Case Report The Neuroradiology Journal 0(0) 1–3 ! The Author(s) 2021 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/19714009211017783 journals.sagepub.com/home/neu Bilateral carotid webs Muhammed Amir Essibayi1 , Deena Nasr2 and Giuseppe Lanzino1,3 Abstract Carotid web is thought to be a focal intimal variant of fibromuscular dysplasia, which comprises a high risk of stroke because of blood stasis and subsequent coagulative reactions that occur distal to the web. These lesions generally involve the posterolateral wall of the carotid and their developmental pathogenesis is controversial. This case report describes a 51year-old woman who presented to the hospital with sudden onset aphasia, right hemi-sensory loss, and right visual field cut. Magnetic resonance imaging (MRI) of the brain demonstrated a left middle cerebral artery (MCA) distribution embolic ischemic infarct with shelf-like linear filling defects in the carotid bulb bilaterally on a computed tomography angiography (CTA) of the head and neck consistent with bilateral carotid webs that were confirmed by catheter angiography. The carotid webs were projecting on the left posteriorly and on the right anteriorly into the inferior aspects of the bilateral proximal internal carotid arteries. The patient was started on clopidogrel and a high-intensity statin and remained on Plavix monotherapy for a 10-month follow up without a recurrent ischemic event. Keywords Bilateral, carotid web, stroke Introduction A carotid web is a focal intimal variant of fibromuscular dysplasia with a shelf-like linear filling defect appearance in the posterolateral aspects of the internal carotid artery bulb.1,2 These lesions have been described in the literature under various names since their first report in 1968,3–5 and association with recurrent strokes is often reported.6 Knowledge about the origin and formation of the carotid webs is scarce and a wide range of management modalities exist with no consensus about the best treatment option. We describe a case of bilateral carotid webs presented with stroke and managed medically with no recurrent stroke for a mid-term follow up. Case report A 51-year-old woman with a past medical history of mitral valve prolapse and migraines with visual aura, who presented to an outside hospital with sudden onset aphasia, right hemi-sensory loss, and right visual field cut. Her imaging included a non-contrast head computed tomography (CT), which was negative for acute findings, brain magnetic resonance imaging (MRI) and a computed tomography angiography (CTA) of the head and neck and that showed a left middle cerebral artery (MCA) distribution embolic ischemic infarct (Figure 1a), and shelf-like linear filling defects in the carotid bulb bilaterally (Figure 1b), respectively. Catheter angiography confirmed bilateral ridge-like appearance projecting on the left posteriorly (Figure 2a) and on the right anteriorly (Figure 2b) into the inferior aspects of the bilateral proximal internal carotid arteries with a similar degree of maximal stenosis on both sides (left: 50% vs right: 40%). Early and late arterial phases demonstrated stagnant contrast around the linear filling defects reported as bilateral carotid dissections. The patient was taking an oral contraceptive, which was subsequently discontinued; she was misdiagnosed with acute carotid dissections, started on clopidogrel and a high-intensity statin, and had an unrevealing rheumatological and genetic evaluation. A 7-month local follow-up carotid ultrasound showed persistent bilateral echogenic linear areas (Figure 3). At 10 months from onset, the patient presented to our institution for further evaluation, and showed near-complete recovery. A review of her prior studies was thought to be more consistent with carotid webs and the patient was appropriately counseled. 1 Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA Department of Neurology, Mayo Clinic, Rochester, MN, USA 3 Department of Radiology, Mayo Clinic, Rochester, MN, USA 2 Corresponding author: Giuseppe Lanzino, Mayo Clinic, Department of Neurosurgery, 200 First St SW, Rochester, MN55905, USA. Email: Lanzino.Giuseppe@mayo.edu 2 The Neuroradiology Journal 0(0) Figure 1. Diffusion MRI shows left MCA embolic infarcts (a) and CTA shows bilateral carotid webs (b). CTA: computed tomography angiography; MCA: middle cerebral artery; MRI: magnetic resonance imaging. Figure 2. A DSA shows ridge-like projections into the posterior inferior aspect of the left proximal ICA bulb (a) and the anterior inferior aspect of the right proximal ICA bulb (b). Early and late arterial phases demonstrate stagnant contrast around the webs. DSA: digital subtraction angiography; ICA: internal carotid artery. Figure 3. B-mode ultrasound images show a thin fibrous band at the left (a) and right (b) carotid bifurcations consistent with carotid webs. Essibayi et al. She remained on Plavix monotherapy and has not had a recurrent ischemic event. Discussion Carotid web is thought to be a rare focal intimal variant of fibromuscular dysplasia;6 however, its origin and development are controversial. It is often misdiagnosed, as seen with this case. Carotid web typically involves the posterior wall of the proximal internal carotid artery (ICA) and results in stroke due to the stasis of blood and platelet activation/thrombus formation that occur rostral to the web.6 Although some authors have proposed de novo formation of the carotid web as a sequela of micro-intimal dissections,7 the most accepted theory postulates that webs are congenital.8 In patients with bilateral carotid webs, typically one side is symptomatic and can be the source of unilateral hemispheric recurrent strokes.6 Haussen et al. suggested that, in patients with bilateral webs, the contralateral (asymptomatic) web remains clinically silent at follow up.9 This was also observed in our case of bilateral carotid webs projected in opposite directions. The treatment strategy of symptomatic carotid webs is controversial and includes various options of medical, surgical, and endovascular treatments. A large systematic review and a small clinical trial suggested superiority of interventional treatments over medical management in symptomatic patients as no recurrent strokes were reported after stenting or endarterectomy compared with a high recurrence rate (29–56%) after medical therapy alone.1,4,6,9 However, generalization of these results is limited by the small sample size analyzed and the high risk of publication and selection biases. Our patient did not suffer recurrent episodes after a 10 month follow up with medical treatment alone. Conclusion Despite the rarity of carotid webs, they constitute an important cause of stroke. Therefore, their origin and pathogenesis should be investigated with further 3 natural history studies. Furthermore, prospective studies are warranted to understand the best management of these uncommon lesions. Conflict of interest The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Funding The author(s) received no financial support for the research, authorship, and/or publication of this article. ORCID iD Muhammed Amir Essibayi 8325-2382 https://orcid.org/0000-0001- References 1. Coutinho JM, Derkatch S, Potvin ARJ, et al. Carotid artery web and ischemic stroke: a case-control study. Neurology 2017; 88: 65–69. 2. Choi PMC, Menon BK, Demchuk AM. Carotid web and stroke. Eur J Neurol 2014; 21: e53. 3. Rainer WG, Cramer GG, Newby JP, et al. Fibromuscular hyperplasia of the carotid artery causing positional cerebral ischemia. Ann Surg 1968; 167: 444–446. 4. Osborn AG, Anderson RE. Angiographic spectrum of cervical and intracranial fibromuscular dysplasia. Stroke 1977; 8: 617–626. 5. Wirth FP, Miller WA, Russell AP. Atypical fibromuscular hyperplasia. Report of two cases. J Neurosurg 1981; 54: 685–689. 6. 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