Widespread axonal injury in gunshot wounds to the head using amyloid precursor protein as a marker.

In order to determine whether axonal injury (AI) is a factor in cases of penetrating head injury, the brains of 14 patients who died shortly after sustaining a fatal gunshot wound (GSW) to the head were examined, and the presence of AI determined using immunohistochemical staining for amyloid precursor protein (APP). The distribution of AI was mapped throughout the cerebral hemispheres and brain stem. AI was present in all cases in a diffuse distribution distant to the missle track with severe involvement of the brain stem in all cases. There was no axonal APP immunoreactivity in the direct region of the missle track at the point of primary axotomy. The APP-positive AI in these cases is likely to be a mixture of primary and secondary AI as APP immunostaining is unable to distinguish primary AI due to mechanical deformation from AI secondary to hypoxic-ischemic damage.