Focal traumatic brain stem injury is a rare type of head injury resulting from assault: a forensic neuropathological study

Proteomic analysis discovers potential biomarkers of early traumatic axonal injury in the brainstem

OBJECTIVE

Application of Tandem Mass Tags (TMT)-based LC-MS/MS analysis to screen for differentially expressed proteins (DEPs) in traumatic axonal injury (TAI) of the brainstem and to predict potential biomarkers and key molecular mechanisms of brainstem TAI.

METHODS

A modified impact acceleration injury model was used to establish a brainstem TAI model in Sprague-Dawley rats, and the model was evaluated in terms of both functional changes (vital sign measurements) andstructural changes (HE staining, silver-plating staining and β-APP immunohistochemical staining). TMT combined with LC-MS/MS was used to analyse the DEPs in brainstem tissues from TAI and Sham groups. The biological functions of DEPs and potential molecular mechanisms in the hyperacute phase of TAI were analysed by bioinformatics techniques, and candidate biomarkers were validated using western blotting and immunohistochemistry on brainstem tissues from animal models and humans.

RESULTS

Based on the successful establishment of the brainstem TAI model in rats, TMT-based proteomics identified 65 DEPs, and bioinformatics analysis indicated that the hyperacute phase of TAI involves multiple stages of biological processes including inflammation, oxidative stress, energy metabolism, neuronal excitotoxicity and apoptosis. Three DEPs, CBR1, EPHX2 and CYP2U1, were selected as candidate biomarkers and all three proteins were found to be significantly expressed in brainstem tissue 30 min-7 days after TAI in both animal models and humans.

CONCLUSION

Using TMT combined with LC-MS/MS analysis for proteomic study of early TAI in rat brainstem, we report for the first time that CBR1, EPHX2 and CYP2U1 can be used as biomarkers of early TAI in brainstem by means of western blotting and immunohistochemical staining, compensating for the limitations of silver-plating staining and β-APP immunohistochemical staining, especially in the case of very short survival time after TAI (shorter than 30 min). A number of other proteins that also have a potential marker role are also presented, providing new insights into the molecular mechanisms, therapeutic targets and forensic identification of early TAI in brainstem.

Forensic neuropathology in the past decade: a scoping literature review

While there has been notable research activity in the field of clinical neuropathology over the recent years, forensic approaches have been less frequent. This scoping literature review explored original research on forensic neuropathology over the past decade (January 1, 2010, until February 12, 2022) using the MEDLINE database. The aims were to (1) analyze the volume of research on the topic, (2) describe meta-level attributes and sample characteristics, and (3) summarize key research themes and methods. Of 5053 initial hits, 2864 fell within the target timeframe, and 122 were included in the review. Only 3-17 articles were published per year globally. Most articles originated from the Europe (39.3%) and Asia (36.1%) and were published in forensic journals (57.4%). A median sample included 57 subjects aged between 16 and 80 years. The most common research theme was traumatic intracranial injury (24.6%), followed by anatomy (12.3%) and substance abuse (11.5%). Key methods included immunotechniques (31.1%) and macroscopic observation (21.3%). Although a number of novel findings were reported, most were of preliminary nature and will require further validation. In order to reach breakthroughs and validate novel tools for routine use, more research input is urged from researchers across the world. It would be necessary to ensure appropriate sample sizes and make use of control groups.

Traumatic axonal injury: neuropathological features, postmortem diagnostic methods, and strategies

Traumatic brain injury (TBI) has high morbidity and poor prognosis and imposes a serious socioeconomic burden. Traumatic axonal injury (TAI), which is one of the common pathological changes in the primary injury of TBI, is often caused by the external force to the head that causes the white matter bundles to generate shear stress and tension; resulting in tissue damage and leading to the cytoskeletal disorder. At present, the forensic pathological diagnosis of TAI-caused death is still a difficult problem. Most of the TAI biomarkers studied are used for the prediction, evaluation, and prognosis of TAI in the living state. The research subjects are mainly humans in the living state or model animals, which are not suitable for the postmortem diagnosis of TAI. In addition, there is still a lack of recognized indicators for the autopsy pathological diagnosis of TAI. Different diagnostic methods and markers have their limitations, and there is a lack of systematic research and summary of autopsy diagnostic markers of TAI. Therefore, this study mainly summarizes the pathological mechanism, common methods, techniques of postmortem diagnosis, and corresponding biomarkers of TAI, and puts forward the strategies for postmortem diagnosis of TAI for forensic cases with different survival times, which is of great significance to forensic pathological diagnosis.

