Prion disease
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Background
- Fatal neurodegenerative disease
- Transmissible forms:
- Variant CJD acquired by consuming diseased tissues of cows (e.g. human form of mad cow disease) or other humans (kuru)
- Iatrogenic (handling diseased corneas/brain or improperly disinfected equipment)
- Hereditary prion disease:
- Familial CJD: mutation in PRNP, which encodes prion protein
- Fatal familial insomnia
- Gerstmann-Sträussler-Scheinker syndrome
- Sporadic CJD: accounts for ~85% of cases, cause is unknown
Clinical Features
- Progressive dementia, behavioral changes, loss of cortical function over several months
- Myoclonus
- Extrapyramidal symptoms (hypokinesia)
- Cerebellar dysfunction- ataxia, dysarthria
- Coma
Differential Diagnosis
Dementia
- Degenerative
- Alzheimer's disease
- Huntington's disease
- Parkinson's disease
- Vascular
- Multiple infarcts
- Hypoperfusion (MI, profound hypotension)
- Subdural hematoma
- SAH
- Infectious
- Meningitis (sequelae of bacterial, fungal, or tubercular)
- Neurosyphilis
- Viral encephalitis (HSV, HIV), Creutzfeldt-Jakob disease
- Inflammatory
- SLE
- Demyelinating disease (e.g. multiple sclerosis)
- Neoplastic
- Primary brain tumor / metastatic disease
- Carcinomatous meningitis
- Paraneoplastic syndromes
- Traumatic
- Toxic
- ETOH
- Meds (anticholinergics, polypharmacy)
- Metabolic
- Psychiatric
- Depression (pseudodementia)
- Hydrocephalic
- Normal pressure hydrocephalus (communicating hydrocephalus)
- Noncommunicating hydrocephalus
Evaluation
- Definitive diagnosis only possible by autopsy
- Evaluate for reversible/treatable causes of dementia
- CBC, B12, folate, thiamine
- LFTs, BMP, TSH, Urinalysis
- ECG, CXR
- ETOH, Utox, urine heavy metals
- RPR, ESR, ANA, HIV
- LP
- MRI:
- Areas of increased signal intensity bilaterally, mostly in caudate and putamen
- Posterior thalamic hyperintensity
- EEG
- Usually nonspecific but abnormal
Management
- No specific treatment