CJD is a rapidly progressive dementia caused by prions (infectious agents composed only of protein). The prion proteins can be transmitted by neurosurgical instruments and huma-derived pituitary hormones.
Features include rapid cognitive impairment, which may be preceeded by anxiety and depression. Eventually, physical features become prominent, including muscle disturbance (rigidity, tremor, wasting, spasticity, fasciculations, cyclonic jerks, and choreoathetoid movements).
Convulsions may also occur. The EEG is acharacteristic (showing stereotypical sharp wave complexes).
Death occurs within 6-8 months
New variant CJD (nvCJD)
Occurs secondary to ingestion of bovine spongiform encephalopathy (BSE) infected beef. It is more common in younger adults.
Same as for CJD but decline is slower, with mortality occurring within 18 months.
There are no typical EEG changes in nvCJD, although there is a characteristic feature on MRI (symmetrical hyperintensity in the posterior nucleus of the thalamus- the pulvinar sign).