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Interscalene Block Horner and Hoarseness — FRCA Final MCQ

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ModerateRegional AnaesthesiaInterscalene Block Horner and HoarsenessFRCA Final

A 40-year-old man (ASA I) with no significant past medical history is undergoing elective arthroscopic shoulder surgery under interscalene nerve block and GA. Post-operatively he develops Horner syndrome AND a hoarse voice on the blocked side. Which TWO structures have been affected by local anaesthetic spread?

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Correct answer: A — Phrenic nerve and vagus nerve

Horner syndrome (ptosis, miosis, enophthalmos, anhidrosis) from cervical sympathetic chain block AND hoarse voice from recurrent laryngeal nerve block are both recognised side effects of interscalene brachial plexus block due to local anaesthetic spreading medially. The cervical sympathetic chain lies on the longus colli muscle medial to the brachial plexus. The recurrent laryngeal nerve runs in the tracheo-oesophageal groove nearby. Both are affected by medial spread of LA from the interscalene space. These effects are temporary and self-limiting. Horner syndrome incidence: up to 75%; RLN block: 1-2%.

Reference: RCOA – 2023 – Regional anaesthesia complications; Barrington MJ – 2020 – Peripheral nerve block complications