Prevalence of secondary brain injuries and association with trauma circumstances in neuropathologically examined medico-legal autopsy cases with primary head trauma.

Primary head injury is often followed by secondary brain damage. However, the association between injury circumstances and the prevalence of secondary injuries remains unclear. We report the prevalence and association of secondary brain injuries with the circumstances in which a head injury was sustained. The sample comprised 76 neuropathologically examined medico-legal autopsy cases with an acute primary head injury. Neuropathology reports were analysed to determine the prevalence of various secondary injuries, i.e., hypoxic-ischaemic neuronal injury, brain oedema, and vascular axonal injury (VAI). The prevalences were compared between cases from three distinct injury circumstances, i.e., fall, assault, and strangulation. The sample had a median age of 49 years (interquartile range 27-73) and 71.1% were identified as male. As for distinct injury circumstances, the sample comprised 14 fall cases, 21 assault victims, and 6 strangulation victims. The prevalence of hypoxic-ischaemic neuronal injury was highest in strangulations (100.0%), followed by assaults (81.0%) and falls (64.3%); of specific brain regions, statistically significant differences between the three case groups were found in frontal and parietal cortex (p ≤ 0.018) and the hippocampus (p = 0.005). Brain oedema was present in approximately half of assault (47.6%) and strangulation cases (50.0%), contrastingly to the lower prevalence in falls (7.1%; p = 0.024). The prevalence of VAI appeared higher among assault (23.8%) and strangulation cases (16.7%) compared to falls (7.1%), but the differences were not statistically significant. We conclude that hypoxic-ischaemic neuronal injury and brain oedema were more prevalent among assault and strangulation cases compared to falls.