Cause:A transmissable spongiform encephalopathy caused by a small slow virus, similar to measles' progressive multifocal leukoencephalopathy, kuru (Nejm 1986;314:547; 1972;287:429), and scrapie; or prions (proteinaceous infectious particles); or a virino consisting of a nucleic acid/host protein combination. Human growth hormone extracts caused it before recombinant types available. Fibrillary structures in brain (Nejm 1985;312:73); rare cases are thought genetic, autosomal dominant (Nejm 1991;324:1091) plus additional genetic impact on incubation period and infectivity
Pathophys:Corticostriatospinal atrophy
Growth hormone rx from brain extracts caused an epidemic in US (Nejm 1985;313:728), and 10000 young people have now received potentially contaminated HGH in US. Not entirely inactivated by heat, formalin, or cold.
From eating beef infected w MAD COW DISEASE(bovine spongiform encephalitis); 20+ cases in Britain, esp in young adults (Jama 1997;278:1008) but not in the US beef (Jama 1999;281:2330) though may be present in hunters eating squirrel brains; this new variant is much more rapidly progressive.
Natural incidence = 1-2/million population; 100× as frequent in Libyan Jews
Sx:Onset usually age >35 yr, all >20 yr except in new variant C-J disease; dementia; myoclonus; psychiatric sx; ataxia
Si:Dementia and myoclonus plus occasionally long tract si's and/or parkinsonism and/or anterior horn cell degeneration
r/o Hashimoto’s thyroiditis which can mimic the sx but is treatable w steroids; anoxic damage, syphilis (by CSF exam), inclusion encephalitis (in children and adolescents), Alzheimer’s (slower course), lipid storage disease (by positive family history), AIDS
Lab:
CSF:LP may be normal, but distinctive CSF proteins (14-3-3 protein) can distinguish from all other dementias, 96% sens but less specif in demented pts (HMS 6/08, Nejm 1996;335:924)
Noninv:EEG shows diagnostic slow waves in bursts; may be focal
Path:Brain bx shows slow virus marker proteins by western blot, 0% false pos, occasionally false negatives occur (Nejm 1986;314:547); or prion protein by western blot in vivo bx of cribiform plate/olefactory bulb (Nejm 2003;348:711)
Xray:MRI shows extensive cortical hyperintensity (Neurol 2007;69:1881)