

Seddon’s axonotmesis and second-degree are the same.

Third-degree (Class III)

Third-degree is included within Seddon’s Neurotmesis. Sunderland’s third-degree is a nerve fiber interruption. In third-degree injury, there is a lesion of the endoneurium, but the epineurium and perineurium remain intact. Recovery from a third-degree injury is possible, but surgical intervention may be required.

Fourth-degree (Class III)

Fourth-degree is included within Seddon’s Neurotmesis. In fourth-degree injury, only the epineurium remain intact. In this case, surgical repair is required.

Fifth-degree (Class III)

Fifth-degree is included within Seddon’s Neurotmesis. Fifth-degree lesion is a complete transection of the nerve. Recovery is not possible without an appropriate surgical treatment

Data from Sunderland S. A classification of peripheral nerve injuries producing loss of function. Brain 1951;74(4):491–516.