50-year old gentleman presented with acute onset inability to read (alexia). However, he was able to write (he had no agraphia). On dictation, he could write on paper, however, he was not able to read what he had written. This clinical syndrome is called “alexia without agraphia” or pure alexia.
MRI brain showed an acute infarct in the left temporo-parietal regions as shown in the MRI brain images above.
Ability to read usually depends on posterior regions (occipital lobe), whereas ability to write depends on anterior brain regions (temporal and frontal lobes). The white matter fibres interconnecting occipital and anterior temporal lobes of brain are called inferior longitudinal fasciculus (ILF). Therefore, I presume that in this case, alexia occurred due to the involvement of ILF due to the infarct.