Axonal injury in head injury.

A histological analysis of 324 unselected fatal head injuries disclosed axonal injury in the form of retraction balls in 100 cases: this was severe in 64 and mild in 36. It is suggested that axonal injury exists as a spectrum without there necessarily being selective involvement of the corpus callosum or the rostral brain stem, and that cases with mild axonal injury may be unconscious for only a short time after their injury.