Diffuse brain injury (DBI) is a frequent occurrence in motor vehicle collisions, falls, assaults, and sports-related activities. Recent epidemiologic data has estimated that nearly 1.5 million new cases occur annually in the United States. The prevalence of these injuries identifies a need to design more robust protective measures to prevent and mitigate DBI. The foundation of injury prevention is tolerance thresholds which correlate kinematic and kinetic measures with injury severity. However, the only currently accepted metric dedicated to brain injury tolerance considers only one mechanical parameter, is not injury specific, and is not applicable to the DBI scenario. Prior experimental literature suggested that rotational kinematics including velocity, acceleration, and duration were responsible for gradations of DBI severity. However, the relative importance of these loading parameters to DBI sequelae remains undefined.

To address this issue, this research sought to develop and implement a unique in-vivo experimental model that utilized real-world loading conditions to reliably induce mild DBI. Experimentation included an analysis of functional, behavioral, and pathological outcomes following graded loading conditions to determine primary kinematic correlates to mild DBI severity. In addition, a numerical correlate to tissue-level injury was defined through the analysis of an anatomically accurate finite element model. Results demonstrated that a nonlinear relationship between rotational acceleration magnitude and duration provided the best description of mild DBI severity. In addition, variable loading kinematics manifested as changes in the tissue-level response that were responsible for distinct pathological and behavioral outcomes. These results have important implications regarding new tolerance thresholds that may be used in conjunction with the development of protective measures to minimize the occurrence and severity of DBI.