Intravascular coagulation: a major secondary insult in nonfatal traumatic brain injury

Early hemorrhagic progression of traumatic brain contusions: frequency, correlation with coagulation disorders, and patient outcome: a prospective study

The focus of this paper is to identify and quantify risk factors for early hemorrhagic progression of brain contusions (HPC) in patients with traumatic brain injury (TBI) and to evaluate their impact on patients' outcome. Further, based on abnormal values in routine blood tests, the role of trauma-induced coagulopathy is analyzed in detail. Therefore, a prospective study of 153 TBI patients was completed at one institution between January 2008 and June 2012. The collected data included demographics, initial Glasgow Coma Scale pupillary response, initial and 6 h follow-up computed tomography scan findings, coagulation parameters (international normalized ratio, partial thromboplastin time, platelet count, fibrinogen, D-dimer and factor XIII), as well as outcome data using the modified Rankin score at discharge and after one year. The overall rate of early HPC within the first 6 h was 43.5%. The frequency of coagulopathy was 47.1%. When analyzing for risk factors that independently influenced outcome in the form of mRS ≥4 at both points, the following variables appeared: elevated D-dimer level (≥10,000 μg/L), HPC, and initial brain contusions ≥3 cm. Patients sustaining early HPC had a hazard ratio of 5.4 for unfavorable outcome at discharge (p=0.002) and of 3.9 after one year (p=0.006). Overall, patients who developed early HPC were significantly more likely to be gravely disabled or to die. Unfavorable neurological outcome after an isolated TBI is determined largely by early HPC and coagulopathy, which seem to occur very frequently in TBI patients, irrespective of the severity of the trauma.

Use of recombinant factor VIIa (rFVIIa) as pre-hospital treatment in a swine model of fluid percussion traumatic brain injury

CONTEXT

Recombinant factor VIIa (rFVIIa) has been used as an adjunctive therapy for acute post-traumatic hemorrhage and reversal of iatrogenic coagulopathy in trauma patients in the hospital setting. However, investigations regarding its potential use in pre-hospital management of traumatic brain injury (TBI) have not been conducted extensively.

AIMS

In the present study, we investigated the physiology, hematology and histology effects of a single pre-hospital bolus injection of rFVIIa compared to current clinical practice of no pre-hospital intervention in a swine model of moderate fluid percussion TBI.

MATERIALS AND METHODS

Animals were randomized to receive either a bolus of rFVIIa (90 μg/kg) or nothing 15 minutes (T15) post-injury. Hospital arrival was simulated at T60, and animals were euthanized at experimental endpoint (T360).

RESULTS

Survival was 100% in both groups; baseline physiology parameters were similar, vital signs were comparable. Animals that received rFVIIa demonstrated less hemorrhage in subarachnoid space (P = 0.0037) and less neuronal degeneration in left hippocampus, pons, and cerebellum (P = 0.00009, P = 0.00008, and P = 0.251, respectively). Immunohistochemical staining of brain sections showed less overall loss of microtubule-associated protein 2 (MAP2) and less Flouro-Jade B positive cells in rFVIIa-treated animals.

CONCLUSIONS

Early pre-hospital administration of rFVIIa in this swine TBI model reduced neuronal necrosis and intracranial hemorrhage (ICH). These results merit further investigation of this approach in pre-hospital trauma care.

Coagulopathy associated with traumatic brain injury

Coagulopathy is often observed after traumatic brain injury (TBI), but the pathogenic mechanisms of this phenomenon remain elusive. Brain injury is the leading cause of trauma deaths, and the development of coagulopathy after TBI is associated with increased morbidity and mortality in these patients. The coagulopathy after TBI comprises a hypocoagulable and a hypercoagulable state with hemorrhagic and thrombotic phenotypes that are both associated with worse outcome. Some theories of its pathogenesis include massive release of tissue factor, altered protein C homeostasis, microparticle upregulation, and platelet hyperactivity. This article aims to examine the coagulopathy associated with blunt head injury, to review its effect on progression of hemorrhagic injury, and to discuss the possible relevant pathophysiological mechanisms.

Blood-brain barrier pathophysiology in traumatic brain injury

The blood-brain barrier (BBB) is formed by tightly connected cerebrovascular endothelial cells, but its normal function also depends on paracrine interactions between the brain endothelium and closely located glia. There is a growing consensus that brain injury, whether it is ischemic, hemorrhagic, or traumatic, leads to dysfunction of the BBB. Changes in BBB function observed after injury are thought to contribute to the loss of neural tissue and to affect the response to neuroprotective drugs. New discoveries suggest that considering the entire gliovascular unit, rather than the BBB alone, will expand our understanding of the cellular and molecular responses to traumatic brain injury (TBI). This review will address the BBB breakdown in TBI, the role of blood-borne factors in affecting the function of the gliovascular unit, changes in BBB permeability and post-traumatic edema formation, and the major pathophysiological factors associated with TBI that may contribute to post-traumatic dysfunction of the BBB. The key role of neuroinflammation and the possible effect of injury on transport mechanisms at the BBB will also be described. Finally, the potential role of the BBB as a target for therapeutic intervention through restoration of normal BBB function after injury and/or by harnessing the cerebrovascular endothelium to produce neurotrophic growth factors will be discussed.

Coagulopathy as prognostic marker in acute traumatic brain injury

Context:

Coagulopathy frequently occurs following traumatic brain injury (TBI) and usually occurs 6-72 hour post-trauma. The incidence and the probable risk factors for development of coagulopathy and poor outcome following TBI are largely unknown and vary considerably.

Aims:

To assess the incidence and probable risk factors for development of coagulopathy and to identify the risk factors for poor outcome in terms of median survival time following TBI.

Materials and Methods:

In this prospective study over two years, patients of isolated moderate and severe traumatic brain injury (GCS≤12) admitted to trauma center had coagulation profile (PT, APTT, thrombin time, fibrinogen and D-dimer), arterial lactate and ABG analysis done on day of admission and on day three. Coagulopathy was defined as prothrombin time (PT) or/and activated partial thromboplastin time (APTT) more than 1.5 times the normal control. Incidence of in-hospital mortality was assessed in all cases.

Statistical Analysis:

A stepwise logistic regression analysis was performed to identify risk factors for coagulopathy and mortality in these patients.

Results:

A total of 208 patients were enrolled in the study. The mean age was 32 ± 12 years and mean GCS was 7.1 ± 2.8. Coagulopathy was present in 46% (n = 96) of patients. Risk factors for development of coagulopathy were found out to be severity of head injury (OR: 2.81), elevated D-dimer (OR: 3.43), low hemoglobin (OR: 3.13), and effaced cisterns in the CT scan (OR: 2.72). Presence of coagulopathy (OR: 2.97) and severity of head injury (OR: 5.70) strongly predicted poor outcome, and were associated with a decreased median survival time.

