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.
