β-App immunoreactivity as diagnostic tool of Diffuse Axonal Injury (DAI)

The Diffuse Axonal Injury (DAI) is a frequent result of traumatic brain deceleration forces and can beinvestigated with immunohistochemistry for the β-amyloid precursor protein (β-APP). The aim of this study is to contribute tothe discussion on the role of such important histopathological finding as routinely diagnostic tool in forensic setting, such as thereconstruction of the traumatic event or of the severity of the injury and the survival time. On these bases 20 cases of blunt headinjuries were studied detecting focal haemorrhages, the distribution and pattern of β-APP axonal immunoreactivity in the corpuscallosum and upper brainstem. β-APP axonal immunoreactivity was found in 13 cases, 6 of which stained in both the examinedsites, while the remaining 7 were positive only in one site. Haemorrhages were present in 10 cases: for 8 cases only in one ofthe evaluated areas, for 5 cases in the same area with axonal β-APP immunoreactivity. β-APP staining was observed in caseswith a survival of at least 1-2 hours. The results remark that for a complete assessment of blunt head injuries, particularly thosewithout head gross damage or suffering for minimal external injury, an appropriate evaluation of the central brain regions can bestrongly supported by microscopic findings such as small haemorrhages and axonal β-APP immunoreactivity. They can providereliable information concerning the survival time and the degree of mechanical forces that developed during the traumatic event,especially in cases in which the circumstantial data are contradictory or unknown by pathologist.