Conclusions:

There is a high incidence of coagulopathy following TBI. The presence of coagulopathy as well as of severity of TBI are strong predictors of in-hospital mortality in these patients.

Treating seizures and epilepsy with anticoagulants?

Thrombin is a serine protease playing an essential role in the blood coagulation cascade. Recent work, however, has identified a novel role for thrombin-mediated signaling pathways in the central nervous system. Binding of thrombin to protease-activated receptors (PARs) in the brain appears to have multiple actions affecting both health and disease. Specifically, thrombin has been shown to lead to the onset of seizures via PAR-1 activation. In this perspective article, we review the putative mechanisms by which thrombin causes seizures and epilepsy. We propose a potential role of PAR-1 antagonists and novel thrombin inhibitors as new, possible antiepileptic drugs.

Effects of platelet and plasma transfusion on outcome in traumatic brain injury patients with moderate bleeding diatheses

Object

Coagulopathy and thrombocytopenia are common after traumatic brain injury (TBI), yet transfusion thresholds for mildly to moderately abnormal ranges of international normalized ratio and platelet count remain controversial. This study evaluates associations between fresh frozen plasma (FFP) and platelet transfusions with long-term functional outcome and survival in TBI patients with moderate hemostatic laboratory abnormalities.

Methods

This study is a retrospective review of prospectively collected data of patients with mild to severe TBI. Data include patient demographics, several initial injury severity metrics, daily laboratory values, Glasgow Outcome Score- Extended (GOSE) scores, Functional Status Examination (FSE) scores, and survival to 6 months. Correlations were evaluated between these variables and transfusion of FFP, platelets, packed red blood cells (RBCs), cryoprecipitate, recombinant factor VIIa, and albumin. Ordinal regression was performed to account for potential confounding variables to further define relationships between transfusion status and long-term outcome. By analyzing collected data, mild to moderate coagulopathy was defined as an international normalized ratio 1.4–2.0, moderate thrombocytopenia as platelet count 50 × 109/L to 107 × 109/L, and moderate anemia as 21%–30% hematocrit.

Results

In patients with mild to moderate laboratory hematological abnormalities, univariate analysis shows significant correlations between poor outcome scores and FFP, platelet, or packed RBC transfusion; the volume of FFP or packed RBCs transfused also correlated with poor outcome. Several measures of initial injury and laboratory abnormalities also correlated with poor outcome. Patient age, initial Glasgow Coma Scale score, and highest recorded serum sodium were included in the ordinal regression model using backward variable selection. In the moderate coagulopathy subgroup, patients transfused with FFP were more likely to have a lower GOSE score relative to those who did not receive a transfusion (OR 5.20 [95% CI 1.72–15.73]). Patients with moderate coagulopathy who received FFP and packed RBCs were even more likely to be have a lower GOSE score (OR 7.17 [95% CI 2.12–24.12]). Moderately anemic patients who received packed RBCs alone were more likely to have a worse long-term functional outcome as determined by GOSE and FSE scores (GOSE: OR 2.41 [95% CI 1.51–3.85]; and FSE: OR 3.27 [95% CI 2.00–5.35]). No transfusion types or combinations were noted to significantly correlate with the 6-month mortality in ordinal regression.

Conclusions

In TBI patients with moderate coagulopathy, FFP transfusions alone or a combination of FFP and packed RBCs were associated with poorer long-term functional outcomes as measured by the GOSE. Red blood cell transfusions were associated with poor long-term functional outcome in TBI patients with moderate anemia. Platelet transfusion in patients with moderate thrombocytopenia was not significantly associated with outcome. Although transfusion is beneficial to many patients with severe hematological abnormalities, it is not without risk, and the indications for transfusion should be carefully considered in patients with moderate hematological abnormalities.

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.

Mild hyperthermia worsens the neuropathological damage associated with mild traumatic brain injury in rats

The effects of slight variations in brain temperature on the pathophysiological consequences of acute brain injury have been extensively described in models of moderate and severe traumatic brain injury (TBI). In contrast, limited information is available regarding the potential consequences of temperature elevations on outcome following mild TBI (mTBI) or concussions. One potential confounding variable with mTBI is the presence of elevated body temperature that occurs in the civilian or military populations due to hot environments combined with exercise or other forms of physical exertion. We therefore determined the histopathological effects of pre- and post-traumatic hyperthermia (39°C) on mTBI. Adult male Sprague-Dawley rats were divided into 3 groups: pre/post-traumatic hyperthermia, post-traumatic hyperthermia alone for 2 h, and normothermia (37°C). The pre/post-hyperthermia group was treated with hyperthermia starting 15 min before mild parasagittal fluid-percussion brain injury (1.4-1.6 atm), with the temperature elevation extending for 2 h after trauma. At 72 h after mTBI, the rats were perfusion-fixed for quantitative histopathological evaluation. Contusion areas and volumes were significantly larger in the pre/post-hyperthermia treatment group compared to the post-hyperthermia and normothermic groups. In addition, pre/post-traumatic hyperthermia caused the most severe loss of NeuN-positive cells in the dentate hilus compared to normothermia. These neuropathological results demonstrate that relatively mild elevations in temperature associated with peri-traumatic events may affect the long-term functional consequences of mTBI. Because individuals exhibiting mildly elevated core temperatures may be predisposed to aggravated brain damage after mTBI or concussion, precautions should be introduced to target this important physiological variable.

Coagulopathy after traumatic brain injury

Traumatic brain injury has long been associated with abnormal coagulation parameters, but the exact mechanisms underlying this phenomenon are poorly understood. Coagulopathy after traumatic brain injury includes hypercoagulable and hypocoagulable states that can lead to secondary injury by either the induction of microthrombosis or the progression of hemorrhagic brain lesions. Multiple hypotheses have been proposed to explain this phenomenon, including the release of tissue factor, disseminated intravascular coagulation, hyperfibrinolysis, hypoperfusion with protein C activation, and platelet dysfunction. The diagnosis and management of these complex patients are difficult given the lack of understanding of the underlying mechanisms. The goal of this review is to summarize the current knowledge regarding the mechanisms of coagulopathy after blunt traumatic brain injury. The current and emerging diagnostic tools, radiological findings, treatment options, and prognosis are discussed.

