1988 Volume 28 Issue 2 Pages 142-147
Temporary occlusion of the internal carotid artery with a balloon catheter (balloon Matas test) and simultaneous dynamic computed tomographic scanning (DCT) were performed in four patients with intracranial aneurysms in order to determine their tolerance for permanent carotid occlusion. Five DCT parameters were evaluated: appearance time (AT), peak time (PT), peak height fitting (PH), first effective moment (MT1E), and transit time (TT). The results of DCT and balloon Matas testing disclosed three patterns. Type 1 consisted of two patients with no neurological dificit during the balloon Matas test, while DCT showed a parallel shift of the time-density curve in the region of the middle cerebral artery on the occluded side relative to that of the contralateral side. Whereas PH, MT1E, and TT were the same on both sides, AT and PT were delayed on the occluded side. The DCT findings indicated that cerebral blood flow (CBF) was equally preserved in the two hemispheres during carotid occlusion. Thus, abrupt internal carotid arterial occlusion appears to be a safe procedure in Type 1 patients. In Type 2, the balloon Matas test showed no neurological deficit, but the time-density curve revealed deficits in all five DCT parameters in the area of the middle cerebral artery on the occluded side. These findings were confirmed by the functional images. A decrease in CBF on the occluded side was also suggested. Therefore, in Type 2 cases, extracranial-to-intracranial (EC-IC) bypass surgery should be performed to prevent ischemic insult. In Type 3, such neurological signs as disturbance of consciousness, aphasia, and right hemiparesis appeared just after the start of the balloon Matas test. The DCT findings were almost the same as those of Type 2 in the region of the middle and anterior cerebral arteries on the occluded side. Occlusion of the internal carotid artery is therefore contraindicated in Type 3 patients unless an EC-IC bypass procedure that can rapidly provide a large supply of blood (e.g., vein graft bypass) is performed. The authors conclude that the balloon Matas/DCT method offers a reliable means of predicting the risk of carotid ligation.
