Erfan Bashar
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Creutzfeldt-Jakob Disease

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Educational scope notice: This is a study note for medical students, not medical advice, diagnosis, or treatment guidance. Clinical management should follow local protocols and current guidelines.

Creutzfeldt-Jakob disease is the most common human prion disease. It sits among the CNS infections because the agent transmits disease, though it carries no nucleic acid at all. A misfolded prion protein induces normally folded copies to misfold in turn. The aggregates destroy neurons, leaving the spongiform vacuolation seen under the microscope.

Three forms share that mechanism. Sporadic disease from spontaneous misfolding is the most common. Familial disease reflects PRNP mutations that ease misfolding. Iatrogenic disease follows contaminated instruments, dura grafts, or cadaveric pituitary hormone.

Weeks, not months or years

Tempo is the clinical hallmark. Alzheimer disease declines over years and vascular dementia over months. Creutzfeldt-Jakob disease produces profound decline over weeks, with onset typically in the late 50s to early 60s and death commonly within 4 to 5 months. Rapidly progressive dementia with myoclonus, pyramidal signs such as spasticity and hyperreflexia, cerebellar ataxia, visual disturbance, and behavioural change forms the recognisable syndrome.

The EEG finding is among the most distinctive in neurology: bilaterally synchronous periodic sharp-wave complexes recurring roughly every second, on a slow disorganised background. It appears in about two-thirds of sporadic cases and fades late, so its absence never excludes the disease.

MRI often shows cortical ribboning and basal ganglia hyperintensity on diffusion-weighted sequences, frequently before the EEG turns characteristic. The signal sits in caudate and putamen or across at least two cortical regions on diffusion or FLAIR imaging. Cerebrospinal fluid RT-QuIC detects seeded misfolding with sensitivity above 90% and near-complete specificity, substantially outperforming the older 14-3-3 assay. Probable sporadic disease can therefore rest on a compatible neuropsychiatric disorder plus positive RT-QuIC, or on rapidly progressive dementia with at least two of myoclonus, visual or cerebellar signs, pyramidal or extrapyramidal signs, or akinetic mutism plus a supportive EEG, 14-3-3, or MRI result. Definite diagnosis still requires brain tissue by biopsy or autopsy: RT-QuIC never substitutes for neuropathology.

Variant disease from the bovine spongiform encephalopathy episode struck younger patients with prominent early psychiatric features, and it is now rare after public health controls.

There is no effective treatment; care is supportive and palliative, including myoclonus control. Sporadic disease does not spread by social contact. Standard sterilisation does not inactivate prions, so the safest course is to destroy instruments exposed to high-infectivity tissue. Where that is impractical, the fallback is sodium hydroxide immersion plus gravity autoclaving at 121 degrees, then cleaning and routine sterilisation. The practical imperative is to exclude treatable rapidly progressive mimics, above all autoimmune encephalitis and herpes encephalitis, before accepting this diagnosis.

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