The carotid arteries are the main bloodvessels to the brain.  These arteries can develop a build-up substance called plaque.  Carotid artery disease occurs when the major arteries in your neck become narrowed or blocked (arrow). These arteries, called the carotid arteries, supply your brain with blood.  Over time, plaque slowly begins to block the flow of blood. The plaque itself may block the artery enough to cause a stroke. In addition, the plaque often causes the blood to flow abnormally, which leads to a blood clot.

A clot can stay at the site of narrowing and prevent blood flow to all of the smaller arteries it supplies. This type of clot, which doesn't travel, is called a thrombus. In other cases, the clot can travel and wedge into a smaller vessel.

By restoring adequate blood flow to the internal carotid artery, strokes can be prevented. This may be accomplished either by a surgery called endarterectomy or a procedure known as angioplasty or balloon angioplasty with stent placement. Traditionally used for the heart, this latter procedure is now being used on blood vessels to the brain as well. Stent placement is an alternative to surgery that enlarges the blockage in the artery. This new technique must only be performed by an experienced physician.

You are more likely to develop carotid artery disease as you age. Only one percent of adults age 50 to 59 have significantly narrowed carotid arteries, but 10 percent of adults age 80 to 89 have this problem.