MCQ Neurology Answer 20

The Correct Answer is C

The rapid decline may be a clue that this man has CJD – questions about this have been asked in prior years.

Prion disorders such as Creutzfeldt-Jakob disease (CJD) are very rare conditions (approximately 1 per million population) that commonly produce dementia. CJD is usually a rapidly progressive disease associated with dementia, rigidity, and myoclonus, causing death in less than 1 to 2 years. These clinical characteristics may also rarely be seen in AD, and the differential diagnosis usually depends on the slower progression of AD and the markedly abnormal periodic EEG discharges seen in CJD.

Ataxia or cortical blindness may also accompany CJD. The transmissible agent, or prion, consists principally of an abnormal isoform of a host-encoded protein, the prion protein (PrP), which accumulates in affected brains. The abnormal disease-causing prion protein (PrPSC) is derived from the normal prion protein (PrPC) by a posttranslation mechanism that may represent a physical conformational change. PrPSC apparently acts as a template that promotes the conversion of PrPC to PrPSC, and this cascading conformational change somehow produces neuronal damage and death.


The disease is transmissible by tissue transplantation to animals or other humans and is occasionally inherited (familial CJD, or Gerstmann-Sträussler-Scheinker disease). The inherited variety has the unique characteristic of being both a genetic and a transmissible disorder. Sporadic cases are not inherited. CJD is not contagious by touch or airborne spread. Bovine spongiform encephalopathy in the United Kingdom is thought to have resulted from cattle feed containing sheep tissues contaminated with infectious prions (PrP scrapie).

Possible transmission to the human population is under investigation. Immunoassay for a 14-3-3 brain protein in CSF may be a useful marker for transmissible spongiform encephalopathies in patients with dementia.

Category: Neurology MCQs