Early diagnosis of a case of Heidenhain variant of Creutzfeld-Jakob disease by cerebrospinal fluid real-time quaking-induced conversion test

Sporadic Creutzfeldt-Jakob disease (sCJD) is a rare, rapidly progressive, and fatal neurodegenerative disorder caused by the accumulation of abnormal prion proteins in the central nervous system. The Heidenhain variant (HvCJD), a rare subtype of sCJD, is characterized by prominent visual symptoms at onset. Diagnosing sCJD remains challenging due to non-specific clinical presentations and the limited sensitivity and specificity of conventional tests such as magnetic resonance imaging (MRI), electroencephalography (EEG), and cerebrospinal fluid (CSF) 14-3-3 protein analysis. Recently, real-time quaking-induced conversion (RT-QuIC) has emerged as a valuable tool for improving diagnostic accuracy. We present the case of a 65-year-old man who initially experienced blurred vision and diplopia, followed by rapidly progressive dementia and dysuria. Brain MRI revealed cortical diffusion-weighted imaging (DWI) hyperintensities in the right temporo-occipital region. While his CSF 14-3-3 protein test was negative, RT-QuIC assay returned positive, leading to a final diagnosis of probable CJD. The patient died 8 weeks after diagnosis. This case highlights that HvCJD is a rare but important clinical variant in which conventional CSF 14-3-3 testing may be negative, particularly early in the disease course. In contrast, RT-QuIC demonstrates high sensitivity and specificity and can significantly aid in the early and accurate diagnosis of CJD.