前頭葉型痴呆—SPECTが診断に有用であった2例

Frontal Lobe Dementia : Two Cases Diagnosed by SPECT

　老年期発症で緩徐進行性の変性性痴呆の2例を報告した。記憶障害，失見当識に加えて病初期より無口，自発性・主体性の低下，性格変化，病識欠如などの前頭葉，側頭葉徴候が前景にたち，脊髄液検査は正常，脳波は全般性に徐波が混入していた。MRIでは大脳が全体的に萎縮し，特に前頭葉，側頭葉，頭頂葉前部に顕著であったが，脳血管障害病変は著明でなかった。SPECTにて前頭葉，側頭葉の血流が選択的に低下しており，大脳後半部の血流が保たれているのと好対照をなし，特徴的であった。以上より，"Frontal lobedementia（前頭葉型痴呆）"と診断し，前頭葉型痴呆をきたす種々の疾患群の中での本2例の位置づけをした。SPECTによる大脳各部の機能評価が診断に非常に有用であった例を示し，痴呆の診断とその病態把握においてSPECT，MRIなどの画像診断の組み合わせが必須であることを述べた。

Both patients 1 and 2 were males 73 and 77 years old, respectively, and over the past several years, both had gradually developed progressive loss of vigor, paucity speech, personality changes, andanosognosia, in addition to memory loss and diso-rientation. Patient 1 experienced emotional lability, mild pyramidal signs and parkinsonian features. The various diseases causing secondary dementia were ruled out. The Mini Mental Scale scores were 13 and 21, respectively. Brain CT scans and MRI showed cerebral atrophy, most prominent in the frontal and the temporal lobes. There were few lesions suggestive of cerebrovascular disease. The EEGs showed nonspecific diffuse slowing, and the cerebrospinal fiuid was normal. 123I-amphetamine SPECT, which provided the most valuable diagnos-tic findings in these two cases, demonstrated selec-tive hypoperfusion of the frontal and the temporal lobes in both patients. Frontal lobe dementia of the non-Alzheimer type (Gustafson, Neary), progres-sive subcortical gliosis (Neumann) , Pick's disease, and Alzheimer's disease with frontal lobe predomi-nance were considered the most likely of the various diseases causing frontal lobe dementia. The useful-ness of SPECT in diagnosing and elucidating the pathophysiology of dementia are discussed.