前交通動脈瘤と鎖骨下動脈瘤を合併した一側内頸動脈欠損の稀な1例

Aneurysms of the Anterior Communicating Artery and Subclavian Artery in Association with Congenital Absence of Unilateral Internal Carotid Artery

一側内頸動脈欠損に，前交通動脈瘤と，右鎖骨下動脈瘤を合併した極めて稀な1例を経験した。

　患者は56歳の男性で，脳血管撮影および3D-CTAでは右内頸動脈と右頸動脈管が欠損しており，前交通動脈に径6mmの右前向きの囊状動脈瘤を認めた。また，右鎖骨下動脈に径40mmの囊状動脈瘤と径25mmの紡錘状動脈瘤を認めた。双方ともに，破裂の危険が高いと考えられ，また鎖骨下動脈瘤は塞栓症の原因ともなり得ることから，それぞれに根治術を施行した。術後の経過には問題なく，独歩退院した。

　内頸動脈欠損は比較的稀な血管奇形であるが，血行力学的ストレスが大きく関与して約3割に脳動脈瘤を合併することが知られている。一方，内頸動脈欠損に鎖骨下動脈瘤を合併した例は，われわれが検索し得た限り2例のみであった。さらに，内頸動脈欠損に頭蓋内動脈瘤と鎖骨下動脈瘤を合併したとする報告は認められず，極めて稀な1例と考え報告する。

We encountered a rare case of unilateral internal carotid arterial defect complicated with anterior communicating aneurysm and subclavian artery aneurysm.

　The patient was a 56-year-old man in whom cerebral angiography and 3D-CTA revealed defects in the right internal carotid artery and the right carotid canal, and an unruptured aneurysm in the anterior communicating artery. In addition, the patient was also found to have an unruptured aneurysm in the right subclavian artery. As both the aneurysms were considered to have a high risk of rupture and such subclavian aneurysms were likely to cause an embolism, radical surgery was performed for each aneurysm. The postoperative course was uneventful, and the patient was discharged without ambulatory limitations.

　Although the defect in the internal carotid artery is a relatively rare vascular deformity, the incidence of cerebral aneurysm is about 30％ in such cases due to the marked hemodynamic stress involved. On the other hand, there have been only two previous case reports of internal carotid arterial defect complicated with a subclavian aneurysm. Moreover, there have been no previous reports of internal carotid arterial defect complicated with both an intracranial aneurysm and a subclavian aneurysm, as observed in the present case. Thus, this case was very rare and is reported here.