Carotid artery stenosis

What it means

The carotid arteries run up either side of the neck and are the main pipeline carrying oxygen-rich blood from the heart to the brain. "Stenosis" simply means narrowing. Carotid artery stenosis develops when fatty, cholesterol-containing plaque builds up along the inner wall of the artery over years, gradually reducing the space through which blood can flow — similar to how mineral scale can build up inside a pipe. This process is a form of atherosclerosis, the same process behind most heart attacks.

Why it appears on a CT or MRI report

Carotid stenosis is usually assessed with Doppler ultrasound, CT angiography, or MR angiography, sometimes as a targeted stroke-risk workup and sometimes as an incidental finding on a scan done for another reason. The report grades the narrowing as a percentage of the artery's normal diameter — commonly described as mild (under 50%), moderate (50-69%), or severe (70% or more) — and notes which side and which specific segment of the artery is involved. It may also describe the plaque's character, since irregular or "soft" plaque is thought to be more prone to breaking loose than smooth, calcified plaque.

What it usually means

Carotid artery stenosis matters because it is a major, modifiable risk factor for stroke: pieces of plaque or small clots that form on its surface can break off and travel into the brain's blood supply, blocking a smaller vessel downstream. Risk rises with the degree of narrowing and is significantly higher in people who have already had stroke-like symptoms from that side (called a symptomatic stenosis) compared with those found incidentally with no symptoms at all. Mild to moderate narrowing found incidentally is common, especially with age, smoking history, high blood pressure, diabetes, and high cholesterol, and is typically managed with medication and risk-factor control rather than surgery. Severe narrowing, particularly if symptomatic, carries a higher stroke risk and is more often discussed alongside procedures to open or bypass the artery.

When to follow up

Any carotid stenosis finding should be reviewed with a primary care physician, neurologist, or vascular specialist, who will weigh the percentage of narrowing, your symptoms, and your overall cardiovascular risk factors to decide on the best plan — which may range from cholesterol-lowering medication and blood pressure control to a procedure such as carotid endarterectomy or stenting for more severe cases. Seek emergency care immediately for any sudden face drooping, arm weakness, slurred speech, sudden vision loss, or confusion, even if brief — these are classic stroke warning signs and a medical emergency regardless of any prior imaging.

A plain-language way to picture it

Imagine a garden hose that has had mineral deposits slowly building up along its inside wall for years, narrowing the channel water flows through. A little buildup barely affects the flow, but as the deposits thicken, the passage gets tighter and flow becomes more turbulent — and occasionally a flake of that buildup can break off and travel downstream, where it might lodge somewhere narrower and block the flow entirely. That's essentially what a piece of carotid plaque can do if it breaks free and travels into a smaller brain vessel, which is why doctors pay close attention to how much of the channel is still open.