Natasha Richardson's family, friends gather to say last goodbyes to brain dead actress

[NYCSkin]

Based on some of the reports it sounds like an epidural hemorrhage.

In this type of injury; a blow to the head (often the side of the head) causes some or no loss of consciousness followed by a period of lucidity. Then the patient can reports an intense headache as the blood from the hemorrhage builds up the pressure within the head. It can then progress to loss of consiousness and worsening symptoms and even death--especially if blood perfusion to the brain itself is compromised.

Though I never wore a helmet skiing, biking, or skating as a kid...I have all my kids in helmets for any of these kinds of activities...