前頭側頭型認知症(FTD)の経過中に運動ニューロン疾患(MND)を併発後短期間で死亡したFTD-MNDの1症例

A Case Report of Frontotemporal Dementia with Motor Neuron Disease

抄録　54歳，男性。49歳の後半から脱抑制行動，性格変化，感情障害で発症し，言語障害(自発語減少，滞続言語，反響言語)，認知機能低下がみられ，1年後には就業不能になった。初期の頭部CTで，前頭・側頭葉萎縮がみられ前頭・側頭型認知症と診断した。発症3年後の脳脊髄液検査では，リン酸化タウ蛋白，アミロイドβ蛋白値は正常。脳波は軽度緩徐波の所見であった。言語障害(発語の減少)，意欲低下，無関心，常同行動，反響言語が高度となった。発症3.5年後に拇指球筋の萎縮，舌萎縮(運動ニューロン疾患：MND)，嚥下障害が併発し，急速に体重が減少した(4か月間に，56.1→46.0kg)。MNDの進行が速くMNDが発症して1年後に死亡した。MND併発後の経過が，筆者らが経験したこれまでの症例とは異なっていた。臨床例からもFTD-MNDの多様性が示唆された。

　We report a 54-year-old man with frontotemporal dementia with motor neuron disease(FTD-MND). From the second half after 49, he developed psychoneurotic problems characterized with disinhibited behaviors with personality change and difficulty of dysfunction of spontaneous speech such as echolalia and “stehende Redensarten”. General cognitive functions were progressively deteriorated. Head CT-scan revealed atrophy of the bilateral frontotemporal regions that made the clinical diagnosis of frontotemporal dementia. The clinical course showed constantly worsening and he was unable to work in one year later. Three years after the onset, study of the cerebrospinal fluid was normal value as phosphrylated tau and amyloid βproteins. The electroencephalogram showed borderline records with generalized slowing without paroxysmal patterns. Three and a half years later of the onset of his illness, progressive atrophy of the selective distal upper limb muscles as thenar, hypothenar and tongue(lower motor neuron involvement：MND) were identified. While the other limb muscles were spared and preserved the ability to walk even at advanced stage of the disease. Rapid body weight loss(from56.1 to 46.0 in 4 months) was observed. He decreased one year after the onset of MND. The clinical course after the onset of MND was different from that of usual cases of FTD-MND. This case could be regarded as a manifestation of wide etiopathogenesis of FTD-MND.