[Homonymous hemianopia and posterior cortical atrophy].

INTRODUCTION: Posterior cortical atrophy (PCA) is a clinically and radiologically defined syndrome, in which predominant symptoms focus on higher visual dysfunction with progressive course and association with cortical atrophy or hypometabolism that predominates in the posterior part of the hemispheres. Homonymous hemianopia (HH) has rarely been described in this syndrome.
METHODS: We report on six patients (four females, two males, aged 63 to 80) referred for visual disorder which led to demonstration of HH using perimetry testing. These patients were followed for 1 to 5 years after discovery of HH. Brain imaging with MRI or CT scan was obtained in the six cases and a SPECT scan was performed in four cases.
RESULTS: HH was left-sided in four cases and right-sided in two cases. Associated symptoms related to higher visual dysfunction were simultagnosia, alone or as part of a full Balint's syndrome, alexia, constructional apraxia, dressing apraxia, visual form agnosia, prosopagnosia and hemispatial neglect. These symptoms were mild at onset but invariably worsened with disease progression. Dementia eventually developed in all cases. The clinical diagnosis was probable Alzheimer's disease in five cases and corticobasal degeneration in one case. Radiology showed posterior cortex atrophy in all cases as well as reduced cerebral blood flow in the same region, with an asymmetrical pattern compatible with the side of HH.
CONCLUSION: Elementary cortical lesions in PCA can develop mainly in the associative visual areas and even in the primary visual area, resulting in HH. HH has rarely been documented in PCA, but its prevalence would probably be higher if systematic search was conducted. Apparently isolated HH of insidious onset should suggest PCA and lead to neuropsychological testing and search for discrete atrophic changes of the posterior cortex on MRI as well as for metabolic alterations with SPECT or PET.