Post-Block Neurological Deficit — FRCA Final MCQ

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HardRegional AnaesthesiaPost-Block Neurological DeficitFRCA Final

A 40-year-old man (ASA I) undergoes arthroscopic shoulder surgery under GA with an interscalene block. Post-operatively he has complete loss of grip strength and wrist drop on the blocked side. This was not present pre-operatively. What is the most likely affected structure?

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Correct answer: B — Posterior cord

An interscalene block targets the C5-C6-C7 nerve roots. Loss of grip strength (C8-T1 territory) and wrist drop (radial nerve, posterior cord) occurring post-block suggests inadvertent deeper spread affecting the posterior cord or lower trunk. However, pure wrist drop with grip weakness is most consistent with posterior cord involvement (radial + axillary + subscapular nerves). Most post-block neurological deficits are neuropraxic and resolve within 6-12 weeks. If symptoms persist beyond 4-6 weeks, nerve conduction studies should be arranged.

Reference: RCOA – 2023 – Regional anaesthesia complications; Barrington MJ – 2020 – Nerve injury after peripheral nerve block