COLLATERALIZATION OF AN OCCLUDED INTERNAL CAROTID-ARTERY VIA A VAS VASORUM

Background-Reopening of an occluded internal carotid artery (ICA) is o ften seen in dissections but only rarely occurs in atherothrombotic oc clusion of the internal carotid artery. Case Description-A 60-year-old man suffered a minor stroke with dysphasia in March 1995. Color-coded duplex ultrasonography of his neck arteries revealed a left ICA occlu sion. He was placed on a regimen of aspirin and followed up clinically and with ultrasonography. At follow-up 18 months later, the patient w as asymptomatic. On duplex ultrasonography his left occluded ICA was f ound to be reopened, with a residual, proximal, high-grade stenosis. H owever, intra-arterial digital subtraction angiography demonstrated a persistent ICA occlusion and a vas vasorum originating from the caroti d bulb and draining into the ICA distal to the occlusion. Conclusions- The rare collateralization of an occluded ICA by vasa vasorum seems to take several months. It can be a pitfall in the ultrasound diagnosis of carotid artery occlusive disease.