INTRODUCTION
Carotid webs are thin, membranous shelf-like projections that result from intimal fibromuscular dysplasia into the lumen of the proximal cervical internal carotid artery (ICA) and have been identified as a potential cause for cryptogenic ischemic stroke [14]. In patients with suspected ischemic stroke, the overall prevalence of a carotid web on a computed tomographic angiogram (CTA) is 1%-7% [4,16]. They can be unilateral or bilateral, and the incidence of bilateral lesions is increasing in frequency of diagnosis [2]. Compared to mild-to-moderate carotid atherosclerotic lesions, carotid webs may cause greater local hemodynamic disturbance that can lead to thrombogenic flow stasis [12].
Although there is equipoise over the optimal course of treatment for carotid web, medical management, carotid endarterectomy, or endovascular stenting have been previously described [16]. We discuss the safety and effectiveness of bilateral carotid artery stenting in patients found to have bilateral carotid webs. Three patients at our center were treated for bilateral carotid webs after symptomatic presentation. Although recent studies support endovascular treatment of the symptomatic carotid web due to increased safety and efficacy [7], there are limited studies discussing the safety and efficacy of endovascular treatment for contralateral asymptomatic carotid webs.
CASE DESCRIPTION
Case 1
A 50-year-old African American woman, a nonsmoker with a medical history of hypertension, gastroesophageal reflux disease (GERD), iron deficiency anemia, and a family history of diabetes and hypertension, was admitted with an acute headache on the left side, accompanied shortly thereafter by tingling and numbness on the left side of her face, arm, and leg, without other neurologic symptoms. On the second day of admission, her symptoms improved spontaneously. Her initial blood pressure was elevated to 185/103 mm Hg, and her vitals were otherwise stable. On exam, she had intact mentation, language, strength, and sensation.
A non-contrast computed tomography (CT) of the head demonstrated no evidence of an acute infarct or hemorrhage, and there was no evidence of restricted diffusion on her magnetic resonance imaging (MRI) of the brain. A CT angiogram was performed that revealed carotid webs bilaterally associated with <20% stenosis. A complete stroke work-up, including transcranial doppler ultrasound and an echocardiogram with bubble study, was carried out without identifying an underlying etiology. She was diagnosed with a transient ischemic attack (TIA) and discharged on a high-dose statin, an antihypertensive, and aspirin 81 mg daily.
After two weeks, she returned to the emergency department with symptoms similar to her initial presentation—a left-sided headache, left-sided tingling and numbness, and stable neurologic exam. Repeat stroke evaluation did not reveal an acute infarction or hemorrhage.
After a multidisciplinary discussion, her TIAs were attributed to the right carotid web. She was premedicated with 300 mg of clopidogrel and 81 mg of aspirin. She underwent successful carotid stenting using an 8-French (Fr) Cerenovus balloon guide catheter with distal embolic protection (FILTERWIRE EZ) of her symptomatic right carotid web with an 8×29 mm carotid WALLSTENT. After 24 hours of post-operative monitoring, she was discharged home the next day on a maintenance dose of aspirin 81 mg daily and clopidogrel 75 mg daily. Three weeks later, she underwent elective stenting of her left-sided carotid web with an 8-Fr Cerenovus balloon guide catheter, FILTERWIRE EZ distal embolic protection, and another 8×29 mm carotid WALLSTENT. Follow-up angiography during this session demonstrated no residual visualization of her bilateral carotid webs. Given left lower extremity (LLE) swelling one month after treatment, she was diagnosed with a non-occlusive left common femoral vein thrombosis, for which apixaban was added to her medication regimen, after discussion with her primary care doctor. After 30 days of triple therapy with aspirin, clopidogrel, and apixaban, the clopidogrel was discontinued. At six-month follow-up, she had not experienced recurrent ischemic symptoms and was left on aspirin monotherapy.
Case 2
A 41-year-old African American woman with a history of oral contraceptive use awoke with the abrupt onset of a right-sided headache, left-sided weakness of her face, arm, and leg, and slurred speech. She had previously experienced similar symptoms transiently that resolved without medical care.
