炭鉱爆発による一酸化炭素中毒後遺症患者40年後の神経心理学的検討―画像失認の1例

A Case of Carbon Monoxide Poisoning by Explosion of Coal Mine Presenting as Visual Agnosia : Re-evaluation after 40 years

要旨　1963年に生じた三池炭塵爆発事故で一酸化炭素中毒となり視覚性失認を呈した1患者について，事故発生から40年後の神経心理学的な再評価を行った。初期の神経心理学的な症候は，視覚性失認ないし視空間失認が前景にあり，前向性健忘，失読，失書，構成障害，左半側空間無視，精神性注視麻痺を認めた。現在なお残存していた症候は視覚性失認が主であり，付随症状として失書と構成障害を伴っていた。視覚性失認は，実物物品の認知は良好であったが，写真や絵の認知は困難であった。本症例は二次元平面に広がる「絵画的手がかり」が障害された画像失認と考えられた。MRIでは両側の頭頂葉下部から後頭葉にかけての損傷を認め，これが責任病巣と考えられた。

We re-evaluated a case of carbon monoxide poisoning presenting as visual agnosia who had been injured by explosion of Miike-Mikawa coal mine 40 years ago. In an early stage, his main neuropsychological symptoms were visual agnosia, severe anterograde amnesia, alexia, agraphia, constructional apraxia, left hemispatial neglect and psychic paralysis of gaze, in addition to pyramidal and extra pyramidal signs. At the time of re-evaluation after 40 years, he still showed visual agnosia associated with agraphia and constructional apraxia. Concerning visual agnosia, recognition of the real object was preserved, while recognition of object photographs and picture was impaired. Thus, this case was considered to have picture agnosia as he could not recognize the object by pictorial cues on the second dimensional space. MRI examination revealed low signal intensity lesions and cortical atrophy in the bilateral parieto-occipital lobes on T1-weighted images. Therefore, the bilateral parieto-occipital lesions are likely to be responsible for his picture agnosia.

（Received : May 20, 2005）