Basilar Skull Fractures by Crash Type and Injury Source

Purpose: This study investigates NASS-CDS data on basilar skull fractures by crash type and injury source for various crash scenarios to understand the injury risks, injury mechanisms and contact sources. Methods: 1993-2008 NASS-CDS data was used to study basilar skull fractures in adult front occupants by crash type and injury source. Injury risks were determined using weighted data for occupants with known injury status in 1994+ model year vehicles. In-depth analysis was made of far-side occupants in side impacts and rear crashes using the NASS electronic cases. Results: Basilar skull fractures occur in 0.507 +/- 0.059% of rollovers and 0.255 +/- 0.025% of side impacts. The lowest risk is in rear impacts at 0.015 +/- 0.007%. The most common contact source is the roof, side rails and header (39.0%) in rollovers, the B-pillar (25.8%) in side impacts and head restraint (55.3%) in rear crashes. Seatbelt use significantly lowers the risk for basilar fracture from 1.77 +/- 0.32% for unbelted to 0.20 +/- 0.03% for belted (p < 0.001) near-side occupants and from 0.92 +/- 0.19% for unbelted to 0.057 +/- 0.012% for belted (p < 0.001) far-side occupants in side impacts. The electronic cases show basilar fractures typically occur in very severe crashes with high delta V and intrusion. Conclusions: Basilar skull fractures occur in 9.7 +/- 0.9% of the crashes where an occupant experiences an AIS 3+ head injury. NASS case reviews show that basilar fractures typically occur in very severe crashes with multiple head injuries from contact with hard surfaces or by components stiffened from intrusion.