This is what all strokes have in common: Each one is a medical emergency that disrupts blood flow to the brain. And brain cells deprived of oxygen and nutrients begin to die.
But how that blood flow is disrupted can vary, which is why doctors divide strokes into different types. If you or someone you care about should ever have a stroke, it's important to know what type it is. So here's a look at each one.
Ischemic stroke—the most common kind
About 87% of strokes fall into this category, according to the American Stroke Association (ASA). Ischemic strokes happen when an artery that feeds the brain becomes blocked, cutting off blood flow and damaging brain tissue.
Often, a blood clot is to blame for this blockage. And that clot can develop in two ways:
- Most often it forms in an artery leading directly to the brain, typically in one clogged with plaque.
- In some cases, a fragment of a clot that formed elsewhere—frequently in the heart—sweeps through the bloodstream and becomes wedged in a brain artery.
Treatment for an ischemic stroke includes a clot-busting drug called tPA (tissue plasminogen activator). It can help people recover with little or no disability. But it must be given within three hours of having a stroke, or within 4.5 hours for certain patients, according to the ASA—and if it's given to anyone having what's known as a hemorrhagic stroke, it can actually be dangerous.
Consequently, it's crucial to know the general warning signs of a stroke so that anyone having one can be quickly evaluated and properly treated.
This type of stroke happens when a weakened artery in the brain bursts and blood seeps into the surrounding tissue. This both disrupts blood supply to the brain and upsets the delicate chemical balance brain cells need to function.
Hemorrhagic strokes can occur in several ways. For example:
- Blood may leak into the brain itself. This usually occurs because of damage to arteries caused by atherosclerosis.
- Blood may spill into the space surrounding the brain. This typically occurs because of a ruptured aneurysm.
Because hemorrhagic strokes are especially likely to be life-threatening, immediate treatment is essential. Treatment will focus on stopping the bleeding and easing any pressure that has built up inside the head.
Trouble ahead—transient ischemic attack
Sometimes stroke symptoms start only to go away quickly, often in less than five minutes, according to the ASA. This is what doctors call a transient ischemic attack (TIA) and the rest of us often call a warning stroke.
That's because roughly a third of all people who have a TIA go on to have a stroke within a year, according to the ASA. This means a TIA always needs medical attention so doctors can detect and treat whatever caused it, thereby preventing a full-blown stroke.
So again, whenever stroke symptoms strike, call 911 right away and, if possible, note the time when the symptoms started. Every minute counts when any type of a stroke starts.