Histological characteristics

DAI is characterized by axonal separation, in which the axon is torn at the site of stretch and the part distal to the tear degrades. While it was once thought that the main cause of axonal separation was tearing due to mechanical forces during the trauma, it is now understood that secondary biochemical cascades, which occur in response to the primary injury and take place hours to days after the initial injury, are largely responsible for the damage to axons (Wolf et al., 2001; Arundine et al., 2004).

Source: http://en.wikipedia.org/wiki/Diffuse_axonal_injury