Unexplained Acute Homonymous Hemianopia as a Presentation of Creutzfeldt-Jakob Disease.

Creutzfeldt-Jakob disease (CJD) is the most common prion disorder that affects humans. The Heidenhain variant (HvCJD) of sporadic CJD (sCJD) is characterized by an array of often bizarre visual symptoms, which may precede progressive fatal neurodegeneration. Here, we describe a patient who presented with left homonymous hemianopia following a fall. Initial MRI and workup for vascular, autoimmune, infectious, paraneoplastic, or metabolic causes were unremarkable. Ophthalmological assessments suggested unexplained visual field loss with a possible functional overlay due to variability on examination. Over the following month, her condition deteriorated with progressive impaired awareness, involuntary movements, and finally akinetic mutism. Serial electroencephalography (EEG) demonstrated abnormalities consistent with significant encephalopathy with the development of periodic discharges. Further magnetic resonance imaging (MRI) showed parieto-occipital cortical ribboning. Altogether, the findings were consistent with a diagnosis of prion disease, more specifically, the Heidenhain or posterior variant of the condition. She died within six weeks of presentation. This report highlights the diagnostic challenges posed by HvCJD in patients with unexplained visual field loss, which can mimic a posterior circulation stroke or a functional neurological disorder. A normal MRI scan does not exclude CJD, especially in the early stages of the disease. Serial MRI and EEGs are needed in patients who present with unexplained and rapidly progressive encephalopathy with associated neurological symptoms. Early CSF analysis, including real-time quaking-induced conversion (RT-QuIC), should be considered in similar cases.