The term major strokeis used to distinguish a full-blown stroke from a minor stroke, or transient ischemic attack (TIA). A TIA is essentially a temporary stroke that resolves on its own without causing permanent damage. When doctors say someone suffered a major stroke, they really just mean a stroke, which is loss of brain function resulting from a blood vessel problem that restricts blood flow to an area of the brain. Usually what happens is that plaque builds up in the arteries, then a piece of plaque dislodges and causes a blood clot to form, clogging a blood vessel.
The brain is very complex, and some areas are much more vulnerable to blood loss from blockages than others. This is one of the main reasons some strokes cause so much more damage than others. The brain requires lots of blood from moment to moment, because it can't store any energy. So when brain cells don't get blood, they start to die right away.
But in some cases, the brain manages to reroute the blood flow through what's essentially alternate plumbing. So then the area still gets blood and there's less damage. It's basically an issue of luck whether the blockage occurs in a place where there are alternate blood pathways or not.
One more difference is that some strokes, called hemorrhagic strokes, are caused by bleeding rather than a blockage, and these can be catastrophic.
How fast a stroke victim gets treatment is also a major factor in how much damage is done. You can lose as many as 32,000 neurons per second during a stroke, so time is really important. When the stroke occurs, there's what's called the clot epicenter, which is completely deprived of blood and typically dies in five or six minutes.
And then there's an area that's called the penumbra, or shadow, around the epicenter, and that area's basically on life support; it's not dead yet, and you may have several days before the neurons die. So with treatment, you can reverse the damage and regain functioning in this area.
That's why TPA, the clot-busting drug, can be so important. So can aspirin, which thins the blood. I tell my patients that the minute you experience symptoms that might be from a stroke, even if you're not sure or they're very mild, you need to get your butt into the hospital and get checked. We can do an MRI and see the damage and injury to the brain within minutes after it happens. How fast someone gets treatment is probably one of the biggest factors in how much damage is done and what the prognosis is for recovery.