Cerebral endothelial injury in severe head injury: the significance of measurements of serum thrombomodulin and the von Willebrand factor

Exploratory factor analysis yields grouping of brain injury biomarkers significantly associated with outcomes in neonatal and pediatric ECMO

In this two-center prospective cohort study of children on ECMO, we assessed a panel of plasma brain injury biomarkers using exploratory factor analysis (EFA) to evaluate their interplay and association with outcomes. Biomarker concentrations were measured daily for the first 3 days of ECMO support in 95 participants. Unfavorable composite outcome was defined as in-hospital mortality or discharge Pediatric Cerebral Performance Category > 2 with decline ≥ 1 point from baseline. EFA grouped 11 biomarkers into three factors. Factor 1 comprised markers of cellular brain injury (NSE, BDNF, GFAP, S100β, MCP1, VILIP-1, neurogranin); Factor 2 comprised markers related to vascular processes (vWF, PDGFRβ, NPTX1); and Factor 3 comprised the BDNF/MMP-9 cellular pathway. Multivariable logistic models demonstrated that higher Factor 1 and 2 scores were associated with higher odds of unfavorable outcome (adjusted OR 2.88 [1.61, 5.66] and 1.89 [1.12, 3.43], respectively). Conversely, higher Factor 3 scores were associated with lower odds of unfavorable outcome (adjusted OR 0.54 [0.31, 0.88]), which is biologically plausible given the role of BDNF in neuroplasticity. Application of EFA on plasma brain injury biomarkers in children on ECMO yielded grouping of biomarkers into three factors that were significantly associated with unfavorable outcome, suggesting future potential as prognostic instruments.

Plasma von Willebrand Factor Is Elevated Hyperacutely After Mild Traumatic Brain Injury

Each year in the United States, ∼2.7 million persons seek medical attention for traumatic brain injury (TBI), of which ∼85% are characterized as being mild brain injuries. Many different cell types in the brain are affected in these heterogeneous injuries, including neurons, glia, and the brain vasculature. Efforts to identify biomarkers that reflect the injury of these different cell types have been a focus of ongoing investigation. We hypothesized that von Willebrand factor (vWF) is a sensitive biomarker for acute traumatic vascular injury and correlates with symptom severity post-TBI. To address this, blood was collected from professional boxing athletes (n = 17) before and within 30 min after competition. Plasma levels of vWF and neuron-specific enolase were measured using the Meso Scale Discovery, LLC. (MSD) electrochemiluminescence array-based multi-plex format (MSD, Gaithersburg, MD). Additional symptom and outcome data from boxers and patients, such as the Rivermead symptom scores (Rivermead Post Concussion Symptoms Questionnaire [RPQ-3]), were collected. We found that, subsequent to boxing bouts, there was a 1.8-fold increase in vWF levels within 30 min of injury (p < 0.0009). Moreover, fold-change in vWF correlates moderately (r = 0.51; p = 0.03) with the number of head blows. We also found a positive correlation (r = 0.69; p = 0.002) between fold-change in vWF and self-reported post-concussive symptoms, measured by the RPQ-3. The receiver operating curve analysis of vWF plasma levels and RPQ-3 scoring yielded a sensitivity of 94.12% and a specificity of 76.5% with an area under the curve of 83% for boxers after a fight compared to the pre-bout baseline. This study suggests that vWF is a potential blood biomarker measurable in the hyperacute period after blunt mild TBI. This biomarker may prove to be useful in diagnosing and monitoring traumatic vascular injury.

Associations of Microvascular Injury-Related Biomarkers With Traumatic Brain Injury Severity and Outcomes: A Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) Pilot Study

Traumatic brain injury (TBI) is characterized by heterogeneity in terms of injury severity, mechanism, outcome, and pathophysiology. A single biomarker alone is unlikely to capture the heterogeneity of even one injury subtype, necessitating the use of panels of biomarkers. Herein, we focus on traumatic cerebrovascular injury and investigate associations of a panel of 16 vascular injury-related biomarkers with indices of TBI severity and outcomes using data from 159 participants in the Transforming Research and Clinical Knowledge in TBI (TRACK-TBI) Pilot Study. Associations of individual biomarkers and clusters of biomarkers identified using non-linear principal components analysis with TBI severity and outcomes were assessed using logistic regression models and Spearman's correlations. As individual biomarkers, higher levels of thrombomodulin, angiopoietin (Ang)-2, von Willebrand factor, and P-selectin were associated with more severe injury; higher levels of Ang-1, Tie2, vascular endothelial growth factor (VEGF)-C, and basic fibroblast growth factor (bFGF) were associated with less severe injury (all p < 0.05 in age-adjusted models). After false discovery rate correction for multiple comparisons, higher levels of Ang-2 remained associated with more severe injury and higher levels of Ang-1, Tie2, and bFGF remained associated with less severe injury at a p < 0.05 level. In principal components analysis, principal component (PC)1, comprised of Ang1, bFGF, P-selectin, VEGF-C, VEGF-A, and Tie2, was associated with less severe injury (age-adjusted odds ratio [OR]: 0.63, 95% confidence interval [CI]: 0.44-0.88 for head computer tomography [CT] positive vs. negative) and PC2 (Ang-2, E-selectin, Flt-1, placental growth factor, thrombomodulin, and vascular cell adhesion protein 1) was associated with greater injury severity (age-adjusted OR: 2.29, 95% CI: 1.49-3.69 for Glasgow Coma Scale [GCS] 3-12 vs. 13-15 and age-adjusted OR 1.59, 95% CI: 1.11-2.32 for head CT positive vs. negative). Neither individual biomarkers nor PCs were associated with outcomes in adjusted models (all p > 0.05). In conclusion, in this trauma-center based population of acute TBI patients, biomarkers of microvascular injury were associated with TBI severity.

circ_0001274 Competitively Binds miR-143-3p to Upregulate VWF Expression to Improve Acute Traumatic Coagulopathy

Accumulating evidence has noted the circRNA-microRNA- (circRNA-miRNA-) mRNA competing endogenous RNA (ceRNA) regulatory network in disease development and progression. The current study explored the ceRNA network in acute traumatic coagulopathy (ATC). Potential ATC-related genes were screened, and upstream miRNAs and circRNAs of VWF (the candidate target) were assayed through database searching and high-throughput sequencing technology. circ_0001274/miR-143-3p/VWF ceRNA regulatory network was constructed and validated. The expression of circ_0001274/miR-143-3p/VWF was determined in the peripheral blood samples from ATC patients and ATC mouse models. Online database and circRNA sequencing analysis results identified VWF as a key gene in ATC as supported by assays and that VWF was lowly expressed in ATC patients and mice. Further experiments demonstrated that miR-143-3p could target and inhibit VWF, and circ_0001274 could competitively sponge miR-143-3p. Functionally, circ_0001274 could competitively sequester miR-143-3p to upregulate VWF expression, potentially improving ATC. Our study highlights the critical role of circ_0001274/miR-143-3p/VWF axis in improving ATC.

