A conversation with Dr. Diogo Haussen, MD (Assistant Professor of Neurology, Emory School of Medicine/Grady Memorial Hospital), and Dr. Thomas Madaelil, MD (Neurointerventional Fellow, Emory School of Medicine), on imaging and clinical significance of carotid web.
Interviewed by Sami Al Kasab, MD (StrokeNet fellow, University of Iowa Hospitals and Clinics).
They will be discussing the paper “Multimodality Imaging in Carotid Web,” published in Frontiers in Neurology.
Dr. Al Kasab: I read with great enthusiasm your recent article comparing different imaging modalities to diagnose a carotid web. Can you please summarize the key findings of your study, and how your results can be applied to our clinical practice?
Drs. Haussen and Madaelil: Thank you for your interest in our manuscript. Acute ischemic stroke is commonly a devastating condition, especially when occurring in young adults. Occasionally, we can get tangled when we cast wide nets for the diagnostic work-up in patients with cryptogenic stroke. Carotid web is a condition that can be overlooked when neurovascular studies are reviewed during this diagnostic work-up period, and it may actually be more common that previously thought. Our study is aimed to help shed light on the performance of different imaging modalities in the diagnosis of carotid web, which is particularly important since there were no previously published comparative studies. We observed that computed tomographic angiogram (CTA) shared very high rates of inter-rater agreement with digital subtraction angiogram (DSA), while the CTA agreement with ultrasonography was much more limited. Therefore, non-invasive multiplanar imaging modalities, such as CTA, should be considered in the evaluation of young patients with otherwise no identified stroke cause considering the possibility of an underlying carotid web.
Dr. Al Kasab: Are there standardized imaging criteria to diagnose a carotid web in the different imaging modalities?
Drs. Haussen and Madaelil: There is an evolving body of literature which identifies a carotid web as a shelf-like intraluminal protrusion arising from the posterior wall of the carotid bulb. These criteria should be applicable to the different imaging modalities.
Dr. Al Kasab: What is the best imaging modality to identify them? In your study, ultrasound was inferior to CTA and DSA in identifying carotid webs. What do you think are some of the reasons for this finding?
Drs. Haussen and Madaelil: As a general rule, the least invasive method, coupled with highest spatial resolution and avoidance of non-ionizing radiation techniques, should be preferred. However, there is no perfect solution. Ultrasonography tends to reveal inconspicuous lesions, non-contrasted (time-of-flight) MRA is prone to artifacts, and DSA, despite being accurate, is invasive. MRA with gadolinium appears to be a valid option; however, data involving this modality is scarce. CTA offers a great blend of spatial resolution, ease for multiplanar reconstructions, and non-invasiveness among the imaging modalities we tested.
Dr. Al Kasab: What is the clinical significance of a carotid web?
Drs. Haussen and Madaelil: In a recent review paper, we noted that carotid webs had been identified in a significant proportion (9-37%) of young (<60 years old) patients with cryptogenic strokes. Moreover, these lesions have been associated with high recurrent stroke/transient ischemic attack (24-71%) risk and may not respond optimally to single antiplatelet regimens. Our treatment approach is highlighted by our answer to the next question.
Dr. Al Kasab: In your practice, how do you manage patients with a carotid web? Is the approach different if they are symptomatic or asymptomatic?
Drs. Haussen and Madaelil: The management to carotid web is controversial, as there is no high-level evidence to guide treatment decision-making. Therefore, our treatment recommendations are highly patient specific and occur in the setting of a multidisciplinary team consisting of the vascular stroke neurologist, neuro-interventionalist, and surgeon. We believe that patient preferences after a careful discussion should be taken into account as well. We do not treat asymptomatic carotid webs. Contrarily, symptomatic carotid webs constitute a higher-risk lesion due to the reported high rates of recurrent events. Unfortunately, the risk factors for recurrence are not known. We have previously observed that the size of the web (and its impact on hemodynamics and potential thrombogenic potential) may play a role in the risk of stroke. In terms of treatment, medical management may be pursued. As discussed, single antiplatelets may not be sufficient in the long term. Dual antiplatelets or anticoagulation may be contemplated. Stenting and surgical resection have been reported to be safe and serve as an option, especially in cases of recurrence.
Dr. Al Kasab: How often are carotid webs associated with super-imposed thrombosis (intraluminal thrombus)? How do you manage patients with these conditions?
Drs. Haussen and Madaelil: Thrombus super-imposed to a carotid web has been reported in 12-29% of carotid web series’. If the patient presents with an emergent large vessel cerebral occlusion, thrombectomy may allow the removal not only of the cerebral clot, but also of the carotid bulb thrombus. In non-hyperacute cases, the difficulty resides in the fact that if a clot is noted at the posterior bulb of the carotid, it may relate to atherosclerosis or to other etiology and the diagnosis can only be made after a repeat scan shows resolution of the clot and depicts the underlying lesion. In terms of secondary prevention, we favor dual antiplatelets or anticoagulation for individuals with superimposed thrombus with repeat non-invasive vascular imaging study within 5-7 days. The optimal duration of dual antiplatelet or anticoagulant therapy is unknown, but the concern is that carotid webs tend to be static lesions (positive remodeling, as seen in atherosclerotic lesions, is unlikely). Therefore, protection may have to be targeted for the long term. Future studies are needed to help understand the natural history, to further define the best imaging diagnostic modality, and to clarify the role of medical management and/or intervention in patients with a symptomatic carotid web.
Dr. Al Kasab: Thank you very much for your time and information.