Question

A 70-year-old patient presents with intermittent myoclonic jerks of recent onset, and the EEG shows bilateral periodic spike-wave complexes. What is the most probable diagnosis?

• A. Herpes simplex encephalitis
• B. Lewy body dementia
• C. Alzheimer's disease
• D. Creutzfeldt-Jakob disease (CJD)

Hint:

Rapidly progressive dementia with myoclonus and periodic EEG complexes in an elderly patient.

Answer 1

The Correct Option is D

Begin from the single most specific clue in the vignette: periodic spike-wave activity on EEG appearing together with myoclonic jerking. Among neurodegenerative and infectious causes of dementia, this electro-clinical pairing is essentially a signature of a transmissible spongiform encephalopathy. Sporadic Creutzfeldt-Jakob disease classically strikes around the seventh decade and is defined by a rapidly progressive dementia, startle myoclonus, and the periodic synchronous discharges that the EEG demonstrates here. Now contrast the distractors. Alzheimer's disease evolves over years as a gradual memory-led decline and does not produce periodic complexes early. Lewy body dementia is recognised by fluctuating attention, well-formed visual hallucinations and spontaneous parkinsonism rather than EEG periodicity. Herpes simplex encephalitis is an acute febrile illness with temporal-lobe involvement and lateralised epileptiform discharges, a separate picture. Because only the prion disease unites recent myoclonus with bilateral periodic spikes in a 70-year-old, the diagnosis is settled.
$ \text{rapid dementia} + \text{myoclonus} + \text{periodic EEG spikes} \Rightarrow \text{CJD} $
\[\boxed{\text{Creutzfeldt-Jakob disease (CJD)}}\]