Pure Alexia in Japanese and Agraphia Without Alexia in Kanji The Ability Dissociation Between Reading and Writing in Kanji vs Kana Hiroshi Mochizuki, MD, Ruriko Ohtomo, MD \s=b\ A 60-year-old right-handed Japanese with infarction of the left occipital lobe and inferior temporal gyrus initially showed pure alexia in kana and kanji. Later, though pure alexia in kana persisted, his kanji reading improved markedly, but with little improvement of kanji writing. We speculate that different pathways are involved in kanji reading and writing. Wernicke's area and its surrounding left middle temporal lobe might play the most important role for kanji reading when visual information is transmitted by any pathway. The pathway from Wernicke's area to the left occipital lobe via the middle and inferior temporal pathway may be indispensable for kanji writing. We postulate "agraphia without alexia in kanji" due to left inferior temporal subcortical damage. man by impaired reading of kana and kan¬ ji, as well as impaired writing of kanji to some degree.14 Alexia with agraphia due to the left angular lesion is characterized by impaired writing of kana and kanji and reading of kana, but kanji reading is preserved.13'5'6 Alexia and agraphia in kanji due to a lesion in the inferior posterior part of left temporal lobe is characterized by impaired reading and writing of kanji but not of kana.1'3'7'9 We describe a patient with pure alexia showing dissociation between reading and writing kanji, and we postulate the new clinical entity termed agraphia without alexia in kanji. REPORT OF A CASE {Arch Neurol 1988;45:1157-1159) 60-year-old right-handed Japanese hospital because of right hemianopsia. He graduated from law school, and became a high school teacher. He had been suffering from hypertension for ten years, and arrhyth¬ A man was admitted to our T^he Japanese language has two dif¬ ferent systems of writing: kana or syllabograms and kanji or morpho- grams. The pathologic mechanism of reading and writing Japanese is dif¬ ferent from that in Indo-European languages. In Japanese, dissociated disturbances between reading and writing in kana vs kanji have been reported (Table). Pure alexia, due to a lesion in the left occipital lobe and the splenium of the corpus callosum, is characterized Accepted for publication Nov 17, 1987. From the Department of Neurology, Institute of Brain Diseases, Tohoku University School of Medicine, Sendai, Japan. Reprint requests to Department of Neurology, Institute of Brain Diseases, Tohoku University School of Medicine, 1-1, Seiryo-machi, Sendai 980, Japan (Dr Mochizuki). mia and diabetes mellitus for five years. In the morning of April 8, 1987, he suddenly had difficulty in reading and writing even the names of his friends. That afternoon while driving, he struck the rear of the car in front of him, and noticed that his right visual field was restricted. On April 9, 1987, a brain computed tomographic (CT) scan performed at another hospi¬ tal revealed a large low-density area in the posterior part of the left cerebral hemi¬ sphere. He was transferred to our hospital on April 10, 1987. On admission, his general physical examination showed no abnormalities but irregular pulse. Neurologically, his con¬ sciousness was clear and alert, he was cooperative, and his faculty was normal. He showed right-sided homonymous hemianopia, but was otherwise normal. He did Downloaded From: http://archneur.jamanetwork.com/ by a University of Michigan User on 06/16/2015 not show right hemiparesis or sensory disturbances. Neuropsychologic examinations revealed pure alexia in both kana and kanji, he had difficulties in naming colors and copying letters, figures, and objects, but he showed no aphasie disturbances; his spontaneous speech, comprehension, repetition, naming objects, and prosody were normal. Dyscalculia, right-left confusion, finger agnosia, and other agnosia and apraxia were not noted. Computed tomography of the brain showed a large low-density area in the left posterior cerebral artery region (Figure). Magnetic resonance imaging of the brain in sagittal sections revealed an intact cor¬ pus callosum. An angiogram of the left vertebral region showed marked stenosis at the postcommunical segment of the left posterior cerebral artery, and poor circula¬ tion in this area. Neuroradiologically, the lesion constricted the