Her neurologic exam was notable for left arm drift (4/5 strength), mild left hip flexion weakness (4/5 strength), and sensory deficits in her face, arm, and leg, and mild dysarthria, with an initial National Institutes of Health Stroke Scale (NIHSS) of 5 in the emergency department. After three hours, her symptoms progressed, and her NIHSS increased to 14. She was outside of the window for intravenous thrombolytics, and a non-contrast CT of the head demonstrated an acute right parietal infarction within the right middle cerebral artery (MCA) territory. CTA showed a right MCA occlusion and probable bilateral carotid webs with approximately 50% residual stenosis. She underwent emergent endovascular thrombectomy, with two passes of aspiration with a 6-Fr Sophia aspiration catheter, with migration of thrombus to the M2 division requiring 2 additional passes, once with additional aspiration and then aspiration with Solitaire 3×20 mm stent retriever. Thrombolysis in Cerebral Infarction (TICI) grade 2C reperfusion was achieved, and full angiography confirmed the presence of bilateral carotid webs.
A thorough stroke work-up did not support a different underlying etiology. Given the degree of stroke volume, she was stabilized for two weeks, and when it was considered safe to begin a dual antiplatelet regimen, she was loaded with clopidogrel 300 mg in addition to aspirin 81 mg daily. Stenting of her symptomatic right carotid artery web with an 8×21 mm carotid WALLSTENT was performed via a 6-Fr TracStar Large Distal Platform catheter with distal embolic protection (FILTERWIRE EZ system). She was maintained on clopidogrel 75mg daily plus aspirin 81mg daily. Four days later, a left carotid stent for her asymptomatic carotid web was successfully placed using the same devices. She was discharged to acute rehabilitation the following day without any noted complications. At nine months post-procedure, she experienced one episode of transient left arm heaviness without objective weakness on neurologic exam and no evidence of large vessel occlusion on CTA, which required no additional intervention.
Case 3
A 41-year-old male, a non-smoker without notable past medical history, presented to the emergency room with the sudden onset of left-sided weakness, numbness, and left facial droop. His neurologic exam demonstrated normal mentation and orientation, no language deficits, mild dysarthria, leftward gaze deviation, a right homonymous hemianopsia, left facial droop, and sensory deficits to light touch on the left side of his face. He had 2/5 motor strength in his left-sided upper extremity and 2/5 strength in his left lower extremity with reduced sensation to light touch on the left arm and leg, yielding an initial NIHSS of 16.
A non-contrast CT of the head demonstrated subtle hypodensity within the right corona radiata, extending into the right putamen, consistent with acute ischemia. He was outside of a window for intravenous thrombolytic therapy. A CTA of the head and neck demonstrated complete occlusion of the M1 segment of the right MCA, and CT perfusion demonstrated significant penumbra and minimal core infarction. He underwent an emergent mechanical thrombectomy with an 8-Fr TracStar guide catheter, 6-Fr Sophia aspiration catheter, and a Velocity microcatheter with a Fathom-16 microwire for positioning. TICI 3 reperfusion was achieved after one pass with aspiration, and further catheter angiography confirmed the presence of bilateral carotid webs. Of note, there was greater contrast stagnation within the symptomatic right carotid web during cerebral angiography when compared to the left.
A complete stroke work-up was completed without revealing any additional embolic sources. The patient was loaded with dual antiplatelet therapy and maintained on aspirin 81mg daily and clopidogrel 75mg daily. He underwent successful carotid artery stenting (8×29 mm carotid WALLSTENT) with distal embolic protection (FILTERWIRE EZ system) of his symptomatic right carotid web via an 8-Fr TracStar guide catheter, without intra- or post-operative complications. Eight weeks later, he underwent successful staged stenting for his asymptomatic left carotid web with an 8×29 mm carotid WALLSTENT (Fig. 1) with distal protection (FILTERWIRE EZ system), with the aid of an 8-Fr Cerenovus balloon catheter placed approximately 3 cm proximal to the carotid bifurcation in the common carotid artery. He recovered well, and at 8-month follow-up he has not experienced recurrent stroke or thromboembolic events since his procedures.
