Linda Searing of The Washington Post wrote the following:
Every 40 seconds, on average, someone in the United States has a stroke — amounting to 795,000 people a year, according to the Centers for Disease Control and Prevention. Most strokes, 80 percent or more, occur when blood flow to the brain is blocked by a clot. Known as an ischemic stroke, it results in brain cells not getting needed oxygen and nutrients, which causes the cells to start dying within minutes.
The other main type of stroke, hemorrhagic stroke, occurs when a blood vessel in the brain leaks or bursts, with the flood of blood putting pressure on and damaging the brain cells. This type of stroke may be caused by high blood pressure (which over time can weaken blood vessel walls) or an aneurysm (a bulge in a blood vessel that bursts).
Both types of stroke can cause lasting brain damage, disability or death, and some 140,000 Americans die each year from a stroke. The likelihood of brain damage and disability increases the longer a stroke goes untreated, making it critical to call 911 and get emergency stroke treatment started as soon as possible. Signs of a stroke usually come on suddenly and may include numbness or weakness in the face, arm or leg, trouble speaking, blurred or double vision, dizziness or stumbling when trying to walk or a very severe headache.
A condition similar to a stroke, known as a transient ischemic attack, occurs when the blood supply to the brain is blocked for a short time (hence its nickname, “mini-stroke”). Though damage to the brain from a TIA is not permanent, it does make the chances of a full-blown stroke more likely. Because of this, the American Stroke Association refers to a TIA as a “warning stroke.”