頭頂後頭葉症状を示したレビー小体型痴呆（probable dementia with Lewy bodies）と考えられる1例

A Clinical Case of Probable Dementia with Lewy Bodies, showing Constructional Apraxia and Bálint's Syndrome

【抄録】　患者は83歳の女性。68歳頃右上肢の筋強剛で発症。l-dopaが有効であり典型的なパーキンソン病（PD）で経過し，79歳頃にはYahrのstage IV〜Vでon-off現象がみられた。加えて痴呆，頻回の幻視，注意の変動，構成障害，Balint症候群，書字障害，失行がみられ，MRIで両側頭頂後頭葉の萎縮，SPECTで両側頭頂後頭葉の血流低下が認められた。本例はPDの長期経過後に，頭頂後頭葉症状を呈したレビー小体型痴呆と考えられたが，頭頂後頭葉症状にも変動がみられたという特徴とともに，呼称障害や感覚性失語様状態はなかったこと，SPECTで内側側頭回の血流低下や閃光刺激視覚誘発電位のP2潜時延長はなかったことから，著しいアルツハイマー病変の合併は否定的であった。

　We report a case of an 83-year-old woman with probable “dementia with Lewy bodies” (DLB), showing constructional apraxia and Bálinfs syndrome after a long duration of Parkinson disease (PD). She experienced clumsiness in her right hand, and was diagnosed as having PD at age 68. Although l-dopa was effective, her parkinsonism gradually worsened. At age 79, she manifested recurrent visual hallucinations, progressive dementia, attentional deficiency, constructional apraxia, and Bálint's syndrome, in addition to frozen phenomenon, on and off phenomenon, and akinesia (Yahr stage IV to V). The case was clinically characterized by the following features; 1) the fluctuation of attentional deficiency, apraxia, and Bálint's syndrome, 2) neither difficulty in finding words nor sensory aphasia, in spite of severe mental deterioration, 3) moderate atrophy of the parieto-occipital cortices on MRI, 4) hypoperfusion of the bilateral parieto-occipital cortices including the medial portion and no hypoperfusion of the bilateral medial temporal regions on SPECT, 5) no prolongation of P 2 latency in flash visual evoked potential. These suggested that the patient was free from Alzheimer's disease.