Conversion Disorder — MRCPsych Paper B MCQ

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ModerateAnxiety & Stress-Related DisordersConversion DisorderMRCPsych Paper B

A 25-year-old woman reports sudden complete loss of vision in both eyes after a distressing event. Pupillary responses, fundus examination and neuroimaging are normal. An optokinetic drum elicits normal nystagmus. Careful assessment finds no evidence of deception, intentional symptom production or an external incentive. Which is the most likely diagnosis?

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Correct answer: B — Functional neurological disorder

The diagnosis is functional neurological disorder presenting as functional visual loss. Normal optokinetic nystagmus despite reported complete bilateral blindness is a positive sign of preserved visual function; the diagnosis should not be made merely because routine investigations are normal. The symptoms are experienced as involuntary. Malingering involves intentional symptom production for an external incentive, whereas factitious disorder involves intentional production to adopt the sick role; neither is supported here. Acute angle-closure glaucoma usually causes severe ocular pain, a red eye, a fixed or sluggish pupil and raised intraocular pressure. Retinal detachment typically causes flashes, floaters or a curtain-like field defect and would usually produce identifiable retinal abnormalities on examination.

Reference: Ramsay N, McKee J, Al-Ani G, Stone J. How do I manage functional visual loss. Eye. 2024;38:2257–2266. https://pubmed.ncbi.nlm.nih.gov/38778139/