Haemostatic and cranial computed tomography characteristics in patients with acute and delayed coagulopathy after isolated traumatic brain injury

PRIMARY OBJECTIVE

To investigate whether the development of coagulopathy at different stages after isolated traumatic brain injury (TBI) is associated with distinct cranial computed tomography characteristics.

RESEARCH DESIGN

Retrospective cohort study in 226 patients with moderate-to-severe isolated TBI who were categorized as subjects without coagulopathy or with acute temporary, acute sustained or delayed coagulopathy.

METHODS AND PROCEDURES

Coagulopathy was defined as an activated partial thromboplastin time >40 seconds and/or prothrombin time (PT) >1.2 and/or platelet count <120*10(9)l(-1). Cranial CT scans were assigned to the six-point Traumatic Coma Data Bank (TCDB) CT-classification.

MAIN OUTCOMES AND RESULTS

Coagulopathy occurred in 44% of patients in the first 24-hours post-trauma. Patients with acute, sustained coagulopathy showed a prolonged PT (1.64 ± 0.89) when compared to patients without (1.03 ± 0.07), acute temporary (1.27 ± 0.22) or delayed coagulopathy (1.08 ± 0.06; p < 0.05). Patients with acute temporary or delayed coagulopathy had the worst TCDB CT classification scores, while mortality rates were the highest in patients with sustained or delayed coagulopathy.

CONCLUSIONS

Not only the mere presence of coagulopathy, but also the course of haemostatic alterations following neurotrauma may hold predictive value for patient outcome, irrespective of the severity level of cerebral injury.

Early parenchymal contrast extravasation predicts subsequent hemorrhage progression, clinical deterioration, and need for surgery in patients with traumatic cerebral contusion

BACKGROUND

This study aimed to identify early radiologic signs that are predictive of hemorrhage progression and clinical deterioration in patients with traumatic cerebral contusion. We hypothesized that contrast extravasation (CE) and blood-brain barrier disruption might be associated with hemorrhage progression, brain edema, and clinical deterioration in these patients.

METHODS

Twenty-two patients with traumatic cerebral contusion (diagnosed on initial noncontrast head computed tomography [CT]) who initially did not require surgical intervention were enrolled in this study. Contrast-enhanced and perfusion CT scans were performed within 6 hours of injury, and follow-up noncontrast CT scans were performed at 24 hours and 72 hours.

RESULTS

In each noncontrast CT scan, the volumes of the contusion hemorrhage and edema were calculated using computerized planimetric techniques. The initial Glasgow Coma Scale, hemorrhage progression, clinical deterioration, and the need for subsequent surgery were recorded. The early radiologic findings were compared with these parameters and functional outcome at 6 months to identify predictive radiologic signs. CE was present in 9 of 22 patients (41%) and was highly associated with hemorrhage progression (p < 0.05), clinical deterioration (p < 0.01), and need for subsequent surgery (p < 0.01). In addition, patients with CE had a greater volume of edema at 24 hours (p < 0.01) and 72 hours (p < 0.01) than those who did not have CE. However, CE was not found to be associated with poor outcome.

CONCLUSIONS

Early parenchymal CE is associated with hemorrhage progression, cerebral edema, clinical deterioration, and need for subsequent surgery. These patients should be monitored closely, and early surgery may be needed if deterioration occurs. Further elucidation of the pathophysiology is needed to formulate effective treatment for these high-risk patients.

Disseminated intravascular coagulopathy in the first 24 hours after trauma: the association between ISTH score and anatomopathologic evidence

BACKGROUND

Recent studies questioned "classical" concepts in trauma care, including whether disseminated intravascular coagulation (DIC) occurs in trauma. The knowledge on trauma DIC is limited to few studies built on diagnosing DIC with laboratory-based scores. This study explores whether DIC diagnosed by the well-established ISTH (International Society for Thrombosis and Hemostasis) score is corroborated by anatomopathologic findings.

METHODS

Prospective observational cohort study of severely injured (ISS ≥ 16) patients. DIC was diagnosed by the ISTH score throughout the first 24 hours after trauma. All organs surgically removed within 24 hours of trauma were reviewed by two independent pathologists. All autopsy reports were reviewed.

RESULTS

Of 423 patients enrolled, ∼11% had "overt DIC" and 85% had "suggestive of non-overt DIC" scores throughout the 24 hours after trauma. "Overt DIC" patients had higher mortality and worse bleeding, receiving more blood and plasma transfusions. One hundred and sixteen patients underwent surgery within 24 hours of trauma, and all 40 excised organs were reviewed by two pathologists. Twenty-seven autopsies reports were reviewed. No anatomopathologic evidence of DIC was identified in the first 24 hours, even after additional histochemical staining. d-dimer was universally elevated after trauma. Common DIC features: platelet count, fibrinogen, clotting time, and factor VIII drop were mostly absent.

CONCLUSIONS

d-dimer has a disproportional participation in trauma DIC scores. Within 24 hours of trauma, most severely injured patients have DIC scores "suggestive for" or of "overt DIC" but no anatomopathologic evidence of DIC. Considering pathologic findings as the gold standard diagnosis, then DIC is exceptionally uncommon and the ISTH score should not be used for trauma.

Acute and delayed mild coagulopathy are related to outcome in patients with isolated traumatic brain injury

INTRODUCTION

The relationship between isolated traumatic brain injury (TBI) associated coagulopathy and patient prognosis frequently lacks information regarding the time course of coagulation disorders throughout the post-traumatic period. This study was conducted to assess the prevalence and time course of post-traumatic coagulopathy in patients with isolated TBI and the relationship of these hemostatic disorders with outcome.

METHODS

The local Human Subjects Committee approved the study. We retrospectively studied the medical records of computed tomography (CT)-confirmed isolated TBI patients with an extracranial abbreviated injury scale (AIS) <3 who were primarily referred to a Level 1 trauma centre in Amsterdam (n = 107). Hemostatic parameters including activated partial thromboplastin time (aPTT), prothrombin time (PT), platelet count, hemoglobin, hematocrit, glucose, pH and lactate levels were recorded throughout a 72-hour period as part of a routine standardized follow-up of TBI. Coagulopathy was defined as a aPPT >40 seconds and/or a PTT in International Normalized Ratio (INR) >1.2 and/or a platelet count <120*109/l.

RESULTS

Patients were mostly male, aged 48 ± 20 years with a median injury severity score of 25 (range 20 to 25). Early coagulopathy as diagnosed in the emergency department (ED) occurred in 24% of all patients. The occurrence of TBI-related coagulopathy increased to 54% in the first 24 hours post-trauma. In addition to an increased age and disturbed pupillary reflex, both coagulopathy upon ED arrival and during the first 24 hours post-trauma provided an independent prognostic factor for unfavorable outcome (odds ratio (OR) 3.75 (95% CI 1.07 to 12.51; P = 0.04) and OR 11.61 (2.79 to 48.34); P = 0.003).

