1.   An autopsy determined that Earnhardt died of a basal skull fracture.

2.   Autopsy results confirmed Earnhardt died from a basal skull fracture, likely caused by the frontal impact, Bohannon said.

3.   Both are designed to prevent basal skull injuries, which killed Dale Earnhardt, Kenny Irwin, Adam Petty and Blaise Alexander.

4.   Each of those drivers also died of basal skull fractures in near head-on crashes with walls.

5.   Tests have shown that the HANS is effective at preventing the type of head injury, a basal skull fracture, that killed Earnhardt.

6.   The death of Dale Earnhardt from a basal skull fracture has led to widespread use of head and neck support systems.

7.   Petty died, however, because his helmeted head was inadequately restrained, allowing it to hyperextend so violently he sustained what trauma specialists call basal skull fracture.