Traumatic brain injury carries a high risk of neurological disability and fatality. The extent of the injury to the neuronal tissue following a head impact defines the primary injury. The acceleration energy delivered at the time of impact provokes this injury. There are numerous secondary responses to the injury that mostly intensify the primary injury. When a head impact causes a contusion, the hemorrhagic injury frequently progresses over the first few hours after impact, either growing or developing new, non-contiguous hemorrhagic lesions, a condition known as the hemorrhagic progression of a contusion.