Biomechanics of concussion.

This report provides an overview of the biomechanics associated with mild traumatic brain injury (TBI), also known as concussion. Specifically, the role of angular acceleration in modulating concussion onset and severity is highlighted. Studies conducted and published from the 1960s to the 1980s provided initial estimates for TBI tolerance due to high rate head rotation. However, injury levels in those studies were more severe than what is considered to be concussion in the contemporary environment. Therefore, this issue deserves additional attention to provide quantitative estimates for concussive tolerance due to head rotational acceleration focusing on the types of clinical outcomes described today. Likewise, concussion in military personnel has notably increased in current conflicts due to the incorporation of improvised explosive devices and roadside bombs. Clinical evidence indicates that outcomes from concussion due to blast may be quite different from those due to head rotational acceleration. This report also provides an overview of blast concussion mechanisms and highlights some of the recent preclinical work in this area. As with head rotational acceleration, blast tolerance is necessary to understand the scope of this problem, better protect these personnel, and provide more informed return-to-duty guidelines for service members.