Table 4.
Neuroanatomical classification of alexia/agraphia.
| Types of alexia/agraphia | Alexia | Agraphia |
|---|---|---|
| I. Aphasic alexia/agraphia | ||
| II. Primary nonaphasic alexia/agraphia | ||
| 1. Pure alexia | ||
| A. Splenium type: medial occipital gyri (or optic radiation, lateral geniculate body) + splenium (or callosal radiation, forceps major) | kanji >= kanaa | |
| B. Nonsplenium type | ||
| Fusiform type: mid-fusiform gyrus (BA 37) | kanji > kana | |
| Posterior occipital type: post-fusiform/inferior occipital gyri (BA 18/19) | kana | |
| 2. Alexia with agraphia | ||
| A. Angular type: angular/lateral occipital gyri (BA 39/19) | kana | kanji |
| B. Posterior inferior temporal type: mid-fusiform/inferior temporal gyri (BA 37) | kanji | kanji |
| 3. Pure agraphia | ||
| A. Posterior middle temporal gyrus (BA 21/37) | kanji | |
| B. Angular gyrus (BA 39) | kanji | |
| C. Supramarginal gyrus (BA 40) | kana | |
| D. Superior parietal lobule (intraparietal sulcus, BA 7) | kanji > kana | |
| E. Posterior middle frontal gyrus (BA 6) | kanji > < kanab | |
| III. Secondary nonaphasic alexia/agraphia | ||
| 1. Alexia | ||
| A. Hemianopic alexia | ||
| B. Neglect dyslexia | ||
| C. Callosal alexia | ||
| D. Thalamic alexia | ||
| 2. Agraphia | ||
| A. Constructional agraphia | ||
| B. Neglect dysgraphia (spatial agraphia) | ||
| C. Callosal agraphia | ||
| D. Thalamic agraphia |
BA, Brodmann area. Revised with permission from Sakurai et al. (2010).
a
Reading is more impaired in kanji than in kana or is equally impaired.
b
Writing is more (or less) impaired in kanji than in kana.