Detecting traumatic brain injury-induced coagulopathy: What we are testing and what we are not

ABSTRACT

Coagulopathy after traumatic brain injury (TBI) is common and has been closely associated with poor clinical outcomes for the affected patients. Traumatic brain injury-induced coagulopathy (TBI-IC) is consumptive in nature and evolves rapidly from an injury-induced hypercoagulable state. Traumatic brain injury-induced coagulopathy defined by laboratory tests is significantly more frequent than clinical coagulopathy, which often manifests as secondary, recurrent, or delayed intracranial or intracerebral hemorrhage. This disparity between laboratory and clinical coagulopathies has hindered progress in understanding the pathogenesis of TBI-IC and developing more accurate and predictive tests for this severe TBI complication. In this review, we discuss laboratory tests used in clinical and research studies to define TBI-IC, with specific emphasis on what the tests detect and what they do not. We also offer perspective on developing more accurate and predictive tests for this severe TBI complication.

Neurointensive Care of Traumatic Brain Injury Patients Based on Coagulation and Fibrinolytic Parameter Monitoring

Coagulopathy, a common complication of traumatic brain injury (TBI), is characterized by a hypercoagulable state developing immediately after injury, with hyperfibrinolysis and bleeding tendency peaking 3 h after injury, followed by fibrinolysis shutdown. Reflecting this timeframe, the coagulation factor fibrinogen is first consumed and then degraded after TBI, its concentration rapidly decreasing by 3 h post-TBI. The fibrinolytic marker D-dimer reaches its maximum concentration at the same time. Hyperfibrinolysis in the acute phase of TBI is associated with poor prognosis via hematoma expansion. In the acute phase, the coagulation and fibrinolysis parameters must be monitored to determine the treatment strategy. The combination of D-dimer plasma level at admission and the level of consciousness upon arrival at the hospital can be used to predict the patients who will "talk and deteriorate." Fibrinogen and D-dimer levels should determine case selection and the amount of fresh frozen plasma required for transfusion. Surgery around 3 h after injury, when fibrinolysis and bleeding diathesis peak, should be avoided if possible. In recent years, attempts have been made to estimate the time of injury from the time course of coagulation and fibrinolysis parameter levels, which has been particularly useful in some cases of pediatric abusive head trauma patients.

Coagulopathy and Traumatic Brain Injury: Overview of New Diagnostic and Therapeutic Strategies

Coagulopathy is a common sequela of traumatic brain injury. Consumptive coagulopathy and secondary hyperfibrinolysis are associated with hypercoagulability. In addition, fibrinolytic pathways are hyperactivated as a result of vascular endothelial cell damage in the injured brain. Coagulation and fibrinolytic parameters change dynamically to reflect these pathologies. Fibrinogen is consumed and degraded after injury, with fibrinogen concentrations at their lowest 3-6 h after injury. Hypercoagulability causes increased fibrinolytic activity, and plasma levels of D-dimer increase immediately after traumatic brain injury, reaching a maximum at 3 h. Owing to disseminated intravascular coagulation in the presence of fibrinolysis, the bleeding tendency is highest within the first 3 h after injury, and often a condition called “talk and deteriorate” occurs. In neurointensive care, it is necessary to measure coagulation and fibrinolytic parameters such as fibrinogen and D-dimer routinely to predict and prevent the development of coagulopathy and its negative outcomes. Currently, the only evidence-based treatment for traumatic brain injury with coagulopathy is tranexamic acid in the subset of patients with mild-to-moderate traumatic brain injury. Coagulation and fibrinolytic parameters should be closely monitored, and treatment should be considered on a patient-by-patient basis.

Targeting the Cerebrovascular System: Next-Generation Biomarkers and Treatment for Mild Traumatic Brain Injury

The diagnosis, prognosis, and treatment of mild traumatic brain injuries (mTBIs), such as concussions, are significant unmet medical issues. The kinetic forces that occur in mTBI adversely affect the cerebral vasculature, making cerebrovascular injury (CVI) a pathophysiological hallmark of mTBI. Given the importance of a healthy cerebrovascular system in overall brain function, CVI is likely to contribute to neurological dysfunction after mTBI. As such, CVI and related pathomechanisms may provide objective biomarkers and therapeutic targets to improve the clinical management and outcomes of mTBI. Despite this potential, until recently, few studies have focused on the cerebral vasculature in this context. This article will begin by providing a brief overview of the cerebrovascular system followed by a review of the literature regarding how mTBI can affect the integrity and function of the cerebrovascular system, and how this may ultimately contribute to neurological dysfunction and neurodegenerative conditions. We then discuss promising avenues of research related to mTBI biomarkers and interventions that target CVI, and conclude that a clinical approach that takes CVI into account could result in substantial improvements in the care and outcomes of patients with mTBI.

Quantification of von Willebrand factor and ADAMTS-13 after traumatic injury: a pilot study

BACKGROUND

Von Willebrand factor (VWF) is an acute phase reactant synthesized in the megakaryocytes and endothelial cells. VWF forms ultra-large multimers (ULVWF) which are cleaved by the metalloprotease ADAMTS-13, preventing spontaneous VWF-platelet interaction. After trauma, ULVWF is released into circulation as part of the acute phase reaction. We hypothesized that trauma patients would have increased levels of VWF and decreased levels of ADAMTS-13 and that these patients would have accelerated thrombin generation.

METHODS

We assessed plasma concentrations of VWF antigen and ADAMTS-13 antigen, the Rapid Enzyme Assays for Autoimmune Diseases (REAADS) activity of VWF, which measure exposure of the platelet-binding A1 domain, and thrombin generation kinetics in 50 samples from 30 trauma patients and an additional 21 samples from volunteers. Samples were analyzed at 0 to 2 hours and at 6 hours from the time of injury. Data are presented as median (IQR) and Kruskal-Wallis test was performed between trauma patients and volunteers at both time points.

RESULTS

REAADS activity was greater in trauma patients than volunteers both at 0 to 2 hours (190.0 (132.0-264.0) vs. 92.0 (71.0-114.0), p<0.002) and at 6 hours (167.5 (108.0-312.5.0) vs. 92.0 (71.0-114.0), p<0.001). ADAMTS-13 antigen levels were also decreased in trauma patients both at 0 to 2 hours (0.84 (0.51-0.94) vs. 1.00 (0.89-1.09), p=0.010) and at 6 hours (0.653 (0.531-0.821) vs. 1.00 (0.89-1.09), p<0.001). Trauma patients had accelerated thrombin generation kinetics, with greater peak height and shorter time to peak than healthy volunteers at both time points.

DISCUSSION

Trauma patients have increased exposure of the VWF A1 domain and decreased levels of ADAMTS-13 compared with healthy volunteers. This suggests that the VWF burst after trauma may exceed the proteolytic capacity of ADAMTS-13, allowing circulating ULVWF multimers to bind platelets, potentially contributing to trauma-induced coagulopathy.

LEVEL OF EVIDENCE

Prospective case cohort study.

