伝導失語を呈した交叉性失語の1症例

A Case of Conduction Aphasia due to Right Hemispheric Lesion

はじめに

　右手利きで右大脳半球損傷によって起こる失語は交叉性失語と呼ばれ，その出現頻度は失語症全体の0.38～1.8％と報告されている^1，2）。その言語症状は，左半球損傷による失語の病巣と同様という報告^3－6）がある一方で，通常の対応関係を示さない変則タイプの報告^7－9）もみられる。変則タイプの中には，Broca失語やWernicke失語など古典分類に当てはまる症状を呈している症例が存在するが，伝導失語の報告は少ない^10－14）。

　今回われわれは，右側頭後頭頭頂葉の広範な脳梗塞で伝導失語を呈した症例を経験したので報告する。

Abstract

　We report the case of conduction aphasia due to injury of the right hemisphere of the brain.　The patient was a right-handed male in his fifties with moyamoya disease.　T₂-weighted MRI showed an extensive high intensity area in the right temporal-parietal-occipital lobes.　In the case of language-related symptoms, comprehension was preserved, but phonemic paraphasias were frequent, and kana paragraphias were also observed.　Despite the extensive injury of the right hemisphere, these language-related symptoms were consistent with the clinical features of conduction aphasia.　Therefore, this patient was diagnosed with atypical crossed aphasia.　Improvement in the phonemic paraphasia differed between words and nonsense words, suggesting that the improvement was dependent on the level of meaning of the words.

（Received: February 23,2009,Accepted: July 3,2009)