Table 1.

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.