By Antonio Ciacciarelli, Department of Clinical and Experimental Medicine, University of Messina, Italy
Carotid web is a non-atheromatous and non-dissecting membrane-like strand that protrudes into the lumen of the carotid artery. Pathological examination reveals aspects similar to the fibromuscular dysplasia, with abnormalities mainly involving the intimal layer 1.
This is an underrecognised cause of stroke. A post-hoc review of Computed Tomography Angiography (CTA) imaging of the MR-CLEAN trial revealed the presence of carotid webs at the symptomatic bifurcation in 2.5% of patients with acute ischemic stroke due to large vessel occlusion. Among these, 82% did not have major risk factors or other causes for ischemic stroke 2. In the case-control study by Coutinho and collaborators, the prevalence of the carotid web in 62 patients with ischemic stroke of undetermined etiology was 8,9% compared to 1,9% of the control group 3.
In both studies, the lesion was predominant in young female patients. Recently, similar results have also been observed in patients with embolic strokes of undetermined source (ESUS) in which the prevalence of a carotid web ipsilateral to an occlusion of a large intracranial artery is higher than in patients with an identified source of thromboembolism 4.
In a prospective series of young cryptogenic strokes, the incidence of recurrent strokes in patients with carotid web was 29% 5. In other studies, this percentage is much higher reaching 74%. The recurrent event is most of the time within 12 months. This high rate of stroke recurrence may be explained by the flow stagnation along the superior surface of the septum that leads to the formation of a superimposed thrombus and ultimately to cerebral embolization (figure).
Carotid web is mostly located in the posterior wall of the carotid bulb. It is hardly detected by Ultra-Sound (US) and it may appear similar to atherosclerotic plaques. CTA and Digital Subtraction Angiography (DSA) have been demonstrated to be the optimal neuroimaging to identify carotid web 6. The oblique projection during the DSA or the oblique sagittal section in CTA may be necessary.
There is no randomized clinical trial regarding treatment options in patients with symptomatic carotid web. Antiplatelet therapy is suggested to be insufficient considering that blood stasis may be the underlying pathogenic mechanism of the clot formation. However, no strong evidence is available on anticoagulation. Remarkably, as reported in the systematic review by Zhang et al., no recurrent strokes, over a median follow-up of 14 months, occurred in patients treated with carotid revascularization 7. Carotid Endarterectomy (CEA) and Carotid Artery Stenting (CAS) are the preferred interventional options and represent, so far, the most promising therapeutic approach.
Lesser is known about the management of asymptomatic carotid web. Does an incidental diagnosis of carotid web require any treatment? Perhaps we need to wait for further studies. Hence, for now, let us settle on the identification of the symptomatic ones, especially in young cryptogenic stroke patients, for the purpose to reduce as far as possible the risk of stroke recurrence.
- Kim SJ, Nogueira RG, Haussen DC. Current Understanding and Gaps in Research of Carotid Webs in Ischemic Strokes. JAMA Neurol 2019; 76: 355.
- Compagne KCJ, Van Es ACGM, Berkhemer OA, et al. Prevalence of carotid web in patients with acute intracranial stroke due to intracranial large vessel occlusion. Radiology 2018; 286: 1000–1007.
- Coutinho JM, Derkatch S, Potvin ARJ, et al. Carotid artery web and ischemic stroke. Neurology 2017; 88: 65–69.
- Labeyrie M-A, Serrano F, Civelli V, et al. Carotid artery webs in embolic stroke of undetermined source with large intracranial vessel occlusion. Int J Stroke 2020.
- Haussen DC, Grossberg JA, Bouslama M, et al. Carotid web (intimal Fibromuscular Dysplasia) has high stroke recurrence risk and is amenable to stenting. Stroke 2017; 48: 3134–3137.
- Madaelil TP, Grossberg JA, Nogueira RG, et al. Multimodality Imaging in Carotid Web. Front Neurol 2019; 10: 220.
- Zhang AJ, Dhruv P, Choi P, et al. A Systematic Literature Review of Patients With Carotid Web and Acute Ischemic Stroke. Stroke 2018; 49: 2872–2876.