Diffuse axonal injury (often shortened to DAI) is one of the most common forms of traumatic brain injury. In traumatic brain injury, the damage is focused to one area of the brain, in diffuse axonal injury, the damage occurs over a larger area of the brain. DAI mainly damages white matter, which makes it one of the major causes of unconsciousness and persistent vegetative state after head trauma. It occurs in about half of all cases of severe head trauma.