Functional Seizure Prevalence — MRCPsych Paper B MCQ

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ModerateLiaison PsychiatryFunctional Seizure PrevalenceMRCPsych Paper B

A liaison psychiatry trainee reviews patients referred to a tertiary epilepsy service because recurrent seizure-like events have persisted despite appropriate antiseizure treatment. Approximately what proportion of such patients are ultimately found to have functional (dissociative) seizures accounting for the apparently treatment-resistant events?

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Correct answer: E — Approximately 20–30%

Option E is correct. In tertiary epilepsy populations referred for apparently treatment-resistant seizures, functional or dissociative seizures account for roughly one in five to one in three patients; a review reports 20–30%, while a UK NHS neuropsychiatry service cites approximately 20% of patients labelled as having intractable epilepsy. The referral setting is crucial: this is not the prevalence in the general population or among all people with epilepsy. Therefore 5% underestimates the proportion, whereas 40–50%, 60–70% and more than 90% substantially overestimate it. Functional seizures can coexist with epilepsy, so identifying functional events does not automatically exclude comorbid epileptic seizures.

Reference: Lanzillotti AI et al. Updated Review on the Diagnosis and Primary Management of Psychogenic Nonepileptic Seizure Disorders. Neuropsychiatric Disease and Treatment. 2021. https://pubmed.ncbi.nlm.nih.gov/34113112/