Diffuse axonal injury.

Diffuse axonal injury is a distinct form of head injury, induced by direct external forces at the time of the trauma, and not produced by secondary changes due to a primary injury. This type of lesion may be without conspicuous findings on gross brain examination, or may be found with coexisting conventional types of brain injuries. It is characterized by diffuse retraction balls (axonal swellings), hemorrhage or laceration of the corpus callosum, and hemorrhages in the brain stem. It is of utmost importance for forensic pathologists to be aware of this little-recognized entity. Five illustrative cases are presented.