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CJD — MRCPsych Paper B MCQ

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HardOld Age PsychiatryCJDMRCPsych Paper B

A 58-year-old man develops rapidly progressive cognitive impairment, visuospatial dysfunction, startle-sensitive myoclonus and gait ataxia over 3 months. There was no early prominent psychiatric prodrome, persistent painful sensory disturbance, relevant healthcare exposure or family history of prion disease. EEG shows generalised periodic sharp-wave complexes at approximately 1 Hz. Diffusion-weighted MRI shows restricted diffusion in the caudate, putamen and parietal and occipital cortices, without predominant pulvinar hyperintensity. Which diagnosis is most likely?

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Correct answer: E — Probable sporadic Creutzfeldt–Jakob disease

The answer is probable sporadic Creutzfeldt–Jakob disease. Rapidly progressive cognitive impairment accompanied by myoclonus and visual or cerebellar dysfunction meets the characteristic clinical pattern. Generalised periodic sharp-wave complexes and restricted diffusion affecting the striatum and multiple cortical regions—the cortical ribbon pattern—provide strong diagnostic support. Definite CJD requires neuropathological confirmation, so “probable” is appropriate during life. Variant CJD usually presents at a younger age with an early psychiatric prodrome or persistent painful sensory symptoms and classically shows predominant pulvinar hyperintensity; typical sporadic-CJD EEG changes are usually absent early. Dementia with Lewy bodies progresses less rapidly and is characterised by fluctuations, visual hallucinations, REM-sleep behaviour disorder and parkinsonism. Anti-LGI1 encephalitis more often causes seizures, particularly faciobrachial dystonic seizures, hyponatraemia and mesial temporal abnormalities. Multiple system atrophy requires prominent autonomic failure and does not usually cause rapidly progressive dementia.

Reference: Hermann P et al. Biomarkers and diagnostic guidelines for sporadic Creutzfeldt-Jakob disease. Lancet Neurology. 2021;20:235–246. https://pubmed.ncbi.nlm.nih.gov/33609480/