Hyperhomocysteinemia-Induced Oxidative Stress Exacerbates Cortical Traumatic Brain Injury Outcomes in Rats

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality among military service members and civilians in the United States. Despite significant advances in the understanding of TBI pathophysiology, several clinical reports indicate that multiple genetic and epigenetic factors can influence outcome. Homocysteine (HCY) is a non-proteinogenic amino acid, the catabolism of which can be dysregulated by stress, lifestyle, aging, or genetic abnormalities leading to hyperhomocysteinemia (HHCY). HHCY is a neurotoxic condition and a risk factor for multiple neurological and cardiovascular disorders that occurs when HCY levels is clinically > 15 µM. Although the deleterious impact of HHCY has been studied in human and animal models of neurological disorders such as stroke, Alzheimer's disease and Parkinson's disease, it has not been addressed in TBI models. This study tested the hypothesis that HHCY has detrimental effects on TBI pathophysiology. Moderate HHCY was induced in adult male Sprague Dawley rats via daily administration of methionine followed by impact-induced traumatic brain injury. In this model, HHCY increased oxidative stress, upregulated expression of proteins that promote blood coagulation, exacerbated TBI-associated blood-brain barrier dysfunction and promoted the infiltration of inflammatory cells into the cortex. We also observed an increase of brain injury-induced lesion size and aggravated anxiety-like behavior. These findings show that moderate HHCY exacerbates TBI outcomes and suggest that HCY catabolic dysregulation may be a significant biological variable that could contribute to TBI pathophysiology heterogeneity.

Conformation-dependent blockage of activated VWF improves outcomes of traumatic brain injury in mice

Traumatic brain injury-induced coagulopathy (TBI-IC) causes life-threatening secondary intracranial bleeding. Its pathogenesis differs mechanistically from that of coagulopathy arising from extracranial injuries and hemorrhagic shock, but it remains poorly understood. We report results of a study designed to test the hypothesis that von Willebrand factor (VWF) released during acute TBI is intrinsically hyperadhesive because its platelet-binding A1-domain is exposed and contributes to TBI-induced vascular leakage and consumptive coagulopathy. This hyperadhesive VWF can be selectively blocked by a VWF A2-domain protein to prevent TBI-IC and to improve neurological function with a minimal risk of bleeding. We demonstrated that A2 given through intraperitoneal injection or IV infusion reduced TBI-induced death by >50% and significantly improved the neurological function of C57BL/6J male mice subjected to severe lateral fluid percussion injury. A2 protected the endothelium from extracellular vesicle-induced injury, reducing TBI-induced platelet activation and microvesiculation, and preventing a TBI-induced hypercoagulable state. A2 achieved this therapeutic efficacy by specifically blocking the A1 domain exposed on the hyperadhesive VWF released during acute TBI. These results suggest that VWF plays a causal role in the development of TBI-IC and is a therapeutic target for this life-threatening complication of TBI.

Diverse activities of von Willebrand factor in traumatic brain injury and associated coagulopathy

Traumatic brain injury (TBI) is a leading cause of death and disability. Patients with isolated TBI lose a limited amount of blood to primary injury, but they often develop secondary coagulopathy, resulting in delayed or recurrent intracranial and intracerebral hematoma. TBI-induced coagulopathy is closely associated with poor outcomes for these patients, including death. This secondary coagulopathy is consumptive in nature, involving not only brain-derived molecules, coagulation factors, and platelets, but also endothelial cells in a complex process now called blood failture. A key question is how a localized injury to the brain is rapidly disseminated to affect systemic hemostasis that is not directly affected the way it is in trauma to the body and limbs, especially with hemorrhagic shock. Increasing evidence suggests that the adhesive ligand von Willebrand factor (VWF), which is synthesized in and released from endothelial cells, plays a paradoxical role in both facilitating local hemostasis at the site of injury and also propagating TBI-induced endotheliopathy and coagulopathy systemically. This review discusses recent progress in understanding these diverse activities of VWF and the knowledge gaps in defining their roles in TBI and associated coagulopathy.

Age-Related Differences in the Time Course of Coagulation and Fibrinolytic Parameters in Patients with Traumatic Brain Injury

Coagulopathy and older age are common and well-recognized risk factors for poorer outcomes in traumatic brain injury (TBI) patients; however, the relationships between coagulopathy and age remain unclear. We hypothesized that coagulation/fibrinolytic abnormalities are more pronounced in older patients and may be a factor in poorer outcomes. We retrospectively evaluated severe TBI cases in which fibrinogen and D-dimer were measured on arrival and 3–6 h after injury. Propensity score-matched analyses were performed to adjust baseline characteristics between older patients (the “elderly group,” aged ≥75 y) and younger patients (the “non-elderly group,” aged 16–74 y). A total of 1294 cases (elderly group: 395, non-elderly group: 899) were assessed, and propensity score matching created a matched cohort of 324 pairs. Fibrinogen on admission, the degree of reduction in fibrinogen between admission and 3–6 h post-injury, and D-dimer levels between admission and 3–6 h post-injury were significantly more abnormal in the elderly group than in the non-elderly group. On multivariate logistic regression analysis, independent risk factors for poor prognosis included low fibrinogen and high D-dimer levels on admission. Posttraumatic coagulation and fibrinolytic abnormalities are more severe in older patients, and fibrinogen and D-dimer abnormalities are negative predictive factors.

Biomarkers in traumatic brain injury: new concepts

Traumatic brain injury is a multifaceted condition that encompasses a spectrum of injuries: contusions, axonal injuries in specific brain regions, edema, and hemorrhage. Brain injury determines a broad clinical and disability spectrum due to the implication of various cellular pathways, genetic phenotypes, and environmental factors. It is challenging to predict patient outcomes, to appropriately evaluate the patients, to determine a suitable treatment strategy and rehabilitation program, and to communicate with patient relatives. Biomarkers detected from body fluids are potential evaluation tools for traumatic brain injury patients. These may serve as internal indicators of cerebral damage, delivering valuable information about the dynamic cellular, biochemical, and molecular environments. The diagnostic and prognostic value of biomarkers tested both in animal models of traumatic brain injury is still under question, despite a considerable scientific literature. Recent publications emphasize that a more realistic approach involves combining multiple types of biomarkers with other investigative tools (imaging, outcome scales, and genetic polymorphisms). Additionally, there is increasing interest in the use of biomarkers as tools for treatment monitoring and as surrogate outcome variables to facilitate the design of distinct randomized controlled trials. This review highlights the latest available evidence regarding biomarkers in adults after traumatic brain injury and discusses new approaches in the evaluation of this patient group.

