両側外転神経麻痺の症状のみで発症した破裂脳底動脈先端部瘤の一例 <症例報告>

症例は54歳，女性。頭痛を伴わない回転性めまいで発症し，診察時には両側外転神経麻痺症状のみ認められた。CT でくも膜下出血，特にprepontine cistern に厚い血腫が認められ，MRA では脳底動脈瘤が認められた。破裂脳動脈瘤に対して，コイル塞栓術を施行した。術後，新たな神経学的異常所見は認められなかった。両側神経麻痺は発症から４か月後に完全回復が得られた。外転神経麻痺には幾つかの機序が挙げられている。動脈瘤の直接的な圧迫，脳浮腫や脳内出血による頭蓋内圧の亢進，外転神経核への栄養血管の攣縮などである。本症例ではprepontine cistern に限局した血腫による圧迫が影響して両側外転神経麻痺のみで発症したと考えられた

A 54-year-old woman presented withdsudden vertigo without headache. Upon admission, neurological examination revealed isolated bilateral abducens nerve palsn. Computed tomography revealed subarachnoid haemorrhage, particularly aythick haematoma, in the prepontine cistern. Magnetic resonanceAangiography）showed a ruptured basilar artery aneurysm. Endovascular coil embolization was performed for this ruptured aneurysm. Postoperatively, no new neurological deficits were observed. Bilateral abducens nerve palsy recovered and disappeared 4 months after onset.sSeveral possible mechanisms can explain the occurrence of abducens nerve palsy, including the following: a direct mass effect of the aneurysmton the abducens nerve, increased intracranial pressure induced by brain swelling or parenchymal haemorrhage, and a vasospasm of thc pontine branch of the basilar artery supplying the abducens nuclei. In this case, we speculated that the isolated bilateral abducens nerve palsy was caused by compression of the local haematoma in the prepontine cistern secondary to a ruptured basilar artery aneurysm.