What is Diffuse Axonal Injury?
Wikipedia defines Diffuse axonal injury (DAI) as
one of the most common and devastating types of traumatic 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. It occurs in about half of all cases of severe head trauma and also occurs in moderate and mild brain injury.
The outcome is frequently coma, with over 90% of patients with severe DAI never regaining 
consciousness. Those who do wake up often remain significantly impaired.
Nowadays, other authors state that DAI can occur in every degree of severity from (very) mild or moderate to (very) severe. Concussion may be a milder type of diffuse axonal injury.
DAI is not easily detected by physicians in mild and moderate cases. Imaging studies and neuropsychological evaluations in addition to observations of relatives, friends and co-workers are some of the devices used when diagnosing DAI. Cases involving mild to moderate brain injuries are harder to tackle than cases in which there is objectively discernible injury such as loss of consciousness, skull fracture, or intracranial bleeding on imaging studies. Often such cases involve allegations of diffuse axonal injury (DAI), an injury to the brain that can occur at the microscopic level and not be detectable even by computerized tomography or magnetic resonance imaging.
Nonetheless, DAI can cause significant changes in personality or cognition which can create significant life change.
