Carotid Webs and Recurrent Ischemic Strokes in the Era of CT Angiography

Abstract

Background and purpose: Carotid webs may cause recurrent ischemic stroke. We describe the prevalence, demographics, clinical presentation, imaging features, histopathology, and stroke risk associated with this under-recognized lesion.

Materials and methods: A carotid web was defined on CTA as a thin intraluminal filling defect along the posterior wall of the carotid bulb just beyond the carotid bifurcation on oblique sagittal section CTA that was seen as a septum on axial CTA. Using a prospective case series from April 2013 to April 2014, we describe the demographics, spectrum of imaging features on CTA, and histopathology of these carotid webs. From a retrospective analysis of patients at our center from May 2012 to April 2013 who had a baseline head and neck CTA followed by a brain MR imaging within 1-2 days of the CTA, we determine the period prevalence of carotid webs and the prevalence of ipsilateral stroke on imaging.

Results: In the prospective series, the mean age was 50 years (range, 41-55 years); 5/7 patients were women. Recurrent stroke was seen in 5/7 (71.4%) patients with the carotid web; time to recurrence ranged from 1 to 97 months. Histopathology suggested a high probability of fibromuscular dysplasia. In the retrospective series, carotid webs were seen in 7/576 patients for a hospital-based-period prevalence of 1.2% (95% CI, 0.4%-2.5%). Two of these 7 patients had acute stroke in the vascular territory of the carotid web.

Conclusions: A carotid web may contribute to recurrent ischemic stroke in patients with no other determined stroke mechanism. Intimal variant fibromuscular dysplasia is the pathologic diagnosis in most cases. The prevalence of carotid web is low, while the optimal management strategy remains unknown.

Fig 1.

Sagittal and axial images of carotid webs. The top panel shows serial sagittal-view CTAs in patient A. A and B, Carotid webs 8 years apart. C, Changing morphology of the right carotid web within days with possible thrombus formation in the setting of dual antiplatelet therapy. D, A return to baseline morphology with the use of unfractionated heparin. The bottom panel shows serial CTAs in patient B. E, A carotid web with possible thrombus in the lumen (arrow). F, The same carotid web 1 month later with no thrombus. G, An axial-view CTA with the same carotid web appearing as a septum (arrow). The broken arrow indicates the carotid bifurcation.

Fig 2.

Small protruding lesions that are distinct from carotid webs in 3 different patients on sagittal and axial CTA (A–C, arrow). Axial CTA shows no septum with this lesion, unlike in carotid webs.

Fig 3.

Figures show the histopathology of carotid webs. A, A shelf-like projection of abnormal intimal fibrous tissue. B, Focal hemorrhagic dissection with early organization. C, Fibrous intimal thickening with focal dissection into the fibrotic intima. D, Focal fibrous intimal thickening with adherent thrombus.

Fig 4.

Animated figures depict thrombogenicity in the internal carotid artery due to the presence of a carotid web. A, Stasis of blood flow developing distal to the carotid web results in thrombus formation (B). This thrombus, when of sufficient size, dislodges and embolizes intracranially (C and D).