2026 年 13 巻 p. 275-279
Detailed evaluation of language function is important in the management of dominant temporal lobe lesions. Although spoken language is routinely evaluated in patients, disturbances in written language may remain undetected without detailed assessment. The Japanese writing system, consisting of logographic Kanji and phonographic Kana, provides a unique framework for identifying selective impairments of the ventral language stream. We report a 51-year-old right-handed Japanese male who presented with selective agraphia for Kanji following a left posterior temporal subcortical hemorrhage. Upon admission, spontaneous speech was fluent, and auditory comprehension was preserved, with no clinically apparent aphasia. However, comprehensive neuropsychological assessment revealed a profound impairment in Kanji writing. Although standard language scores improved significantly by the chronic phase (Day 87), qualitative assessment revealed persistent deficits in Kanji retrieval, characterized by frequent non-responses and morphologically related errors. Conversely, Kana writing and reading abilities were largely preserved. This case demonstrates that selective impairment of written language (pure agraphia for Kanji) may occur in association with posterior temporal lesions, despite preserved spoken language. Unlike typical cortical lesions that destroy the orthographic representation itself, we propose that this specific subcortical hemorrhage caused a transient disconnection within the ventral language stream, selectively disrupting the semantic access pathway to Kanji. From a functional and clinical perspective, systematic evaluation of writing function is essential for neurosurgeons and clinicians to prevent overlooked disabilities.
