流域動脈に脳動脈瘤を合併したhigh flow脳静脈奇形

HIGH FLOW MEDULLARY VENOUS MALFORMATION WITH ANEURYSM ON THE PROXIMAL ARTERY : A CASE REPORT

　脳静脈奇形に脳動脈瘤を合併した症例を報告する。48歳女性，頭痛と右手指のしびれを主訴に来院した。脳血管撮影上左前頭葉内側に動脈相後期でearly blushを伴う脳静脈奇形が認められた。その近位動脈である前交通動脈部に脳動脈瘤を認めた。MRI画像上sagittal sliceで皮質を横切る細い線状影がsignal voidとして描出された。吸入法によるXe-SPECTでは，病変部に一致してhigh flowを呈し，半球血流平均値は右59にたいし左69ml／100g／minと病変側に高値を示した。脳脈動瘤にたいし予防的手術を施行した。

　脳静脈奇形は，従来"low flow system"と考えられてきたが本例は"high flow，low resistance"の病変と考えられた。文献的に血流検査が施行された13例を検討すると，high flowが測定されたものは本例を含め3例であり，これらは全て血管撮影上early blushを認める4cm以上の大型例であった。また，動脈瘤の合併例は過去4例が報告されているに過ぎなかった。

Medullary Venous Malformation with an aneur-ysm is uncommon and only 4 cases have been reported in previous papers. We reported a case of a medullary venous malformation (MVM) of the frontal lobe with an aneurysm on its proximal artery.

A 48 year old female with numbness of right fingers visited our hospital. On the CT scan, an abnormal enhanced area was found inside the left frontal lobe. The left carotid angiography showed both of an aneurysm around A corn A in early arterial phase, and "MVM with early blush" in capillary-early venous phase. MRI showed linear signal void crossing the cortex to join paravent-ricular low intensity area (LIA) with slight cor-tical atrophy on sagittal slice. The CBF study by Xe-SPECT proved a high flow lesion, with mean CBF 69 (left), 59 (right) mg/100 g brain/min, Pro-tective operation only for aneurysm was perfor-med.

The MVM in our case was proved to be a "high flow-low resistance system" by CBF study, although MVM has been considered a "low flow system". Reviewing papers, there were 3 cases of "high flow MVMs" confirmed by the measur-ment of CBF, all of them were large sized (＞4 cm) and with early blush angiographically.

We conculude that lagre sized MVM with early blush needs hemodynamic inspectation and special care to prevent "high flow MVMs" from hemorrhage and the steal.