Pure alexia: two cases and a new neuroanatomical classification

Abstract

Pure alexia without visual or language accompanying deficits (isolated pure alexia), represents an infrequent finding in clinical practice. It has been linked to lesions involving the splenium of the callosal corpus in classical descriptions; however, it has also been reported after occipito-temporal cortex damage in the absence of white matter implication. In this regard, a functional region called the visual word form area has been recently related to the posterior aspect of the occipitotemporal gyrus. We report two new cases of cortical hematomas leading to this rare condition and we discuss the neuroanatomical evolution of this syndrome. Finally, we propose a new classification of pure alexia based on the neuroanatomical location of the lesion, namely: (1) disconnection alexia, after posterior and dorsal lesions involving the splenium of the callosal corpus or the paraventricular white matter, often associated with visual deficits, and (2) cortical alexia, after more anterior and ventral lesions in the occipito-temporal cortex with damage of the visual word form area, that usually manifests as isolated pure alexia.