The carotid arteries, one on each side of the neck, carry blood to the brain. Like other arteries, the carotid arteries can become blocked with plaque, a condition called atherosclerosis. A blockage can narrow the blood vessel, reducing blood flow to the brain. Pieces of plaque can break off and travel to the brain. Blockage in the carotid arteries can cause severe, life threatening complications.
Transient Ischemia Attacks
Narrowed carotid arteries that aren't treated reduce blood flow to the brain. Small clots can break off and can cause transient ischemic attack, or TIA, a temporary reduction in blood to the brain. A TIA, also known as a mini-stroke, normally resolves within an hour, but can last up to 24 hours, MayoClinic.com states. Symptoms include sudden weakness, numbness, tingling or paralysis on one side of the body, garbled or slurred speech or trouble swallowing. A person having a TIA may complain of dizziness, confusion or may faint or go into a coma. Some people complain of severe and sudden headache or vision changes or vision loss.
Vision Problems
Amaurosis fugax, a temporary loss of vision, can affect a person with untreated carotid artery blockage. A person may notice a curtain coming down over part of the visual field and part of the part of the vision going totally black, usually affecting only one eye. Over a 15 to 30 minute period, the vision improves as the curtain appears to be slowly drawn back, Damien Mosquera, M.D. of New Zealand states on his website, Vascular.co.nz. Amaurosis is caused by small fragments of plaque breaking off of a blockage in the artery. Amaurosis can precede central retinal artery occlusion, or CRAO, which is blockage of the retinal vein by a blood clot. Around 25 percent of people with CRAO have significant carotid artery disease. If not treated within 90 minutes, CRAO leads to irreversible vision loss, the website, All About vision states.
Stroke
Untreated carotid artery blockage can lead to stroke if a piece of plaque lodges in an artery and blocks blood flow to part of the brain. Stroke, which affects 750,000 people each year in the United States, according to lead author Piotr Sobieszczyk, M.D. in a 2006 article in "Circulation," can lead to coma or death. Paralysis or loss of feeling on one side of the face or body, vision loss in one eye, confusion, cognitive defects or speech difficulties can permanently affect a person after a stroke.
