Cortical venous drainageを有する頸動脈海綿静脈洞瘻に対する治療前後の1H-MRSによる評価

Evaluation of Carotid-Cavernous Fistula with Cortical Venous Drainage by Proton Magnetic Resonance Spectroscopy

I．はじめに

　頸動脈海綿静脈洞瘻（以下CCFと略す）は特発性と外傷性のものに分類できるが，いずれの原因にせよ，動静脈瘻の流出経路がsylvian veinなどを経由して脳表の静脈まで逆流する症例，すなわちcortical venous drain—ageを有する症例は少ない．このような症例は，くも膜下出血や，脳出血，静脈性梗塞による重篤な症状を起こしやすく，またそれに至らないまでも，脳循環不全による脳代謝障害を起こしやすい^5,6）．

　脳代謝の状態を無侵襲に測定できる方法として，近年magnetic resonance spectroscopy（以下MRSと略す）が臨床に応用されている^2-4）．今回われわれは，CCFによりcortical venous drainageを認めた2症例に対し，塞栓術ならびに放射線療法を施行し，治療前後でprotonMRS（以下¹H-MRS）で，脳代謝の状態を経時的に検討したので報告する．

Cases with carotid-cavernous fistula (CCF) associ-ated with cortical venous drainage through the sylvian veins are rather rare. However, such cases involve risk for subarachnoid hemorrhage, subcortical hemorrhage and venous infarction due to venous hypertension in the brain. Even without these symptoms, CCF under these conditions provokes disturbance in cerebral meta-bolism. We report two cases of CCF associated with cortical venous drainage evaluated by proton magnetic resonance spectroscpy (¹H-MRS).

Case 1: A 56 year-old female suffered from a right CCF associated with cortical venous drainage through the sylvian veins after trauma. Before embolization with a detachable balloon catheter, the ratios of N-acetyl-aspartate (NAA)/Choline (Cho) and NAA/ Creatine (Cr) in ¹H-MRS on the right temporo-basal ganglia were lower than those in normal volunteers. After curative balloon embolization of the CCF, serial ¹H-MRS still demonstrated laterality (NAA/Cho and NAA/Cr ratios on the right side were lower than those on the left). Six months after embolization, these ratios on the right became closer to those on the left. Case 2: A 48 year-old female suffered from spon-taneous CCF associated with cortical venous drainage. Before embolization of the CCF, ratios of NAA/Cho and NAA/Cr on the temporo-basal ganglia of the drainage side (left side) were lower than those on the contralateral side. After partial embolization of the CCF, which caused the angiographical disappearanceof the cortical venous drainage, NAA/Cho and NAA/Cr ratios on the affected side increased to almost the same levels as those on the contralateral side. We consider that ¹H-MRS is nonivasive and is a use-ful method to generate data evaluation of affected brain metabolism by venous reflux in cases of CCF associ-ated' with cortical venous drainage.