territory of the left posterior cerebral artery, including corti¬ cal and subcortical structures of the occip¬ ital lobe and the inferior temporal gyrus. The splenium of the corpus callosum, left cingulate, lingular, fusiform, superior and middle temporal, and angular gyri were intact. The diagnosis of cerebral infarction due to thromboembolism in the left posterior cerebral artery lesion with pure alexia was made. Laboratory tests also revealed hyperlipidemia, glucose intolerance, and atrial fibrillation. The Table summarizes the time course of his reading and writing ability in kana vs kanji. The examinations were performed as follows: we selected 48 kana letters (all of the hira-kana letters) and 100 kanji letters that are taught during the first and second grades of elementary school. The average Japanese adult can read and write all the test letters. In each examination, a random sample of 50 kana letters and 50 kanji letters from the test letters were used. On April 10, 1987, the day of admission, he showed marked reading disturbance in both kana and kanji to the same degree. The kinesthetic facilitation gave no signif¬ icant improvement. Although his writing ability in kana was almost normal, he showed moderate difficulty in kanji writ¬ ing. On April 19, 1987, the 12th day after onset, he showed slight improvement in reading and writing in both kana and kanji. He could read 40% of the kana test letters with kinesthetic facilitation, but 20% without. In contrast, kinesthetic gave no significant improvement in kanji read¬ ing; 45% with and 40% without. On May 1, 1987, his reading ability in kanji improved greatly. The kanji reading (74% ) was better than the writing (58% ). On the other hand, the pattern of pure alexia persisted in kana letters (kana read¬ ing, 38%; writing, 98%). He was discharged on May 21, 1987. pally pure alexia in both kana and kanji, and the functional damage might have been greater than the low-density area detected by CT. The it might involve a different pathway, ventral route from Wernicke's area to occipital lobe via the posteroinferior temporal lobe, which is indispensable for kanji processing. The most important feature of our case was the dissociated improvement in reading and writing in kanji. At first, the patient showed princi- pathologic mechanism is speculated to be a visuoverbal disconnection at the paraventricular white matter of the left occipital and temporal lobes, which would compromise the inter- Dissociated Alexia and/or Agraphia in Three Pathologic Conditions: Our Case, Oka and Coworkers' Case, and Our Hypothesis* Kanji Kana Lesion Reading Pure alexia Left occipital, XX Alexia with Left angular XX Writing Reading Writing XX splenium XX XX agraphia Alexia and COMMENT agraphia in Iwata13 proposed a hypothetical neuronal mechanism in the reading and writing of kanji and kana as follows: neuropsychologic processing of the kana is phonological, and that of the kanji is visuosemantic. In read¬ ing, visually perceived graphemes recognized in the visual area of the occipital lobe. This information is then conveyed to Wernicke's area by two different pathways.10 The dorsal pathway via the angular gyrus mainly mediates the phonological processes involved in kana reading. The ventral route passing through the posterior are part of the middle and inferior tempo¬ ral gyri is the semantic reading path¬ way, and is indispensable for kanji reading. In writing, the Broca's and motor kanji XX Left XX posteroinferior temporal_ Our case April 10, %t Left occipital, 86 18 94 40 74 inferior, and middle temporal gyri April 19, %f May 1, %t 20 Left occipital, inferior 38 56 58 temporal gyrus Oka and Left fusiform and coworkers'8 inferior case, %t temporal Agraphia without alexia in 99 gyrus Left inferior 86 XX temporal gyrus kanji (hypothesis) *0 indicates preserved; X, moderately disturbed; and XX, markedly disturbed. ( Values indicate percentage of correct answers. association areas are the final coordi¬ nation centers, but the angular gyrus plays an important role in sending the graphic information to the motor areas. However, spontaneous writing and responses to dictation are usually initiated by Wernicke's area that gives rise to two different pathways to the angular gyrus. One is the auditory-somesthetic association pathway leading directly from Wernicke's area to the angular