Medical personnel recommend keeping cholesterol levels below certain limits, and with good reason. High cholesterol levels, particularly high low-density lipoprotein -- often called "bad" cholesterol -- can increase your risk of heart disease as well as your risk of ischemic stroke. Atherosclerosis, plaque build-up in arterial blood vessels, can cause ischemic stroke. High cholesterol levels in the blood can increase your risk of developing atherosclerosis.
Stroke Types
There are two types of stroke, ischemic and hemorrhagic. Ischemic is by far the more common of the two, accounting for about 87 percent of all strokes. Ischemic strokes can be further divided into two categories, embolic and thrombolytic. Embolic stroke occurs when clots form in one part of the artery, break off, travel to the brain and lodge in the blood vessel, blocking blood flow to part of the brain. Cerebral thrombosis occurs when blood clots form within the blood vessels of the brain.
Role of Atherosclerosis
Atherosclerosis occurs when cholesterol and other debris attach to blood vessel walls. Cigarette smoking, diabetes and high cholesterol levels all contribute to damaging the blood vessel walls, allowing plaque to form more easily. As plaque builds up, the interior lumen of the blood vessel narrows. Blood has a harder time flowing through the vessels, and clots may form as the blood flows more slowly. Clots that cause cerebral thrombosis can form in the brain or in the carotid arteries, which supply blood and oxygen to the brain. Emboli can break loose from atherosclerosis plaques in any artery and travel through the circulatory system and lodge in the brain.
Warning Signs
Ischemic stroke may be preceded by transient ischemic attacks, also called TIAs. This type of attack occurs when a blood clot temporarily blocks blood flow through an artery. A TIA can serve as a warning that atherosclerosis is starting to block blood vessels and that stroke could occur. About 33 percent of people who experience a TIA later have an ischemic stroke, and in 50 percent, the stroke occurs within a year of the TIA, the Mayo Clinic says.
Prevention
If tests show that the carotid arteries have blockage of up to 70 percent, an endarterectomy done to remove part of the plaque from the artery walls may help prevent a stroke. Stents can also be placed into the artery to keep the artery open. A small filter to catch small clots and prevent them from traveling to the brain is also placed. Measures to reduce cholesterol levels such as quitting smoking, losing weight, increasing exercise, reducing alcohol intake if you drink excessively and reducing saturated fats in your diet can help reduce atherosclerotic plaque elsewhere. Taking medications to lower low-density lipoprotein can also help reduce atherosclerosis. Blood thinners may also reduce the risk of clot formation.
