A 68-year-old man develops subacute cognitive decline over 3 months with myoclonus, cerebellar ataxia, visual disturbances, and pyramidal signs. EEG shows periodic sharp wave complexes. What is the most likely diagnosis?
- A Frontotemporal dementia
- B Creutzfeldt-Jakob Disease (CJD) ✓
- C Autoimmune limbic encephalitis
- D Vascular dementia
Explanation
Sporadic CJD presents with rapidly progressive dementia (weeks to months), myoclonus, cerebellar signs, visual disturbances (Heidenhain variant), and pyramidal/extrapyramidal features. EEG showing periodic sharp wave complexes (PSWCs) — 1–2 Hz triphasic waves — is characteristic. CSF 14-3-3 protein and RT-QuIC assay are diagnostic aids. MRI DWI shows cortical ribboning and basal ganglia signal changes. Prion protein (PrPSc) accumulation is the pathological hallmark. Median survival is 4–6 months after symptom onset. Autoimmune encephalitis would show limbic signs and CSF pleocytosis.
Reference: Kaplan & Sadock's Synopsis of Psychiatry, 11th ed.
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