Investigations/work-up
| Screen in all CJD mimic patients | Second-line test |
| Basic blood tests: routine haematology, biochemistry, calcium, magnesium, vitamin B12, HIV serology, thyroid function, antinuclear antibody, antineutrophil cytoplasmic antibody, inflammatory markers | Serum ammonia, drug levels (as appropriate) |
| Serology: Voltage-gated K-channel antibodies, NMDA-R antibodies, TPHA (neurosyphilis) | Serology for specific infections (eg, Lyme), paraneoplastic antibodies |
| Imaging: MR scan of brain, dementia protocol, including diffusion-weighted axial images and post-gadolinium imaging for lymphoma/inflammatory CNS conditions | Angiography (vasculitis, dural arteriovenous fistula, intravascular lymphoma) |
| EEG: routine recording | Electromyography and nerve conduction studies |
| CSF: for cells, biochemistry, oligoclonal bands, 14-3-3 protein, S100b protein, RT-QUIC assay, amyloid beta protein (1–42), total tau | CSF serology for NMDA-R encephalitis, measles serology, PCR for JC virus and for viruses associated with other encephalitides |
| PRNP: gene analysis | Dementia gene panel diagnostics |
| Urine: test for infection | Brain biopsy |
CJD, Creutzfeldt–Jakob disease; CNS, central nervous system; CSF, cerebrospinal fluid; EEG, electroencephalogram; JC, John Cunnigham, NMDA-R, N-methyl-D-aspartate; PRNP, prion protein gene; RT-QUIC, real-time quaking-induced conversion assay.