Immediately after a closed traction injury to the radial nerve in the spiral groove, nerve conduction studies show normal distal motor and sensory action potentials despite complete wrist drop. The axon is anatomically continuous. This pattern corresponds to:

• A Neurotmesis
• B Axonotmesis
• C Avulsion injury
• D Neurapraxia ✓

Explanation

Neurapraxia is a conduction block across the injured segment with intact axonal continuity, so distal conduction studies remain normal and Wallerian degeneration does not occur. Recovery is expected within days to weeks. In axonotmesis the axon is disrupted, so distal action potentials disappear after about 7 to 10 days as Wallerian degeneration proceeds, even though the connective tissue sheaths remain intact. Neurotmesis disrupts the entire nerve trunk including perineurium.

Reference: Campbell's Operative Orthopaedics, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.