非外傷性頭蓋内内頸動脈解離性動脈瘤3症例の経験

Non-traumatic Dissecting Aneurysms on the Intracranial Internal Carotid Artery : report of three cases

I．はじめに

　頭蓋内解離性動脈瘤の報告例は近年，脳血管撮影検査やmagnetic resonance images（MRI）の普及によって増加傾向にある^29）．しかし，その報告例の多くは椎骨脳底動脈系のものであり^{5,22,23,31）}，頭蓋内内頸動脈系に関しては症例報告のみである^{8,10,13,14,16,18-20,26-28,30,33）}．

　今回われわれは，頭蓋内内頸動脈解離性動脈瘤を3例経験したので文献的考察と共に，その発生要因について流体力学的に検討を加え報告する．

Subarachnoid hemorrhage (SAH) due to non-traumatic dissecting aneurysms is uncommon. Most ofsuch cases are reported to occur in the posterior circulation. We encountered three cases of non-traumaticdissecting aneurysms on the intracranial internal carotid artery. Two cases developing SAH from the dis-secting aneurysms were surgically treated by such means as proximal ligation and trapping. Two cases,which were treated surgically during the acute phase, showed poor surgical outcome, because a large cere-bral infarction took place during the course of vasospasm. Trapping of the ICA or the contralateral ICAwith the dissecting aneurysm failed to keep enough blood supply despite hypervolemic hypertensive ther-apy. Operative results seemed to depend on the collateral circulation during vasospasm, so appropriatebypass surgery was recommended in cases of dissecting aneurysm on the ICA manifesting SAH. Fur-thermore, the mechanism of initiation of a dissecting aneurysm on the intracranial carotid artery was dis-cussed from the biorheological aspect.