Pathological study of diffuse axonal injury patients who died shortly after impact

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.

Calcium overloading in traumatic axonal injury by lateral head rotation: a morphological evidence in rat model

The study investigated morphologically axonal calcium overloading and its relationship with axonal structural changes. Twelve SD rats were divided into an injury and a sham group. The rat model of traumatic axonal injury (TAI) by lateral head rotation was produced. The oxalate-pyroantimonate technique for calcium localization was used to process the rat's medulla oblongata tissues with thin sections observed electron-microscopically for axonal structure and calcium precipitates on it. The axonal damage in medulla oblongata appeared at 2 h post-injury, gradually became diffuse and severe, and continued to exist at 24 hours. At 2 hours, calcium precipitates were deposited on separated lamellae and axolemma, but were rarely distributed in the axoplasm. At 6 hours, calcium precipitates occurred on separated lamellae and axolemma in much higher density, but on axoplasm in extremely small amounts. Some axons, though lacking structural changes of the myelin sheath, sequestered plenty of calcium deposits on their swollen mitochondria. At 24 hours, damaged axons presented with much more severe lamellae separation and calcium deposits. Axonal calcium overloading developed in rat TAI model using lateral head rotation. This was significantly related to structural damage in the axons. These findings suggest the feasibility of using calcium antagonists in cope the management of human DAI in its very early stage.

Severe head injury and the risk of early death

BACKGROUND

Severe head injury (SHI) is one of the most important health, social and economic problems in industrialised countries. Unfortunately, none of the neuroprotection trials for traumatic brain injury have shown efficacy. One of the reasons for this failure could be the inclusion of patients with high probability of early death. A population-based, retrospective study was conducted to develop a prognostic model for identification of these patients.

METHODS

Between January 1987 and August 1999, a total of 895 patients (> or = 15 years of age) with non-missile SHI were studied, in whom a computed tomography scan was carried out within the first 6 h of injury. The association between early death (first 48 h after injury) and independent prognostic factors was determined by logistic regression analysis. A scoring system was also constructed.

RESULTS

The early-death rate was 20%. Independent predictors of early mortality after SHI were non-evacuated mass (odds ratio (OR) 65, 95% confidence interval (CI) 11 to 379), diffuse injury IV (OR 25, 95% CI 5 to 112), diffuse injury III (OR 8, 95% CI 3 to 22), flaccidity (OR 7, 95% CI 3 to 15), non-reactive bilaterally mydriasis (OR 6, 95% CI 3 to 12), evacuated mass (OR 4, 95% CI 1 to 11), age > or = 65 years (OR 4, 95% CI 1 to 9), decerebration (OR 3, 95% CI 2 to 7) and shock (OR 3, 95% CI 2 to 6). The prognostic model correctly identified 93% of the patients.

CONCLUSIONS

This prognostic model is based on simple clinical and radiological data readily available during the first 6 h after injury and is useful for identification of early death after SHI.

[Prognostic factors in severe head injury]

The knowledge of the so called prognostic factors or indicators involved in severe head injury (SHI) is an issue of great interest to make predictions about the future of patients with this pathology. Those indicators constitute the basic elements of the different prognostic formulas or models carried out in order to make predictions in SHI. The mentioned models, therefore, will be constructed by a group of variables (prognostic indicators or factors) and several scales (prognostic scales) that are useful for measuring the final outcome of these patients. In this paper we resume, after an exhaustive review of the literature, the knowledge about the prognostic factors related to SHI. These indicators have been classified as follows: clinical, radiological, physiological, and biochemical. Moreover, we have briefly described the prognostic scales more commonly used in SHI.

The Correlation Between Skull Fractures and Intracranial Lesions Due To Traffic Accidents

In this study, it was aimed to investigate the relationship between skull fractures and intracranial lesions following head injury. For this purpose, 500 cases, which were referred to the Third Committee of Council of Forensic Medicine in Istanbul due to traffic accidents by the courts of laws between 1998 and 2000, were examined retrospectively. They were categorized in 3 groups based on findings of their cranium x-rays and brain tomographies. 1- The cases who have fractures in skull bones with brain lesions 2- The cases who have fractures in skull bones with no brain lesions 3- The cases who have brain lesions with no skull fractures. They were examined in detail according to age, sex, localization of skull fractures and brain lesions, and if surgery was applied or not. Of the cases, 152 (30.4%) had only linear fractures, 69 (13.8%) had depressed fractures, 92 (18.4%) had linear fractures plus intracranial lesions, 49 (9.8%) had depressed fractures plus intracranial lesions and 138 (27.6%) had only intracranial lesions. The rate of intracranial lesion among the cases with the skull fracture was 38.9% (141/362), while the rate of skull fracture among the cases with the intracranial lesion was 50.3% (141/279) (P < 0.001). Male to female ratios were 2.4/1 for linear fractures, 5.2/1 for depressed fractures, and 3.5/1 for intracranial lesions. Linear fractures were more frequent among females whereas depressed fractures were often among males (chi2: 9.68, df: 4, p: 0.046). The mean age was 26.3. The rate of depressed fractures was higher the age groups of 0-30 years. (chi2: 16.28, df: 4, p: 0.003). Depressed fractures in the regions of frontal and parietal and, linear fracture in the regions of temporal and occipital were found at higher rates (P < 0.001). In conclusion, we reviewed skull fractures and/or intracranial lesions due to traffic accidents, and found depressed fractures to be more common among males whereas linear fractures to be more common among females and young males. In the male, the skull architecture is thicker and stronger than females and young males. We can state that presence of skull fractures lowers the incidence of intracranial lesions by lowering the intracranial pressure.

