Posterior Cortical Atrophy (PCA) or Benson’s syndrome is a rare progressive clinico-radiological entity, characterized by the clinical consequences of an atrophy of the primary visual cortex (occipital), as well as the dorsal (occipitoparietal, “where?”) and ventral (occipitotemporal, “what?”) visual streams (for a recent review, see Beh and coworkers). Problems start typically in the late sixth, early seventh decade, and patients present initially with–often vague-visual complaints due to disturbed high-order visual processes, in the absence of significant ophthalmological abnormalities. Most prominent features of PCA are elements of Balint’s syndrome (simultanagnosia, ocular apraxia and optic ataxia) and of Gerstmann’s syndrome (finger agnosia, right-left confusion, agraphia and acalculia), but also spatial disorientation, visual agnosia, alexia, anomia, apraxia, prosopagnosia, hemineglect or transcortical sensory aphasia.
PCA is often considered as an atypical form of Alzheimer’s disease (AD), since most cases present findings compatible with this diagnosis, either because of post-mortem evidence of plaques and tangles or of in vivo evidence of abnormal amyloid burden, as measured by amyloid positron emission tomography (PET) imaging or cerebrospinal fluid (CSF) biomarker analysis. However, in some cases, pathological studies have found alternative diagnoses, such a prion diseases, corticobasal degeneration (CBD), subcortical gliosis or Lewy body disease (LBD).