My thoughts and prayers are with the family of Natasha Richardson.  My wife and I loved her in the Disney favorite, The Parent Trap.  I can truly empathize with the family as I had experienced an almost identical incident with my Dad.

What I would really like to share is the importance to recognize any injury to the head.  A couple years ago, my Dad was walking his dog when he slipped on some black ice.  Back then, he was a very physically active man in his 60s who still practiced medicine.  When he returned home from the walk, he complained about having a headache, however, he found it to be of minor concern and still drove his 2 tween children to school.  Upon returning home (about 2 hours after the accident), he asked his wife to drive him to the hospital to get a CAT scan.  At the arrival of the hospital, my Dad became unable to move from the car and was rushed into the emergency room.  The CAT scan revealed severe bleeding on the brain, called a subdural hematoma.  When he fell backwards onto the ground, not only did his brain get injured at the place of impact with the ground, but he also incurred an injury when his brain bounced back and hit the front, internal part of his skull. 

Long story short, my Dad needed emergency surgery to relieve the pressure in his brain.  He was in intensive care for a month, intermediate intensive care for another month, and then in the hospital therapy section for another month.  Even after coming home, he did not remember the accident or the months that followed.  He is doing much better now, but he is one of the fortunate few.

What frighten me the most was when his doctor, a family friend, said that this was one of the most serious subdural hematomas he had ever seen.  If my Dad had not gone to the emergency room sooner, he would have died.