A stroke is a sudden interruption in the blood supply of the brain. Because strokes occur rapidly and require immediate treatment, a stroke is also called a brain attack. Most strokes are caused by an abrupt blockage of arteries leading to the brain (ischemic stroke). Other strokes are caused by bleeding into the brain tissue when a blood vessel bursts (hemorrhagic stroke).

When the symptoms of a stroke last only a short time (less than 24 hours), this is called a transient ischemic attack (TIA).

According to the World Health Organization, 15 million people suffer strokes worldwide each year. Of these, 5 million die and another 5 million are permanently disabled. Strokes are the second leading cause of death in Korea and the top cause of serious, long-term disability.

The most common sign of a stroke is sudden weakness of the face, arm or leg, most often on one side of the body. 

Other warning signs may include:

― sudden numbness of the face, arm or leg, especially on one side of the body

― sudden confusion, trouble speaking or understanding speech

― sudden trouble seeing in one or both eyes

― sudden trouble walking, dizziness, loss of balance or coordination

― sudden severe headache with no known cause.

The signs of a stroke depend on the side of the brain that’s affected, the part of the brain, and how severely the brain is injured. Therefore, each person may have different stroke warning signs. Anyone can have a stroke no matter your age, race or gender. But, the chances of having a stroke increase if certain risk factors are present.

The good news is that up to 80 percent of strokes can be prevented, and the best way to protect yourself and loved ones from stroke is to understand personal risk and how to manage it.

There are two types of risk factors for stroke: controllable and uncontrollable. Controllable risk factors generally fall into two categories: lifestyle risk factors or medical risk factors.

Lifestyle risk factors can often be changed, while medical risk factors can usually be treated.

Uncontrollable risk factors include being over age 55, being male, being black, Hispanic or Asian/Pacific Islander, or having a family history of stroke or TIA. High blood pressure is a major stroke risk factor if left untreated. Have blood pressure checked frequently by a doctor or at health fairs, a local pharmacy or supermarket or with an automatic blood pressure machine.

Atrial fibrillation is an abnormal heartbeat that can increase stroke risk five-fold. Atrial fibrillation can cause blood to pool in the heart and may form a circulating clot and cause an ischemic stroke. A doctor must diagnose and treat atrial fibrillation.

Cholesterol is a fatty substance in blood that is made by the body. It also comes in food. High cholesterol levels can block arteries carrying blood to the brain and lead to a stroke. It is recommended that good cholesterol (HDL) should be higher than 35mg/dl, and bad cholesterol (LDL) should be between 100 and 160, based on your health history. Triglycerides, which are fats, should be below 200mg/dl.

Patients with diabetes mellitus are two to three times more likely to have a stroke. The carotid arteries are the two main arteries that carry blood to your brain and neck. When plaque build-up narrows these arteries, ischemic stroke may result.

Medicine or surgery to clean out plaque in the carotid arteries can reduce the risk for stroke. Smoking doubles the risk of stroke. It damages blood vessel walls, speeds up artery clogging, raises blood pressure and makes the heart work harder. Abdominal obesity and excess body weight strain the circulatory system.

Exercise five times a week. Maintain a diet low in calories, salt, saturated fats, transfats and cholesterol. Eat more fruits and vegetables daily. Alcohol use has been linked to strokes in many studies.

Most doctors recommend not drinking or drinking only in moderation ― no more than two drinks each day. If you or someone you know is having stroke warning signs, call emergency medical service and seek medical help immediately.

A stroke is a medical emergency. Treatment is available, but the therapeutic time window is very limited. It is essential that you not try to diagnose the problem by yourself, and not wait to see if the symptoms go away spontaneously. 

By Kim Gyeong-moon , M.D., Ph.D.

The author is an associate professor of the stroke service, department of neurology at the Samsung Medical Center. ― Ed.