Impact of Road Traffic Injury to Pediatric Traumatic Brain Injury in Southern Thailand

Background

Motor vehicle is a major transportation in Southern Thailand as the result of road traffic injury and death. Consequently, severe disability and mortality in pediatric traumatic brain injury (TBI) were observed from traffic accident, particularly motorcycle accident. To identify the risk of intracranial injury in children, the association of treatment outcome with various factors including mechanisms of injury, clinical characteristics, and intracranial pathology can be assessed.

Materials and Methods

This was a retrospective study conducted on children, who were younger than 15 years old with TBI and were enrolled from 2004 to 2015. Several clinically relevant issues were reviewed and statistically analyzed.

Results

A total of 948 casualties were enrolled. Compared with falling down, the motorcycle accident was significantly associated with intracranial injury (odds ratio 1.73, 95% confidence interval [CI] 1.08-2.76). Other factors associated with intracranial injury were hemiparesis (odds ratio 5.69, 95% CI 1.44-22.36), positive of basal skull fracture signs (odds ratio 15.66, 95% CI 3.44-71.28), and fixed reaction to light of both pupils (odds ratio 5.74, 95% CI 1.71-19.23). Mortality found in thirty cases (3.2%). Furthermore, the risk of death correlated with motorcycle accident (P = 0.02) and severe head injury (P < 0.001). Neurosurgical intervention was not associated with outcome, but severe head injury, hemorrhagic shock, epidural, and subdural hematoma were impact factors.

Conclusion

The findings demonstrate road traffic injury, especially motorcycle accident leading to brain injury and death. Prevention program is a necessary key to decrease mortality and disability in pediatric TBI.

Pathological and immunohistochemical study of lethal primary brain stem injuries

BACKGROUND

Many of the deaths that occur shortly after injury or in hospitals are caused by mild trauma. Slight morphological changes are often found in the brain stems of these patients during autopsy. The purpose of this study is to investigate the histopathological changes involved in primary brain stem injuries (PBSI) and their diagnostic significance.

METHODS

A total of 65 patients who had died of PBSI and other conditions were randomly selected. They were divided into 2 groups, an injury group (25 cases) and a control group (20 cases). Slides of each patient's midbrain, pons, and medulla oblongata were prepared and stained with HE, argentaffin, and immunohistochemical agents (GFAP, NF, amyloid-β, MBP). Under low power (×100) and NF staining, the diameter of the thickest longitudinal axon was measured at its widest point. Ten such diameters were collected for each part of the brain (midbrain, pons, and medulla oblongata). Data were recorded and analyzed statistically.

RESULTS

Brain stem contusions, astrocyte activity, edema, and pathological changes in the neurons were visibly different in the injury and control groups (P < 0.05). Characteristic changes occurred in the neural axons, axon diameter varied from axon to axon and even over different segments of one axon, and several pathological phenomena were observed. These included segmental thickening and curving, wave-like processing, disarrangement, and irregular swelling. A few axons ruptured and intumesced into retraction balls. Immunohistochemical MBP staining showed enlargement and curving of spaces between the myelin sheaths and axons in certain areas. The myelin sheaths lining the surfaces of the axons were in some cases incomplete and even exfoliated, and segmentation disappeared. These pathological changes increased in severity over time (P < 0.05).

CONCLUSIONS

These histopathological changes may prove beneficial to the pathological diagnosis of PBSI during autopsy. The measurement of axon diameters provides a referent quantitative index for the diagnosis of the specific causes of death involved in PBSI.

VIRTUAL SLIDES

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1345298818712204.