Ivy Anne Sebastian, MD, DM, associate professor of neurology at Christian Medical College and Hospital

Ivy Anne Sebastian, MD

evaluation should extend beyond stenosis to plaque morphology, webs, and dissection, said Ivy Anne Sebastian, MD, DM, associate professor of neurology at Christian Medical College and Hospital, during the 

The Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification, still used to assign stroke etiology, requires stenosis of > 50% to label large-artery atherosclerosis.

In an interview at WSC, Sebastian described this threshold as likely one of the biggest diagnostic blind spots in the field, citing studies linking stenosis < 50% to recurrent stroke.

"We are moving beyond just the degree of stenosis to looking at the vessel wall itself," said Sebastian. "We're looking at the plaque morphology, looking at vulnerable plaque characteristics such as an ulcerated plaque or intra-plaque hemorrhage, and then also looking at things beyond atherosclerosis."

Carotid Disease Beyond Stenosis, With Ivy Anne Sebastian, MD

Symptomatic Non-Stenotic Carotid Disease and Embolic Imaging Patterns

Growing recognition of these lesions has produced the concept of symptomatic non-stenotic carotid disease (SyNC). No consensus criteria exist, and Sebastian offered a pragmatic definition: stenosis < 50%, an embolic infarct pattern, and no other explanation for the stroke. Goyal and colleagues proposed stratifying SyNC into “definite, probable, and possible.”

On imaging, Sebastian said an embolic pattern should prompt consideration of a carotid source even when the lesion is not significantly stenotic. A lesion with < 40% stenosis may represent the culprit if an embolic pattern is present and no competing etiology explains the stroke.

She also flagged intraluminal thrombus as an uncommon finding with high thrombogenic potential, particularly in the short term after stroke. A 2024 review by Ospel and colleagues proposed a probabilistic framework for SyNC.

 It weighs carotid lesion imaging characteristics, brain imaging findings, and alternative etiologies.

Carotid Webs and Dissection in Younger Patients

Among non-atherosclerotic pathologies, Sebastian first pointed to carotid webs, which she described as small shelf-like protrusions from the carotid wall. She said webs are considered an intimal variant of fibromuscular dysplasia and appear more often in younger patients and women.

Webs may produce little to no luminal narrowing, so they can escape detection on axial images alone. Sebastian recommended multiplanar CT angiography with sagittal reformats, particularly for younger patients with recurrent strokes and no explainable cause. Stasis of blood around the web creates its thrombogenic potential, she said.

Dissection was the second entity she highlighted, again in younger patients and usually tied to a mechanical trigger. She advised taking a history for chiropractic manipulation, intense gym sessions, and even roller coaster rides. Patients may report neck pain and headache, with stroke or transient ischemic attack-like symptoms following hours to days later and occasionally as long as 1 month afterward. A painful partial Horner syndrome is a frequent clinical clue.

"Even if you do not find imaging evidence, but you have clinical suspicion, you should go ahead and treat it as dissection,” she said.

Chung JW, Park SH, Kim N, et al. Trial of ORG 10172 in Acute Stroke Treatment (TOAST) classification and vascular territory of ischemic stroke lesions diagnosed by diffusion-weighted imaging. 

. 2014;3(4):e001119. Published 2014 Aug 11. 

Goyal M, Singh N, Marko M, et al. Embolic stroke of undetermined source and symptomatic nonstenotic carotid disease. 

Ospel JM, Kappelhof M, Ganesh A, et al. Symptomatic non-stenotic carotid disease: current challenges and opportunities for diagnosis and treatment. 

Zedde M, Stoenoiu MS, Persu A, Pascarella R. Carotid web: an update focusing on its relationship with fibromuscular dysplasia and therapeutic strategy. 

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Sebastian outlines why carotid webs, symptomatic non-stenotic carotid disease, and dissection can be missed when stroke workups focus on luminal narrowing.

Ivy Anne Sebastian, MD

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