Carotid artery dissection is a separation of the layers of the artery wall supplying oxygen-bearing blood to the head and brain and is the most common cause of stroke in young adults. ( In vascular medicine, dissection is a blister-like de-lamination between the outer and inner walls of a blood vessel, generally originating with a partial leak in the inner lining.) Carotid artery stenosis means that the arteries have become blocked by cholesterol deposits, also called hardening of the arteries. If these vessels become completely blocked, it could cause a stroke and permanent brain damage within three to six hours. A diet high in fatty foods may cause carotid artery pain. Strokes might also occur if an artery ruptures or if plaque breaks loose and enters. Carotid artery duplex scan. This test is done to assess the blood flow of the carotid arteries. A probe called a transducer sends out ultrasonic sound waves. When the transducer (like a microphone) is placed on the carotid arteries at certain locations and angles, the ultrasonic sound waves move through the skin and other body tissues to the blood vessels, where the waves echo off of the blood. Carotid ultrasound: Carotid (kuh-ROT-id) ultrasound is a safe, painless procedure that uses sound waves to examine the blood flow through the carotid arteries.