21 low velocity direct occipital and lateral head impacts were performed on 17 cadavers. Both damped and undamped impacts were performed at impact velocities of between 2.8 and 6.1 m/s. Head responses were measured using a 9-accelerometer array, and in 8 cases epidural pressure was measured at the contre-coup site. Base of skull and temporal fractures of AIS severity 3 or 4 were produced with undamped impacts at velocities greater than 4.0 m/s. Brain injuries were also observed; these were subdural and sub-arachnoid haematomas of AIS severity 3 or 4. Only minor cervical spine injuries were observed.
Head responses were calculated from the 9-accelerometer array data. Linear centre of gravity head acceleration, HIC and angular accelerations are presented. Angular acceleration time-histories calculated with this method appear to be sensitive to local skull deformations and shock wave transmission. At the contre-coup site in lateral impacts, negative epi-dural pressure pulses were measured.
Clear relationships exist between MAIS head injury severity and the variables: impact force and velocity, resultant centre of gravity head acceleration, 3ms. head acceleration and HIC. Logistic regression analyses are presented. At resultant centre of gravity head accelerations greater than 200 g's., HICs > 800, and 3 ms values > 100 moderate severity head injuries (AIS = 3) can be expected.