Strokes happen for two different reasons. The most common cause is blood stops flowing to the brain. The flow of blood is blocked by a clot or a buildup of a fatty substance called plaque in an artery leading to the brain—a process called atherosclerosis, or more generally, cardiovascular disease. Strokes caused by blockage of blood flow to the brain are called ischemic strokes. More than 85 percent of strokes are ischemic.

Ischemic strokes (sometimes called “brain attacks”), like heart attacks, are preventable because they are caused by cardiovascular disease. And cardiovascular disease can be prevented by living a healthy lifestyle that includes eating right, exercising and not smoking.

The other 15 percent of strokes are caused by blood leaking into the brain or between the brain and the skull. These are hemorrhagic strokes. These strokes happen when an artery leading to the brain bursts because it is weak or damaged from aging or from years of high blood pressure. It’s important for you and your healthcare team to know the cause of the stroke to determine the best treatment.

If you are relatively young and have no obvious risk factors for stroke, your doctor may want to check for patent foramen ovale (PFO), commonly known as a hole in the heart. We are all born with this hole between the left and right upper chambers of the heart, but the hole usually closes soon after birth. If you are among the 20 percent of people whose PFO never closed, then you may not know it or have any symptoms, but it may increase your risk of stroke and migraines.

TIA (Mini-Stroke)

A transient ischemic stroke (TIA) or mini-stroke is an ischemic stroke that passes quickly. It is caused by a blood clot or piece of plaque blocking or restricting blood from flowing through an artery to the brain. In a mini-stroke, whatever was blocking the artery breaks loose and moves along, allowing blood to once more flow freely to the brain. And you feel better—for now.

You may or may not notice if you’ve had a mini-stroke, but if you think you are having a stroke of any kind, the best thing to do is call 911. Mini-strokes are often a warning that a full-blown ischemic strokes will happen next.

If you discover that you’ve had a mini-stroke, check with your doctor about steps to prevent another stroke.

Silent Stroke

It is possible to have a stroke and not know it. A test taken for some unrelated purpose may show lesions on your brain. Those lesions are evidence of damage to the brain tissue caused by a stroke. At that point, you can’t really repair the damage, but it is important to know that you are at greater risk for stroke than you may have realized. Talk with your doctor about what you can do to reduce your risk of having another stroke in the future.