Changes in Plasma von Willebrand Factor and Cellular Fibronectin in MRI-Defined Traumatic Microvascular Injury

The neuropathology of traumatic brain injury (TB) is diverse, including primary injury to neurons, axons, glial cells, vascular structures, and secondary processes, such as edema and inflammation that vary between individual patients. Traumatic microvascular injury is an important endophenotype of TBI-related injury. We studied patients who sustained a TBI requiring ER evaluation and had an MRI performed within 48 h of injury. We classified patients into 3 groups based on their MRI findings: (1) those that had evidence of traumatic microvascular injury on susceptibility or diffusion weighted MRI sequences without frank hemorrhage [Traumatic Vascular Injury (TVI) group; 20 subjects]. (2) those who had evidence of intraparenchymal, subdural, epidural, or subarachnoid hemorrhage [Traumatic Hemorrhage (TH) group; 26 subjects], and (3) those who had no traumatic injuries detected by MRI [MRI-negative group; 30 subjects]. We then measured plasma protein biomarkers of vascular injury [von Willebrand Factor (vWF) or cellular fibronectin (cFn)] and axonal injury (phosphorylated neurofilament heavy chain; pNF-H). We found that the TVI group was characterized by decreased expression of plasma vWF (p < 0.05 compared to MRI-negative group; p < 0.00001 compared to TH group) ≤48 h after injury. cFN was no different between groups ≤48 h after injury, but was increased in the TVI group compared to the MRI-negative (p < 0.00001) and TH (p < 0.00001) groups when measured >48 h from injury. pNF-H was increased in both the TH and TVI groups compared to the MRI-negative group ≤48 h from injury. When we used the MRI grouping and molecular biomarkers in a model to predict Glasgow Outcome Scale-Extended (GOS-E) score at 30–90 days, we found that inclusion of the imaging data and biomarkers substantially improved the ability to predict a good outcome over clinical information alone. These data indicate that there is a distinct, vascular-predominant endophenotype in a subset of patients who sustain a TBI and that these injuries are characterized by a specific biomarker profile. Further work to will be needed to determine whether these biomarkers can be useful as predictive and pharmacodynamic biomarkers for vascular-directed therapies after TBI.

von Willebrand factor enhances microvesicle-induced vascular leakage and coagulopathy in mice with traumatic brain injury

von Willebrand factor (VWF) is an adhesive ligand, and its activity is proteolytically regulated by the metalloprotease ADAMTS-13 (a disintegrin and metalloprotease with thrombospondin type 1 repeat 13). An elevated level of plasma VWF has been widely considered a marker for endothelial cell activation in trauma and inflammation, but its causal role in these pathological conditions remains poorly defined. Using a fluid percussion injury mouse model, we demonstrated that VWF released during acute traumatic brain injury (TBI) was activated and became microvesicle-bound. The VWF-bound microvesicles promoted vascular leakage and systemic coagulation. Recombinant ADAMTS-13 given either before or after TBI reduced the VWF reactivity with minimal influence on VWF secretion. rADAMTS-13 protected the integrity of endothelial cell barriers and prevented TBI-induced coagulopathy by enhancing VWF cleavage without impairing basal hemostasis. Promoting microvesicle clearance by lactadherin had efficacy similar to that of rADAMTS-13. This study uncovers a novel synergistic action between VWF and cellular microvesicles in TBI-induced vascular leakage and coagulopathy and demonstrates protective effects of rADAMTS-13.

Male and Female Mice Exhibit Divergent Responses of the Cortical Vasculature to Traumatic Brain Injury

We previously reported that traumatic brain injuries (TBI) alter the cerebrovasculature near the injury site in rats, followed by revascularization over a 2-week period. Here, we tested our hypothesis that male and female adult mice have differential cerebrovascular responses following a moderate controlled cortical impact (CCI). Using in vivo magnetic resonance imaging (MRI), a new technique called vessel painting, and immunohistochemistry, we found no differences between males and females in lesion volume, neurodegeneration, blood-brain barrier (BBB) alteration, and microglia activation. However, females exhibited more astrocytic hypertrophy and heme-oxygenase-1 (HO-1) induction at 1 day post-injury (dpi), whereas males presented with increased endothelial activation and expression of β-catenin, shown to be involved in angiogenesis. At 7 dpi, we observed an increase in the number of vessels and an enhancement in vessel complexity in the injured cortex of males compared with females. Cerebrovasculature recovers differently after CCI, suggesting biological sex should be considered when designing new therapeutic agents.

Sympathoadrenal Activation is Associated with Acute Traumatic Coagulopathy and Endotheliopathy in Isolated Brain Injury

Background:

Acute coagulopathy after traumatic brain injury (TBI) involves a complex multifactorial hemostatic response that is poorly characterized. Objectives: To examine early posttraumatic alterations in coagulofibrinolytic, endothelial, and inflammatory blood biomarkers in relation to sympathetic nervous system (SNS) activation and 6-month patient outcomes, using multivariate partial least-squares (PLS) analysis.

Patients and Methods:

A multicenter observational study of 159 adult isolated TBI patients admitted to the emergency department at an urban level I trauma center, was performed. Plasma concentrations of 6 coagulofibrinolytic, 10 vascular endothelial, 19 inflammatory, and 2 catecholamine biomarkers were measured by immunoassay on admission and 24 h postinjury. Neurological outcome at 6 months was assessed using the Extended Glasgow Outcome Scale. PLS-discriminant analysis was used to identify salient biomarker contributions to unfavorable outcome, whereas PLS regression analysis was used to evaluate the covariance between SNS correlates (catecholamines) and biomarkers of coagulopathy, endotheliopathy, and inflammation.

Results:

Biomarker profiles in patients with an unfavorable outcome displayed procoagulation, hyperfibrinolysis, glycocalyx and endothelial damage, vasculature activation, and inflammation. A strong covariant relationship was evident between catecholamines and biomarkers of coagulopathy, endotheliopathy, and inflammation at both admission and 24 h postinjury.

Conclusions:

Biomarkers of coagulopathy and endotheliopathy are associated with poor outcome after TBI. Catecholamine levels were highly correlated with endotheliopathy and coagulopathy markers within the first 24 h after injury. Further research is warranted to characterize the pathogenic role of SNS-mediated hemostatic alterations in isolated TBI.

Acute Traumatic Endotheliopathy in Isolated Severe Brain Injury and Its Impact on Clinical Outcome

