Lewy Body Dementia as an Underlying Etiology for Posterior Cortical Atrophy Initially Presented with Visual Agnosia and Alexia: A Case Report

Posterior cortical atrophy (PCA) is a neurodegenerative disorder with cerebral atrophy in the parietal, occipital, or occipitotemporal cortices, and is characterized by visuospatial and visuoperceptual impairments. The majority of the disorder is compatible pathologically with Alzheimer’s disease (AD). However, many patients show no memory loss until late stages of the disease. We encountered a case where a combination of several imaging modalities, in conjunction with symptoms and neuropsychological exams, led not only to a diagnosis of PCA but also identified its underlying etiology. A 62-year-old Japanese man presented to ophthalmology with visual impairment and without abnormalities in his visual acuity or visual fields. Alexia was identified, particularly pertinent to reading Kanji, at the neurology clinic. His initial Mini-Mental State Examination (MMSE) revealed a score of 27/30 points with delayed recall (-2) and constructional apraxia (-1). The score dropped to 25 points six months later. Brain MRI demonstrated occipital atrophy. Brain single photon emission computed tomography (SPECT) showed hypoperfusion in the medial and lateral occipital lobes. The myocardial meta-iodobenzylguanidine (MIBG) scintigraphy showed no evidence of myocardial postganglionic sympathetic dysfunction. Posterior cortical atrophy (PCA) was diagnosed in conjunction with the symptoms, including alexia and visual impairment. He developed symmetric parkinsonism one year later. Lewy body dementia (DLB) was thus considered as the underlying etiology for the PCA. Additionally, alexia pertinent to reading Kanji has not been reported before. We herein report this rare case.