Transient Facial Nerve Palsy — ORE Part 1 MCQ

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ModeratePharmacology & TherapeuticsTransient Facial Nerve PalsyORE Part 1

Immediately after an inferior alveolar nerve block on the right side, a patient cannot close the right eye and develops right-sided facial asymmetry. Which complication is most likely?

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Correct answer: C — Transient facial nerve block from parotid spread

This is transient facial nerve (VII) palsy caused by local anaesthetic spreading posteriorly into the parotid region, where the facial nerve traverses before branching. Loss of orbicularis oculi function explains the inability to close the ipsilateral eye, and weakness of the muscles of facial expression causes asymmetry. The immediate onset following the block is the discriminating feature. Trigeminal injury would cause sensory disturbance, not paralysis of facial expression. Local-anaesthetic toxicity produces systemic neurological and/or cardiovascular features. Immediate allergy more usually causes urticaria, angioedema, wheeze or hypotension. A stroke is not the expected isolated, injection-timed peripheral facial pattern. The deficit should resolve as the local anaesthetic wears off; eye protection is important while eyelid closure is impaired.

Reference: Sanghavi S, et al. Neurological Complications of Local Anesthesia in Dentistry: A Review. 2024. https://pubmed.ncbi.nlm.nih.gov/38239523/