Sunderland's classification of peripheral nerve injuries divides injuries into 5 degrees. A Sunderland Grade III injury involves:

• A Disruption of the axon and myelin sheath only (endoneural tube intact) — complete spontaneous recovery expected
• B Disruption of axon, endoneurium, and perineurium; only epineurium intact — poor spontaneous recovery, surgery often needed
• C Disruption of axon, myelin, and endoneurium, but perineurium intact — incomplete/mixed recovery ✓
• D Complete nerve trunk transection — no spontaneous recovery

Explanation

Sunderland's classification: Grade I = conduction block (neurapraxia — Seddon); Grade II = axon and myelin disrupted, endoneurial tube intact (axonotmesis — Seddon) — complete spontaneous recovery; Grade III = axon + endoneurium disrupted, perineurium intact — incomplete, mixed recovery because regenerating axons may enter wrong endoneurial tubes; Grade IV = axon + endoneurium + perineurium disrupted, only epineurium intact (neurotmesis — Seddon equivalent) — neuroma-in-continuity, surgical exploration needed; Grade V = complete transection — neurotmesis, surgical repair mandatory. Grades III–V correspond to Seddon's neurotmesis with increasing severity.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.