Sporadic CJD
Definite
Diagnosed by standard neuropathological techniques
- And/Or immunocytochemically
- And/Or Western blot confirmed protease-resistant PrP
- And/Or presence of scrapie-associated fibrils.
Probable
Neuropsychiatric disorder plus positive RT-QuIC in cerebrospinal fluid (CSF) or other tissues.
OR
Rapidy progressive dementia and at least two out of these four clinical features:
- Myoclonus
- Visual or cerebellar signs
- Pyramidal/extrapyramidal signs
- Akinteic 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 a disease duration of less than 2 years
- High signal in 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 investigations indicating an alternative diagnosis.
Possible
Progressive dementia; and at least two out of these four clinical features:
- Myoclonus
- Visual or cerebellar signs
- Pyramidal/extrapyramidal signs
- Akinteic 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 investigations indicating an alternative diagnosis.
Iatrogenic CJD
About 1 percent of Classic CJD cases are iatrogenic, meaning spread through healthcare products or in a healthcare setting.
To meet the definition for an iatrogenic case, the case must meet the following criteria:
Progressive cerebellar syndrome in a recipient of human cadaveric-derived pituitary hormone
OR
Sporadic CJD with a recognized exposure risk, 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.
