視床変性症における痴呆と意識障害—病理学的所見との対比

DEMENTIA AND DISTURBANCE OF CONSCIOUSNESS IN THALAMIC DEGENERATION

　抄録　痴呆・意識障害，眼球運動異常，小脳症状，錐体路症状および錐体外路症状がみられ，臨床的にGerstmann-Sträus症候群が疑われた視床変性症の1剖検例を報告した。本例の中心症状の一つである痴呆・意識障害の内容は言語・行動の自発性の低下や注意・記銘力の低下，嗜眠などであり，臨床上痴呆と意識障害の鑑別および重畳とが問題になったが，その臨床経過から本例は痴呆で始まり，経過中に意識障害が加わり，両者がともに進行し無動無言状態になったものと考えられた。一方，本例の病理学的検討では，視床非特殊核群の吻側にあたる内側核に細胞脱落，グリオーシスが最も高度にみられ，次いで前核にみられた。同様な病変は視床尾側の視床枕から中脳被蓋に及び，その他下オリーブ核，小脳歯状核，淡蒼球内節，黒質などにも認められた。脳血管障害では，視床非特殊核群吻側の内側核・前核の障害により痴呆が生じ，尾側の視床枕や中脳被蓋に障害が及ぶと意識障害が強くなることが知られており，本例では視床内側核・前核病変による痴呆で発症し，病変が後方へ伸展し，視床枕や中脳吻側に及んで意識障害が加わったものと推定された。

A 53-year-old male with thalamic degeneration is presented. He had double vision, cerebellar signs, and pyramidal and extrapyramidal tracts signs in addition to hypersomnia, decrease in spon-taneity and attention, and impairment of memory as psychic symptoms. These signs and symptoms were progressive, and he subsequently developed akinetic mutism and died of pneumonia 17 months after the onset of the disease. His clinical diag-nosis was considered as Gerstmann-Sträus syndrome due to progressive dementia, cerebellar signs and the other signs mentioned above. The postmortem pathological investigations, however, revealed thalamic degeneration.

The pathological observations showed marked loss of nerve cells and glial proliferation in the medial and anterior nuclei of thalamus. The same pathological changes were more or less demon-strated in the pulvinar, the periaqueductal gray matter of midbrain, inferior olivary nucleus, the medial parts of globus pallidus, the substantia nigra and the dentate nucleus.

In the early stage of the clinical course, it was difficult to know whether the main symptoms were caused by dementia or by the disturbance of cons-ciousness. Retrospective considerations, however, showed that dementia had appeared at first, and subsequently the disturbance of consciousness had joined. As the result, it seems that they finally caused akinetic mutism.

It is known as thalamic dementia that in the cerebrovascular disease the lesions in the medial and anterior parts of bilateral non-specific thalamicnuclei cause dementia. The expansive lesions to the pulvinar and the periaqueductal gray matter of midbrain accompany the disturbance of conscious-ness.

The clinical course and pathological investiga-tions in the case suggested that the lesions in the medial and anterior nuclei of the thalamus caused dementia at first, and then expansive lesions to the pulvinar and midbrain accompanied the disturb-ance of consciousness.