Injury Predictors for Traumatic Axonal Injury in a Rodent Head Impact Acceleration Model

To quantify traumatic axonal injury (TAI) in the corpus callosum (CC) and brainstem pyramidal tract (Py), to determine injury predictors and to establish injury thresholds for severe TAI in a rat head, a modified Marmarou impact acceleration injury model was developed. Thirty-one anesthetized rats were impacted using a modified impact acceleration injury device. Beta-amyloid precursor protein immunocytochemistry was used to assess and quantify axonal changes in CC and Py. Linear and angular responses of the rat heads were monitored and measured in vivo with an attached accelerometer and angular rate sensor, and were correlated to TAI data. Logistic regression analysis suggested that the occurrence of severe TAI in CC was best predicted by average linear acceleration, followed by power and time to surface righting. In Py, severe TAI was best predicted by time to surface righting, followed by peak and average angular velocity. When both CC and Py were combined, power was the best predictor, and the combined average linear acceleration and average angular velocity was also found to have good injury predictive ability.