Time course of cortical hemorrhages after closed traumatic brain injury: statistical analysis of posttraumatic histomorphological alterations

Epidemiology, Risk Factors, and Biomarkers of Post-Traumatic Epilepsy: A Comprehensive Overview

This paper presents an in-depth exploration of Post-Traumatic Epilepsy (PTE), a complex neurological disorder following traumatic brain injury (TBI), characterized by recurrent, unprovoked seizures. With TBI being a global health concern, understanding PTE is crucial for effective diagnosis, management, and prognosis. This study aims to provide a comprehensive overview of the epidemiology, risk factors, and emerging biomarkers of PTE, thereby informing clinical practice and guiding future research. The epidemiological aspect of the study reveals PTE as a significant contributor to acquired epilepsies, with varying incidence influenced by injury severity, age, and intracranial pathologies. The paper delves into the multifactorial nature of PTE risk factors, encompassing clinical, demographic, and genetic elements. Key insights include the association of injury severity, intracranial hemorrhages, and early seizures with increased PTE risk, and the roles of age, gender, and genetic predispositions. Advancements in neuroimaging, electroencephalography, and molecular biology are presented, highlighting their roles in identifying potential PTE biomarkers. These biomarkers, ranging from radiological signs to electroencephalography EEG patterns and molecular indicators, hold promise for enhancing PTE pathogenesis understanding, early diagnosis, and therapeutic guidance. The paper also discusses the critical roles of astrocytes and microglia in PTE, emphasizing the significance of neuroinflammation in PTE development. The insights from this review suggest potential therapeutic targets in neuroinflammation pathways. In conclusion, this paper synthesizes current knowledge in the field, emphasizing the need for continued research and a multidisciplinary approach to effectively manage PTE. Future research directions include longitudinal studies for a better understanding of TBI and PTE outcomes, and the development of targeted interventions based on individualized risk profiles. This research contributes significantly to the broader understanding of epilepsy and TBI.

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.

Keloidal dermatofibroma: Clinicopathological comparison of 52 cases with a series of 2077 other dermatofibromas

Dermatofibroma is a common benign skin lesion with a contested etiology: some believe it is a neoplasm while others propose minor injuries initiate it. Many dermatofibroma variants have been described, including keloidal dermatofibroma, which is unusual by bearing keloidal collagen. Keloidal dermatofibroma was first described in 1998 and only 15 cases have been reported. Since keloids are driven by skin injuries, the existence of keloidal dermatofibroma has been suggested to support the injury hypothesis of dermatofibroma etiology. To better understand keloidal dermatofibroma characteristics and gain clues regarding dermatofibroma etiology, consecutive keloidal dermatofibroma cases (n = 52) and dermatofibroma without keloidal collagen (n = 2077) that were histopathologically diagnosed in 2016-2019 were identified from the records of a Japanese dermatopathology laboratory and compared in terms of demographic, clinical, and histopathological characteristics by univariate analyses. Compared to other dermatofibromas, keloidal dermatofibromas occurred more frequently on the forearm and hand (P < 0.0001 and 0.0019), especially the wrist dorsum, and in the superficial skin layer (P < 0.0001). Keloidal dermatofibromas also demonstrated more cellularity and hemorrhage (both P < 0.0001). Correlation analyses between keloidal collagen amount and keloidal dermatofibroma size (a proxy of time-since-onset) did not support the notion that keloidal collagen deposition and keloidal dermatofibroma formation are triggered simultaneously. Recent injury, as indicated by fresh hemorrhage, was equally common in putatively older and younger keloidal dermatofibromas. Thus, keloidal collagen in keloidal dermatofibromas could be due to injury to preexisting dermatofibromas, which suggests that the keloidal dermatofibroma entity does not prove the injury hypothesis. Commonalities between keloids and keloidal dermatofibromas suggest a link between genetics, provocative events that induce myofibroblast differentiation, and keloidal collagen production.

Histological examination of carotid artery tissue in cases of ligature strangulation and hanging

Violence against the neck can result in a range of macromorphological and micromorphological findings. However, the forensic relevance of the carotid sinus in cases of violence against the neck remains controversial. In this follow-up study of 22 cases of suicidal and accidental strangulations, carotid bifurcations were examined histologically for morphological changes implying direct trauma, including haemorrhage and immunohistochemical expression of heat-shock proteins 27, 60, and 70 and aquaporin-3. These cases were compared with a control group (82 cases) without neck compression or head trauma and with variable causes of death. No relevant histopathological findings implying direct trauma of the carotid bifurcation were found. No cases showed positive aquaporin-3 staining and only five cases showed positive heat-shock protein-27 staining, all of which were hangings. Without massive trauma of the carotid bifurcation, histological alterations cannot be expected. Without signs of rapid death, findings of acute circulatory failure, macromorphological and micromorphological findings of neck compression, and reliable markers indicating relevant impact on the carotid bifurcation the diagnosis of a lethal reflex cannot be verified.

Case report: fatal bleeding from a duodenal ulcer-Dieulafoy's lesion?

