Possible Coexistence of Traumatic Cerebral Microbleeds and Axonal Injury? Postmortem Immunohistochemical Analysis

Abstract

Diffuse axonal injury (DAI) is a common type of traumatic brain injury, whose detection remains a significant clinical challenge. Recent studies suggest that traumatic cerebral microbleeds (TCMs) may serve as indirect indicators of axonal injury. Given the similar mechanisms underlying the formation of axonal injury and cerebral microbleeds, the aim of this study is to investigate the potential association between these two types of cerebral trauma.
In the total sample of 36 brains, axonal injury was detected in 32 cases (88.9%), identical to the incidence of traumatic cerebral microbleeds. βAPP immunopositivity was relatively evenly distributed across the examined brain regions, with slightly stronger expression in the posterior brain regions and the highest frequency of intense immunopositivity in the pons, albeit without statistical significance. The χ2 test, along with the Spearman correlation test, indicates an association between traumatic microbleeds in the genu of the corpus callosum and βAPP immunopositivity in all four observed brain regions, with the strongest correlation observed in the genu of the corpus callosum (p=0.011).
βAPP immunohistochemical staining revealed a relatively uniform distribution of axonal injury and microhemorrhages throughout the examined mid-sagittal brain structures. A slightly stronger βAPP expression was detected in the pons, though without statistical significance. The observed positive correlation between traumatic cerebral microbleeds and axonal injury in the anterior aspects of the corpus callosum aligns with current assumptions that the mid-sagittal brain regions are critical for the relationship between these two types of cerebral lesions