第4脳室内に発生した後下小脳動脈末梢部動脈瘤の1例

A Distal Posterior Inferior Cerebellar Artery Aneurysm in the Fourth Ventricle:A case report

I．はじめに

　後下小脳動脈末梢部動脈瘤は、全脳動脈瘤中のおよそ0.5-1.0％を占める比較的まれな動脈瘤である^4）．最近はその報告例も散見されるが^6,8,13,17），第4脳室内に発生したという報告は少ない．今回われわれは，脳室内出血にて発症した，後下小脳動脈の脈絡叢動脈に生じた動脈瘤の1例を経験したので文献的考察を加え報告する．

The authors reported a case of a fourth ventricle aneurysm originating from the choroidal branch of the posterior inferior cerebellar artery (PICA). A 65-year-old woman became comatose following the acute onset of a severe headache and vomiting. She was moribund on admission, showing decerebrate posture. CT scan re-vealed a massive hematoma in the fourth ventricle up to the lateral ventricle. Extension of blood to the cister-ns magna through the cerebellar vermis was also noted. Angiography demonstrated an aneurysm distally lo-cated on the right PICA across the midline.

The aneurysm lodged in the choroid plexus which was exclusively fed by the right PICA was excisedwith nit difficulty through suboccipital craniectomy. Postoperative course was uneventful. She regained her full consciousness by two days after the operation, and was discharged with a minimal truncal ataxia.

To our knowledge, this is the first report of a rup-tured aneurysm developing in the choroid plexus of the fourth ventricle. Hemodymimic stress is speculated to be a causative factor of such a lesion.