A 46-year-old man was admitted to the hospital by ambulance due to syncope. A standard blood screening showed a normal Hb value. The man had known hemorrhoids and a single fresh rectal bleeding earlier at home. On the following morning, the patient suddenly required resuscitation within a few minutes and subsequently died. Autopsy revealed a fatal hemorrhage with blood loss in the stomach and small and large intestines and a mucosal defect of the duodenum. After autopsy, the question arose whether the cause of death might have been a rare Dieulafoy’s lesion—aim of this case report was to clarify the diagnosis.

Myelin basic protein and neurofilament H in postmortem cerebrospinal fluid as surrogate markers of fatal traumatic brain injury

The aim of this study was to investigate if the biomarkers myelin basic protein (MBP) and neurofilament-H (NF-H) yielded informative value in forensic diagnostics when examining cadaveric cerebrospinal fluid (CSF) biochemically via an enzyme-linked immunosorbent assay (ELISA) and comparing the corresponding brain tissue in fatal traumatic brain injury (TBI) autopsy cases by immunocytochemistry versus immunohistochemistry. In 21 trauma and 19 control cases, CSF was collected semi-sterile after suboccipital puncture and brain specimens after preparation. The CSF MBP (p = 0.006) and NF-H (p = 0.0002) levels after TBI were significantly higher than those in cardiovascular controls. Immunohistochemical staining against MBP and against NF-H was performed on cortical and subcortical samples from also biochemically investigated cases (5 TBI cases/5 controls). Compared to the controls, the TBI cases showed a visually reduced staining reaction against MBP or repeatedly ruptured neurofilaments against NF-H. Immunocytochemical tests showed MBP-positive phagocytizing macrophages in CSF with a survival time of > 24 h. In addition, numerous TMEM119-positive microglia could be detected with different degrees of staining intensity in the CSF of trauma cases. As a result, we were able to document that elevated levels of MBP and NF-H in the CSF should be considered as useful neuroinjury biomarkers of traumatic brain injury.

Microglial Metabolism After Pediatric Traumatic Brain Injury - Overlooked Bystanders or Active Participants?

Microglia play an integral role in brain development but are also crucial for repair and recovery after traumatic brain injury (TBI). TBI induces an intense innate immune response in the immature, developing brain that is associated with acute and chronic changes in microglial function. These changes contribute to long-lasting consequences on development, neurologic function, and behavior. Although alterations in glucose metabolism are well-described after TBI, the bulk of the data is focused on metabolic alterations in astrocytes and neurons. To date, the interplay between alterations in intracellular metabolic pathways in microglia and the innate immune response in the brain following an injury is not well-studied. In this review, we broadly discuss the microglial responses after TBI. In addition, we highlight reported metabolic alterations in microglia and macrophages, and provide perspective on how changes in glucose, fatty acid, and amino acid metabolism can influence and modulate the microglial phenotype and response to injury.

Cellular infiltration in traumatic brain injury

Traumatic brain injury leads to cellular damage which in turn results in the rapid release of damage-associated molecular patterns (DAMPs) that prompt resident cells to release cytokines and chemokines. These in turn rapidly recruit neutrophils, which assist in limiting the spread of injury and removing cellular debris. Microglia continuously survey the CNS (central nervous system) compartment and identify structural abnormalities in neurons contributing to the response. After some days, when neutrophil numbers start to decline, activated microglia and astrocytes assemble at the injury site—segregating injured tissue from healthy tissue and facilitating restorative processes. Monocytes infiltrate the injury site to produce chemokines that recruit astrocytes which successively extend their processes towards monocytes during the recovery phase. In this fashion, monocytes infiltration serves to help repair the injured brain. Neurons and astrocytes also moderate brain inflammation via downregulation of cytotoxic inflammation. Depending on the severity of the brain injury, T and B cells can also be recruited to the brain pathology sites at later time points.

Neuroinflammatory mechanisms of post-traumatic epilepsy

BACKGROUND

Traumatic brain injury (TBI) occurs in as many as 64-74 million people worldwide each year and often results in one or more post-traumatic syndromes, including depression, cognitive, emotional, and behavioral deficits. TBI can also increase seizure susceptibility, as well as increase the incidence of epilepsy, a phenomenon known as post-traumatic epilepsy (PTE). Injury type and severity appear to partially predict PTE susceptibility. However, a complete mechanistic understanding of risk factors for PTE is incomplete.

MAIN BODY

From the earliest days of modern neuroscience, to the present day, accumulating evidence supports a significant role for neuroinflammation in the post-traumatic epileptogenic progression. Notably, substantial evidence indicates a role for astrocytes, microglia, chemokines, and cytokines in PTE progression. Although each of these mechanistic components is discussed in separate sections, it is highly likely that it is the totality of cellular and neuroinflammatory interactions that ultimately contribute to the epileptogenic progression following TBI.

CONCLUSION

This comprehensive review focuses on the neuroinflammatory milieu and explores putative mechanisms involved in the epileptogenic progression from TBI to increased seizure-susceptibility and the development of PTE.

