Diffuse axonal injury (DAI) is a form of traumatic brain injury. It happens when the brain rapidly shifts inside the skull as an injury is occurring. The long connecting fibers in the brain called axons are sheared as the brain rapidly accelerates and decelerates inside the hard bone of the skull. DAI typically causes injury to many part of the brain, and people who suffer a DAI are usually left in a coma. The changes in the brain are often very tiny and can be difficult to detect using CT or MRI scans.
It is one of the most common types of traumatic brain injury and also one of the most devastating.
The prevailing symptom of DAI is loss of consciousness. This typically lasts six or more hours. If the DAI is mild, then people might remain conscious but display other signs of brain damage. These symptoms can be extremely varied, as they depend upon which area of the brain has been damaged. They can include:
- disorientation or confusion
- nausea or vomiting
- drowsiness or fatigue
- trouble sleeping
- sleeping longer than normal
- loss of balance or dizziness
Causes and risk factors
DAI occurs when the brain moves backward and forward quickly inside the skull as a result of acceleration and deceleration.
Some examples of when this might occur are:
- in car accidents
- in a violent attack
- during a fall
- in a sports accident
- as a result of child abuse, such as shaken baby syndrome
The immediate course of action needed in the case of a DAI is to reduce any swelling inside of the brain, as this can cause further damage. In select cases, a course of steroids will be given to reduce the swelling.
There is no surgery available to people who have sustained a DAI. If the injury is severe, there is a likelihood of a vegetative state or even death. But if the DAI is mild to moderate, rehabilitation is possible.
A recovery program will depend on the individual, but may include:
- speech therapy
- physical therapy
- recreational therapy
- occupational therapy
- adaptive equipment training
Many people do not survive severe head injuries. A great number of people who do survive the injury are left unconscious and never regain consciousness. Of the few who do wake up, many are left with long-term problems even after rehabilitation.
However, there are differing levels of severity of DAI, with concussion being considered one of the milder forms. Thus, complete recovery is possible in very mild cases.
DAI is a serious but common type of traumatic brain injury. It can be fatal, but it is also possible to regain consciousness after a DAI. For those who recover, intensive rehabilitation will be needed.