両側視床出血により聴覚失認となった症例のリハビリテーション

Rehabilitation of Auditory Agnosia for Bilateral Thalamic Hemorrhage : A Case Report

はじめに

　大脳の一次聴覚野皮質，または聴放線の損傷が原因で，言語音の認知障害の有無にかかわらず，非言語音とくに環境音が認知できない状態を聴覚失認と呼ぶ^1,2）．今回我々は両側視床出血により，言語音と環境音に対する認知が低下し，聴覚失認となった症例のリハビリテーション（以下，リハ）を経験したので報告する．

　聴覚モダリティーの失認の症状に関する定義・分類は統一されていない．本報告では，環境音のみの認知障害（狭義の聴覚失認）を「環境音失認」，言語音のみの認知障害を「純粋語聾」と呼び，環境音の認知障害に語聾を伴う広義の聴覚失認を「聴覚失認」とし，皮質・皮質下病変も含めてさらに聾と呼ぶほど，言語音・環境音の認知障害を示した病態を「いわゆる皮質聾」と呼ぶことにする^3）．

Abstract : Bilateral lesions damaging the primary auditory cortex or the auditory radiation may cause auditory agnosia. We describe a 67-year-old woman with auditory agnosia after bilateral thalamic hemorrhage. Initially, she showed subcortical deafness for words and environmental sounds. Pure tone audiometry showed a moderate-to-severe hearing loss (mean hearing level, right 56 dB ; left 57 dB), while the recording of auditory brainstem response was normal. Brain CT demonstrated a hematoma in the left thalamus and a narrow low density area suggesting a sequel of the right thalamic hemorrhage. Hearing training was begun using sound sources that were easily recognizable for the patient. Her recognition was better for words than for individual Japanese vowel or consonant-vowel sounds, and the use of lip reading contributed to her better recognition of words. After 2 months, she was able to communicate with medical staff and family members in daily conversation.