A traumatic brain injury is classified according to two types: penetrating and closed-head injuries. In a penetrating injury, damage is caused by an object that penetrates the skull and rips through the delicate brain tissue. A closed-head injury is any injury that does not penetrate the skull, such as a blow to the head. The extent of the damage determines the severity of the brain injury. The brain damage may result in communication problems with expressing and retrieving words. Additionally, cognitive changes with attention, memory, planning, and organization may occur and significantly impact daily functioning.