Concussions are a mild form of brain injury. Even though a concussion may be short-lived, the injury can cause tearing and stretching of the brain’s nerve fibers. Over time and with cumulative concussions, traumatic brain injury begins to manifest itself in a change of behavior. Most concussions do not show up in CT scans, MRIs or other examinations. The physical results of a concussion are referred to as Post Concussion Syndrome.