Carotid Web Phenotype Is Uncommonly Associated With Classic Fibromuscular Dysplasia: A Retrospective Observational Study

Background and Purpose: Carotid web (CaW) is an intimal form of fibromuscular dysplasia (FMD) involving the carotid bulb which has been increasingly recognized as a potential cause of recurrent ischemic strokes. It is overlooked as a separate entity and often dismissed if no coexistent signs of classic FMD changes are observed. We aim to evaluate the frequency of classic FMD in high-yield vascular territories in patients with symptomatic CaW. Methods: This was a retrospective analysis of a symptomatic CaW database of 2 comprehensive stroke centers (spanning September 2014–October 2020). The diagnosis of a CaW during a stroke workup was defined as the presence of a shelf-like linear filling defect in the posterior aspect of the carotid bulb on computed tomography angiography in patients with acute ischemic stroke or transient ischemic attack of undetermined cause after a thorough evaluation. Neck computed tomography angiography and renal conventional angiography images were independently evaluated by two readers blinded to the laterality and clinical details to inspect the presence of underlying classic FMD. Results: Sixty-six patients with CaW were identified. Median age was 51 years (interquartile range, 42–57), and 74% were women. All patients had neck computed tomography angiography (allowing for bilateral vertebral and carotid evaluation), whereas 47 patients had additional digital subtraction angiography (which evaluated 47 carotids ipsilateral to the stroke and 10 contralateral carotids). Internal carotid artery classic FMD changes were noted in only 6 out of 66 (9%) in the ipsilateral carotids. No contralateral carotid or vertebral artery classic FMD changes were observed. Renal artery catheter-based angiography was obtained in 16 patients/32 arteries and only 1 patient/2 renal arteries demonstrated classic FMD changes. Conclusions: CaW phenotype is uncommonly associated with classic FMD changes. Coexistent classic FMD does not constitute a useful marker to corroborate or exclude CaW diagnosis.

Prospective Evaluation of Circulating miR-126, mir-197 and mir-223 in Relation to Cardiometabolic Diseases

We aim to investigate if serum levels of microRNAs: miR-126, mir-197 and mir-223, previously implicated in cardiometabolic disease, are reproducibly associated with incident-diabetes (inc-DM), incident-cardiovascular disease (inc-CVD) and with carotid atherosclerosis (measured for the maximum thickness of the intima-media of the carotid bulb (IMT)). The microRNAs were measured, one: in serum of 553 subjects from the baseline exam of the Swedish prospective cohort, Malmö Diet and Cancer Study (MDC-CC), with 169 subjects who developed CVD and 140 DM (16 years follow-up) and, two: in 1221 subjects from the Malmö Offspring Study (MOS), with 14 de-veloped CVD and 12 DM (3.7 years follow-up). Multivariate logistic and linear regression models were used to investigate the relationship of serum-concentrations of the microRNAs and inc-DM, inc-CVD, IMT-bulb respectively. In MDC-CC, miR-126 showed significant positive association with inc-DM (p= 0.01) whereas in fully adjusted model, the association was borderline significant (p= 0.05). The results were not replicated in MOS. There was no consistent significant association between the microRNAs with IMT or inc-CVD in any cohort. Our results do not support previous reports on significant associations between these microRNAs and the risk of CMD, as they were not reproducible in our cohorts. In addition, the directionality of any associations found were not consistent with those previously reported.

Abstract 1122‐000128: Imaging Follow‐Up in Carotid Webs: Is There Vascular Remodeling?

Introduction : Carotid web (CaW) is a shelf‐like fibrotic projection at the carotid bulb and constitutes an underrecognized cause of ischemic stroke. Atherosclerotic lesions are known to have dynamic remodeling with time however, little is known regarding the evolution of CaW over time. We aimed to better understand if CaW is a static or dynamic entity on delayed vascular imaging. Methods : This was a retrospective analysis of the CaW database at our comprehensive stroke center, including patients diagnosed with CaW between September 2014 through June 2021. Patients who had at least two good quality CT angiograms (CTAs) that were at least 6 months apart were included (CTAs with CaW and superimposed thrombus were excluded). CaW were quantified with 3‐D measurements using Horos software. This was done via volumetric analysis of free‐hand delineated CaW borders on thin cuts of axial CTA (Figure 1 Panel A). NASCET criteria was used to evaluate the degree of stenosis. Results : Sixteen CaW in 13 patients were identified and included. The median imaging follow‐up window was 16 months (IQR 12–22, range 6–29). Median patient age was 45.5 years‐old, 69% were women, 25% had hypertension, 38% hyperlipidemia, 25% diabetes mellitus, 0% atrial fibrillation, and 13% active smokers. 75% of the included CaW were symptomatic while 25% were asymptomatic. Median volume of CaW on initial CTA (8.52 mm3 [IQR 3.7‐13], range 2.2‐30.4) was comparable to median volume of CaW on most recent CTA (8.47 mm3 [IQR 4.0‐12.8], range 2.3‐29.4; p = <0.001 (Figure 1 Panel B). The CaW volumetric measurement correlation between the initial and most recent CTA was near perfect (rs = ‐0.99, p = <0.001). The median change in measured volume of CaW between first and last CTA was ‐0.19 mm3 [IQR ‐0.6‐0.4], range ‐1‐0.8. Median degree of stenosis was 8.1% [IQR 4.5‐17.1], range 0.4‐31.2. The duration of follow‐up imaging was not correlated with the change in CaW volume (Kendall tau‐b[τb] = ‐0.17, p = 0.93). The initial CaW volume was not found to be correlated to the degree of stenosis (τb = ‐0.08, p = 0.65). Conclusions : The volume of the CaW was not found to change over time, reinforcing the idea that this is a relatively static lesion. The CaW volume was not found to correlate with the degree of stenosis caused by it. Further longitudinal studies with longer follow‐up intervals are warranted.

