Developing an Ovine Model of Impact Traumatic Brain Injury

Abstract

<div>Traumatic brain injury is a leading cause of global death and disability. Clinically relevant large animal models are a vital tool for understanding the biomechanics of injury, providing validation data for computation models, and advancing clinical translation of laboratory findings. It is well-established that large angular accelerations of the head can cause TBI, but the effect of head impact on the extent and severity of brain pathology remains unclear. Clinically, most TBIs occur with direct head impact, as opposed to inertial injuries where the head is accelerated without direct impact. There are currently no active large animal models of impact TBI. Sheep may provide a valuable model for studying TBI biomechanics, with relatively large brains that are similar in structure to that of humans. The aim of this project is to develop an ovine model of impact TBI to study the relationships between impact mechanics and brain pathology. An elastic energy impact injury device has been developed to apply scalable head impacts to rapidly rotate the head without causing hard tissue damage. A motion constraint device has been developed to limit the head motion to a single plane of rotation. The apparatus has been tested using deceased animals to assess the controllability of impact velocities, the repeatability of head kinematics, and the dynamic response of the head to impact. Impact velocities are effectively controlled by modulating the elastic energy stored in the impact piston. The resulting head kinematics are somewhat variable, and are influenced by impact location, time-dependent postmortem tissue changes, and specimen head and neck physiology. Model development will continue, and in vivo testing will be conducted to assess the brain pathology following impacts of varying severity.</div>