An open head injury, also known as penetrating head injury, is a physical trauma to the brain in which the dura mater, the outer most layer, is penetrated. For instance, a victim of a mass shooting had a gunshot to the head; the bullet broke the skull and entered the brain. If not fatal, these injuries are serious medical emergencies which may lead to disability or even death. Unfortunately, as many as 50% of patients who have had an open head injury develop epilepsy.