Traumatic brain injury (TBI) happens when a bump, blow, jolt or other head injury causes damage to the brain. Every year, millions of people in the United States suffer brain injuries. More than half are bad enough that people must go to the hospital. The worst injuries can lead to permanent brain damage or death. Half of all TBIs are from motor vehicle accidents. Military personnel in combat zones also are at risk.
Symptoms of a TBI may not appear until days or weeks following the injury. A concussion is the mildest type of TBI. It can cause a headache or neck pain, nausea, ringing in the ears, dizziness and tiredness. People with a moderate or severe TBI may have those, plus other symptoms