gyrus, kana writing mainly depends on the intactness of this route. The second pathway is from Wernicke's area to the occipital lobe by way of the posteroinferior temporal area. This is the pathway involved in selecting the correct kanji graphemes according to the meaning of the word, and thus recalled visual engrams of letters are sent to the angular gyrus. Though kana processing is similar to the neural mechanism of the Indo- European languages, kanji processing is different. As the kanji system has complex visuosemantic information, Computed tomography confirmed lesion in left occipital lobe and inferior temporal gyrus. Notice that Wernicke's area, middle temporal, and angular gyri were spared. Downloaded From: http://archneur.jamanetwork.com/ by a University of Michigan User on 06/16/2015 hemispheric and intrahemispheric visual pathways.1113 The difficulty in kanji writing could be explained by Iwata's1'3 hypothesis. Later, though pure alexia in kana persisted, he showed marked improve¬ ment in reading kanji, but not in writing kanji. The dissociated im¬ provement between kanji reading and writing was obvious. The problem of reading and writing dissociation in kanji remains to be solved. If the inferior temporal gyrus is indispensable for kanji reading, no improvement could occur in our case. The great improvement in kanji read¬ ing may be related to the middle tem¬ poral gyrus in which CT did not dem¬ onstrate organic damage. We specu¬ late that visual information is trans- ferred from the right visual cortex to the right middle temporal gyrus via the inferior longitudinal fasciculus,10 from right to left middle temporal gyrus via the intact corpus callo¬ sum,12·13 finally reaching Wernicke's area. In rare instances, patients show the dissociation in reading and writing in kanji. Oka and coworkers8 described a patient, with subcortical hemorrhage of left inferior temporal gyrus and fusiform gyrus, who showed 84% kan¬ ji reading, 54% kanji writing, 94% kana reading, and 99% kana writing ability. The common lesion between the case of Oka and coworkers8 and our case is the subcortical lesions of the inferior temporal gyrus. The pathways of Kanji reading and kanji writing should be near each other in the ventral route for the visuosemantic kanji processing, but they are different and separable. The inferior temporal gyrus is not indis¬ pensable for kanji reading. Wer¬ nicke's area and its surrounding left middle temporal lobe might play the most important role when visual information reaches it by any path¬ way. In kanji writing, the pathway from Wernicke's area to the left occip¬ ital lobe via the middle and inferior temporal pathway is indispensable. We propose a new clinical entity agraphia without alexia in kanji due to left inferior temporal subcortical damage considering our case and the case of Oka and coworkers.8 References 1. Iwata M, Sugishita M, Toyokura Y: The Japanese writing system and functional hemispheric specialization, in Katsuki S, Tsubaki T, Toyokura Y (eds): 12th World Congress of Neurology. Amsterdam, Excerpta Medica, 1981, pp 53\x=req-\ 62. 2. Iwata M: Kanji vs Kana: Neuropsychological correlations of the Japanese writing system. Trends Neurosci 1984;7:290-293. 3. Iwata M: Neural mechanisms of reading and writing: Neurogrammatological approach, in Tsukada Y (ed): Perspectives on Neuroscience: From Molecule to Mind. Tokyo, University of Tokyo Press, 1985, pp 299-312. 4. Torii H, Enokida H: Alexia without agraphia: Its seminological features in Japanese language. Shinkei Naika 1979;10:413-419 (in Japa- nese). 5. Yamadori A: Alexia with agraphia and angular gyrus. Shitsugoshou- Kenkyu 1982;2:41-47 (in Japanese). 6. Yamadori A, Motomura N, Endo M, et al: Category-specific alexia and a neuropsychological model of reading. Shitsugoshou Kenkyu 1985;5:23-27 (in Japanese). 7. Shiota J, Kawamura M, Isono 0, et al: Alexia with agraphia produced by a localized infarction in the inferior posterior region of the left temporal lobe. Nou Shinkei 1986;38:1051-1055 (in Japanese). 8. Oka H, Asano T, Hattori S, et al: Pure alexia and alexia with agraphia caused by lesion of the left inferior temporal and fusiform gyri. Shinkei Naika 1985;23:73-76 (in Japanese). Downloaded From: http://archneur.jamanetwork.com/ by a University of Michigan User on 06/16/2015 9. 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