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Brain & Nervous System Health Center

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Natasha Richardson Dies After Brain Injury

Brain Experts Weigh In on Natasha Richardson's Head Injuries From a Skiing Accident

What would account for a delayed reaction after a fall? continued...

A hematoma is a blood clot that's growing, says Jill Bolte Taylor, PhD, a brain scientist who had a stroke at age 37 and wrote a book -- My Stroke of Insight -- about it.

"The problem with any kind of blood clot is that you have a fixed and rigid size of the bone. And, so if you've got blood accumulating somewhere, getting bigger and bigger, it has to push against whatever else is in there, which stunts and traumatizes the cells so that they can't function," Taylor tells WebMD.

"The first thing that the body does anywhere there's trauma is send more blood in order to bring the immune system, so the immune system can make an assessment and clean up what it needs to clean up. The same thing is true inside of the brain. So now, not only is there a bleeding into the brain region, but more blood is wanting to get there in order to bring the immune system in order to clean it up," Taylor explains.

"At this point, the brain's in trauma and as long as the cells are essentially swimming in a pool of blood, they cannot perform their function," Taylor says.

How long can that delay last?

Symptoms of brain injury may take an hour or two, or perhaps longer, to develop.

"If something bad is going to occur, it's almost always within the first 24 hours," Grafman says. "That's why anybody who's had any kind of a head injury should be watched closely ... certainly for the first 24 hours, and should almost always go see a doctor," Grafman says.

How rare is a serious traumatic brain injury?

As a rough estimate, there are "probably at least a million head injuries per year in the United States. Probably 80% or more are mild sort of dings you might get playing football or something of that nature, or a slight fall," says Grafman, who has studied brain injuries for nearly 30 years.

"The overwhelming majority of those people who have that kind of very mild head injury are going to recover nicely, either very quickly or certainly with six to nine months," Grafman says.

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