破裂脳動脈瘤に合併してみられた多発性脳血管奇形—前大脳動脈窓形成，副中大脳動脈，重複中大脳動脈—の1例

Ruptured Intracranial Aneurysm Combined with Multiple Cerebral Vessel Anomalies; A case report

I．はじめに

　前大脳動脈の窓形成，重複中大脳動脈および副中大脳動脈は何れも稀な血管奇形である．特に，重複中大脳動脈および副中大脳動脈は血管撮影上の頻度が0.2-4％^11，19）程度と推察され，注意深く検討すれば，それほど稀でないとの報告もある^19）．しかし，これら中大脳動脈奇形が同時に存在した報告は，これまでに北見らの1例のみである^10）．頭蓋内血管の窓形成は椎骨脳底動脈系では時に経験されるが，内頸動脈系では稀であり，特に脳血管撮影による報告は非常に少ない．

　今回，われわれはこれら3種類の血管奇形が一側内頸動脈系に同時に存在し，重複中大脳動脈起始部に発生した内頸動脈瘤の破裂症例を経験したので報告する．

Abstract

We report a very rare case of subarachnoid hemor-rhage associated with fenestration of the anterior cere-bral artery (ACA) , the accessory middle cerebral artery (A-MCA) and the duplication of the middle cerebral artery (D-MCA) . It seems that this is the first report of these combined intracranial vascular anoma-lies, although many authors have reported each anoma-ly in isolation.

A 50-year-old male visited a local physician com-plaining of the sudden onset of a severe pulsating headache. A lumbar puncture showed bloody cerebro-spinal fluid, and he was transferred to our institution. An emergency CT scan showed no apparent subarach-noid hemorrhage, but the left internal carotid angiogra-phy showed a saccular aneurysm at the origin of the D-MCA. Other anomalies, such as the fenestration of the ACA and the A-MCA, were also apparent during angiography. The ruptured aneurysm was safely clip-ped on the next day and the patient was discharged with no neurological deficits three weeks after the op-eration.

The incidence of fenestration of the ACA is 0.2% in the angiographic series, and 0.1 - 7.2% at autopsy. Fenestration of the ACA is thought to be less than that of the vertebral artery. Ever since it was proposed by Teal et al, the term A-MCA has been restricted to an artery that arises from the ACA, and a branch arising from the internal carotid artery has been termed as the D-MCA. These anomalous vessels supply the cortex in the distribution of the middle cerebral artery. The angiographic incidence of A-MCA is about 4%, and six cases of aneurysm located at the origin of the A-MCA have been reported so far. There has been controversy about the relationship between the A-MCA and the re-current artery of Heubner. In this case, A-MCA has some perforating vessels supplying the basal ganglia and is thought to represent hyperplasia of the recurrent artery of Heubner. A D-MCA is a rarer vascular anomaly than an A-MCA and only five cases of aneurysms located at the origin of the D-MCA have been reported so far. The combination of these vascular anomalies may suggest that they share the same de-velopmental etiology. This is, to the best of our know-ledge, the first report of the combination of fenestration of the ACA, A-MCA, and D-MCA.