Which disease is associated with rapidly progressive dementia and characteristic EEG periodic sharp wave complexes?

• A. Alzheimer disease
• B. Creutzfeldt-Jakob disease
• C. Parkinson disease
• D. Multiple sclerosis

Answer: (B)

Rapidly progressive dementia with a characteristic EEG pattern points to a prion disease, most classically Creutzfeldt-Jakob disease. This condition causes fast decline in cognition over weeks to months and often comes with myoclonus and visual or cerebellar symptoms. The EEG shows periodic sharp wave complexes—episodes of high-amplitude sharp waves that recur at regular intervals (often every half to a couple of seconds). This pattern, in the right clinical context, is highly suggestive of CJD and helps distinguish it from other dementias that progress more slowly (like Alzheimer disease) or from conditions with different motor or demyelinating features (such as Parkinson disease or multiple sclerosis). In practice, this clue would lead to targeted imaging (MRI with diffusion-weighted sequences) and CSF testing to support the diagnosis, with brain tissue confirmation only rarely needed.