CONCLUSIONS

Our study confirms a high prevalence of early and delayed coagulopathy in patients with isolated TBI, which is strongly associated with an unfavorable outcome. These data support close monitoring of hemostasis after TBI and indicate that correction of coagulation disturbances might need to be considered.

Rehabilitation intervention in animal model can improve neuromotor and cognitive functions after traumatic brain injury: pilot study

The aim of the present study was to quantify the effect of multisensory rehabilitation on rats' cognition after an experimental brain trauma and to assess its possible clinical implications. The complex intermittent multisensory rehabilitation consisted of currently used major therapeutic procedures targeted at the improvement of cognitive functions; including multisensory and motor stimulation and enriched environment. We have confirmed this positive effect of early multisensory rehabilitation on the recovery of motor functions after traumatic brain injury. However, we have been able to prove a positive effect on the recovery of cognitive functions only with respect to the frequency of efficient search strategies in a Barnes maze test, while results for search time and travelled distance were not significantly different between study groups. We have concluded that the positive effects of an early treatment of functional deficits are comparable with the clinical results in early neurorehabilitation in human patients after brain trauma. It might therefore be reasonable to apply these experimental results to human medical neurorehabilitation care.

[Coagulation disorders after traumatic brain injury: pathophysiology and therapeutic implications]

Early activation of coagulation is common after traumatic brain injury. Its origin is probably mainly intracerebral, due to tissue factor release from the injured brain. Abnormalities in blood coagulation tests are associated with poor neurological prognosis. Coagulation activation may induce disseminated intravascular coagulation and fibrinolysis. Disseminated intravascular coagulation is linked to brain ischemia caused by intravascular microthrombosis. This review will focus on pathophysiology of coagulation disorders after traumatic brain injury, and on their implications for therapeutic approaches.

Temporal profile of thrombogenesis in the cerebral microcirculation after traumatic brain injury in mice

Traumatic brain injury (TBI) is associated with an almost immediate reduction in cerebral blood flow (CBF). Because cerebral perfusion pressure is often normal under these circumstances it was hypothesized that the reduction of post-traumatic CBF has to occur at the level of the microcirculation. The aim of the current study was to investigate whether cerebral microvessels are involved in the development of blood flow disturbances following experimental TBI. C57/BL6 mice (n = 12) were intubated and ventilated under control of end-tidal Pco(2) ((ET)P(CO2)). After preparation of a cranial window and baseline recordings, the animals were subjected to experimental TBI by controlled cortical impact (CCI; 6 m/sec, 0.5 mm). Vessel lumina and intravascular cells were visualized by in vivo fluorescence microscopy (IVM) using the fluorescent dyes FITC-dextran and rhodamine 6G, respectively. Vessel diameter, cell-endothelial interactions, and thrombus formation were quantified within the traumatic penumbra by IVM up to 2 h after CCI. Arteriolar diameters increased after CCI by 26.2 +/- 2.5% (mean +/- SEM, p < 0.01 versus baseline), and remained at this level until the end of the observation period. Rolling of leukocytes on the cerebrovascular endothelium was observed both in arterioles and venules, while leukocyte-platelet aggregates were found only in venules. Microthrombi occluded up to 70% of venules and 33% of arterioles. The current data suggest that the immediate post-traumatic decrease in peri-contusional blood flow is not caused by arteriolar vasoconstriction, but by platelet activation and the subsequent formation of thrombi in the cerebral microcirculation.

Predictors of early versus late timing of pulmonary embolus after traumatic injury

OBJECTIVE

To identify risk factors predictive of pulmonary embolus (PE) timing after a traumatic injury.

METHODS

One hundred eight traumatic injury patients with a confirmed diagnosis of PE were classified as early PE (≤4 days, n = 54) or late PE (>4 days, n = 54). Independent predictors of early versus late PE were identified using multivariate logistic regression.

RESULTS

Half the PEs were diagnosed ≤4 days of injury. Only long bone fractures independently predicted early PE (odds ratio 2.8; 95% confidence interval, 1.1-7.1). Severe head injuries were associated with late PE (odds ratio 11.1; 95% confidence interval, 3.9-31). Established risk factors such as age did not affect timing.

CONCLUSIONS

Half the PEs were diagnosed ≤4 days after injury. The risk of early PE appeared highest in patients with long bone fractures, and the benefits of immediate prophylaxis may outweigh risks. Patients with severe head injuries appear to have later PE events. Prospective interventional trials in these injury populations are needed.

Blood constituents trigger brain swelling, tissue death, and reduction of glucose metabolism early after acute subdural hematoma in rats

Outcome from acute subdural hematoma is often worse than would be expected from the pure increase of intracranial volume by bleeding. The aim was to test whether volume-independent pathomechanisms aggravate damage by comparing the effects of blood infusion with those of an inert fluid, paraffin oil, on intracranial pressure (ICP), cerebral perfusion pressure (CPP), local cerebral blood flow (CBF), edema formation, glucose metabolism ([18F]-deoxyglucose, MicroPET ), and histological outcome. Rats were injured by subdural infusion of 300 muL venous blood or paraffin. ICP, CPP, and CBF changes, assessed during the first 30 mins after injury, were not different between the injury groups at most time points (n=8 per group). Already at 2 h after injury, blood caused a significantly more pronounced decrease in glucose metabolism in the injured cortex when compared with paraffin (P<0.001, n=5 per group). Ipsilateral brain edema did not differ between groups at 2 h, but was significantly more pronounced in the blood-treated groups at 24 and 48 h after injury (n=8 per group). These changes caused a 56.2% larger lesion after blood when compared with paraffin (48.1+/-23.0 versus 21.1+/-11.8 mm(3); P<0.02). Blood constituent-triggered pathomechanisms aggravate the immediate effects due to ICP, CPP, and CBF during hemorrhage and lead to early reduction of glucose metabolism followed by more severe edema and histological damage.

