Acute thrombosis on a carotid web associated with an ipsilateral embolic stroke.

A 56-year-old man without cardiovascular risk factors presented with an acute right middle cerebral artery stroke (figure, A) treated by IV tissue plasminogen activator and endovascular thrombectomy. CT angiogram (CTA) showed a triangular filling defect along the posteromedial margin of the proximal right internal carotid artery (ICA) consistent with a carotid web (CaW), without atherosclerosis (figure, B). Follow-up CTA within 2 days revealed evolving in situ thrombus overlying the CaW (figure, C), after which anticoagulation was started. A CaW is a shelf-like linear filling defect of the ICA bulb thought to represent an intimal variant of fibromuscular dysplasia.1 Hypothetically, blood stasis along CaW downstream surface may cause thrombus formation and thromboembolic strokes.2