Embolectomy of acute embolic stroke associated with ipsilateral carotid web: a case report and literature review

A carotid web is a thin intraluminal protrusion located in the posterolateral wall of the carotid bulb, which might be a risk factor for cryptogenic stroke. The mechanism of ischemic stroke caused by carotid web is still unclear, but it might be related to hemodynamic changes distal to the web, resulting in flow forces and remote embolization of fibrin-based clots. The diagnosis of a carotid web mainly depends on carotid artery imaging examinations. The main therapeutic strategies include medical treatment with oral antiplatelet agents and anticoagulants, and operative treatment, such as carotid endarterectomy and carotid artery stenting. Few cases of acute large-vessel occlusion undergoing mechanical thrombectomy in the setting of carotid web as the etiology have been reported. We report here a case of a 37-year-old woman who underwent stent retriever embolectomy after acute ischemic stroke. Carotid artery imaging examinations, including digital subtraction angiography and magnetic resonance imaging, and pathology showed that a carotid web was located at the proximal right internal carotid artery. We also discuss the clinical pathophysiological and imaging features, and the treatment of carotid web as described in the currently available literature.

Improving Blood Flow Visualization of Recirculation Regions at Carotid Bulb in 4D Flow MRI Using Semi-Automatic Segmentation with ITK-SNAP

Assessment of carotid bulb hemodynamics using four-dimensional (4D) flow magnetic resonance imaging (MRI) requires accurate segmentation of recirculation regions that is frequently hampered by limited resolution. This study aims to improve the accuracy of 4D flow MRI carotid bulb segmentation and subsequent recirculation regions analysis. Time-of-flight (TOF) MRI and 4D flow MRI were performed on bilateral carotid artery bifurcations in seven healthy volunteers. TOF-MRI data was segmented into 3D geometry for computational fluid dynamics (CFD) simulations. ITK-SNAP segmentation software was included in the workflow for the semi-automatic generation of 4D flow MRI angiographic data. This study compared the velocities calculated at the carotid bifurcations and the 3D blood flow visualization at the carotid bulbs obtained by 4D flow MRI and CFD. By applying ITK-SNAP segmentation software, an obvious improvement in the 4D flow MRI visualization of the recirculation regions was observed. The 4D flow MRI images of the recirculation flow characteristics of the carotid artery bulbs coincided with the CFD. A reasonable agreement was found in terms of velocity calculated at the carotid bifurcation between CFD and 4D flow MRI. However, the dispersion of velocity data points relative to the local errors of measurement in 4D flow MRI remains. Our proposed strategy showed the feasibility of improving recirculation regions segmentation and the potential for reliable blood flow visualization in 4D flow MRI. However, quantitative analysis of recirculation regions in 4D flow MRI with ITK-SNAP should be enhanced for use in clinical situations.

Delayed Collet-Sicard syndrome after internal carotid dissection and Jefferson fracture. Case report and Review of Literature

Background: Lower cranial nerve palsies, or Collet-Sicard syndrome, can be caused by many different etiologies including head trauma, basilar occipital fractures, tumors, and interventions. Few reports describe different presentations of this condition, and we present here a case study to increase awareness of and add to the variable spectrum. Case Description: A 56-year-old who had been hit while diving was admitted to our department. On examination, he was conscious without any signs of lateralization but presented with severe neck pain. CT brain and cervical spine revealed a C1 fracture with bilateral symmetrical fracture of the anterior and posterior arches (Jefferson’s fracture) and slight bilateral joint dislocation C1-C2 discreetly predominant on the left. One week later, he presented with dysarthria, dysphonia, swallowing disorder, anisocoria, tongue deviation, and palate deviation (XII, IX, and X). CT Angiography showed dissection of the internal carotid artery immediately after the carotid bulb. He has been treated conservatively with curative anticoagulants with stable symptoms. No surgical intervention had been proposed. Conclusion: Adding to the literature, delayed Collet-Sicard syndrome and lower cranial affection can be caused by missed carotid wall hematoma following severe craniocervical trauma associated with Jefferson’s fracture.

Adenovirus-Vectored COVID-19 Vaccine–Induced Immune Thrombosis of Carotid Artery: A Case Report

Objective:Venous thromboses and thrombocytopenia after vaccination with the adenovirus-vectored COVID-19 vaccine ChAdOx1 nCov-19 (AstraZeneca) have been linked to serum antibodies against platelet factor 4 (PF4)–polyanion complexes. We here report vaccine-induced isolated carotid arterial thrombosis.Methods:Imaging and laboratory findings, treatment decisions and outcome of this case are presented.Results:Eight days after having received the first dose of ChAdOx1 nCov-19 vaccine, a 31-year-old man was admitted to our stroke unit with acute headache, aphasia, and hemiparesis. D-dimers were slightly elevated, but platelet count and fibrinogen level were normal. MRI-confirmed mainstem occlusion of middle cerebral artery resolved within 1 hour after start of IV thrombolysis. A wall-adherent, non-occluding thrombus in the ipsilateral carotid bulb was identified as the source of embolism. Cardiac or paradoxical (venous) embolism was excluded. Screening for presence of heparin-induced thrombocytopenia-related antibodies was positive, and highly elevated serum IgG antibodies against PF4–polyanion complexes were subsequently proven. Treatment with aspirin and subcutaneous danaparoid, followed by phenprocoumon, led to thrombus shrinkage and dissolution within 19 days, and favorable clinical outcome.Discussion:Vaccine history is important in patients not only with venous but also with arterial thromboembolic events. Vaccine-induced immune thrombosis of brain-supplying arteries may well be handled.

Bilateral carotid webs

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 51-year-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.