Erythrocyte-bound tissue plasminogen activator is neuroprotective in experimental traumatic brain injury

The purpose of this study was to test the effects of exogenous tissue plasminogen activator (tPA) in traumatic brain injury (TBI).We tested two different tPA formulations, free tPA and tPA bound to erythrocytes (RBC/tPA).Vehicle and each of the tPA treatments were injected intravenously into anesthetized rats 15 min after moderate lateral fluid percussion injury. The animals were sacrificed at 2 days for calculating microclot burden (n=13) and IgG staining area (n=13) in the brain sections as indicators of post-traumatic thrombosis and blood-brain barrier (BBB) breakdown, respectively. Another set of injured animals treated in the same way were sacrificed at 7 days to compare cortical lesion volumes (n=28) and CA3 hippocampal cell loss (n=24). All evaluations were done blinded with respect to treatment. No significant differences were found with respect to microclot burden or IgG staining volume. Injection of wild-type tPA caused significantly ( p<0.05) larger cortical injuries and greater cerebral hemorrhage. In contrast, there was significantly less cortical injury ( p<0.01) and hippocampal cell loss ( p<0.01) in the RBC=tPA group than in all other groups. These results reveal that RBC/tPA is more neuroprotective in experimental TBI than is unbound tPA.

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.

The role of recombinant activated Factor VII in major obstetric haemorrhage: the Farnborough experience

Major obstetric haemorrhage is one of the commonest causes of maternal mortality and morbidity worldwide. It may result in coagulopathy and diffuse pelvic or vaginal bleeding. Correction of coagulopathy when administering Factor VII may be crucial to the management of selected cases. We report the use of recombinant activated factor in three cases of massive obstetric haemorrhage. Prolonged international normalised ratio, activated partial thromboplastin time, and reduced fibrinogen were the trigger to use rFVIIa. It was effective to halt the process of coagulopathy, secure haemostasis and improve laboratory parameters in all three patients. We review the relevant literature and discuss its indications, the potential benefits and possible complications. Recombinant activated Factor VII is a potential haemostatic agent in massive obstetric haemorrhage. Its successful use has been reported in post-surgical bleeding and consumptive coagulopathy. It may abolish the need for hysterectomy, which has a devastating effect on the patient future fertility and psychological well-being.

An analysis of regional microvascular loss and recovery following two grades of fluid percussion trauma: a role for hypoxia-inducible factors in traumatic brain injury

Secondary hypoxic/ischemic injuries, stemming from reductions in cerebral blood flow are important contributing factors in progressive neuronal dysfunction after brain trauma. A greater preclinical understanding of how brain trauma leads to secondary hypoxia/ischemia is necessary in the development of posttraumatic brain injury (TBI) therapeutics. To this end, we examined the density of microvascular coverage in the injured and contralateral cortical hemispheres using two intensities of fluid percussion trauma in rats. A silicone microangiography technique showed a significant loss in microvascular density in 2 atmosphere (atm) (16.9+/-3.8%) and 3 atm (15.7+/-1.3%) injured animals relative to sham animals (29.9+/-2.5%; P<0.01). RECA-1 immunohistochemistry indicated that capillary changes involved a reduction in capillary number and diameter. Reduction in microvascular density was shown to be a diffuse phenomenon occurring up to 4 mm rostral and caudal to the injury epicenter. Recovery of microvasculature occurred by 2 weeks after injury only in the 2 atm injury group. Expression of HIF1alpha and increased vascular endothelial growth factor expression were observed in the ipsilateral hippocampus suggesting sufficiently impaired microcirculation resulting in the expression of hypoxic-response proteins. Collectively, the results indicate diffuse and heterogeneous microvascular alterations as well as endogenous expression of neuroprotective and neovascularization pathways after TBI.

Lactate and glucose as energy substrates and their role in traumatic brain injury and therapy

Traumatic brain injury is a leading cause of disability and mortality worldwide, but no new pharmacological treatments are clinically available. A key pathophysiological development in the understanding of traumatic brain injury is the energy crisis derived from decreased cerebral blood flow, increased energy demand and mitochondrial dysfunction. Although still controversial, new findings suggest that brain cells try to cope in these conditions by metabolizing lactate as an energy substrate ‘on-demand’ in lieu of glucose. Experimental and clinical data suggest that lactate, at least when exogenously administered, is transported from astrocytes to neurons for neuronal utilization, essentially bypassing the slow, catabolizing glycolysis process to quickly and efficiently produce ATP. Treatment strategies using systemically applied lactate have proved to be protective in various experimental traumatic brain injury studies. However, lactate has the potential to elevate oxygen consumption to high levels and, therefore, could potentially impose a danger for tissue-at-risk with low cerebral blood flow. The present review outlines the experimental basis of lactate in energy metabolism under physiological and pathophysiological conditions and presents arguments for lactate as a new therapeutical tool in human head injury.

The coagulopathy of trauma: a review of mechanisms

BACKGROUND

Bleeding is the most frequent cause of preventable death after severe injury. Coagulopathy associated with severe injury complicates the control of bleeding and is associated with increased morbidity and mortality in trauma patients. The causes and mechanisms are multiple and yet to be clearly defined.

METHODS

Articles addressing the causes and consequences of trauma-associated coagulopathy were identified and reviewed. Clinical situations in which the various mechanistic causes are important were sought along with quantitative estimates of their importance.

RESULTS

Coagulopathy associated with traumatic injury is the result of multiple independent but interacting mechanisms. Early coagulopathy is driven by shock and requires thrombin generation from tissue injury as an initiator. Initiation of coagulation occurs with activation of anticoagulant and fibrinolytic pathways. This Acute Coagulopathy of Trauma-Shock is altered by subsequent events and medical therapies, in particular acidemia, hypothermia, and dilution. There is significant interplay between all mechanisms.

CONCLUSIONS

There is limited understanding of the mechanisms by which tissue trauma, shock, and inflammation initiate trauma coagulopathy. Acute Coagulopathy of Trauma-Shock should be considered distinct from disseminated intravascular coagulation as described in other conditions. Rapid diagnosis and directed interventions are important areas for future research.

Progesterone and its metabolite allopregnanolone differentially regulate hemostatic proteins after traumatic brain injury

Our laboratory has shown in numerous experiments that the neurosteroids progesterone (PROG) and allopregnanolone (ALLO) improve molecular and functional outcomes after traumatic brain injury (TBI). As coagulopathy is an important contributor to the secondary destruction of nervous tissue, we hypothesized that PROG and ALLO administration may also have a beneficial effect on coagulation protein expression after TBI. Adult male Sprague-Dawley rats were given bilateral contusions of the medial frontal cortex followed by treatments with PROG (16 mg/kg), ALLO (8 mg/kg), or vehicle (22.5% hydroxypropyl-beta-cyclodextrin). Controls received no injury or injections. Progesterone generally maintained procoagulant (thrombin, fibrinogen, and coagulation factor XIII), whereas ALLO increased anticoagulant protein expression (tissue-type plasminogen activator, tPA). In addition, PROG significantly increased the ratio of tPA bound to neuroserpin, a serine protease inhibitor that can reduce the activity of tPA. Our findings suggest that in a model of TBI, where blood loss may exacerbate injury, it may be preferable to treat patients with PROG, whereas it might be more appropriate to use ALLO as a treatment for thrombotic stroke, where a reduction in coagulation would be more beneficial.

