The Relationship between Head Impact Characteristics and Brain Trauma

Brain injury is complex in nature and extraordinarily challenging when attempting to describe the relationship between the event and the resulting injury. In an effort to reduce its severity and incidence a great deal of research investigating mechanisms of brain injury has involved the areas of anatomical, reconstructive, and finite elements modeling. The anatomical research primarily examines functional and mechanical failure thresholds for different types of brain tissue [1-3]. Approximate strain levels are described for the different tissues that are then used to represent human responses [4]. Anatomical research examines individual brain tissues while reconstructive research simulates how injured individuals were impacted in order to discover relationships between engineering variables such as acceleration, stress, and strain and the resulting brain injury [5-7]. Currently, much of this research has focused on sporting concussions as they are frequent and often documented providing information for accurate reconstructions [5,6]. Finite element modeling provides a tool to obtain brain tissue response values resulting from an impact. Within the term traumatic brain injury (TBI) there are several different types of brain injury lesions, each with their own respective mechanisms and possibly predictive variables [8]. The multiple types of injuries described within TBI may also expound concussion, which has been described to have different levels of severity: sub concussive, transient, and persistent. In addition to examining the nature of the continuum of brain injury associated with the severity of impact, the mechanisms of injury contributing to these outcomes are also examined. The most common mechanisms of brain injury include: falls, collisions, projectiles, and punches. These mechanisms are examined and a synthesis of how they contribute to the outcome of the injury within the continuum of TBI and concussion is discussed. This provides information on how accelerations, resulting from an impact, affect brain tissue response and the location of the highest magnitudes of stress and strain. This review examines the nature of traumatic and concussive brain injury within the context of a continuum based upon impact severity using anatomical, reconstructive and finite element methodologies.