Epilepsy and Anaesthetic Agents — FRCA Final MCQ

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EasyGeneral AnaesthesiaEpilepsy and Anaesthetic AgentsFRCA Final

A 22-year-old woman with well-controlled epilepsy taking sodium valproate requires general anaesthesia for an emergency appendicectomy. Which anaesthetic agent is characteristically associated with epileptiform EEG activity at high concentrations, particularly during hypocapnia?

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Correct answer: A — Enflurane

Enflurane has a characteristic concentration-dependent proconvulsant effect, producing epileptiform EEG activity and occasionally clinical seizures. This effect is enhanced by hypocapnia or respiratory alkalosis and may be facilitated by auditory stimulation. It is an intrinsic pharmacodynamic property, not a specific interaction with sodium valproate. Propofol and thiopental are predominantly anticonvulsant at anaesthetic doses, while isoflurane generally suppresses cerebral electrical activity. Sevoflurane can also cause epileptiform activity or seizures, particularly at high concentrations and in younger patients, making the original broad wording insufficiently discriminating. The addition of hypocapnia identifies the classical enflurane effect and leaves a single best answer.

Reference: Baxter Healthcare Ltd. Sevoflurane Baxter 100% inhalation vapour, liquid, Summary of Product Characteristics, sections 4.4 and 5.1. Updated 18 January 2024. https://www.medicines.org.uk/emc/product/1866/smpc