Moderate and severe traumatic brain injury in adults

Traumatic brain injury (TBI) is a major health and socioeconomic problem that affects all societies. In recent years, patterns of injury have been changing, with more injuries, particularly contusions, occurring in older patients. Blast injuries have been identified as a novel entity with specific characteristics. Traditional approaches to the classification of clinical severity are the subject of debate owing to the widespread policy of early sedation and ventilation in more severely injured patients, and are being supplemented with structural and functional neuroimaging. Basic science research has greatly advanced our knowledge of the mechanisms involved in secondary damage, creating opportunities for medical intervention and targeted therapies; however, translating this research into patient benefit remains a challenge. Clinical management has become much more structured and evidence based since the publication of guidelines covering many aspects of care. In this Review, we summarise new developments and current knowledge and controversies, focusing on moderate and severe TBI in adults. Suggestions are provided for the way forward, with an emphasis on epidemiological monitoring, trauma organisation, and approaches to management.

The impact of preinjury antiplatelet and anticoagulant pharmacotherapy on outcomes in elderly patients with hemorrhagic brain injury

BACKGROUND

More elderly trauma patients are identified with preinjury use of clopidogrel, aspirin, or warfarin (CAW). The purpose of this study was to determine whether preinjury CAW use was an important predictor of mortality in patients aged >or=50 years with blunt, hemorrhagic brain injury (HBI).

METHODS

A retrospective review of patients with blunt, HBI aged >or=50 years with subgroup analysis for older (>70 years) and younger (50-70 years) patients was performed. CAW use was analyzed for differences in age, gender, hospital length of stay (LOS), Injury Severity Score (ISS), Glasgow Coma Score (GCS), mechanism of injury (MOI), platelet transfusion therapy (PLT), disposition at discharge, and in-hospital mortality.

RESULTS

From January 2003 to October 2005, 416 patients were identified. The mean age was 69+/-1 years. No differences were found for ISS (24 +/- 0.5), GCS (12 +/- 0.2), or LOS (8 +/- 0.4 days). CAW use was present in 40% of patients and significantly higher in older patients. Mortality was not different between older and younger CAW(+) patients, but it significantly increased for older CAW(-) patients. Significant predictors of death included age, ISS, and GCS (P<.02).

CONCLUSIONS

Preinjury CAW use in older blunt, HBI patients is not associated with increased mortality. Age was a significant predictor of mortality independent of CAW use.

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.

Monitoring brain tissue oxygen tension in brain-injured patients reveals hypoxic episodes in normal-appearing and in peri-focal tissue

OBJECTIVE

We compared brain tissue oxygen tension (PtiO2) measured in peri-focal and in normal-appearing brain parenchyma on computerized tomography (CT) in patients following traumatic brain injury (TBI).

DESIGN

Prospective observational study.

SETTING

Neurointensive care unit.

PATIENTS AND PARTICIPANTS

Thirty-two consecutive TBI patients were subjected to PtiO2 monitoring.

INTERVENTIONS

Peri-focal tissue was identified by the presence of a hypodense area of the contusion and/or within 1 cm from the core of the contusion. The position of the tip of the PtiO2 probe was assessed at follow-up CT scan.

MEASUREMENTS AND RESULTS

Mean PtiO2 in the peri-contusional tissue was 19.7+/-2.1 mmHg and was lower than PtiO2 in normal-appearing tissue (25.5+/-1.5 mmHg, p < 0.05), despite a greater cerebral perfusion pressure (CPP) (73.7+/-2.3 mmHg vs. 67.4+/-1.4 mmHg, p < 0.05). We observed both in peri-focal tissue and in normal-appearing tissue episodes of brain hypoxia (PtiO2 < 20 mmHg for at least 10 min), whose median duration was longer in peri-focal tissue than in normal-appearing tissue (51% vs. 34% of monitoring time, p < 0.01). In peri-focal tissue, we observed a progressive PtiO2 increase from pathologic to normal values (p < 0.01).

CONCLUSIONS

Multiple episodes of brain hypoxia occurred over the first 5 days following severe TBI. PtiO2 was lower in peri-contusional tissue than in normal-appearing tissue. In peri-contusional tissue, a progressive increase of PtiO2 from pathologic to normal values was observed over time, suggestive of an improvement at microcirculatory level.

Probable right atrial thrombus immediately after recombinant activated factor VII administration

We report the finding of a probable right atrial thrombus in a 33-yr-old male patient with severe head, chest, and abdominal trauma. Refractory coagulopathy and gross haemodynamic instability ensued, which was only partially controlled with massive blood product transfusion and high-dose inotropic support during laparotomy. Continuous transoesophageal echocardiography revealed a probable atrial thrombus partially occluding the right ventricular inflow tract, which appeared immediately after the patient received 100 microg kg(-1) of recombinant activated factor VII (rFVIIa) via a left internal jugular central line. This is the first report documenting an immediate temporal relationship between rFVIIa administration and a space-occupying lesion compatible with localized thrombosis, despite ongoing severe systemic coagulopathy. We review the clinical use of rFVIIa and discuss possible factors contributing to this event.

Prognostic value of admission laboratory parameters in traumatic brain injury: results from the IMPACT study

Abnormalities in laboratory parameters are frequent following traumatic brain injury (TBI), but few studies have investigated their predictive value. We aimed to describe and quantify the relation between laboratory parameters that are routinely determined on admission and final outcome following TBI. Individual patient data were available in the IMPACT database from six Phase III randomized controlled trials and one observational study in TBI. We studied glucose (N = 4834), sodium ( N = 5270), pH ( N = 3398), hemoglobin (Hb, N = 3875), platelet count ( N = 1629), and prothrombin time (PT; N = 840) for their associations with outcome at 6 months (Glasgow Outcome Scale [GOS]). We used logistic regression models with linear, quadratic, and restricted cubic spline functions. The strength of the associations was expressed as an unadjusted odds ratio, calculated over the shift in outcome between the 25th and 75th percentiles. Proportional odds methodology was further applied to quantify the strength of the associations across the full range of the GOS. All parameters were consistently associated with outcome in a continuous relationship: glucose and prothrombin time showed a positive linear relation to outcome (i.e., increasing values associated with poorer outcome) and Hb, platelets, and pH an inverse linear relation (i.e., low values associated with poorer outcome). Sodium demonstrated a U-shaped relation to outcome, with low levels being more strongly related to poorer outcome. Effects were strongest for increasing levels of glucose (odds ratio 1.7; 95% CI 1.54-1.83) and decreasing levels of Hb (odds ratio 0.7; CI 0.60-0.78). Higher glucose values were associated with increasing age, but on adjusted analysis, the strength of the association with outcome remained. Whether treatment of abnormal values may improve outcome needs further rigorous study.