Axonal injury in falls

Amyloid precursor protein (APP) immunocytochemistry was used as a marker for axonal injury (AI) in a series of 16 cases of head trauma associated with fatal falls. Nine cases were falls from not more than the person's own height (falls from < or = own height) and seven cases were falls from a distance greater than the person's own height (falls from > own height). AI was recorded on a series of line diagrams of standard brain sections divided into 116 sectors. AI around focal lesions (infarcts, hemorrhages, contusions) was distinguished from nonfocal axonal injury that was distant from any focal area of damage. The percentage of sectors showing focal AI provided the Focal Axonal Injury Score (FAIS) and the percentage showing nonfocal AI the Non-Focal Axonal Injury Score (NFAIS). The FAIS is a measure of secondary AI and the NFAIS of diffuse axonal injury (DAI). The percentage of sectors involved with AI (focal and nonfocal) provided the cumulative Axonal Injury Score (AIS). A semiquantitative grading system was also used to assess the severity of axonal injury in each sector and the sum of the grades from all sectors was expressed as a percentage to provide the Axonal Injury Severity Score (AISS). Widespread AI was present in all cases irrespective of the height of the fall. AI was present in the midbrain (94%), pons (94%), corpus callosum (100%), central grey matter (100%), and cerebral hemispheric white matter (94%). AIS ranged from 10 to 94 in falls from < or = own height (mean 73) and from 38 to 92 in falls from > own height (mean 82). AISS ranged from 6 to 95 in falls from < or = own height (mean 65) and 28 to 95 in falls from > own height (mean 72). There was no statistically significant difference in AIS or AISS between the two groups. The extent and severity of AI cannot be predicted from biomechanical data, such as the height of the fall, as the total AI in a given case is a variable mixture of Nonfocal AI (DAI) and Focal AI arising by secondary mechanisms, and APP immunostaining is unable to distinguish primary from secondary AI. However, the combination of the Hypoxic-Ischemic Score (HIS) defined as the percentage of sectors showing any hypoxic-ischemic damage ranging from neuronal "red cell change" to infarction in conjunction with the FAIS and NFAIS provided a measure of the relative contribution of primary and secondary AI in a given brain.

Fundamental studies on alcohol dependence and disposition

This article reviews some recent studies on alcohol preference, dependence, metabolism and pharmacokinetics which were mainly carried out in our department. The inbred strains of mice with genetically different alcohol drinking behavior and alcohol animal model treated with the neurotoxins, 6-hydroxydopamine and 5,7-dihydroxytryptamine, are useful for a behavioral and pharmacological approach to evaluate the contribution of specific neural systems to alcohol, drug dependence mechanism and alcohol drinking behavior. The relations between alcohol preference and some physiological conditions are reviewed. On the drug-alcohol interaction, some drugs containing the chemical group = CHONO2, antimony and methamphetamine are addressed. This article also deals with recent topics in the pharmacokinetics and pharmacodynamics of alcohol. The dose-dependency of the alcohol elimination rate, the first-pass metabolism during alcohol drinking, and the pharmacodynamic model for describing pulse rate reaction to plasma acetaldehyde are discussed.

Somatosensory evoked potentials and intracranial pressure in severe head injury

The purpose of this study was to explore the relationship between neurologic function, using a quantitative measurement of continuous somatosensory evoked potentials (SSEPs), and intracranial pressure (ICP) following traumatic brain injury. During a 6 year period, severely head-injured patients with a Glascow Coma Scale < or = 8 who were not moribund were monitored with SSEPs and ICP measurements. SSEPs from each hemisphere and ICP were recorded hourly for each patient. Neurologic outcomes were scored using the Glasgow Outcome Scale at three months post injury. Although initial SSEP amplitude did not correlate well with outcome, final SSEP summed peak to peak amplitude from both hemispheres (p = .0001), the best hemisphere (p = .0004), and the worst hemisphere (p = .0001) correlated well with the Glasgow Outcome Scale groups. Of a total of 72 patients, 40 had deteriorating SSEPs and 32 had stable or improving SSEPs. Peak ICP values were not statistically different in these groups (p = .6). Among patients with deteriorating SSEPs, 52.5% lost the greatest proportion of hemispheric electrical activity prior to ICP elevation. In the remaining patients, the percent reduction of SSEP activity after peak ICP levels was not statistically different from the percent reduction in SSEP activity prior to the peak ICP levels (p = .9). This data suggests that in a select group of patients with severe head injury, ICP does not cause SSEP deterioration, but rather is the consequence of deterioration of brain function.