Sporadic CJD

Specific

Diagnosed by standard neuropathological techniques

• And/or immunocytochemical
• And/or Western blot confirmed protease-resistant PrP
• And/or presence of scrapie-associated fibrils.

Likely

Neuropsychiatric disorder plus positive RT-QuIC in cerebrospinal fluid (CSF) or other tissue.

OR

Rapidly progressive dementia and at least two out of these four clinical features:

• Myoclonus
• Visual or cerebellar signs
• Pyramidal/extrapyramidal signs
• Akinthean mutism

AND

A positive result on at least one of the following laboratory tests:

• a typical EEG (periodic sharp wave complexes) during an illness of any duration
• a positive 14-3-3 CSF assay in patients with disease duration of less than 2 years
• High signal in the caudate/putamen on magnetic resonance imaging (MRI) brain scan or at least two cortical regions (temporal, parietal, occipital) either on diffusion-weighted imaging (DWI) or fluid-attenuated inversion recovery (FLAIR)

AND

Without routine tests that indicate an alternative diagnosis.

Possible

Progressive dementia; and at least two of these four clinical features:

• Myoclonus
• Visual or cerebellar signs
• Pyramidal/extrapyramidal signs
• Akinthean mutism

AND

The absence of a positive result for any of the four tests above that would classify a case as “probable”

AND

Duration of illness less than two years

AND

Without routine tests that indicate an alternative diagnosis.

Iatrogenic CJD

About 1 percent of classic CJD cases are iatrogenic, meaning spread through health products or in health care.

To meet the definition for an iatrogenic case, the case must meet the following criteria:

Progressive cerebellar syndrome in a recipient of human-derived pituitary hormone

OR

Sporadic CJD with a recognized risk of exposure, such as neurosurgery with dura mater implantation.

Familial CJD

An estimated 5-15 percent of classic CJD cases are familial due to an inherited gene mutation. To meet the case definition for familial CJD, a case must:

Have definite or probable CJD and definite or probable CJD in a first-degree relative

AND/OR

Neuropsychiatric disorder and disease-specific PrP gene mutation.