Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Traumatic Brain Injury ?
    ### Response:
    Traumatic brain injury (TBI), a form ofacquired brain injury, occurs when a sudden trauma causes damage to the brain. TBI can result when the head suddenly and violently hits an object, or when an object pierces the skull and enters brain tissue.Symptoms of a TBI can be mild, moderate, or severe, depending on the extent of the damage to the brain.
    