[Evaluation by proton magnetic resonance spectroscopy of carotid-cavernous fistula with cortical venous drainage].

Cases with carotid-cavernous fistula (CCF) associated 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 metabolism. We report two cases of CCF associated with cortical venous drainage evaluated by proton magnetic resonance spectroscopy (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 spontaneous 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 disappearance of 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 noninvasive and is a useful method to generate data evaluation of affected brain metabolism by venous reflux in cases of CCF associated with cortical venous drainage.