High signal-intensity abnormalities in susceptibility-weighted imaging for primary intracerebral hemorrhage

Purpose: To identify the regularity of signal evolution of intracerebral hemorrhage on susceptibility-weighted imaging (SWI) at different stages compared with T1-weighted imaging (T1WI) and T2-weighted imaging (T2WI). Methods: We retrospectively evaluated a series of 365 patients who underwent T1WI, T2WI, and SWI examination simultaneously or sequentially in our hospital from January 2015 to May 2017. Two neuroradiologists assessed the images and discrepancies between their interpretations were resolved by consensus. Statistical analysis was performed using Chi-squared and Kappa tests. Results: Of the 365 patients on SWI sequence, 94 were enrolled. SWI detected the cases at different stages; T1WI detected 89 cases and T2WI detected 91 cases. The signal intensity of intracerebral hemorrhage on SWI was significantly associated with T1WI imaging and T2WI (χ² = 4.651; p < 0.05; χ² = 26.396; p < 0.01, respectively), especially at the late subacute stage. There was moderate consistency between the signal intensity of intracerebral hemorrhage on T2WI and SWI (Kappa coefficient = 0.530). Conclusion: Intracerebral hemorrhage has a varied appearance on SWI, and the evolution of signal of intracerebral hemorrhage on SWI sequence is influenced by T1WI and T2WI. Hematoma detection should be closely combined with clinical manifestation.

An experimental study on the early diagnosis of traumatic brain injury in rabbits based on a noncontact and portable system

Closed cerebral hemorrhage (CCH) is a common symptom in traumatic brain injury (TBI) patients who suffer intracranial hemorrhage with the dura mater remaining intact. The diagnosis of CCH patients prior to hospitalization and in the early stage of the disease can help patients get earlier treatments that improve outcomes. In this study, a noncontact, portable system for early TBI-induced CCH detection was constructed that measures the magnetic induction phase shift (MIPS), which is associated with the mean brain conductivity caused by the ratio between the liquid (blood/CSF and the intracranial tissues) change. To evaluate the performance of this system, a rabbit CCH model with two severity levels was established based on the horizontal biological impactor BIM-II, whose feasibility was verified by computed tomography images of three sections and three serial slices. There were two groups involved in the experiments (group 1 with 10 TBI rabbits were simulated by hammer hit with air pressure of 600 kPa by BIM-II and group 2 with 10 TBI rabbits were simulated with 650 kPa). The MIPS values of the two groups were obtained within 30 min before and after injury. In group 1, the MIPS values showed a constant downward trend with a minimum value of −11.17 ± 2.91° at the 30th min after 600 kPa impact by BIM-II. After the 650 kPa impact, the MIPS values in group 2 showed a constant downward trend until the 25th min, with a minimum value of −16.81 ± 2.10°. Unlike group 1, the MIPS values showed an upward trend after that point. Before the injury, the MIPS values in both group 1 and group 2 did not obviously change within the 30 min measurement. Using a support vector machine at the same time point after injury, the classification accuracy of the two types of severity was shown to be beyond 90%. Combined with CCH pathological mechanisms, this system can not only achieve the detection of early functional changes in CCH but can also distinguish different severities of CCH.

Post-mortem cerebrospinal fluid diagnostics: cytology and immunocytochemistry method suitable for routine use to interpret pathological processes in the central nervous system

Due to its protected anatomical location, cerebrospinal fluid (CSF) is a very stable fluid which undergoes comparatively little change in the early post-mortem phase. While many immunohistochemical markers already established for clinical diagnostic issues in tissue samples obtained by biopsy could meanwhile be translated also to post-mortem tissue, no systematic immunocytochemical investigations have generally been conducted on post-mortem body fluids and for CSF specifically, have not been established at all. CSF as the fluid directly surrounding the brain should also be examined to allow a more detailed characterization of processes in the central nervous system. Comparing traumatized tissue and CSF can complete forensic assessment and complement neuropathological evaluation.

Noninvasive magnetic resonance imaging stratifies injury severity in a rodent model of male juvenile traumatic brain injury

Age and severity are significant predictors of traumatic brain injury (TBI) outcomes in the immature brain. TBI studies have segregated TBI injury into three severity groups: mild, moderate, and severe. While mild TBI is most frequent form in children and adults, there is debate over the indicators used to denote mild injury. Clinically, magnetic resonance imaging (MRI) and computed tomography (CT) are used to diagnose the TBI severity when medically warranted. Herein, we induced mild, moderate, and severe TBI in juvenile rats (jTBI) using the controlled cortical impact model. We characterized the temporal and spatial injury after graded jTBI in vivo using high-field MRI at 0.25 (6 hr), 1 and 3 days post-injury (dpi) with comparative histology. Susceptibility-weighted imaging (SWI) for blood and T2-weighted imaging (T2WI) for edema were quantified over the 0.25-3 dpi. Edema volumes increased linearly with severity at 0.25 dpi that slowly continued to decrease over the 3 dpi. In contrast, blood volumes did not decrease over time. Mild TBI had the least amount of blood visible on SWI. Fluoro-jade B (FJB) staining for cell death confirmed increased cellular death with increasing severity and increased FJB + cells in the corpus callosum (CC). Interestingly, the strongest correlation was observed for cell death and the presence of extravascular blood. A clear understanding of acute brain injury (jTBI) and how blood/edema contribute to mild, moderate, and severe jTBI is needed prior to embarking on therapeutic interventions. Noninvasive imaging should be used in mild jTBI to verify lack of overt injury.

