Unexpected reading dissociation in a Brazilian Nisei with crossed aphasia

There is an increased interest in reading impairments in the Japanese language, due to its particular writing system which includes two different scripts, Kanji (logograms) and Kana (phonograms). Reading dissociations between Kanji and Kana have been described, showing that each system is processed differently by the cerebral hemispheres. We describe the case of a 68 year old Brazilian "nisei" (i.e. born from Japanese parents) who had knowledge of both Japanese and Portuguese. He presented an ischemic stroke affecting the right hemisphere and subsequently developed a Broca's aphasia and an unexpected reading dissociation, with an impairment in Kana reading comprehension and a good performance in Kanji and in Portuguese. These findings suggest that the patient's right and left hemispheres have assumed opposite roles not only for oral but also for written language decodification. Keywords: Brazil-Broca's aphasia -Cerebral dominance -Cerebral infarction -Japan -Reading disability INTRODUCTION Japanese is a unique language since it includes two different writing systems, Kana (phonograms) and Kanji (logograms). Reading impairments in Japanese have been increasingly investigated in the last two decades and several studies have described reading dissociations between Kana and Kanji in aphasic and alexic patients Much debate still exists about the anatomical basis of the Japanese reading process. Recent data suggest that the left hemisphere participates in both Kana and Kanji reading, but that different structures are involved in the process of each writing system In the present study, we addressed this question describing a particular reading dissociation found in a bilingual patient presenting an aphasia of the Broca's type, following a right hemispheric stroke. The patient spoke both Japanese and Portuguese. We discuss our findings and suggest some possible factors that could have determined the striking cerebral organization for language observed in this patient. Moreover, the articulation of a functional model for reading allows an interpretation of the clinical picture of an unexpected reading dissociation between three writing systems. CASE REPORT The patient was a 68 year old right-handed man born in Brazil, called a "nisei" since his parents were Japanese, and who had no family history of left handedness. He studied both Portuguese and Japanese at school (2 years of schooling in Portuguese and 3 years in Japanese). Despite his low educational level, he was a skilled reader, was able to speak both languages at home and at work, and to write fluently in both. His writing skills in Japanese were so good that he became a scribe for his friends and relatives who wanted to send letters to Japan. In December 1989, he developed left hemiparesis and an aphasia of sudden onset. This clinical picture remained stable until he was first seen in January 1990 in the Hospital das Clinicas of the University of Sao Paulo School of Medicine, Brazil. At the time of neurological examination, the patient was alert, oriented, and aphasic. His left hemiparesis included the face and was more pronounced in the left upper limb. There were also marked oral and constructional apraxias. There were no signs of anosognosia, prosopagnosia or hemineglect; no visual field deficits were observed on confrontation. A campimetric evaluation was not available. The computed tomography (CT) scan showed a large low-density area in the distribution of the right 166 Behavioural Neurology. Vol 7 . 1994 P. CARAMELLI ET AI.. middle cerebral artery. Magnetic resonance imaging (MRI) revealed that this ischemic lesion involved the cortical and subcortical aspects of the medial, superior and transversal temporal gyri and of the inferior frontal gyrus, the lateral parts of the precentral and post-central gyri, the inferior parietal lobule and the insula. An older and smaller lesion, located posteriorly to the left lateral ventricle and subcortically distributed, was also identified in the left hemisphere Language evaluation Five months later, in May 1990, the patient was submitted to a formal language evaluation using the Portuguese version of the Montreal-Toulouse (MT-86 If) Aphasia Battery The spontaneous speech was mainly characterized by unintelligible segments. The patient was unable to produce correct responses in naming tasks. In repetition of Portuguese words and non-words, he presented phonemic paraphasias in 40.4% of the stimuli and a 44.2% rate of absence of response. Among the 15.4% of words correctly produced, there were 10 open-class words, one closed-class, and five neologisms, with an evident word length effect. In repetition tasks of Japanese words and non-words, the patient correctly repeated only 27.9% of the stimuli (15 open-, two closed-class