小脳皮質構築異常を伴った小脳嚢腫の1例

INTRACEREBELLAR CYST ASSOCIATED WITH ABNORMAL ARCHITECTURE OF CEREBELLAR CORTEX:REPORT OF A CASE

　抄録　小脳皮質構築異常はTrisomy症候群，Down症候群，福山型筋ジストロフィーなどの遺伝子異常に伴う一連の奇形として小児剖検例で報告されている。高齢者の小脳皮質構築異常でしかも嚢腫を伴ったという報告は我々が調べ得たかぎりでは認められない。本症例は62歳でvertigo, nausea, vomitingで発症し，症状が徐々に悪化した。神経学的には軽い水平性眼振と左F-Ntestが拙劣で軽度の小脳症状が認められた。CT scanで左小脳半球を中心に巨大な？腫が認められ，　CSF系との交通は認められなかった。頸椎にatlanto-occipital fusion, Klippel-Feii症候群を認めたが，その他に奇形は認めなかった。後頭下開頭術を施行し，？腫を開放したが，？腫腔脳側に約1cm×1cm程度で色がreddish-grayの結節を認め生検した。組織学的検討でこの部が皮質構築異常であった。嚢腫壁は萎縮した小脳組織であり，嚢腫は小脳髄質内に存在したことを確認した。？腫の成因に関しては，構築異常組織の深部髄質に小腔胞が多数認められ，長年月を経てこれらが融合したと推察したい。術後vertigoは消失し社会復帰している。また本症は染色体異常は認められず，部分的な小脳皮質構築異常は重篤な遺伝子異常を伴わなくとも発生し得ることを示した。

The patient, 64-year-old female, had episode of ^ sudden attack of severe vertigo, headache, nausea, and vomiting which lasted for about twenty minutes on May 20th in 1980. She had hyperten-sion, polyp of stomach, diverticum of duodenum in her past history.

Neurological examination on her admission revealed fine horizontal nystagmus on bilateral gaze and slight clumsy movement on left F-N test. On plain skull and cervical X-P, atlanto-occipital fusion and Klippel-Feil syndrome (C₂-C₃ fusion) were seen. Plain CT scanning revealed a large cystic lesion which extended from the vermis to the left cerebellar hemisphere. No enhanced area was seen. The forth ventricle was seemed to be enlarged. And the left-sided dosal part of the forth ventricle attached to the cyst. Metrizamide CT cisternogram showed there was no direct communication between them. Angio-graphically, the vertebrobasilar arteries were noted screrotic changes and poor vascularities in the left cerebellar hemisphere was noted.

On opening the dura during surgery, the left cerebellar hemisphere appeared buldging state and the bilateral cerebellar tonsils were hypo-plastic. Outer thin membrane of the cyst was removed. The cyst has no communication with the subarachnoid space as well as with the forth ventricle. The cystic fluid was slightly yellowish, but had no Froin's sign. Reddish-gray color nodular area, which seemed to be similar to mural nodule macroscopically, was noted in the area of inner surface of the cyst. This part was removed. Histological findings of this area showed abnormal architecture with malarranged layer of cerebdllar cortex. However, no tumor cells or tissue weredetected. This cyst splitted the cerebellar medulla, and there was no neuroepithelium on inner surface of the cyst.

It is said that abnormal architecture such as histogenetic malformation is a kind of develop-mental disorder at fetus period. However, the pathogenesis of cyst formation in this case of cerebellar malformation has remained unknown. We discussed that the malformation was considered as the primary etiology, and the cyst might be formed by some degenerative process of the malformed tissue secondarily in this particular case. We realized that such partial abnormal architecture of cerebellum could be caused without disorder of gene.