Diagnostic criteria for sporadic Creutzfeldt-Jakob disease.

BACKGROUND Making a clinical diagnosis of sporadic Creutzfeldt-Jakob disease relies on the evaluation of rapidly progressive dementia, ataxia, myoclonus, changes on the electroencephalogram, and other neurological signs. A definite diagnosis, however, is confined to cases that have been evaluated neuropathologically or by equivalent diagnostic techniques. This places a high priority on the establishment of reliable neuropathologic methods for the investigation and diagnosis of Creutzfeldt-Jakob disease. OBJECTIVE To evaluate existing morphological and laboratory diagnostic techniques to reach a consensus on the definition of "definite Creutzfeldt-Jakob disease." METHODS The existing morphological techniques, particularly immunohistochemistry, used in 4 laboratories--Germany, Great Britain, Japan, and the United States--are evaluated, and various laboratory diagnostic techniques are discussed. RESULTS Immunohistochemistry with antibodies against the prion protein combined with special tissue pretreatment regimens gives reliable diagnostic results and, for its applicability to formalin-fixed and paraffin-embedded tissue, is superior to other techniques that may be more sensitive but require fresh, unfixed brain tissue. CONCLUSIONS Our experience suggests the following regimen for the diagnosis of suspected Creutzfeldt-Jakob disease: light microscopy of various brain regions, which in typical cases may lead to definite diagnosis. Immunohistochemistry with antibodies against the prion protein is preferable in all suspected cases of Creutzfeldt-Jakob disease and is mandatory whenever a routine histological workup does not yield definite results. Additional special techniques can be applied if required.