A Seddon-classified neurapraxia (Sunderland Grade I) differs from axonotmesis (Sunderland Grade II) in which critical aspect that determines clinical management?

• A Axonotmesis requires surgical nerve repair (suture/grafting) for recovery
• B Neurapraxia causes Wallerian degeneration distally while axonotmesis does not
• C Both require surgical exploration; only the timing differs
• D Neurapraxia has conduction block with intact axon; complete spontaneous recovery expected without surgical intervention ✓

Explanation

Neurapraxia (Sunderland Grade I) is a physiological block of conduction with no axonal disruption — the myelin sheath is damaged (demyelination) but axon continuity is preserved. Recovery is complete and usually within days to 12 weeks without surgical intervention. Electromyography shows reduced conduction velocity but no denervation potentials. Axonotmesis (Sunderland Grade II) involves axon disruption with intact endoneurium — Wallerian degeneration occurs distally but spontaneous regeneration along intact endoneurial tubes occurs at 1–3 mm/day. Neurotmesis (Sunderland Grade IV/V) requires surgical repair or grafting.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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