“A brain injury is any occurrence that causes damage to your brain. The scope of what qualifies as a brain injury is fairly large. Brain injury can be anything from a mild concussion to traumatic brain injury, also known as craniocerebral trauma. Mild traumatic brain injury may affect your brain cells temporarily. More-serious traumatic brain injury can result in bruising, torn tissues, bleeding and other physical damage to the brain. These injuries can result in long-term complications or death (like bullet, shattered piece of skull, .
Not all brain injury results in TBI. In fact, some low-grade concussions may heal just fine on their own but any head hit or injury have checked by MD or ER.”
MAYO CLINIC