A pre-stroke is sometimes called a ministroke. Both terms describe a transient ischemic attack. A transient ischemic attack is a stroke that lasts for only a brief moment and does not cause any permanent damage. It happens due to a temporary disruption in blood supply to the brain.
Because a pre-stroke resolves on its own without any permanent damage, many people ignore it. This is a huge mistake. A pre-stroke is called a pre-stroke because it often precedes a major stroke. Think of it as an early warning sign.
According to the American Stroke Association, about 12 percent of people  who had a stroke experienced a pre-stroke before it happened. If you have a pre-stroke, your chances of suffering a stroke are highest within the first 90 days of your attack. Around 9 to 17 percent  of people who had a pre-stroke suffered a stroke within the first 90 days. Most people still get it within a year even if they exceed the 90-day window.