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

Abstract

The Diffuse Axonal Injury (DAI) is a frequent result of traumatic brain deceleration forces and can be investigated with immunohistochemistry for the β-amyloid precursor protein (β-APP). The aim of this study is to contribute to the discussion on the role of such important histopathological finding as routinely diagnostic tool in forensic setting, such as the reconstruction of the traumatic event or of the severity of the injury and the survival time. On these bases 20 cases of blunt head injuries were studied detecting focal haemorrhages, the distribution and pattern of β-APP axonal immunoreactivity in the corpus callosum and upper brainstem. β-APP axonal immunoreactivity was found in 13 cases, 6 of which stained in both the examined sites, while the remaining 7 were positive only in one site. Haemorrhages were present in 10 cases: for 8 cases only in one of the evaluated areas, for 5 cases in the same area with axonal β-APP immunoreactivity. β-APP staining was observed in cases with a survival of at least 1-2 hours. The results remark that for a complete assessment of blunt head injuries, particularly those without head gross damage or suffering for minimal external injury, an appropriate evaluation of the central brain regions can be strongly supported by microscopic findings such as small haemorrhages and axonal β-APP immunoreactivity. They can provide reliable 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.