About Stroke
Sutter Stroke Center
Facts and Myths
One of the greatest myths about stroke is the idea that it is untreatable. While that was once true, medical science has made remarkable advances in the past few decades. New treatment techniques, medications and medical devices are remarkably effective at minimizing the impact of strokes – if the patient gets to the hospital in time. Stroke damage happens quickly and medical tools can't reverse the damage once it's done.
Each year, more than 700,000 people experience a stroke and about 160,000 people die as a result, making stroke the nation's third leading cause of death. Some people walk away from a stroke with no lasting effects, but more than two-thirds of survivors are left with some form of disability, making stroke the leading cause of adult disability. Once a patient has a stroke there is also a 25 percent chance of having another one within five years. That's why learning about strokes is so important. The more you know and the faster you act, the better able you will be to prevent a stroke from happening or minimize its damage once it occurs.
The American Heritage® Dictionary defines the word stroke as "a sudden action or process having a strong impact or effect." While that's not the medical definition, it is an accurate description of what a stroke often means to a patient's life. Strokes happen suddenly and without warning when the blood supply to a portion of the brain is interrupted due to a blood vessel becoming blocked by a blood clot (an ischemic stroke) or when a blood vessel breaks open (a hemorrhagic stroke). While strokes most often occur in older people, they can happen in people of any age. 
Ischemic Strokes
About 85 percent of all strokes are ischemic. Just as blood clots travel to the heart and cause heart attacks, blood clots that form in or travel to the brain's blood vessels cause brain attacks, or strokes. A blood clot that travels through a blood vessel to the brain is called a cerebral embolism and one that forms at the clogged part of the vessel is called a cerebral thrombus.
Thrombotic strokes are the most common type of stroke, accounting for roughly 60 percent of all strokes. Thrombotic strokes occur when arteries leading to or within the brain become clogged when fatty buildup of cholesterol on the artery wall (plaque) breaks off and blocks blood flow. They can also occur when plaque builds up enough to close down the artery so that blood cannot pass through, a condition called stenosis. Thrombotic strokes often occur in the morning or evening and may be preceded by transient ischemic attacks (TIA), also called a mini stroke. TIAs leave no lasting damage, but they often forewarn of an impending stroke and indicate plaque is building up to dangerous levels within the patient's arteries.
Embolic strokes result from blood clots traveling from another part of the body, usually the heart or chest, to the brain. The blood clot travels through smaller and smaller arteries until it is trapped in a vessel too small to allow passage. Embolic strokes are often caused when irregular heartbeats (atrial fibrillation) cause the heart chamber to retain some blood rather than emptying completely. The blood that remains in the chamber can stagnate and form clots that enter into the arteries connecting the heart and brain.
Hemorrhagic Stroke
About 15 percent of strokes occur when a blood vessel in or leading to the brain breaks open, diverting blood from its destination and instead sending it into the brain (cerebral hemorrhage) or into the space between the brain and skull (subarachnoid hemorrhage). The most common causes of hemorrhagic strokes are buildup of fatty plaque on artery walls that eventually lose their elasticity (atherosclerosis), especially when combined with hypertension (high blood pressure); trauma to blood vessels in the head or neck; and brain aneurysms. Hemorrhagic strokes may also occur as the result of an arterial vascular malformation, an abnormal tangle of brain blood vessels present from birth.
Transient Ischemic Attack
Many patients experience a stroke-like episode called a Transient Ischemic Attack (TIA) that can last for a few minutes or several hours. Though TIAs are not strokes, they serve as a warning and an indicator of cardiovascular disease. If you experience a TIA, call 9-1-1 immediately and get prompt medical care.
Find Out More
For additional information, please see stroke in our health information section.You can find additional information by calling the American Stroke Association at 1-888-4STROKE or by visiting their Web site at www.strokeassociation.org. If you or someone you know has had a stroke, please call the American Stroke Association "Warmline" at 1-800-553-6321. Ask about how you can receive their award-winning Stroke Connection Magazine. In addition, the National Institute of Health's National Institute of Neurological Disorders and Stroke offers booklets and additional information. You can also find useful information on the National Stroke Association Web site.