Study design: Prospective observational cohort. Objective: To investigate the difference in plasma levels of syndecan-1 (due to glycocalyx degradation) and soluble thrombomodulin (due to endothelial damage) in isolated severe traumatic brain injury (TBI) patients with/without early coagulopathy. A secondary objective was to compare the effects of the degree of TBI endotheliopathy on hospital mortality among patients with TBI-associated coagulopathy (TBI-AC). Methods: Data was prospectively collected on isolated severe TBI (sTBI) patients with Glasgow Coma Scale (GCS) ≤8 less than 12 h after injury admitted to a level I trauma centre. Isolated sTBI patients with samples withdrawn prior to blood transfusion were stratified by conventional coagulation tests as coagulopathic (prothrombin time (PT) ≥ 16.7 s, international normalized ratio (INR) ≥ 1.27, and activated partial thromboplastin time (aPTT) ≥ 28.8 s) and non-coagulopathic. Twenty healthy controls were also included. Plasma levels of thrombomodulin and syndecan-1 were estimated by ELISA. With receiver operating characteristic curve (ROC) analysis, we defined endotheliopathy as a syndecan-1 cut-off level that maximized the sum of sensitivity and specificity for predicting TBI-AC. Results: Inclusion criteria were met in 120 cases, with subjects aged 35.5 ± 12.6 years (88.3% males). TBI-AC was identified in 50 (41.6%) patients, independent of age, gender, and GCS, but there was an association with acidosis (60%; p = 0.01). Following isolated sTBI, we found insignificant changes in soluble thrombomodulin (sTM) levels between patients with isolated TBI and controls, and sTM levels were lower in coagulopathic compared to non-coagulopathic patients. Elevations in plasma syndecan-1 (ng/mL) levels were seen compared to control (31.1(21.5–30.6) vs. 24.8(18.5–30.6); p = 0.08). Syndecan-1(ng/mL) levels were significantly elevated in coagulopathic compared to non-coagulopathic patients (33.7(21.6–109.5) vs. 29.9(19.239.5); p = 0.03). Using ROC analysis (area under the curve = 0.61; 95% Confidence Interval (CI) 0.50 to 0.72), we established a plasma syndecan-1 level cutoff of ≥30.5 ng/mL (sensitivity % = 55.3, specificity % = 52.3), with a significant association with TBI-associated coagulopathy. Conclusion: Subsequent to brain injury, elevated syndecan-1 shedding and endotheliopathy may be associated with early coagulation abnormalities. A syndecan-1 level ≥30.5 ng/mL identified patients with TBI-AC, and may be of importance in guiding management and clinical decision-making.

Age-related differences in fibrinolytic parameters in patients with acute traumatic brain injury

Background:

Coagulopathy and old age have been associated with poor outcomes in traumatic brain injury (TBI) patients; however, the relationships of coagulopathy and age with the acute phase of TBI remain unclear. We hypothesized that coagulation/fibrinolytic abnormalities are more severe in older patients in the acute phase of TBI and may explain, in part, their poor outcome.

Methods:

We analyzed the relationship between coagulation/fibrinolytic parameters and age in the acute phase of TBI by retrospectively evaluating 274 patients with initial blood samples obtained no more than 1 hour after injury. Measurement of platelet count, prothrombin time, activated partial thromboplastin time, plasma levels of fibrinogen, and D-dimer was done in the emergency department on arrival as well as 3, 6, and 12 hours following injury. Values were compared between patients aged 16–55 years (group 1) and those aged older than 55 years (group 2) with an Abbreviated Injury Score (AIS)-head of 3–5 to identify any relationship between these parameters and age.

Results:

When groups 1 and 2 were matched for AIS-head, plasma levels of D-dimer in group 2 were significantly higher than those in group 1 from hospital admission to 12 hours after injury. The Glasgow Outcome Scale scores at 3 months post-injury of group 2 with AIS 4 and 5 were significantly lower than those of group 1 (both P < 0.0001).

Conclusions:

Fibrinolytic abnormalities are more severe in older acute-phase TBI patients, which may be a factor associated with their poor prognosis.

Disseminated intravascular coagulation with increased fibrinolysis during the early phase of isolated traumatic brain injury

Background

There is evidence to demonstrate that the coagulopathy which occurs in patients with traumatic brain injury coincides with disseminated intravascular coagulation (DIC). We hypothesized that DIC with increased fibrinolysis during the early stage of isolated traumatic brain injury (iTBI) affects the outcome of the patients and that hypoperfusion contributes to hyperfibrinolysis in the DIC.

Methods

This retrospective study included 92 patients with iTBI who were divided into DIC and non-DIC groups according to the Japanese Association Acute Medicine DIC scoring system. The DIC patients were subdivided into those with and without hyperfibrinolysis. The platelet counts and global markers of coagulation and fibrinolysis were measured. Systemic inflammatory response syndrome (SIRS), organ dysfunction (assessed by the Sequential Organ Failure Assessment score), tissue hypoperfusion (assessed by the lactate levels) and the transfusion volume were also evaluated. The outcome measure was all-cause hospital mortality.

Results

DIC patients showed consumption coagulopathy, lower antithrombin levels and higher fibrin/fibrinogen degradation products (FDP) and D-dimer levels than non-DIC patients. All of the DIC patients developed SIRS accompanied by organ dysfunction and required higher blood transfusion volumes, leading to a worse outcome than non-DIC patients. These changes were more prominent in DIC with hyperfibrinolysis. A higher FDP/D-dimer ratio suggests that DIC belongs to the fibrinolytic phenotype and involves fibrin(ogen)olysis. The mean blood pressures of the patients with and without DIC on arrival were identical. Hypoperfusion and the lactate levels were not identified as independent predictors of hyperfibrinolysis.

Conclusions

DIC, especially DIC with hyperfibrinolysis, affects the outcome of patients with iTBI. Low blood pressure-induced tissue hypoperfusion does not contribute to hyperfibrinolysis in this type of DIC.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-017-1808-9) contains supplementary material, which is available to authorized users.

Response of the cerebral vasculature following traumatic brain injury

The critical role of the vasculature and its repair in neurological disease states is beginning to emerge particularly for stroke, dementia, epilepsy, Parkinson's disease, tumors and others. However, little attention has been focused on how the cerebral vasculature responds following traumatic brain injury (TBI). TBI often results in significant injury to the vasculature in the brain with subsequent cerebral hypoperfusion, ischemia, hypoxia, hemorrhage, blood-brain barrier disruption and edema. The sequalae that follow TBI result in neurological dysfunction across a host of physiological and psychological domains. Given the importance of restoring vascular function after injury, emerging research has focused on understanding the vascular response after TBI and the key cellular and molecular components of vascular repair. A more complete understanding of vascular repair mechanisms are needed and could lead to development of new vasculogenic therapies, not only for TBI but potentially vascular-related brain injuries. In this review, we delineate the vascular effects of TBI, its temporal response to injury and putative biomarkers for arterial and venous repair in TBI. We highlight several molecular pathways that may play a significant role in vascular repair after brain injury.

Time Course of Coagulation and Fibrinolytic Parameters in Patients with Traumatic Brain Injury

Traumatic brain injury (TBI) has long been associated with coagulopathy; however, the time course of coagulation/fibrinolytic parameters in the acute phase of TBI remains unclear. The purpose of the study was to analyze the time course of coagulation/fibrinolytic parameters in the acute phase of TBI and to elucidate parameter relationships to prognosis. We retrospectively evaluated 234 patients with severe isolated TBI with initial blood samples obtained no more than 1 h after injury. Platelet count, prothrombin time, activated partial thromboplastin time (aPTT), plasma levels of fibrinogen, and D-dimer were measured on arrival in the emergency department and 3, 6, and 12 h after injury. Multivariate logistic regression analysis was performed to identify risk factors for poor prognosis at each time point. From hospital admission to 12 h after injury, an elevated D-dimer level was a significant negative prognostic indicator (admission: p < 0.0001; 3 h after injury: p = 0.0005; 6 h after injury: p = 0.005; 12 h after injury: p = 0.0009). An upward trend of aPTT on admission and 3 h after injury was also a significant negative prognostic indicator (admission: p = 0.0011; 3 h after injury: p = 0.013). On multivariate logistic regression analysis, which included all initial variables, independent risk factors for poor prognosis included older age (p = 0.0005), low Glasgow Coma Scale score (p < 0.0001), high Abbreviated Injury Score (p = 0.015), aPTT >30.2 sec (p = 0.019), and elevated D-dimer level (p = 0.0005). We concluded that D-dimer is the best coagulation/fibrinolytic parameter to monitor for prediction of outcome.