The role of recombinant activated factor VII in neurosurgery: hope or hype?

✓ Recombinant activated factor VII (rFVIIa) is a relatively new pharmaceutical agent developed for use in patients with hemophilia in whom inhibitors to clotting factors VIII or IX have developed. Use of this drug has become common in recent years because of its efficacy and safety in patients with coagulation disorders as well as in patients who are at high risk for thromboembolism, even when other means of establishing hemostasis have failed. The use of rFVIIa in neurosurgery has lagged behind its use in other fields, although there is a growing body of literature on such uses. In this article the authors review the history and science of rFVIIa as well as dosing and safety information. Various uses pertinent to the neurosurgeon are reviewed, including the treatment of patients with coagulation disorders, those suffering trauma, and those with perioperative hemorrhage, intracerebral hemorrhage, or subarachnoid hemorrhage. Based on their review of the uses of rFVIIa, the authors conclude that rFVIIa is a safe and effective agent with the potential to revolutionize the treatment of neurosurgical patients with hemorrhage. Cost is a major impediment to the widespread use of rFVIIa, and there is some evidence that its use in the neurosurgical population may be subject to higher risk than in other populations studied thus far. Although further study is needed to better delineate the safety and efficacy of the drug in many nonlicensed uses, it is clear that rFVIIa is an agent with tremendous promise.

Thromboembolism and delayed cerebral ischemia after subarachnoid hemorrhage: an autopsy study

OBJECTIVE

Recent findings have cast doubt on vasospasm as the sole cause of delayed cerebral ischemia after subarachnoid hemorrhage.

METHODS

We reviewed the medical records of 29 patients who died after subarachnoid hemorrhage. Brain sections were taken from the insula, cingulate gyrus, and hippocampus. Adjacent sections were stained with hematoxylin-eosin and immunostained for thromboemboli. The density (burden) of the latter was calculated blindly and correlated with evidence for ischemia and with the amount of subarachnoid blood.

RESULTS

There is a strong correlation between microclot burden and delayed cerebral ischemia. Patients with clinical or radiological evidence of delayed ischemia had mean microclot burdens of 10.0/cm2 (standard deviation [SD], +/-6.6); those without had mean burdens of 2.8 (SD, +/-2.6), a highly significant difference (P = 0.002). There is also significant association (P = 0.001) between microclot burden and histological evidence of ischemia, with the mean burdens being 10.9 in sections exhibiting severe ischemia and 4.1 in those in which ischemia was absent. Microclot burden is high in patients who died within 2 days of hemorrhage, decreasing on Days 3 and 4. In delayed ischemia, the numbers rise again late in the first week and remain high until after the second week. In contrast, the average clot burden is low in patients dying without developing delayed ischemia. The amount of blood on an individual slide influenced the microclot burden on that slide to a highly significant extent (P < 0.001).

CONCLUSION

Thromboembolism after subarachnoid hemorrhage may contribute to delayed cerebral ischemia, which parallels that caused by vasospasm. The pathogenesis of thromboembolism is discussed.

The effect of fresh frozen plasma in severe closed head injury

OBJECTIVE

Traumatic brain injury (TBI) is one of the most common causes of morbidity and mortality. Coagulopathy, commonly occurring after severe TBI, is associated with poor outcome and secondary complications, especially delayed traumatic intracerebral hematoma (DTICH). In this study we evaluated the effect of fresh frozen plasma (FFP) on the reduction in the incidence of DTICH in severe closed head injury victims.

METHODS

This study was carried out as a double-blind randomized clinical trial. Ninety patients were entered in two parallel groups taking either FFP or normal saline (N/S). Patients' selection criteria for both groups were: severe closed head injury (Glasgow coma scale < or =8), no mass lesion required evacuation and no history of coagulopathy. The clinical findings, laboratory data, computed tomography (CT) scans and Glasgow outcome scale after 1 month were assessed and compared in two groups.

RESULTS

Out of 90 patients, 44 received FFP and 46 received N/S. The development of new intracerebral hematoma in follow-up CT scans were more common in the FFP group than the N/S group (p=0.012). Both groups showed similar frequency of poor outcome (p=0.343). The mortality was significantly more common in the FFP group than in the N/S group (63% versus 35%, p=0.006).

CONCLUSION

The result of this study revealed that early empirical infusion of FFP in patients with severe head injury may lead to adverse effects, such as an increase in the frequency of DTICH and an increase in the mortality.

Late effects of enriched environment (EE) plus multimodal early onset stimulation (MEOS) after traumatic brain injury in rats: Ongoing improvement of neuromotor function despite sustained volume of the CNS lesion

Recently we showed that the combination between MEOS and EE applied to rats for 7-15 days after traumatic brain injury (TBI) was associated with reduced CNS lesion volume and enhanced reversal of neuromotor dysfunction. In a continuation of this work, we tested whether these effects persisted for longer post-operative periods, e.g. 30 days post-injury (dpi). Rats were subjected to lateral fluid percussion (LFP) or to sham injury. After LFP, one third of the animals (injured and sham) was placed under conditions of standard housing (SH), one third was kept in EE-only, and one third received EE+MEOS. Standardized composite neuroscore (NS) for neurological functions and computerized analysis of the vibrissal motor performance were used to assess post-traumatic neuromotor deficits. These were followed by evaluation of the cortical lesion volume (CLV) after immunostaining for neuron-specific enolase, caspase 3 active, and GFAP. Finally, the volume of cortical lesion containing regeneration-associated proteins (CLV-RAP) was determined in sections stained for GAP-43, MAP2, and neuronal class III beta-tubulin. We found (i) no differences in the vibrissal motor performance; (ii) EE+MEOS rats performed significantly better than SH rats in NS; (iii) EE-only and EE+MEOS animals, but not SH rats, showed better recovery at 30 dpi than at 15 dpi; (iv) no differences among all groups in CLV (larger than that at 15 dpi) and CLV-RAP, despite a clear tendency to reduction in the EE-only and EE+MEOS rats. We conclude that EE+MEOS retards, but cannot prevent the increase of lesion volume. This retardation is sufficient for a continuous restoration of neurological functions.

