ECT seizure mechanism — MRCPsych Paper A MCQ

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ModerateNeurophysiology and neurochemistryECT seizure mechanismMRCPsych Paper A

A 52-year-old woman with severe depression undergoes modified electroconvulsive therapy under general anaesthesia with a neuromuscular blocking drug. Which physiological event is intentionally produced by the electrical stimulus, despite suppression of most peripheral convulsive movements?

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Correct answer: B — Induction of a generalised cerebral seizure

The correct answer is B. ECT delivers a controlled electrical stimulus to induce generalised cerebral seizure activity. General anaesthesia prevents awareness, while the neuromuscular blocking drug suppresses peripheral motor manifestations and reduces injury risk; it does not prevent the therapeutic cerebral seizure. The precise molecular basis of ECT's clinical efficacy remains uncertain, so the question should not imply a proven receptor-level mechanism. Dopamine D2 blockade is associated with antipsychotic drugs, and direct vagal stimulation describes vagus nerve stimulation. Depolarising neuromuscular blockade may be produced by suxamethonium but is a procedural modification rather than the central therapeutic event. ECT does not selectively destroy hippocampal neurones.

Reference: National Institute for Health and Care Excellence. Guidance on the use of electroconvulsive therapy, TA59, section 3.1–3.2: The technology. Updated 2009. https://www.nice.org.uk/guidance/ta59/chapter/the-technology