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Creutzfeldt-Jakob Disease — RACP Adult Medicine MCQ

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HardNeurologyCreutzfeldt-Jakob DiseaseRACP Adult Medicine

A 65-year-old man presents with a 6-month history of progressive memory loss, personality change, and myoclonus. MRI brain shows cortical ribboning on DWI sequences. CSF 14-3-3 protein is positive and RT-QuIC assay is positive. What is the most likely diagnosis?

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Correct answer: D — Creutzfeldt-Jakob disease (CJD)

Rapidly progressive dementia with myoclonus, cortical ribboning on MRI DWI, positive CSF 14-3-3 protein, and positive RT-QuIC (real-time quaking-induced conversion) assay are diagnostic of sporadic CJD. RT-QuIC has >95% sensitivity and near-100% specificity. Autoimmune encephalitis should also be considered in the differential of rapid cognitive decline.

Reference: eTG – 2025 – Neurology; WHO – 2022 – CJD Diagnostic Criteria