A carotid web is an abnormal formation of tissue inside one of the main arteries supplying blood to the brain. It presents as a thin, shelf-like membrane that extends into the vessel, most often at the carotid bulb. This is the widened area of the internal carotid artery just after it branches from the common carotid artery in the neck. It is considered a rare variant of fibromuscular dysplasia, a condition involving excess fibrous tissue in the artery’s inner lining.
This membrane disrupts the smooth flow of blood through the artery. The shelf-like structure creates an area of stagnation where blood can pool and form a thrombus, or blood clot. If a piece of the clot breaks off, it becomes an embolus that travels through the bloodstream directly to the brain.
Once in the brain, the embolus can lodge in a smaller artery, blocking blood flow and causing an ischemic stroke. This mechanism is a cause of cryptogenic strokes, where an initial investigation reveals no common cause like heart conditions or arterial disease. In some cases, the web may lead to a transient ischemic attack (TIA), or “mini-stroke,” which causes temporary stroke-like symptoms without permanent damage.
Associated Health Risks
The primary health risk of a carotid web is ischemic stroke. Unlike plaque from atherosclerosis, the web is a structural anomaly of fibrous tissue. Its danger comes from its ability to alter blood flow, creating an environment where clots can form. If a clot dislodges and travels to the brain, it can block an artery, causing an artery-to-artery embolic stroke.
Identifying a Carotid Web
A carotid web is discovered during the diagnostic workup following a stroke or TIA, particularly when the cause is not apparent. Since most webs do not significantly narrow the artery, they often go undetected until they have caused a thromboembolic event. The diagnosis relies on advanced imaging techniques that can visualize the structure of the carotid arteries in high detail.
Computed Tomography Angiography (CTA) is a common diagnostic tool. This test uses an injected contrast agent and X-rays to create a detailed 3D view of the arteries. A CTA can show the web’s thin, shelf-like projection into the vessel’s open channel, or lumen.
Other imaging modalities can also be used for confirmation. Magnetic Resonance Angiography (MRA) uses magnets and radio waves to create images of the blood vessels. The most definitive imaging study is Catheter Angiography, or Digital Subtraction Angiography (DSA). In this procedure, a catheter guides contrast dye directly to the carotid arteries, providing a highly detailed map of blood flow and arterial structure.
Patient Demographics and Risk Factors
The demographic profile for patients with a carotid web differs from those with typical stroke risk factors. Carotid webs are diagnosed more frequently in people under 60, in contrast to strokes caused by atherosclerosis, which is more common in older populations.
Studies have shown a higher prevalence of carotid webs among women, and there is a higher incidence in individuals of African descent. These demographic patterns suggest a genetic or developmental component to the condition.
A carotid web is not caused by lifestyle choices such as diet or smoking. It is a congenital or developmental issue, meaning a person is likely born with it. Because it is a structural feature, traditional risk factors for vascular disease like high cholesterol or hypertension are not direct causes.
Medical Management and Treatment
Once diagnosed, management of a carotid web aims to prevent a stroke. The treatment strategy depends on whether the patient has already experienced symptoms, like a stroke or TIA. For asymptomatic patients, medical management is the first step, which involves antiplatelet therapy like daily low-dose aspirin to reduce the likelihood of clot formation.
If a patient has had a stroke caused by the web, more definitive treatment is recommended due to a high rate of recurrence with medical therapy alone. One option is a surgical procedure called a carotid endarterectomy. During this operation, a surgeon opens the carotid artery and physically removes the web to restore a smooth arterial surface.
A less invasive alternative is carotid artery stenting. In this endovascular procedure, a catheter is used to place a stent—a small, mesh-like tube—across the web. The stent is expanded to press the web flat against the artery wall, eliminating the pocket where blood could stagnate and form clots. The choice between medical management, endarterectomy, or stenting is tailored to the individual patient, considering their specific anatomy and overall health.