Brain MRI Lesions in Alexia Without Agraphia: A Case-Control Study.

Background: Alexia without agraphia (AWA) is an acquired reading disturbance associated with left posterior cerebral artery (PCA) infarction. Based on autopsy and neuroimaging, there are two explanations for its pathogenesis: a visual cortex-language cortex disconnection and a visual word-form agnosia. Our goal was to discover if more refined brain imaging in a case-control study would provide further imaging support for either of these hypotheses.

Methods: A neuroradiologist masked to the presence of AWA reviewed diffusion-weighted and fluid-attenuated inversion recovery brain MRIs in patients who had left PCA infarctions with AWA (9 patients) or without AWA (18 patients) to characterize lesions in the splenium, left forceps major, and left fusiform gyrus.

Results: Patients with AWA had various combinations of lesions in the splenium, left forceps major, and left fusiform gyrus. One of these regions was involved in 3 patients, 2 were involved in 3 patients, and 3 were involved in 3 patients. Most (89%) patients without AWA lacked involvement of any of these 3 regions.

Conclusions: Our data provide imaging evidence for the two existing hypotheses of AWA. Involvement of any of these lesions on MRI imaging should encourage clinicians to obtain further neuropsychological testing.