Even though the PET study revealed a total
infarct in the territory of the left PCA in our 3 cases of
pure alexia, it is still obscure which part of the left occipital lobe is most closely associated with the occurrence of the
pure alexia. In order to elucidate the intralobar localization of the
pure alexia, it is needed to have an ideal case who shows an
pure alexia due to the localized lesion within the left occipital lobe. Furthermore, high-resolution PET scanner will circumvent the problem in detecting the metabolism and blood flow in the corpus callosum which plays an important role in the pathogenesis. We have shown that the occlusion of the right PCA also produced a left unilateral
agnosia which is one of the common neurological signs in the right
MCA infarction. To tell whether the responsible lesion for the unilateral spatial
agnosia differs between the PCA occlusion and the MCA occlusion, the correlation study should be carried out in a greater number of the subjects. Two distinctive neuropsychological manifestations, cerebral
color blindness and
prosopagnosia, have been considered to be produced by the bilateral occipital lesion. The PET studies disclosed reduction of blood flow and
oxygen metabolism in both occipital lobes in our particular patient who exhibited cerebral
color blindness and
prosopagnosia.