Abstract
Introduction Creutzfeld-Jakob disease (CJD) often presents as a rapidly progressive dementia with prominent cerebellar signs and myoclonus. However, variants are recognised, including a posterior or visual presentation known as the Heidenhain variant.
Case A previously well 70-year-old man presented with a 2-month history of progressive visual and perceptual distortions. Symptoms included intense colour perception (e.g. of green grass), macropsia and micropsia (e.g. of road signs), impaired depth perception (especially when driving), and simultanagnosia (e.g. of cars and Ishihara plates). Formal neuropsychological testing was initially within normal limits. Visual acuity and formal visual field testing were normal. MRI brain performed for unrelated reasons a few weeks prior to symptom onset demonstrated increased T2/FLAIR and DWI signal restricted to the occipital and parietal cortices, mostly on the right. Repeat MRI brain at time of presentation found significant progression of these changes bilaterally. EEG showed intermittent bilateral posterior slowing but no triphasic waves or sharp wave complexes. CSF analysis revealed normal cell counts and biochemistry, along with normal protein 14–3-3 and total tau levels. However, real-time quaking-induced conversion (RT-QuIC) was positive. Sequencing of the PRNP gene did not reveal any variants to suggest familial CJD, but did demonstrate methionine/valine heterozygosity at codon 129.
Discussion The Heidenhain variant of CJD is rare but distinctive. This case is notable for highlighting radiological changes before symptom onset, limitations of traditional CSF testing, and the usefulness of RT-QuIC. Lastly, methionine/valine heterozygosity at codon 129 contrasts with prior reported cases of the variant, which usually feature methionine homozygosity.
