Four blood vessels in the neck carry oxygen and nutrients to the brain -- the right and left carotid arteries and the right and left vertebral arteries. The carotids are much larger than the vertebrals and nourish a correspondingly larger portion of the brain. Narrowing of these vessels by atherosclerosis may cause a stroke, which is a medical emergency. If you or a companion experiences stroke symptoms, call 911 for immediate care at a hospital.
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Complete Blockage of a Carotid Artery
Complete clogging of the carotid arteries is uncommon. A sudden and complete blockage of the right or left carotid causes a massive stroke of the brain on the same side, often rapidly fatal. Such a stroke causes complete paralysis of one side of the body and face. This paralysis is usually permanent among survivors. Emergency treatment at a stroke center may improve survival and decrease long-term disability.
Partial Blockage of the Carotid Arteries
The carotids are more commonly partially clogged by atherosclerosis, causing a buildup of fatty substances. The larger the deposits and the greater the narrowing of the artery, the greater the risk of stroke. Small pieces of the clog may break off and travel to parts of the brain by branches of the carotid artery. The blood supply is stopped wherever the debris becomes lodged, causing brain cell death in that area. Symptoms depend upon the affected part of the brain and may include confusion; weakness or numbness in an arm or leg, or both; drooping of the face; difficulty in forming words; severe headache; and changes in vision.
Clogging of the Vertebral Arteries
The right and left vertebral arteries run along the spinal column and join together inside the skull to supply the rear and underside of the brain. The vertebrals may be narrowed by atherosclerosis, causing symptoms of partial vision loss, double vision, dizziness, clumsiness, nausea, numbness of parts of the face, difficulty in speaking, or weakness, particularly of the leg. Disease in the vertebral artery system is responsible for approximately 20 percent of strokes.
The American Stroke Association recommends that you use the FAST acronym as a reminder to recognize warning signs of a stroke. "F" stands for face drooping; "A" stands for arm weakness; and "S" is for slurred speech. "T" is a reminder that it is time to call 911 if you or a loved one experiences any of these symptoms.