World Health Organization Case Definition for vCJD (6)
| Class or Diagnosis | Definition |
|---|---|
| I | |
| A | Progressive neuropsychiatric disorder. |
| B | Duration of illness > 6 months. |
| C | Routine investigations do not suggest alternative diagnosis. |
| D | No history of potential iatrogenic exposure. |
| E | No history of familial form of transmissible spongiform encephalopathy. |
| II | |
| A | Early psychiatric symptoms.* |
| B | Persistent painful sensory symptoms.† |
| C | Ataxia. |
| D | Myoclonus or chorea or dystonia. |
| E | Dementia. |
| III | |
| A | EEG does not show typical appearance of sCJD (or no EEG).‡ |
| B | Brain MR image shows bilateral symmetrical pulvinar high signal intensity.§ |
| IV | |
| A | Positive tonsil biopsy.‖ |
| Definite | Class IA and neuropathologic confirmation of vCJD.# |
| Probable | Class I and 4 of 5 of class II and classes IIIA and IIIB, or class I and class IVA. |
| Possible | Class I and 4 of 5 of class II and class IIIA. |
* Depression, anxiety, apathy, withdrawal, delusions.
† This includes both frank pain and/or dysesthesia.
‡ Generalized triphasic periodic complexes at approximately one per second.
§ Relative to the signal intensity of the other deep gray matter nuclei and cortical gray matter. (Modification of the case definition of the characteristic MR imaging features [IIIB] to “Brain MR image shows bilateral symmetrical pulvinar hyperintensity relative to the signal intensity of the anterior putamen” is recommended to improve the accuracy of the pulvinar sign in vCJD).
‖ Tonsil biopsy is not recommended routinely, nor in cases with an EEG appearance typical of sCJD, but may be helpful in suspect cases in which the clinical features are compatible with vCJD and in which the MR image does not show bilateral pulvinar high signal intensity.
# Spongiform change and extensive prion protein deposition with florid plaques throughout the cerebrum and cerebellum.