Proximal clipping直後に出血した未破裂解離性椎骨動脈瘤

Bleeding from Unruptured Dissecting Aneurysm in the Vertebral Artery after Proximal Clipping

I．はじめに

　近年，解離性椎骨動脈瘤の報告が多数行われその病態についての認識が深まりつつある．特にクモ膜下出血（以下，SAH）を起こした症例の場合，治療法として椎骨動脈のproximal clippingが広く行われてきたがこの方法で再出血をきたす報告が相次ぐようになり^1,5,7,12），trappingの有用性が注目されてきている^3,4,12）．今回われわれは未破裂の解離性椎骨動脈瘤にproximal clip—pingを施行したところ，その4時間後に同部が破裂しSAHをきたした症例を経験した．この出血の成因と治療法について考察を加え報告する．

This is a case report of a patient with unruptured dis-secting aneurysm in the vertebral artery that bled after being treated by proximal clipping.

A 53-year-old male was admitted to our hospital due to transient right hemiparesis which occurred 20 days prior to his admission. He had been medicated for hy-pertension for the previous 33 years. CT scan and MRI showed lacunar infarction in the left corona radiata, and an aneurysm was accompanied with clot in the pre-pontine cistern. Angiography revealed a dissecting aneurysm in the right intracranial vertebral artery. His right hemiparesis was derived from infarction in the left corona radiata. It was likely that the dissecting aneurysm might rupture in the future. Proximal clip-ping was performed to prevent rupture of the aneurysm. After clipping of the right vertebral artery distal to the PICA, the wall of the aneurysm appeared to be drawn toward the clip blades and to be tensed by the blades. Four hours after the operation, he com-plained of severe headache, and experienced a sudden loss of consciousness and the immediate development of a deep comatose state. CT scan disclosed massive SAH in the right cerebellopontine and basal cistern. Repeat angiography demonstrated that the aneurysm was not visualized and the right vertebral artery distal to the aneurysm was opacified through the left vetebral artery. Ventricular drainage was performed, but the pa-tient died on the 20th day after bleeding.

It was suspected that the aneurysmal clip might have produced shear force on the weak adventitia of the dis-secting aneurysm, and that the intraaneurysmal pres-sure might have increased because of blood backflow via the contralateral vertebral artery after the proximal clipping.