Clinical-pathological study on β-APP, IL-1β, GFAP, NFL, Spectrin II, 8OHdG, TUNEL, miR-21, miR-16, miR-92 expressions to verify DAI-diagnosis, grade and prognosis

Traumatic brain injury (TBI) is one of the most important death and disability cause, involving substantial costs, also in economic terms, when considering the young age of the involved subject. Aim of this paper is to report a series of patients treated at our institutions, to verify neurological results at six months or survival; in fatal cases we searched for βAPP, GFAP, IL-1β, NFL, Spectrin II, TUNEL and miR-21, miR-16, and miR-92 expressions in brain samples, to verify DAI diagnosis and grade as strong predictor of survival and inflammatory response. Concentrations of 8OHdG as measurement of oxidative stress was performed. Immunoreaction of β-APP, IL-1β, GFAP, NFL, Spectrin II and 8OHdG were significantly increased in the TBI group with respect to control group subjects. Cell apoptosis, measured by TUNEL assay, were significantly higher in the study group than control cases. Results indicated that miR-21, miR-92 and miR-16 have a high predictive power in discriminating trauma brain cases from controls and could represent promising biomarkers as strong predictor of survival, and for the diagnosis of postmortem traumatic brain injury.

Retroocular and Subdural Hemorrhage or Hemosiderin Deposits in Pediatric Autopsies

The presence of hemosiderin in the optic nerve sheath and/or retina is sometimes used to estimate the timing of injury in infants or children with suspected non-accidental head trauma. To determine the prevalence of hemosiderin in deaths not associated with trauma, we performed a prospective study of retroocular orbital tissue, cranial convexity, and cervical spinal cord dura mater in infants and children <2.5 years age. In 53 cases of non-traumatic death, approximately 70% had blood or hemosiderin within the orbital fat, ocular muscles, and parasagittal cranial and/or cervical spinal subdural compartment. This bleeding is likely a consequence of the birth process. None had evidence of hemorrhage within the optic nerve sheath. Premature birth was less likely associated with orbital tissue hemorrhage. Caesarean section birth (mainly nonelective) was not associated with lower prevalence. Residual hemosiderin was identifiable up to 36 weeks postnatal age, suggesting gradual disappearance after birth. Cardiopulmonary resuscitation (performed in the majority of cases) was not associated with acute hemorrhage. In 9 traumatic deaths, 6 had blood and/or hemosiderin within the optic nerve sheath. Knowledge of the potential presence and resolution of hemosiderin in these locations is important for medicolegal interpretation of childhood deaths associated with head or brain injury.

Intracranial hemorrhage detection over time using susceptibility-weighted magnetic resonance imaging

BACKGROUND

The reliable detection of intracranial hemorrhages is important, but just 1 year after the hemorrhage onset it might be missed using T2-weighted spin-echo and gradient-echo sequences. Susceptibility-weighted imaging (SWI) is a new magnetic resonance imaging sequence that is extremely sensitive in hemorrhage detection and that might improve the detection of hemorrhages over time.

PURPOSE

To investigate whether the detectability of intracranial blood and its degradation products is independent of the time span after intracranial hemorrhage using SWI.

MATERIAL AND METHODS

Sixty-six consecutive patients (28 men, 38 women) with definitely known time point of intracranial hemorrhage and available SWI sequence (1.5 or 3 T) were analyzed retrospectively. Twenty-one patients had a SWI follow-up. All SWI images were assessed by two radiologists in consensus regarding hemorrhage visibility using a 5-point scale. Statistical analysis was performed using Spearman's correlation test.

RESULTS

Median time interval between hemorrhage and first available SWI measurement was 819 days (range, 0 days to 13.2 years). Nine of 66 patients had an isolated subarachnoid hemorrhage (iSAH) and were therefore analyzed separately. In eight of these nine patients the hemorrhage could clearly be detected, the remaining one had minor iSAH. Spearman analysis showed no significant correlation between time span and visibility (P = 0.660). In the remaining 57 patients (no iSAH) the hemorrhage was always visible achieving at least 3/5 points on the 5-point scale, and Spearman's analysis revealed only a weak correlation between time span and visibility (r = 0.493, P < 0.001).

CONCLUSION

The detectability of blood and its degradation products using SWI is reliably possible over a long period after intracranial hemorrhage.

Evidence to support mitochondrial neuroprotection, in severe traumatic brain injury

Traumatic brain injury (TBI) is still the leading cause of disability in young adults worldwide. The major mechanisms - diffuse axonal injury, cerebral contusion, ischemic neurological damage, and intracranial hematomas have all been shown to be associated with mitochondrial dysfunction in some form. Mitochondrial dysfunction in TBI patients is an active area of research, and attempts to manipulate neuronal/astrocytic metabolism to improve outcomes have been met with limited translational success. Previously, several preclinical and clinical studies on TBI induced mitochondrial dysfunction have focused on opening of the mitochondrial permeability transition pore (PTP), consequent neurodegeneration and attempts to mitigate this degeneration with cyclosporine A (CsA) or analogous drugs, and have been unsuccessful. Recent insights into normal mitochondrial dynamics and into diseases such as inherited mitochondrial neuropathies, sepsis and organ failure could provide novel opportunities to develop mitochondria-based neuroprotective treatments that could improve severe TBI outcomes. This review summarizes those aspects of mitochondrial dysfunction underlying TBI pathology with special attention to models of penetrating traumatic brain injury, an epidemic in modern American society.

