Abstract
We have already pointed out that some of the patients with negative Balloon Matas test (BMT) have a risk of subclinical ischemia. In this study of eleven cases with giant aneurysms of ICA and five cases with traumatic carotid-cavernous fistula (CCF), we performed BMT of the internal carotid artery (ICA) and the common carotid artery (CCA), then examined the neurological findings, wedge pressure of ICA and CCA, and flow direction of ICA under CCA occlusion by the balloon catheter. These cases were classified into six types as follows. Type 1, BMT of ICA and CCA were both negative and flow direction of ICA during CCA occlusion was retrograde. Type 2, BMT of ICA was negative, BMT of CCA was positive, and flow direction of ICA was retrograde. Type 3, BMT of ICA and CCA were both positive and flow direction of ICA was retrograde. Type 4, BMT of ICA and CCA were both negative and flow direction of ICA was antegrade. Type 5, BMT of ICA was positive, BMT of CCA was negative, and flow direction of ICA was antegrade. Type 6, BMT of ICA and CCA were both positive and flow direction of ICA was antegrade. In cases of Type 1, ICA occlusion can be performed safely, because the collateral flow has the pressure to send the blood to the external carotid system. In cases of aneurysms of Type 4, subclinical ischemia may exist after ICA occlusion, because the external carotid system works as the collateral flow. Therefore, bypass surgery is recommended. In cases of aneurysms of Type 5 and 6, ICA occlusion cannot be performed without bypass surgery. Type 2 and 3 did not exist in our series. The flow direction of ICA can be used to show the presence of subclinical ischemia in patients with a negative BMT.
