Author response: Teaching NeuroImages: DWI and EEG findings in Creutzfeldt-Jakob disease

We thank Drs. Yuan and Hu for their comments on our article.¹ We agree that CSF testing for prions, particularly the real-time quaking-induced conversion assay (RT-QuiC), which is superseding 14-3-3 as the test of choice in many centers, can be helpful in confirming the diagnosis of sporadic Creutzfeldt-Jakob disease (CJD) in suspected cases.² We did not pursue such testing in our patient. She already met the proposed updated diagnostic criteria for probable CJD based on having rapidly progressive dementia (criterion A); myoclonus, cerebellar signs, extrapyramidal signs (3 of the B criteria, only 2 required); EEG periodic sharp discharges and MRI diffusion-weighted imaging abnormalities in caudate and putamen (2 of the C criteria, only 1 required); and no indication of an alternative diagnosis on routine investigations (criterion D; however, some may consider CSF to be an important routine investigation, though it carries safety risks in suspected prion disease). Nevertheless, to establish the diagnosis of definite CJD, as Drs. Yuan and Hu indicated, prion disease would need to be identified by standard neuropathologic or immunocytochemical techniques, or positive RT-QuiC of CSF or nasal brushings.