Neuroimaging biomarkers in mild traumatic brain injury (mTBI)

Reviewed herein are contemporary neuroimaging methods that detect abnormalities associated with mild traumatic brain injury (mTBI). Despite advances in demonstrating underlying neuropathology in a subset of individuals who sustain mTBI, considerable disagreement persists in neuropsychology about mTBI outcome and metrics for evaluation. This review outlines a thesis for the select use of sensitive neuroimaging methods as potential biomarkers of brain injury recognizing that the majority of individuals who sustain an mTBI recover without neuroimaging signs or neuropsychological sequelae detected with methods currently applied. Magnetic resonance imaging (MRI) provides several measures that could serve as mTBI biomarkers including the detection of hemosiderin and white matter abnormalities, assessment of white matter integrity derived from diffusion tensor imaging (DTI), and quantitative measures that directly assess neuroanatomy. Improved prediction of neuropsychological outcomes in mTBI may be achieved with the use of targeted neuroimaging markers.

The 70 kDa heat shock protein protects against experimental traumatic brain injury

Traumatic brain injury (TBI) causes disruption of the blood brain barrier (BBB) leading to hemorrhage which can complicate an already catastrophic illness. Matrix metalloproteinases (MMPs) involved in the breakdown of the extracellular matrix may lead to brain hemorrhage. We explore the contribution of the 70 kDa heat shock protein (Hsp70) to outcome and brain hemorrhage in a model of TBI. Male, wildtype (Wt), Hsp70 knockout (Ko) and transgenic (Tg) mice were subjected to TBI using controlled cortical impact (CCI). Motor function, brain hemorrhage and lesion size were assessed at 3, 7 and 14 days. Brains were evaluated for the effects of Hsp70 on MMPs. In Hsp70 Tg mice, CCI led to smaller brain lesions, decreased hemorrhage and reduced expression and activation of MMPs compared to Wt. CCI also significantly decreased right-biased swings and corner turns in the Hsp70 Tg mice. Conversely, Hsp70 Ko mice had significantly increased lesion size, worsened brain hemorrhage and increased expression and activation of MMPs with worsened behavioral outcomes compared to Wt. Hsp70 is protective in experimental TBI. To our knowledge, this is the direct demonstration of brain protection by Hsp70 in a TBI model. Our data demonstrate a new mechanism linking TBI-induced hemorrhage and neuronal injury to the suppression of MMPs by Hsp70, and support the development of Hsp70 enhancing strategies for the treatment of TBI.

Computed tomographic and histological findings of Hansen type I intervertebral disc herniation in dogs

OBJECTIVE

To evaluate whether non-contrast-enhanced computed tomography (CT) as a stand-alone imaging modality can be used to define the Hansen type I intervertebral disc herniation (IVDH) lesion and also whether the Hounsfield unit (HU) value of herniated disc is relevant to clinical duration and to histopathological chronicity of extruded disc material.

METHODS

Information from a series of CT studies performed on 45 dogs with a presumptive diagnosis of Hansen type I IVDH was used. Clinical duration of IVDH was estimated based on time from onset of signs per owner communication to time of surgical intervention. Hansen type I IVDH was confirmed at surgery. Retrieved herniated disc was histologically examined. The HU values were analyzed to correlate the clinical duration and histopathological chronicity of the disc lesion.

RESULTS

Non-contrast-enhanced CT provided sufficient diagnostic information to plan surgery in 42 of 45 dogs (93%). The value of the HU was significantly higher in clinically chronic cases (n = 12) compared to peracute cases (n = 11) (p <0.05). The HU values were significantly correlated with clinical duration (r = 0.482, p = 0.0008) and histopathological chronicity of the herniated disc (r = 0.408, p = 0.0056).

CONCLUSION

Consistent with the previous reports, the use of non-contrast-enhanced CT alone was sufficient for the diagnosis and surgical planning in most patients with Hansen type I IVDH in the thoracolumbar spine. In addition, the present study suggested that HU values on CT images may be useful in the evaluation of disease chronicity of IVDH.

Computational analysis reveals increased blood deposition following repeated mild traumatic brain injury

Mild traumatic brain injury (mTBI) has become an increasing public health concern as subsequent injuries can exacerbate existing neuropathology and result in neurological deficits. This study investigated the temporal development of cortical lesions using magnetic resonance imaging (MRI) to assess two mTBIs delivered to opposite cortical hemispheres. The controlled cortical impact model was used to produce an initial mTBI on the right cortex followed by a second injury induced on the left cortex at 3 (rmTBI 3d) or 7 (rmTBI 7d) days later. Histogram analysis was combined with a novel semi-automated computational approach to perform a voxel-wise examination of extravascular blood and edema volumes within the lesion. Examination of lesion volume 1d post last injury revealed increased tissue abnormalities within rmTBI 7d animals compared to other groups, particularly at the site of the second impact. Histogram analysis of lesion T2 values suggested increased edematous tissue within the rmTBI 3d group and elevated blood deposition in the rm TBI 7d animals. Further quantification of lesion composition for blood and edema containing voxels supported our histogram findings, with increased edema at the site of second impact in rmTBI 3d animals and elevated blood deposition in the rmTBI 7d group at the site of the first injury. Histological measurements revealed spatial overlap of regions containing blood deposition and microglial activation within the cortices of all animals. In conclusion, our findings suggest that there is a window of tissue vulnerability where a second distant mTBI, induced 7d after an initial injury, exacerbates tissue abnormalities consistent with hemorrhagic progression.

