Left hemisphere pathways in reading: inferences from pure alexia without hemianopia.

In pure alexia, reading is impaired despite almost normal speech, spelling, and writing. We studied a right-handed man with pure alexia, but no hemianopia. He had more difficulty reading longer words (word-length effect), but had no selective reading impairment in phonologic or semantic analysis. Clinical-CT correlation suggests that (1) left hemisphere visual pathways crucial for reading arise from or pass close to the left occipitotemporal or inferior temporal gyrus, and (2) relevant transcallosal fibers from the right hemisphere course inferior to the posterior horn of the left lateral ventricle before ascending to left hemisphere language areas.