The recent death of actress Natasha Richardson is highlighting the delayed dangers of traumatic head injuries.

Richardson was injured during a ski trip in Canada. Shortly after the accident, the actress reported feeling fine. Later that night, she began to complain of a headache when at her hotel. She was taken to a hospital where she died on Wednesday.

On Thursday, an autopsy revealed that Richardson had experienced a blow to the head, which resulted in bleeding between the skull and the brain's covering, called an epidural hematoma.

Doctors refer to Richardson's experience as a "lucid interval," during which patients report no complications until symptoms later emerge.

"Once you have more swelling, it causes more trauma which causes more swelling," Dr. Edward Aulisi, neurosurgery chief at Washington Hospital Center, told the AP.

"It's a vicious cycle because everything's inside a closed space."

Swelling often results in dangerous pressure that forces the brain to press down on the brain stem where vital functions such as breathing are controlled. In order to reverse the effects of swelling, doctors can remove a portion of the skull or drain the blood.

"This is a very treatable condition if you're aware of what the problem is and the patient is quickly transferred to a hospital," said Dr. Keith Siller of New York University Langone Medical Center.

"But there is very little time to correct this."

Aulisi said it is crucial for patients who have experienced head trauma to seek a CT scan, which can show whether or not internal bleeding is ongoing.

"If there's any question in your mind whatsoever, you get a head CT," Aulisi advised. "It's the best 20 seconds you ever spent in your life."