A 63-year-old right-handed man was referred for a neurologic consultation for difficulties with word finding. The patient could not name familiar objects and had to resort to pointing at them. On examination, he scored a 25/30 on the Montreal Cognitive Assessment, revealing issues with visuospatial relations. In the clock-drawing test, he reversed the positions of 3 and 9. On the Boston Naming Test, he required phonemic cueing for objects such as “stethoscope” and “accordion.” Neuropsychological testing revealed moderately impaired visual sequencing and psychomotor speed. A magnetic resonance image demonstrated mild atrophy of the left occipital lobe (image A, arrow), suggesting a diagnosis of posterior cortical atrophy (PCA). Fluorodeoxyglucose positron emission tomography was ordered, and images revealed hypometabolism in bilateral occipital cortices, more on the left than on the right (image B), confirming the diagnosis of PCA. 

Posterior cortical atrophy is a rare variant of Alzheimer dementia. Diagnostic criteria include insidious onset and gradual progression; visual deficits without ocular disease; relatively preserved episodic memory, verbal fluency, and personal insight; visual agnosia, simultanagnosia, optic ataxia, ocular apraxia, dyspraxia, and environmental disorientation; and absence of stroke or tumor.^1,2 Neurodegeneration occurs mainly in the primary visual and secondary visual associative cortices. Although this patient's symptoms were limited to visual agnosia, the neurodegeneration found on imaging confirmed the presence of PCA.