words and 10 neologisms), also presenting a length effect. Phonemic paraphasias accounted for 51 .9% of the responses and there was a 20.2% rate of no response. The patient's performance in reading aloud in Portuguese was extremely poor (81.3% of no response). In 14.9% of the stimuli, the patient produced phonemic paralexias or he produced the word only after phonemic/ semantic facilitators given by the examiner. Only four words (3.7%) were correctly read, all of them being open-class and highly frequent words. He READING DISSOCIATION IN A BRAZILIAN "NISEI" was unable to read any non-word. In Kanji reading, only four words were correctly produced. In 52.7% of the stimuli there was an absence of response and in the remaining 32.6% of the words either phonemic paralexias occurred or the words were produced following the presentation of phonemic facilitators. In reading aloud Kana stimuli, the patient did not read any of the 72 words and 72 non-words presented to him. These overall results indicate that the patient showed deficits of the Broca's aphasia type. Finally, a severe constructional apraxia allowed him to draw only simple geometric forms and drastically affected his written output. Additional matching tasks were devised to further assess his auditory comprehension of both Portuguese and Japanese words. He was also submitted to written language comprehension tests, in Portuguese and Japanese, including Kana and Kanji stimuli. In each test, the patient was requested to point to the correct response. Patient's performance was compared with that of two normal controls, matched for age, languages and education. The first subject (Controll) was a 58 year old Brazilian "nisei" woman, with 4 years of schooling in Japanese and 12 in Portuguese, who was also a skilled reader and writer in Japanese. The second control was a 63 year old female "nisei", who learned Japanese and Portuguese essentially at home, and was thus able to read and write in both languages, especially in Japanese (she writes letters and reads newspapers regularly). The patient and the controls gave informed consent for all tests. The patient's and controls' results were as follows. Auditory word and picture-matching task. This task included 50 different line drawings of common objects. The subjects were requested to match an utterance of the examiner with one of four line drawings presented to them on a single display. The patient's score was perfect (100%) in Portuguese. He made few errors in Japanese, obtaining a score of 88.0%. Control subjects obtained perfect scores (100%) in both languages. Written word and picture-matching task. This task comprised 50 written words and the same 50 line drawings used previously. The subjects were requested to match a written word with one of four line drawings presented on a single display. In Portuguese, the patient obtained a score of 80.0010 whereas in Japanese, his score was better in Kanji (86.0%), than in Kana (20.0%). Control 1 achieved 100% in Portuguese and in Kanji, and 98% correct responses in Kana. The second control made no errors in this task (100% of correct responses in the three writing systems). Auditory and written word-matching task. In this task, a card with four written words was presented to the subjects. The examiner read one of the words aloud and the subjects had to select the appropriate word. They were submitted to a total of 80 trials in Kanji and in Portuguese. Targets included an equal number of frequent and non-frequent words, and also an equal number of imageable and nonimageable words, that is, 20 for each type. Kanji frequent words were coded between levels 1 and 4, and non-frequent Kanjis between levels 6 and 8, according to the classification of The patient was correct on 56.2% of the items in Kanji and on 76.2% of the items in Portuguese. As for the frequent and imageable words, he recognized 80.0010 of them when they were written in Kanji and 95.0% when written in Portuguese. On the other hand, the patient could identify neither Katakana writing nor Hiragana writing. His performance attained 12.5% of correct responses and was totally at random. Both controls performed flawlessly in this task (100%). Auditory and written non-word matching task. Non-words were presented to the subjects, once in Portuguese and once in Hiragana. For each language, there was a total of 45 trials. It is impossible to create non-words in Kanji because Kanji characters do not have separable phonemic components. The subjects were asked to select among four written non-words the one spoken by the examiner. The patient was able to correctly select only 28.9% in Portuguese and 11.1% of the non-words in Hiragana. Control 1 obtained a perfect score (100%) in Portuguese and in Kana, while Control 2 achieved 95.5% correct responses in Portuguese and a perfect score (100%) in Kana