Diffuse axonal injury (DAI) is one of the most common an devastating types of traumatic brain injury, occurring in about half of all cases of severe head trauma and also occurring in moderate and mild brain injury. It is a type of diffuse brain injury, meaning that damage occurs over a more widespread area than in focal brain injury. DAI, which refers to extensive lesions in white matter tracts, is one of the major causes of unconsciousness and persistent vegetative state after head trauma.