An experimental protocol for mimicking pathomechanisms of traumatic brain injury in mice

Traumatic brain injury (TBI) is a result of an outside force causing immediate mechanical disruption of brain tissue and delayed pathogenic events. In order to examine injury processes associated with TBI, a number of rodent models to induce brain trauma have been described. However, none of these models covers the entire spectrum of events that might occur in TBI. Here we provide a thorough methodological description of a straightforward closed head weight drop mouse model to assess brain injuries close to the clinical conditions of human TBI.

Silent intralesional microhemorrhage as a risk factor for brain arteriovenous malformation rupture

BACKGROUND AND PURPOSE

We investigated whether brain arteriovenous malformation silent intralesional microhemorrhage, that is, asymptomatic bleeding in the nidal compartment, might serve as a marker for increased risk of symptomatic intracranial hemorrhage (ICH). We evaluated 2 markers to assess the occurrence of silent intralesional microhemorrhage: neuroradiological assessment of evidence of old hemorrhage-imaging evidence of bleeding before the outcome events-and hemosiderin positivity in hematoxylin and eosin-stained paraffin block sections.

METHODS

We identified cases from our brain arteriovenous malformation database with recorded neuroradiological data or available surgical paraffin blocks. Using 2 end points, index ICH or new ICH after diagnosis (censored at treatment, loss to follow-up, or death), we performed logistic or Cox regression to assess evidence of old hemorrhage and hemosiderin positivity adjusting for age, sex, deep-only venous drainage, maximal brain arteriovenous malformation size, deep location, and associated arterial aneurysms.

RESULTS

Evidence of old hemorrhage was present in 6.5% (n=975) of patients and highly predictive of index ICH (P<0.001; OR, 3.97; 95% CI, 2.1-7.5) adjusting for other risk factors. In a multivariable model (n=643), evidence of old hemorrhage was an independent predictor of new ICH (hazard ratio, 3.53; 95% CI, 1.35-9.23; P=0.010). Hemosiderin positivity was found in 36.2% (29.6% in unruptured; 47.8% in ruptured; P=0.04) and associated with index ICH in univariate (OR, 2.18; 95% CI, 1.03-4.61; P=0.042; n=127) and multivariable models (OR, 3.64; 95% CI, 1.11-12.00; P=0.034; n=79).

CONCLUSIONS

The prevalence of silent intralesional microhemorrhage is high and there is evidence for an association with both index and subsequent ICH. Further development of means to detect silent intralesional microhemorrhage during brain arteriovenous malformation evaluation may present an opportunity to improve risk stratification, especially for unruptured brain arteriovenous malformations.

In vivo iron quantification in collagenase-induced microbleeds in rat brain

Brain microbleeds (BMB) are associated with chronic and acute cerebrovascular disease. Because BMB present in the brain is a source of potentially cytotoxic iron proportional to the volume of extravasated blood, BMB iron content is a potentially valuable biomarker both to assess tissue risk and small cerebral vessel health. We recently reported methods to quantify focal iron sources using phase images that were tested in phantoms and BMB in postmortem tissue. In this study, we applied our methods to small hemorrhagic lesions induced in the in vivo rat brain using bacterial collagenase. As expected by theory, measurements of geometric features in phase images correlated with lesion iron content measured by graphite furnace atomic absorption spectrometry. Iron content estimation following BMB in an in vivo rodent model could shed light on the role and temporal evolution of iron-mediated tissue damage and efficacy of potential treatments in cerebrovascular diseases associated with BMB.

Macrophage subsets in mechanical brain injury (MBI)--a contribution to timing of MBI based on immunohistochemical methods: a pilot study

Cortical hemorrhages as a consequence of closed mechanical brain injury (MBI) trigger an inflammatory response including a distinct increase of macrophages. According to published data this reactive macrophage population is heterogenous as to their immunological properties. The expression of certain immunohistochemically detectable epitopes of macrophages, however, may correlate with the posttraumatic interval (PTI). In a pilot study, 50 selected cases of cortical hemorrhages with 1 min to 1.5 years PTI were examined by light microscopy and macrophages were labeled with CD68-, HLA-D-, HAM-56-, LN-5-, and 25F9-antibodies, while hemosiderin was detected by a Prussian-blue reaction. Qualitative and semiquantitative investigations were performed. The semiquantitative study included 5 different classes. The results of the study revealed a distinct timetable of the appearance of macrophages labeled with certain antibodies. While HLA-D immunoreactivity was detected after a PTI of 6h in the cortex and white matter bordering the traumatic hemorrhage, CD68 immunopositive macrophages were present after 12h, LN-5 and HAM-56 after 48h, and 25F9 within 10d. Hemosiderin-containing macrophages were detectable within 100h in the same region. Within the hemorrhage itself a certain immunoreactivity of macrophages starts several hours before: CD68 after 3h, LN-5 after 24h, HAM-56 after 31h, hemosiderin after 76h, and 25F9 after 4d. For forensic purposes these observations are of crucial importance because the time course of the appearance of certain immunopositive macrophages labeled with different antibodies allows a differentiated timing of contusional injuries; however, the cause of this different immunopositive reaction remains unexplained. The observed time dependency of different macrophage antigen expressions in cortical hemorrhages after closed head injury is a suitable method to estimate the PTI and will allow a forensic reliable estimation if future investigations are extended on higher numbers of cases and/or additional markers.

