Balloon Matas TestおよびDynamic CTによる内頸動脈閉塞の可否に関する検討

Temporary occlusion test of the internal carotid artery with a balloon catheter (balloon Matas test) was performed on seven patients with cerebral aneurysms of the internal carotid artery to determine the tolerance of a permanent carotid occlusion. And, on five out of these seven patients, dynamic CT (DTC) was performed to examine the cerebral hemodynamics during balloon Matas test.<BR>For the DCT, the Toshiba TCT-70A was used and rapid injection of amidotrizoate sodium meglumine (Urografin) was carried out. Five parameters, appearance time (AT), peak time (PT), peak height (PH), first moment effective (MT1E), and transit time (TT), were examined for DCT. The results of five patients were classified into three types according to the pattern on the findings of the balloon Matas test and of the DCT. Type 1 patients (Case 1, 2, 7) showed normal neurological signs during the balloon Matas test, and DCT findings showed a parallel shift of the time-density curve of the middle cerebral arterial territory of the occluded side compared to that contralateral to the occluded side. Functional images of PH, MT1E and TT were equal in both sides, while AT and PT were delayed in the occluded side. From the DCT findings, cerebral blood flow (CBF) is thought to have been preserved equally in both cerebral hemispheres during the carotid occlusion. Therefore, an abrupt internal carotid arterial occlusion can be performed without any trouble in this group. In type 2 (Case 3), the balloon Matas test showed no neurological deficit, but the time-density curve revealed a delay of AT and PT as well as the elongation of MT1E, TT and a decrease of PH in the middle cerebral arterial territory of the occluded side. These findings were also confirmed in the functional images. The decrease of CBF in the occluded cerebral hemisphere is suggested from the DCT findings. Therefore, extracranial to intracranial (EC-IC) bypass surgery should be recommended to prevent the ischemic insult in the future. In type 3 (Case 4), the neurological signs (disturbance of consciousness, aphasia and right hemiparesis) appeared just after the start of the balloon Matas test and DCT findings showed almost the same pattern as demonstrated in type 2 in the middle and anterior cerebral arterial territory of the occluded side. The occlusion of the internal carotid artery is contraindicated unless EC-IC bypass surgery, such as a vein graft bypass, which can supply large amount of blood flow rapidly, is performed. Our method offers reliable information to predict the risk of carotid occlusion.