DISCUSSION
Carotid webs, an intimal and non-circumferential atypical type of fibromuscular dysplasia found near the carotid bulb’s origin, are membrane-like lesions that protrude into the lumen of the internal carotid artery. They may be unilateral or bilateral; bilateral lesions are being diagnosed with increasing frequency [16]. Carotid webs are typically found in middle-aged adults, with a female preponderance [4,9,14] and may represent a cause of cryptogenic ischemic stroke that is becoming more widely acknowledged. A case-control study of 164 cryptogenic stroke patients matched for age and gender found that the prevalence of carotid webs was 9.4% in the population with cryptogenic stroke and 1.0% in the control group [9]. A recent systematic review noted that patients of African descent accounted for the majority (58.6%) of documented symptomatic carotid web cases [10].
The precise mechanism for thromboembolism secondary to carotid webs is not completely understood, though it is believed to be related to blood stasis rostral to the carotid web, thrombus generation, and later clot fragmentation with distribution to the ipsilateral cerebrovasculature [3].
Carotid webs are often subtle and difficult to detect with noninvasive imaging methods and, as such, may be underdiagnosed. CTA is considered the preferred noninvasive imaging modality, and an additional benefit of CTA is the ability to create three-dimensional reconstructions [4,7,16]. This is particularly useful when evaluating a patient for stenting versus carotid endarterectomy. Another safe, low-cost imaging method, duplex ultrasonography, is especially useful for evaluating the carotid bulb to analyze the arterial wall and hemodynamic effects, although this was not done pre-procedurally for these patients [5,6]. Digital subtraction angiography (DSA) is often considered the “gold standard” method for accurately diagnosing carotid web disease [13]. Some studies promote the role of CTA, asserting that unique imaging features of carotid webs are best characterized on CTA [14] and that CTA should be the approach of choice [15], though this is still an area of controversy. Compared to DSA, CTA is comparatively less expensive, more generally accessible, and does not require an invasive procedure.
Previous research has shown that the risks of a recurrent stroke are relatively significant while using only conservative therapy with antiplatelets. In one study, patients with carotid artery webs receiving antiplatelet monotherapy experienced a 30% (6/20) recurrent ischemic event rate (median time to recurrence: 12 months) [9]. Therefore, treatment of the web to reduce the risk of stroke recurrence, either with carotid artery endarterectomy or carotid artery stenting, is suggested [1]. Both options are well tolerated, for example, after receiving carotid artery endarterectomy or stenting, 23 individuals in a cohort study had no recurrences even after a median follow-up of 39 months [11]. Additionally, endovascular procedures have been reported to be safe for the treatment of carotid web. A recent study showed that carotid artery stenting was successful in preventing stroke recurrence after a median of 12 months of clinical follow-up for 24 symptomatic carotid web patients [2,11].
Carotid artery stenting on the symptomatic side has been shown to prevent ischemic stroke [8], but there is less known about the role of staged bilateral endovascular carotid web treatment. Our series of three bilateral carotid web patients who underwent effective bilateral carotid stenting supports the use of this technique. These patients were younger than typically seen for carotid stenosis (our range 41-50 years old), and 2/3 did not have classic atherosclerotic risk factors, reinforcing the belief that carotid webs constitute a significant cause of ischemic stroke in younger patients. Additionally, the extent of stenosis varied and was at most moderate: the first had 15-20% stenosis, the second had 50% bilaterally, and the third had 10-20% on the right side and <10% on the left side. These data highlight that carotid web-associated stroke episodes may occur regardless of the severity of stenosis. These patients underwent stenting in the acute-to-subacute window of two or three days after admission on the symptomatic side, whereas the contralateral carotid web was treated two to eight weeks later. The optimal time frame for treatment of contralateral asymptomatic carotid webs has not been fully investigated, and additional research is needed. Bilateral lesions were stented safely in a staged fashion for all three patients, and there were no adverse intra- or postoperative complications. All three patients remained stroke recurrence-free at their most recent follow-up.
CONCLUSIONS
In our small case series of patients with bilateral carotid webs, treatment of the symptomatic side followed by the asymptomatic contralateral web was safe and effective. Treating symptomatic carotid webs to prevent TIA/stroke recurrence is valuable, however, there is less understanding of the role of treatment for asymptomatic contralateral carotid webs. Our experience demonstrates the safety and effectiveness of staged bilateral carotid artery stenting in this clinical scenario. Further study will be required to support this finding.
PDF Links
PubReader
ePub Link
XML Download
Full text via DOI
Download Citation
Print