Thrombomodulin regulation in human brain microvascular endothelial cells in vitro: role of cytokines and shear stress

Thrombomodulin (TM), an important determinant of blood vessel homeostasis, is expressed on the luminal vascular endothelial cell surface and is released into serum in response to circulatory signals. This includes the cerebrovascular endothelium, where the anti-coagulant and anti-inflammatory properties of TM are thought to be critical to the brain microcirculation and blood-brain barrier (BBB) integrity. Much is still unknown however about how circulatory stimuli may regulate TM activity within the brain microvasculature. To address this, the current short paper investigated the effects of opposing regulatory signals, namely cytokines (TNF-α, IL-6) and laminar shear stress, on the cellular levels and release of TM in cultured human brain microvascular endothelial cells (HBMvECs). Treatment of confluent HBMvECs with either TNF-α or IL-6 (100ng/ml, 18h) reduced TM protein levels by up to 70%, whilst inducing TM release into media by up to 4.4 and 5.5 fold, respectively. The effects of either cytokine (0-100ng/ml) on TM protein levels (6 or 18h) and release (0-18h) were also found to be concentration- and time-dependent. Either cytokine (100ng/ml, 24-72h) also reduced TM mRNA levels by >50%. When exposed to laminar shear stress for 24h at 8dyn/cm(2) (SI unit equivalent=0.8Pa), TM protein levels were upregulated by 65% in parallel with a 2-fold increase in TM mRNA levels. Shear stress also proved to be a much more potent stimulus for TM release from HBMvECs, yielding media TM levels of 1000pg/10(5) cells, when compared to 175 and 210pg/10(5) cells for TNF-α and IL-6, respectively, after parallel 18h treatments. Finally, shear-conditioned media was found to completely block thrombin-induced permeabilization of HBMvECs, confirming the functional efficacy of released TM. In summary, our data indicate that TM is differentially regulated within cultured HBMvECs by humoral and biomechanical signals.

Traumatic brain injury-associated coagulopathy

Traumatic injury is a common cause of coagulopathy, primarily due to blood loss and hemodilution secondary to fluid resuscitation. Traumatic injury-associated coagulopathy often follows a course of transition from hyper- to hypocoagulable state exemplified in disseminated intravascular coagulation. The incidence of coagulopathy is significantly higher in patients with traumatic brain injury (TBI), especially those with penetrating trauma compared to injury to the trunk and limbs. This occurs despite the fact that patients with isolated TBI bleed less and receive restricted volume load of fluids. TBI-associated coagulopathy is extensively documented to associate with poor clinical outcomes, but its pathophysiology remains poorly understood. Studies in the past have shown that brain tissue is highly enriched in key procoagulant molecules. This review focuses on the biochemical and cellular characteristics of these molecules and pathways that could make brain uniquely procoagulant and prone to coagulopathy. Understanding this unique procoagulant environment will help to identify new therapeutic targets that could reverse a state of coagulopathy with minimal impacts on hemostasis, a critical requirement for neurosurgical treatments of TBI.

Correlation between coagulopathy and outcome in severe head trauma in neurointensive care and trauma units

BACKGROUND

Abnormal blood coagulation after traumatic brain injury is a common finding. Some studies have proposed these changes as useful predictors of outcome in patients with head trauma. This study aimed at evaluating the association of the routine tests of blood coagulation within the first hours after severe head trauma with prognosis of patients with severe head trauma.

MATERIALS AND METHODS

A total of 52 patients with severe head trauma (Glasgow Coma Scale [GCS], ≤8) were admitted at Tabriz University Hospital for 1 year. Patients with major accompanying trauma were excluded. On admission, serum levels of hemoglobin and hematocrit as well as the platelet count, prothrombin time (PT), partial thromboplastin time (PTT), and international normalized ratio (INR) were documented. The relation between these parameters with final outcome and also with GCS at admission, 24 hours, 48 hours, and 1 week after admission and discharge time and Glasgow Outcome Scale (GOS) were studied.

RESULTS

Thirty three patients were discharged, and 19 died. There were significant negative correlations between PT, PTT, and INR with all GCS and GOS scores. These correlations were significant and positive between the platelet count and all GCS and GOS scores. Median PT, PTT, and INR were significantly higher in nonsurvivors. Median serum platelets count was significantly lower in nonsurvivors.

CONCLUSION

On-admission PT, PTT, INR and platelet count may be used as predictors of outcome and prognosis of patients with severe head trauma.

Prehospital resuscitation with hypertonic saline-dextran modulates inflammatory, coagulation and endothelial activation marker profiles in severe traumatic brain injured patients

Background

Traumatic brain injury (TBI) initiates interrelated inflammatory and coagulation cascades characterized by wide-spread cellular activation, induction of leukocyte and endothelial cell adhesion molecules and release of soluble pro/antiinflammatory cytokines and thrombotic mediators. Resuscitative care is focused on optimizing cerebral perfusion and reducing secondary injury processes. Hypertonic saline is an effective osmotherapeutic agent for the treatment of intracranial hypertension and has immunomodulatory properties that may confer neuroprotection. This study examined the impact of hypertonic fluids on inflammatory/coagulation cascades in isolated head injury.

Methods

Using a prospective, randomized controlled trial we investigated the impact of prehospital resuscitation of severe TBI (GCS < 8) patients using 7.5% hypertonic saline in combination with 6% dextran-70 (HSD) vs 0.9% normal saline (NS), on selected cellular and soluble inflammatory/coagulation markers. Serial blood samples were drawn from 65 patients (30 HSD, 35 NS) at the time of hospital admission and at 12, 24, and 48-h post-resuscitation. Flow cytometry was used to analyze leukocyte cell-surface adhesion (CD62L, CD11b) and degranulation (CD63, CD66b) molecules. Circulating concentrations of soluble (s)L- and sE-selectins (sL-, sE-selectins), vascular and intercellular adhesion molecules (sVCAM-1, sICAM-1), pro/antiinflammatory cytokines [tumor necrosis factor (TNF)-α and interleukin (IL-10)], tissue factor (sTF), thrombomodulin (sTM) and D-dimers (D-D) were assessed by enzyme immunoassay. Twenty-five healthy subjects were studied as a control group.