Effects of Recombinant Activated Factor VII in Traumatic Nonsurgical Intracranial Hemorrhage

OBJECTIVE

To determine whether treatment with recombinant activated factor VII (rFVIIa) will prevent progression of bleeding in nonsurgical hemorrhagic traumatic brain injury (TBI).

METHODS

Chart review from the trauma registry of a level 1 trauma center between January 1, 2002 and December 31, 2004 identified 2 patients who received rFVIIa for progressive hemorrhagic TBI. These patients were given a single dose of rFVIIa (120 mcg/kg) after a repeat head computed tomography (CT) scan showed worsening of intracranial bleeding. Pre-rFVIIa and post-rFVIIa coagulation parameters and postintervention CT scans were performed. A matched convenience sample was drawn from the institution's trauma registry reflecting similar injury patterns.

RESULTS

The 2 patients who received rFVIIa were ages 61 and 79 years; the patients in the matched convenience sample were 57 and 63 years. Both sets of patients comprised 1 man and 1 woman who had suffered blunt trauma, including hemorrhagic TBI, and were matched according to age, gender, and injury severity score (ISS). During their hospital course, repeat CT scans documented worsening of intracranial hemorrhage in both cohorts. In the rFVIIa patients, follow-up CT showed overall improvement of head injury compared with the convenience sample. The rFVIIa patients also saw an appreciable decrease in both prothrombin time (PT) and international normalized ratio (INR).

CONCLUSIONS

In hemorrhagic TBI, rFVIIa has the potential to limit or even halt the progression of bleeding that would otherwise place growing pressure on the brain. A prospective, randomized multicenter trial is planned to elucidate this hypothesis.

Impaired fibrinolysis and traumatic brain injury in mice

Traumatic brain injury (TBI) has been associated with intravascular coagulation, which may be a result of thromboplastin released following brain injury. Clots thus formed are lysed by plasmin, which is activated by tissue-type and urokinase-type plasminogen activators (uPA). To evaluate the association between traumatic intravascular coagulation and post-traumatic outcome, uPA knockout (uPA-/-) transgenic mice (n=12) or wild-type littermates (WT; n=12) were anesthetized and subjected to controlled cortical impact (CCI) brain injury. A second group of uPA-/- (n=12) and WT mice (n=12) were subjected to sham injury. Motor function was assessed over 2 weeks using the composite neuroscore test and cognition (learning) was assessed with the Morris Water Maze (MWM) at 2 weeks post-injury, whereupon the animals were sacrificed for cortical lesion volume analysis. Motor function was significantly worse in the brain-injured uPA-/- mice when compared to brain-injured WT mice at 48 h (p<0.05) and one week post-injury (p<0.05). These differences resolved by 2 weeks post-injury. There was no significant difference in post-injury cognitive function between uPA-/- mice and WT mice. However, at 2 weeks post-injury, the brain-injured uPA-/- had a significantly larger volume of cortical tissue loss than their WT counterparts (p<0.05). These results demonstrate that the absence of uPA in mice aggravates acute motor deficit and exacerbates cortical tissue loss following CCI brain injury, and suggests a neuroprotective role of the fibrinolytic process following TBI.

Animal models of post-traumatic epilepsy

Epilepsy is a major unfavorable long-term consequence of traumatic brain injury (TBI). Moreover, TBI is one of the most important predisposing factors for the development of epilepsy, particularly in young adults. Understanding the molecular and cellular cascades that lead to the development of post-traumatic epilepsy (PTE) is key for preventing its development or modifying the disease process in such a way that epilepsy, if it develops, is milder and easier-to-treat. Tissue from TBI patients undergoing epileptogenesis is not available for such studies, which underscores the importance of developing clinically relevant animal models of PTE. The goal of this review is to (1) provide a description of PTE in humans, which is critical for the development of clinically relevant models of PTE, (2) review the characteristics of currently available PTE models, and (3) provide suggestions for the development of future models of PTE based on our current understanding of the mechanisms of TBI and epilepsy. The development of clinically relevant models of PTE is critical to advance our understanding of the mechanisms of post-traumatic epileptogenesis and epilepsy, as well as for producing breakthroughs in the development and testing of novel antiepileptogenic treatments.

Coagulopathy and the role of recombinant human activated protein C in sepsis and following polytrauma

Recombinant human activated protein C (rhAPC) also known as drotrecogin alfa (activated) has known antithrombotic, anti-inflammatory, and profibrinolytic properties in severe sepsis. Treatment with rhAPC (Xigris) has been shown to reduce mortality in patients with severe sepsis. The lack of any trials of rhAPC in trauma patients means that a definitive recommendation regarding its use in the polytraumatised patient, in whom severe head trauma or other contraindications for the use of rhAPC have been excluded remains controversial at present. This article describes the current evidence of its efficacy and safety in severe sepsis with relation to surgery and trauma.

Treatment of severe coagulopathy after gunshot injury to the head using recombinant activated factor VII

PURPOSE

Patients with severe penetrating head injury often have a coagulopathy that is difficult to correct. In this report, we describe 3 such patients who were treated with activated factor VII (FVIIa) to stop ongoing hemorrhage that was refractory to conventional treatment.

SUBJECTS AND METHODS

We treated 3 patients with severe head injury secondary to gunshot wounds to the head. All 3 patients had ongoing bleeding secondary to a severe consumptive coagulopathy that was refractory to treatment with fresh frozen plasma, platelets, and cryoprecipitate. Recombinant FVIIa was then administered to achieve hemostasis.

RESULTS

Administration of FVIIa (90-120 microg/kg) was successful in rapidly achieving hemostasis and correcting abnormal laboratory parameters indicative of coagulopathy in all patients. Although all 3 patients died, control of bleeding made organ donation possible in 2 patients.

CONCLUSION

In patients with a severe head injury and coagulopathy, use of FVIIa may help in correction of coagulopathy and decrease transfusion requirements. In patients where ongoing bleeding precludes the declaration of brain death, the use of this agent might help in achieving hemodynamic stability and preserve the possibility of organ donation. The ethical implications of using FVIIa in this situation are discussed.

Apo E genotype not associated with intravascular coagulation in traumatic brain injury

There is considerable evidence linking both genotype and coagulopathy to vascular complications of traumatic brain injury (TBI) and other cerebral insults. The authors explored a possible connection between the apolipoprotein E (Apo E) genotype, coagulopathy and intravascular microthombosis (IMT) in TBI. The predicted association was not confirmed.