A Case of Reading Errors Particularly on the Right Side of Horizontally Printed Kana Words

Abstract

We encountered a case of pure alexia that selectively affected kana accompanied by agraphia due to a left occipito-temporal medial hemorrhage that resulted in difficulty reading horizontally written kana words aloud in letter-by-letter and whole-word at the right end. To clarify the factors leading to alexia, we examined (1) the effect of the number of letters, (2) the difference in oral reading performance between vertically and horizontally printed words, (3) whole-word reading of horizontally and vertically printed words under a short presentation time of 100 msec, and (4) nonverbal visual information processing ability. The results showed that (1) there was a word-length effect, and although letter-by-letter reading was generally accurate, there were morphological similarity errors, (2) horizontally printed words had longer reading time than vertically printed words, (3) horizontally printed words had lower performance than vertically printed words, and there were frequent phonological errors at the end of words, and (4) reaction time was longer for discrimination of differentiation on the right side of the stimulus than on the left side. These findings suggest that subcortical lesions in the left occipitotemporal region may result in a specific type of alexia, characterized by difficulty in reading horizontally printed words aloud.