Diffusion tensor imaging reliably detects experimental traumatic axonal injury and indicates approximate time of injury

Traumatic axonal injury (TAI) may contribute greatly to neurological impairments after traumatic brain injury, but it is difficult to assess with conventional imaging. We quantitatively compared diffusion tensor imaging (DTI) signal abnormalities with histological and electron microscopic characteristics of pericontusional TAI in a mouse model. Two DTI parameters, relative anisotropy and axial diffusivity, were significantly reduced 6 h to 4 d after trauma, corresponding to relatively isolated axonal injury. One to 4 weeks after trauma, relative anisotropy remained decreased, whereas axial diffusivity "pseudo-normalized" and radial diffusivity increased. These changes corresponded to demyelination, edema, and persistent axonal injury. At every time point, DTI was more sensitive to injury than conventional magnetic resonance imaging, and relative anisotropy distinguished injured from control mice with no overlap between groups. Remarkably, DTI changes strongly predicted the approximate time since trauma. These results provide an important validation of DTI for pericontusional TAI and suggest novel clinical and forensic applications.

Cellular localization of pituitary adenylate cyclase-activating peptide (PACAP) following traumatic brain injury in humans

The pituitary adenylate cyclase-activating peptide (PACAP) is involved in many processes of the developing and mature central nervous system, such as proliferation, differentiation, apoptosis, neurotransmission, inflammation and neuroprotection. Alternative posttranslational processing of PACAP results in two biologically active, amidated 27- and 38-amino acid peptides termed PACAP27 and PACAP38. In the present study, we examined whether traumatic brain injury (TBI) affects cellular immunopositivity for PACAP27 and PACAP38. Patients (n = 55) were classified into three groups dependent on their survival time (under 24 h, between 24 h and 7 days and between 7 days and 99 days postinjury). PACAP27 and PACAP38 were expressed by neurons and glial cells in normal human neocortex (n = 10). Following TBI, the total number of PACAP27- and PACAP38-positive cells was significantly decreased for a prolonged survival period within the traumatized neocortex. In the pericontusional cortex, the number of cells expressing PACAP27 and PACAP38 was significantly increased at all survival times examined. Triple immunofluorescence examinations revealed a significant increase in the absolute numbers of GFAP-positive reactive astrocytes as well as a decrease in the CNP-positive oligodendrocytes, each coexpressing PACAP27 or PACAP38 in the contusional and pericontusional cortex. We hypothesize that the increase of glial PACAP immunoreactivity may be interpreted as part of a complex endogenous neuroprotective response in the pericontusional regions, but the precise role of PACAP following TBI is yet to be determined.

Decreased Expression of Glutamate Transporters in Astrocytes after Human Traumatic Brain Injury

The primary mechanism for eliminating synaptically released glutamate is uptake by astrocytes. In the present study, we examined whether traumatic brain injury (TBI) affects the cellular expression of glutamate transporters EAAT1 and EAAT2. Morphometrical immunohistochemical analysis demonstrated a predominant expression of EAAT1 and EAAT2 in astrocytes of normal human neocortex (n = 10). Following traumatic injury of human brain (n = 55), the number of EAAT2-positive cells was decreased for a prolonged survival period within the traumatized neocortex and the pericontusional region. GFAP-positive astrocytes decreased in number within the first 24 h. Thereafter, the number of GFAP-positive astrocytes increased again, indicating formation of reactive gliosis. Double immunofluorescence examinations revealed a reduction in absolute numbers of GFAP-positive astrocytes coexpressing EAAT1 or EAAT2 at survival times up to 7 days. In addition, the relative fractions of astrocytes coexpressing glutamate transporters decreased following TBI. We conclude that the posttraumatic reduction in cellular EAAT 1 and EAAT2 expression is predominantly due to degeneration of astrocytes and to downregulation in surviving astrocytes. Our results support the view that reduced glutamate uptake by astrocytes contributes to posttraumatic elevation of extracellular glutamate in humans.

Cerebral Hypoxia and Ischemia: The Forensic Point of View: A Review

In cases with suspected brain anoxia/ischemia and hypoxia/hypoxemia a neuropathological investigation should give additional information to elucidate the cause of death and its pathophysiological mechanisms. Primary ischemic brain damage is associated with morphological and biochemical alterations. While acute ischemic neuronal injury reveals axon sparing and selective neuronal lesions due to the release of large quantities of glutamate, late neuronal death is associated with antiapoptotic growth factors, and decreased expression of microtubule-associated proteins and tubulin. On the morphological level ischemia can be detected by necrosis of neurons, proliferation of microglia, and astrocytes in vulnerable regions of the brain. In cases of permanent ischemia the so-called pale nervous cell injury is observed, in cases of partial perfusion the so-called dark nerve cell injury and apoptosis are detectable. In spite of the considerable advantages of recent research, presently there is no reliable qualitative marker to ascertain death due to acute hypoxic or ischemic events.

