重度理解障害を伴う失語1例における聴覚的理解課題で示すエラーの経時的分析

Sequential changes in error content reflecting the improvement of auditory comprehension deficit in an aphasic patient

　重度の聴覚的理解障害を示す流暢性失語1例(32歳男性)に対し，目標項目と選択肢(foil)間の意味的関連性を統制した「音声単語と絵のマッチング課題」を用いて，聴覚的理解障害の改善に伴うエラーの変化を分析した．発症12か月時は高頻度単語の理解も困難であり，エラー内容は目標項目と異なるカテゴリー項目へのエラーが最も多かった．その後，発症20か月時には，目標項目と異なるカテゴリーのfoilを提示した条件(目標項目：犬，foil：キャベツ・金づちなど)では正答数の有意な増加を認めたが，同じカテゴリーのfoilを提示した条件(目標項目：犬，foil：猫・豚など)では12か月時と有意差を認めなかった．エラー内容は目標項目と異なるカテゴリー項目へのエラーは有意に減少し，目標項目と同一のカテゴリー項目へのエラーが最も多かった．さらに発症32か月時には，目標項目と同じカテゴリーのfoilを提示した場合でも正答数の有意な増加がみられた．本例の聴覚的理解障害の改善は，まず大まかな語の意味理解から可能となり，その後さらに細かい意味内容も理解できるようになったものと考えられた．

　We investigated sequential changes in the error content of an aphasic patient using auditory word/picture-matching tasks. The subject was a 32-year-old male who developed severe sensory aphasia following a left cerebral hemorrhage. At the initial examination 12 months after the onset of aphasia, he was unable to comprehend even simple words. Unrelated errors were more common than semantically related errors for the target items. The patient was able to comprehend some words at 20 months after onset, when the target items were presented with foils of different semantic categories (e.g., target is "dog" and foils are "cabbage" or "hammer"). The correct answer ratio had significantly improved compared with that recorded at 12 months after onset. However, when the target items were presented with the same-category foils (e.g., target is "dog" and foils are "cat" or "pig"), no significant improvement was noted, although the proportion of unrelated errors had significantly decreased. Then, the patient showed significant improvement at 32 months after onset, even when same-category foils were presented. These results suggest that the error content changes according to the improvement in comprehension deficit.