A traumatic brain injury (TBI) can range from a mild concussion to a severe head injury. It is caused by a blow to the head or body, a wound that breaks through the skull (such as from a gunshot), a fall, or another injury that jars or shakes the brain. This can cause bruising, swelling, or tearing of brain tissue.

With rest, most people fully recover from a mild brain injury. But some people who have had a severe or repeated brain injury may have long-lasting problems with movement, learning, or speaking.