RETURN TO ABSTRACT LISTING


Background
Carotid webs are increasingly implicated in recurrent ischemic stroke and transient ischemic attacks, particularly in patients without traditional risk factors. Carotid webs may be found in as much as 1.2% of the population. Most are likely asymptomatic; however, recurrent strokes are reported to occur in up 29% of patients with this pathology. Carotid webs seem to be easily overlooked on initial imaging, with one study showing that up to 62% of webs were missed on initial imaging in symptomatic patients. Even when an abnormality is correctly identified, differentiating a carotid web from the much more common atherosclerosis remains challenging. Carotid webs can be treated medically or surgically, however there are no consensus management guidelines for wither symptomatic or incidentally discovered lesions. Medical treatment typically includes anticoagulation with dual antiplatelet therapy while surgical treatment may involve carotid stenting or endarterectomy. Studies have shown that medical therapy alone for symptomatic webs is likely insufficient with up to 30% of patients developing recurrent stroke on medical therapy alone.

Educational Goals / Teaching Points
This exhibit will review imaging findings and key differentiating features of carotid webs on multiple imaging modalities including ultrasound, computed tomography arteriogram, magnetic resonance angiography including vessel wall imaging, and digital subtraction angiography. Inclusion of corresponding intra-operative photographs of webs with thrombus formation helps highlight the underlying anatomy and pathological mechanisms of this disease. Utilizing a case-based approach including dozens of real-life examples augmented by a review of relevant literature, this exhibit will illustrate the imaging manifestations, underlying histopathology, and current treatment options for carotid webs.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Carotid webs typically appear as a thin linear band presenting as a filling defect on angiographic imaging. This is found in a characteristic location, along posterior aspect of the internal carotid artery origin just beyond the bifurcation. To the unfamiliar eye these lesions may appear innocuous as the associated luminal stenosis is not considered hemodynamically significant. However, resultant disruption of laminar flow can result in relative stasis behind the web and increased wall stress, serving as a nidus for local thrombus formation. Subsequent embolus may result in a devastating ischemic event. Histopathologically, these lesions are thought of as a variant of fibromuscular dysplasia characterized by intimal fibrosis and hyperplasia, without involvement of the media or adventitia.

Conclusion
Through a thorough imaging review, this exhibit is aimed to raise awareness of an under-recognized but clinically significant disease entity.