Results

TBI provoked marked alterations in a majority of the inflammatory/coagulation markers assessed in all patients. Relative to control, NS patients showed up to a 2-fold higher surface expression of CD62L, CD11b and CD66b on polymorphonuclear neutrophils (PMNs) and monocytes that persisted for 48-h. HSD blunted the expression of these cell-surface activation/adhesion molecules at all time-points to levels approaching control values. Admission concentrations of endothelial-derived sVCAM-1 and sE-selectin were generally reduced in HSD patients. Circulating sL-selectin levels were significantly elevated at 12 and 48, but not 24 h post-resuscitation with HSD. TNF-α and IL-10 levels were elevated above control throughout the study period in all patients, but were reduced in HSD patients. Plasma sTF and D-D levels were also significantly lower in HSD patients, whereas sTM levels remained at control levels.

Conclusions

These findings support an important modulatory role of HSD resuscitation in attenuating the upregulation of leukocyte/endothelial cell proinflammatory/prothrombotic mediators, which may help ameliorate secondary brain injury after TBI.

Trial registration

NCT00878631.

Cerebral cortical gene expression in acutely anemic rats: a microarray analysis

PURPOSE

Hemodilution in perioperative patients has been associated with neurological morbidity and increased mortality by undefined mechanisms. This study assesses whether hemodilutional anemia up-regulated inflammatory cerebral gene expression (microarray) to help define the mechanism.

METHODS

Hemodilution was performed in anesthetized rats by exchanging 50% of the estimated blood volume (30 mL kg(-1)) with pentastarch. Two groups of control animals were utilized, i.e., a non-anesthetized control (Normal Control) and an anesthetized control group (Anesthesia Control). Blood pressure, hemoglobin concentration, and arterial blood gas analysis were performed before and after hemodilution. Cerebral cortex was harvested from isoflurane-anesthetized rats (n = 6) after 6 and 24 hr of recovery and was used to perform complimentary DNA (cDNA) microarray analyses. Pro-inflammatory chemokine and cytokine protein levels were also measured.

RESULTS

Microarray analysis demonstrated up-regulation of 72 and 27 genes (6 and 24 hr, respectively) in anemic cerebral cortex. These genes were involved in a number of biological functions, including (1) inflammatory responses; (2) angiogenesis; (3) vascular homeostasis; (4) cellular biology; and (5) apoptosis. Chemokine ribonucleic acid (RNA) expression (CXCL-1, -10, and -11) was highest in anemic brain tissue (P < 0.0125 for each). Protein measurements demonstrated a significant increase in interleukin-6, tumor necrosis factor alpha, and monocyte chemoattractant protein-1 (P < 0.05 for each).

CONCLUSION

This study utilizes microarray technology to elucidate changes in cerebral cortical gene expression in response to acute hemodilution. These findings demonstrate an increase in pro-inflammatory chemokines (RNA, protein) and cytokines (protein). An improved understanding of the inflammatory response to anemia may help to minimize associated morbidity and mortality.

Hemostatic and hemorrhagic problems in neurosurgical patients

BACKGROUND

Abnormalities of the hemostasis can lead to hemorrhage, and on the other hand to thrombosis. Intracranial neoplasms, complex surgical procedures, and head injury have a specific impact on coagulation and fibrinolysis. Moreover, the number of neurosurgical patients on medication (which interferes with platelet function and/or the coagulation systems) has increased over the past years.

METHOD

The objective of this review is to recall common hemostatic disorders in neurosurgical patients on the basis of the "new concept of hemostasis". Therefore the pertinent literature was searched to provide a structured and up to date manuscript about hemostasis in Neurosurgery.

FINDINGS

According to recent scientific publications abnormalities of the coagulation system are discussed. Pathophysiological background and the rational for specific (cost)-effective perioperative hemostatic therapy is provided.

CONCLUSIONS

Perturbations of hemostasis can be multifactorial and maybe encountered in the daily practice of neurosurgery. Early diagnosis and specific treatment is the prerequisite for successful treatment and good patients outcome.

Coagulation disorders after traumatic brain injury

BACKGROUND

Over the past decade new insights in our understanding of coagulation have identified the prominent role of tissue factor. The brain is rich in tissue factor, and injury to the brain may initiate disturbances in local and systemic coagulation. We aimed to review the current knowledge on the pathophysiology, incidence, nature, prognosis and treatment of coagulation disorders following traumatic brain injury (TBI).

METHODS

We performed a MEDLINE search from 1966 to April 2007 with various MESH headings, focusing on head trauma and coagulopathy. We identified 441 eligible English language studies. These were reviewed for relevance by two independent investigators. A meta-analysis was performed to calculate the frequencies of coagulopathy after TBI and to determine the association of coagulopathy and outcome, expressed as odds ratios.

RESULTS

Eighty-two studies were relevant for the purpose of this review. Meta-analysis of 34 studies reporting the frequencies of coagulopathy after TBI, showed an overall prevalence of 32.7%. The presence of coagulopathy after TBI was related both to mortality (OR 9.0; 95%CI: 7.3-11.6) and unfavourable outcome (OR 36.3; 95%CI: 18.7-70.5).

CONCLUSIONS

We conclude that coagulopathy following traumatic brain injury is an important independent risk factor related to prognosis. Routine determination of the coagulation status should therefore be performed in all patients with traumatic brain injury. These data may have important implications in patient management. Well-performed prospective clinical trials should be undertaken as a priority to determine the beneficial effects of early treatment of coagulopathy.

Cerebral endothelial damage after severe head injury

We demonstrate that in head injuries the degree of cerebral endothelial activation or injury depends on the type of brain injury and the patients age, and that in severe head injuries measuring the serum levels of thrombomodulin (TM) and von Willebrand factor (vWF) is useful in evaluating cerebral endothelial injury and activation. The values of vWF in the cases of focal brain injury were significantly higher than in the cases of diffuse axonal injury. The serum levels of TM in focal brain injuries were higher than in diffuse axonal injuries, but the differences were not statistically significant. In patients with delayed traumatic intracerebral hematoma (DTICH), vWF levels were much higher than in patients without DTICH. The values of TM and vWF in elderly patients were significantly higher than in younger patients. These findings indicate that: 1) the degree of endothelial activation in focal brain injury is significantly higher than in diffuse brain injury; 2) the degree of cerebral endothelial injury in patients with DTICH is much higher than in those without DTICH; and 3) the degree of cerebral endothelial activation and injury in elderly head injury patients is significantly higher than in younger patients.

Plasma von Willebrand factor levels correlate with clinical outcome of severe traumatic brain injury

Biochemical markers of cellular stress/injury have been proposed to indicate outcome after head injury. The aim of the present study was to determine whether plasma von Willebrand factor (VWF) levels correlate with primary outcome and with clinical variables in severe traumatic brain injury (TBI). Forty-four male patients, victims of severe TBI, were analyzed. Clinical outcome variables of severe TBI comprised survival and neurological assessment using the Glasgow Outcome Scale (GOS) at intensive care unit (ICU) discharge. Computerized tomography (CT) scans were analyzed according to Marshall CT classification. Three consecutive venous blood samples were taken: first sample (11.4 +/- 5.2 h after trauma, mean +/- SD), and 24 h and 7 days later. The result of mean plasma VWF concentration was significantly higher in the TBI group (273 U/dL) than in the control group (107 U/dL; p < 0.001). Severe TBI was associated with a 50% mortality rate. Nonsurvivors presented significantly higher APACHE II scores than survivors (nonsurvivors mean, 18.8; survivors mean, 12.7; p < 0.001), and also presented higher scores in Marshall CT classification (nonsurvivors mean, 4.6; survivors mean, 2.7; p < 0.05). There was a significant positive correlation between plasma levels at second plasma sampling and scores in Marshall CT classification (p < 0.05). The sensitivity of plasma VWF concentration in predicting mortality according to the cut-off of 234 U/dL was 64%, with a specificity of 68%. Therefore, VWF increases following severe TBI may be a marker of unfavorable outcome.

