Seddon classified peripheral nerve injuries into three types. A Sunderland Grade 4 injury is equivalent to which Seddon classification and has what surgical implication?

• A Axonotmesis with endoneurial tube disruption — surgical repair usually needed ✓
• B Neuropraxia — recovers spontaneously in weeks
• C Axonotmesis — recovers by axon regeneration at 1 mm/day
• D Neurotmesis — requires surgical repair (neurorraphy or nerve grafting)

Explanation

Sunderland's classification has 5 grades: Grade 1 = neuropraxia (myelin disruption only), Grade 2 = axonotmesis (axon disruption, endoneurium intact), Grade 3 = axon + endoneurium disrupted but perineurium intact, Grade 4 = axon + endo + perineurium disrupted (only epineurium intact), Grade 5 = neurotmesis (complete transection). Grade 4 corresponds to Seddon's neurotmesis functionally — there is no internal architecture for guided regeneration, and fibrosis predominates. Surgical repair (neurorraphy or nerve grafting) is required because regenerating axons cannot navigate the disorganized scar. Grade 2 (axonotmesis) recovers spontaneously at 1 mm/day (Tinel's sign progresses). Grade 3 may or may not recover spontaneously depending on gap length.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.