Even as an autopsy gets underway in New York the day after her death, many questions remain about just what happened on a Quebec mountain that left Natasha Richardson with ultimately fatal,severe brain trauma.

Roughly 1.4 million people in the U.S. suffer from traumatic brain injuries each year, according to the California Brain Injury Association – and 50,000 die from it. A majority of these injuries result from falls just like Richardson's.

"There is no telling what the forces are that were applied to her head," says Dr. Jeff Victoroff, Associate Professor of Neurology at USC's School of Medicine. "People underestimate the enormous amount of physical force that can be generated by nothing more than a standing level fall."

Medical experts say Richardson likely suffered a subdural hemotoma – the breaking of blood vessels inside the brain. Usually, the body responds to such an injury instantly by clotting the blood around the injured area to keep it from bleeding out. So why, presumably, didn't that happen here?

"The speculation that comes first to mind is that there is something wrong with her blood so that it doesn't clot properly," says Dr. Victoroff, adding that pain killers such as Motrin or Nuprin could interfere with natural blood clotting.

Others wonder if Richardson might have suffered an aneurysm, and whether the real damage occurred even before she even fell down the slope.

"You always have to wonder if the fall was the result of something that happened in the brain rather than the cause, like a stroke or a massive brain hemorrhage," says Dr. Neil Martin, Chairman of Neurosurgery at UCLA Medical School. "But arguing against a massive problem like that is that immediately after the fall she seemed to be OK."

Still, says Martin, "It could have been a minor warning leak from an aneurysm and the deterioration an hour later might have been a second massive hemorrhage. It is scary and more than a bit puzzling."

Could She Have Been Saved?

For Richardson's loved ones, the most haunting question is whether she could have been saved had she been treated immediately. According to a spokesperson for the Mont Tremblant ski resort, Richardson was lucid after she fell on a beginner's slope, and declined medical attention until she started complaining of headaches about an hour later.

According to experts, there is no way of knowing, at least until a full CT scan shows the depth and breadth of her injuries. And that information may be revealed when the results of the autopsy are released later on Thursday.

"If the hemorrhage can occur over the surface of the brain, where it can be corrected by surgery if detected early, perhaps yes there could have been another outcome," says Dr. Martin. "At the same time, the injury could have very well occurred deep inside the brain, in which case surgery – or any other treatment for that matter – probably wouldn't have helped."