Cerebral endothelial injury in elderly patients with severe head injury measured by serum thrombomodulin and von Willebrand factor

Elevated serum levels of thrombomodulin (TM) and von Willebrand factor (vWf) are good indicators of injury and activation of cerebral endothelium in patients with severe simple head injury. The present study evaluated cerebral endothelial injury or activation as the serum levels of TM and vWf in elderly and younger patients with similar brain trauma, to evaluate the primary parenchymal injury of the brain. Patients with head injury were classified into the young group (16-30 years), the middle-aged group (31-65 years), and the elderly group (over 66 years). There was no difference in Glasgow Coma Scale on admission between the three groups. The serum levels of TM and vWf at 2 hours after injury were significantly higher in the elderly group than in the other groups. However, the serum levels of TM and vWf were not significantly different at 3 and 7 days after injury. Cerebral endothelial activation and injury were significantly higher in elderly patients just after head injury than in younger patients, which suggests that greater sensitivity to endothelial injury and activation may be important in the worse outcome after head injury in elderly patients compared with younger patients.

Non-neurologic organ dysfunction in acute brain injury

Patients with acute brain injury are a distinct group within the ICU who may develop non-neurologic organ dysfunction in the absence of systemic injury or infection. This dysfunction may arise directly as a result of the brain injury or indirectly with complications of brain-specific therapies. This article reviews the current literature with respect to the incidence of organ dysfunction or failure and its association with outcome in patients with acute brain injury. Organ system-specific etiologic considerations and management are discussed.

Retinal vascular integrity following correction of diabetic ketoacidosis in children and adolescents

OBJECTIVE

Increased permeability of the cerebral microvasculature occurs during the treatment of diabetic ketoacidosis (DKA). Microvascular changes consistent with diabetic retinopathy have been reported prior to and after the treatment of DKA. This study evaluated the structural and functional aspects of the retina immediately following the correction of DKA.

METHODS

Seven young patients had comprehensive ophthalmologic examinations, including fluorescein angiography, within 24 h after the correction of severe DKA (pH <7.2).

RESULTS

None of the patients had clinical, photographic, or angiographic evidence of a retinal abnormality.

CONCLUSION

The blood-retinal barrier (BRB) does not experience the same degree of perturbation as the blood-brain barrier (BBB) does and may be a protected site during the insult of DKA and its treatment. The greater stability of the retinal microvasculature may be due to the increased number of pericytes in the BRB in comparison with the BBB.

Atorvastatin reduction of intravascular thrombosis, increase in cerebral microvascular patency and integrity, and enhancement of spatial learning in rats subjected to traumatic brain injury

OBJECT

Atorvastatin, a beta-hydroxy-beta-methylglutaryl coenzyme A reductase inhibitor, has pleiotropic effects, such as promoting angiogenesis, increasing fibrinolysis, and reducing inflammatory responses, and has shown promise in enhancing recovery in animals with traumatic brain injury (TBI) and stroke. The authors tested the effect of atorvastatin on vascular changes after TBI.

METHODS

Male Wistar rats subjected to controlled cortical impact injury were perfused at different time points with fluorescein isothiocyanate (FITC)--conjugated dextran 1 minute before being killed. Spatial memory function had been measured using a Morris Water Maze test at various points before and after TBI. The temporal profile of intravascular thrombosis and vascular changes was measured on brain tissue sections by using a microcomputer imaging device and a laser confocal microscopy. The study revealed the following results. 1) Vessels in the lesion boundary zone and hippocampal CA3 region showed a variety of damage, morphological alterations, reduced perfusion, and intraluminal microthrombin formation. 2) Atorvastatin enhanced FITC-dextran perfusion of vessels and reduced intravascular coagulation. 3) Atorvastatin promoted the restoration of spatial memory function.

CONCLUSIONS

These results indicated that atorvastatin warrants investigation as a potential therapeutic drug for TBI.

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.

Association between intravascular microthrombosis and cerebral ischemia in traumatic brain injury

OBJECTIVE

To determine the association between traumatic cerebral ischemia and intravascular thrombosis, a common finding after traumatic brain injury (TBI).

METHODS

We reviewed samples of the frontal cortex and hippocampus from individuals who had sustained a fatal TBI. Sections stained with hematoxylin and eosin were reviewed and rated for severity of selective neuronal necrosis (SNN). Because intravascular fibrin microthrombi may lyse within a few days of TBI, we restricted our analysis to patients who had died within 48 hours of injury. Medical records in all cases were reviewed to rule out severe or prolonged hypotension or hypoxemia. Eleven patients with severe or global SNN were compared with 11 patients in whom SNN was mild or absent. Slides adjacent to the hematoxylin and eosin sections were stained with an immunofluorescent antibody to antithrombin III and were reviewed for intravascular microthrombosis. The number of microthrombi on each slide was counted by an investigator blinded to the hematoxylin and eosin findings, and density of intravascular microthrombi was calculated.

RESULTS

Intravascular microthrombi were noted in every section, excluding control (non-TBI) brain tissue. However, the density of microthrombi varied with the degree of SNN. We found a highly significant difference in the mean density of microthrombi between patients with severe SNN (7.74 +/- 3.7/cm(2)) and those with little or no SNN (2.58 +/- 1.0/cm(2)). Furthermore, a good correlation was noted between the location of intravascular microthrombi and that of SNN.

CONCLUSION

These data support a strong link between intravascular microthrombosis and neuronal death after brain trauma in humans and may have important implications for new therapeutic approaches.

Traumatic Cerebral Vascular Injury: The Effects of Concussive Brain Injury on the Cerebral Vasculature

In terms of human suffering, medical expenses, and lost productivity, head injury is one of the major health care problems in the United States, and inadequate cerebral blood flow is an important contributor to mortality and morbidity after traumatic brain injury. Despite the importance of cerebral vascular dysfunction in the pathophysiology of traumatic brain injury, the effects of trauma on the cerebral circulation have been less well studied than the effects of trauma on the brain. Recent research has led to a better understanding of the physiologic, cellular, and molecular components and causes of traumatic cerebral vascular injury. A more thorough understanding of the direct and indirect effects of trauma on the cerebral vasculature will lead to improvements in current treatments of brain trauma as well as to the development of novel and, hopefully, more effective therapeutic strategies.