[Cerebral cavernomas, epilepsy and seizures. Natural history and therapeutic strategy]

PURPOSE

To review, from a retrospective series of 48 patients presenting with seizures associated with one or more supratentorial cavernoma(s), the natural history of the seizures and outcome according to medical and surgical treatment.

METHODS

Patients were divided into two groups: group A included patients presenting with a single seizure or rare seizures (n=21), and group B patients having intractable epilepsy (n=27). All received antiepileptic drugs and 35 were operated on (12 in the group A and 23 in the group B). Stereo-EEG was performed in 8 patients in group B. Surgery included lesionectomy alone (n=16), resection of the cavernoma and perilesional tissue (n=7) or tailored corticectomy including the cavernoma (n=12).

RESULTS

The natural history of seizures was different in the two groups: mean age at seizure onset was 25 years in group B and 33 years in group A (p<0.05), seizures were partial in all patients in group B and 8 patients in group A (p<0.05). Seizure frequency and periodicity also varied. Prolonged seizure-free periods were observed. The cavernoma was temporal in 17 patients in group B and 4 patients in group A (p<0.01). In group A, seizure outcome was favorable following surgery or with antiepileptic medication only (7 patients out of 12 operated were seizure-free, as were 5 out of 7 non-operated). In group B, seizure outcome was better after surgery than with medication only (17 patients out of 23 operated were in Engel's Class I, while 3 patients of 4 non-operated patients had persisting seizures despite antiepileptic polytherapy).

CONCLUSION

Variations in seizure severity in patients harboring cavernomas suggest different therapeutic approaches. In case of unique or rare seizures, surgical resection of the cavernoma is appropriate, but benefits of surgery over antiepileptic medication in terms of seizure control remains unclear. Intractable epilepsy associated with cavernomas is better controlled after surgery rather than with medication only. In these patients, a detailed preoperative work-up is necessary and should be followed by wide resection associated or not with corticectomy, especially in the temporal lobe. Evaluation of outcome after surgery should consider the surgical strategy, antiepileptic medications and the patient's seizure history.

Vitality and time course of wounds

The term "wound" describes the morphologic-functional disruption of the continuity of a tissue structure. A wound can be inflicted during life--when the cardiovascular and respiratory system is still intact--or after death, i.e. after cardiac and respiratory arrest. Traumatization during life triggers vital reactions that do not occur in postmortem wounds. Three types of vital reactions in wound healing can be distinguished: Reactions of the scavenger type, which are almost exclusively mediated by blood cells. Reactions by complex signal transduction pathways, which involves cascade-like release of chemokines, cytokines and adhesion molecules and may influence type 1 and type 3 reactions. Reactions of the scarring type, which involve the final repair of the damaged tissue and are carried out primarily by cells residing at the wound edges, i.e. partly concerning mesenchymal cells and partly tissue-specific cells dependent on the involved organ system. The three different types of reaction follow roughly parallel temporal courses that include cascade-like interactions among themselves. Whereas demonstration of a vital reaction suffices to differentiate an intravital wound from a postmortem wound, the vital reactions themselves follow strictly temporal courses. The regular time-dependent occurrence of each phenomenon allows--in limits--a reliable temporal classification of wound healing. A review will be given especially demonstrating the actual German scientific research in vitality and in skin wound timing as well as in timing of mechanical injury of the brain.

Research in forensic neurotraumatology

Over the past 100 years forensic research in neurotraumatology was focusing on the genesis, e.g. biomechanis, and the origin of epidural, subdural, subarachnoidal, intracerebral and brain stem haemorrhage, particularly under aspects to enable the differential diagnosis of bleeding due to non-traumatic diseases. Moreover the estimation of the age of brain injuries has important criminological implications (survival time following traumatic forces to the head, alibi etc.). Beside these main fields of research, aspects of expertise in special areas such as head trauma due to child abuse, capability to act despite severe brain injuries and research on cervical trauma are reviewed.

Neuropsychological results and neuropathological findings at autopsy in a case of mild traumatic brain injury

Autopsy studies were undertaken in a 47-year-old college-educated male patient who, 7 months prior to an unexpected death, had sustained a mild traumatic brain injury (TBI) as manifested by brief loss of consciousness and an initial Glasgow Coma Scale score of 14. The patient died from cardiac arrest secondary to an undiagnosed and unknown arteriosclerotic cardiovascular disease as assessed by the coroners office at the time of autopsy. Gross inspection of the brain at autopsy was normal; however, microscopic analysis demonstrated what were considered trauma findings of hemosiderin-laden macrophages in the perivascular space and macrophages in the white matter, particularly the section taken from the frontal lobe. The patient had partially returned to work at the time of death, but had encountered problems with diminished cognitive performance in his work as an appraiser. Neuropsychological studies were generally within normal limits although several tests of either speed of processing or short-term memory showed lower than expected performance. This case demonstrates the presence of subtle neuropathological changes in the brain of a patient who sustained a mild TBI and was still symptomatic for the residual effects of the injury 7 months post injury when he unexpectedly died.