仮性動脈瘤を伴った頸部内頸動脈解離の1例

A Case of Spontaneous Dissection of the Cervical Carotid Artery with Pseudoaneurysm

要旨　症例は60歳男性，左頸部に拍動性の腫瘤と痛みを自覚し発見された特発性頸部内頸動脈解離である。頸部内頸動脈解離に合併した仮性動脈瘤がmass effectの原因であった。内頸動脈を温存する目的でself-expandableステントおよびGuglielmi detachable coil（GDC）にて初回治療を行ったが，4カ月後再発し，GDCおよびバルーンを用いて親血管閉塞を行った。しかしながら，その後も網膜中心動脈分枝閉塞症を発症，さらにmass signの増悪を認め，外頸動脈系から内頸動脈へ逆行した血流が動脈瘤を造影するようになっていたため，外科的動脈瘤摘出術を施行した。摘出標本の検討から，動脈瘤中膜から内膜に豊富な新生血管が存在し，外膜にこれらの栄養血管と考えられるvasa vasorumを認めた。以上より，本症例の再発・増大の機序は，豊富なvasa vasorumより栄養を受けた新生血管からの繰り返される出血とコラーゲン線維の増殖と考察され，部分血栓化巨大動脈瘤において考察されるmembranous capsuleからの出血に類似したものが考えられた。

We experienced the case of a dissecting carotid artery presenting with a pulsatile neck mass. This 60-year-old man was admitted to our department due to a progressive, painful left neck mass. The lesion was diagnosed as a dissecting left internal carotid artery with the subsequent formation of a giant pseudoaneurysm. First, the patient underwent an endovascular treatment using self-expandable stent and Guglielmi detachable coils （GDCs）. However, four months after the treatment, recurrence of the pseudoaneurysm happened to him, and he was readmitted to our department. Angiographies revealed an enlargement of the pseudoaneurysm. Then, proximal occlusion of the left internal carotid artery was performed using a balloon and GDCs. Ten months after the second endovascular treatment, since symptoms of the central retinal artery embolism and progression of the mass effect occurred, surgical treatment with trapping and resection of the pseudoaneurysm was performed. We investigated pathologically the surgical specimen and could observe a partial thrombosed wall of the pseudoaneurysm. The multiple neovascular channels in the intima and media layers of the aneurysmal wall could be found, and the vasa vasorum in the adventitia was also noted. We thus suggest that mechanism of the enlargement of the pseudoaneurysm may be due to the retrograde neovascular supplies from the vasa vasorum. As a consequence, repeated bleeding and thrombosis in the dissecting arterial wall may result in the formation of partial thrombosed giant aneurysms.

（Received : April 14, 2005）