A head or brain injury is any damage that affects the head or brain, including concussions, skull fractures, and traumatic brain injuries. These types of injuries can be caused by many accidents and incidents, such as car accidents, falls, and sports injuries. The severity of a head or brain injury can vary widely. Some injuries may have long-term or permanent effects on a person's physical, cognitive, and emotional functioning. Symptoms of a head or brain injury may include headache, dizziness, nausea, confusion, memory loss, and changes in behavior or mood.