When a patient sustains a traumatic brain injury there are two phases to the injury. First, the head-impact causes immediate damage to the brain. The secondary injury, which can evolve over hours or weeks, is a very complicated process. It involves many, linked, changes to the cells, brain chemistry, tissues or blood vessels that can destroy brain tissue. The treatment of brain injury focuses on trying to minimize the secondary injury and there is much research being done to try to find treatments that will prevent it.