Peripheral Nerve Surgery
What you must own
Know peripheral nerve anatomy: axon, myelin, endoneurium, perineurium, epineurium. Understand the classification of nerve injury (Seddon: neurapraxia, axonotmesis, neurotmesis; Sunderland grades I-V). Neurapraxia is reversible conduction block; axonotmesis involves axonal loss with intact connective tissue and spontaneous regeneration; neurotmesis is complete transection requiring surgery.
Recognise common entrapment neuropathies: carpal tunnel syndrome (median nerve), cubital tunnel syndrome (ulnar nerve), and radial nerve palsy (wrist drop). Understand the role of electrodiagnostic studies (nerve conduction studies and electromyography) in localisation and prognosis.
Traumatic nerve injury: timing of repair (primary versus delayed), the role of nerve grafting and conduits, and the concept of Wallerian degeneration. Know the difference between a neuroma (painful, disorganised regeneration) and a true nerve tumour (schwannoma, neurofibroma).
Brachial plexus: Erb (upper, C5-C6) versus Klumpke (lower, C8-T1) palsy patterns.
Traps
Questions test the Seddon classification and whether spontaneous recovery is expected. Another trap: confusing carpal tunnel (median) with cubital tunnel (ulnar) symptoms.
Rule of thumb
Neurapraxia recovers spontaneously; neurotmesis needs surgery. Wallerian degeneration occurs distal to the injury.
Worked example
A patient with wrist drop after a humeral shaft fracture has radial nerve palsy. If there is no recovery after an appropriate period, exploration is considered; many are neuropraxic and recover spontaneously.