Delayed Brain Injury after Head Trauma: Significance of Coagulopathy

Pathophysiology of Coagulopathy Induced by Traumatic Brain Injury Is Identical to That of Disseminated Intravascular Coagulation With Hyperfibrinolysis

Background: Traumatic brain injury (TBI)-associated coagulopathy is a widely recognized risk factor for secondary brain damage and contributes to poor clinical outcomes. Various theories, including disseminated intravascular coagulation (DIC), have been proposed regarding its pathomechanisms; no consensus has been reached thus far. This study aimed to elucidate the pathophysiology of TBI-induced coagulopathy by comparing coagulofibrinolytic changes in isolated TBI (iTBI) to those in non-TBI, to determine the associated factors, and identify the clinical significance of DIC diagnosis in patients with iTBI.

Methods: This secondary multicenter, prospective study assessed patients with severe trauma. iTBI was defined as Abbreviated Injury Scale (AIS) scores ≥4 in the head and neck, and ≤2 in other body parts. Non-TBI was defined as AIS scores ≥4 in single body parts other than the head and neck, and the absence of AIS scores ≥3 in any other trauma-affected parts. Specific biomarkers for thrombin and plasmin generation, anticoagulation, and fibrinolysis inhibition were measured at the presentation to the emergency department (0 h) and 3 h after arrival.

Results: We analyzed 34 iTBI and 40 non-TBI patients. Baseline characteristics, transfusion requirements and in-hospital mortality did not significantly differ between groups. The changes in coagulation/fibrinolysis-related biomarkers were similar. Lactate levels in the iTBI group positively correlated with DIC scores (rho = −0.441, p = 0.017), but not with blood pressure (rho = −0.098, p = 0.614). Multiple logistic regression analyses revealed that the injury severity score was an independent predictor of DIC development in patients with iTBI (odds ratio = 1.237, p = 0.018). Patients with iTBI were further subdivided into two groups: DIC (n = 15) and non-DIC (n = 19) groups. Marked thrombin and plasmin generation were observed in all patients with iTBI, especially those with DIC. Patients with iTBI and DIC had higher requirements for massive transfusion and emergency surgery, and higher in-hospital mortality than those without DIC. Furthermore, DIC development significantly correlated with poor hospital survival; DIC scores at 0 h were predictive of in-hospital mortality.

Conclusions: Coagulofibrinolytic changes in iTBI and non-TBI patients were identical, and consistent with the pathophysiology of DIC. DIC diagnosis in the early phase of TBI is key in predicting the outcomes of severe TBI.

Combination Therapy Using Prothrombin Complex Concentrate and Vitamin K in Anticoagulated Patients with Traumatic Intracranial Hemorrhage Prevents Progressive Hemorrhagic Injury: A Historically Controlled Study

Warfarin remains crucially involved in the treatment of patients at thrombotic or thromboembolic risk. However, warfarin increases the mortality rate among patients with traumatic intracranial hemorrhage (TICH) through progressive hemorrhagic injury (PHI). Therefore, a rapid anticoagulation reversal could be required in patients with TICH to prevent PHI. Differences in the warfarin reversal effect between combination therapy of prothrombin complex concentrate (PCC) with vitamin K (VK) and VK monotherapy remain unclear. However, studies have reported that PCC has greater effectiveness and safety for warfarin reversal compared with fresh frozen plasma (FFP). This retrospective study aimed to evaluate the warfarin reversal effects of combination therapy of PCC with VK and VK monotherapy on TICH. We compared the clinical outcomes between the periods before and after the PCC introduction in our hospital. There were 13 and 7 patients who received VK monotherapy and PCC with VK, respectively. PHI predictors were evaluated using univariate regression analyses. Warfarin reversal using PCC had a significant negative association with PHI (odds ratio: 0.03, 95% confidence interval: 0.00-0.41, P = 0.004). None of the patients presented with thrombotic complications. Warfarin reversal through a combination of PCC with VK could be more effective for inhibiting post-trauma PHI compared with VK monotherapy. This could be attributed to a rapid and stable warfarin reversal. PCC should be administered to patients with TICH taking warfarin for PHI prevention.

Assessment of Platelet Function in Traumatic Brain Injury-A Retrospective Observational Study in the Neuro-Critical Care Setting

BACKGROUND

Despite seemingly functional coagulation, hemorrhagic lesion progression is a common and devastating condition following traumatic brain injury (TBI), stressing the need for new diagnostic techniques. Multiple electrode aggregometry (MEA) measures platelet function and could aid in coagulopathy assessment following TBI. The aims of this study were to evaluate MEA temporal dynamics, influence of concomitant therapy, and its capabilities to predict lesion progression and clinical outcome in a TBI cohort.

MATERIAL AND METHODS

Adult TBI patients in a neurointensive care unit that underwent MEA sampling were retrospectively included. MEA was sampled if the patient was treated with antiplatelet therapy, bled heavily during surgery, or had abnormal baseline coagulation values. We assessed platelet activation pathways involving the arachidonic acid receptor (ASPI), P2Y12 receptor, and thrombin receptor (TRAP). ASPI was the primary focus of analysis. If several samples were obtained, they were included. Retrospective data were extracted from hospital charts. Outcome variables were radiologic hemorrhagic progression and Glasgow Outcome Scale assessed prospectively at 12 months posttrauma. MEA levels were compared between patients on antiplatelet therapy. Linear mixed effect models and uni-/multivariable regression models were used to study longitudinal dynamics, hemorrhagic progression and outcome, respectively.

RESULTS

In total, 178 patients were included (48% unfavorable outcome). ASPI levels increased from initially low values in a time-dependent fashion (p < 0.001). Patients on cyclooxygenase inhibitors demonstrated low ASPI levels (p < 0.001), while platelet transfusion increased them (p < 0.001). The first ASPI (p = 0.039) and TRAP (p = 0.009) were significant predictors of outcome, but not lesion progression, in univariate analyses. In multivariable analysis, MEA values were not independently correlated with outcome.

CONCLUSION

A general longitudinal trend of MEA is identified in this TBI cohort, even in patients without known antiplatelet therapies. Values appear also affected by platelet inhibitory treatment and by platelet transfusions. While significant in univariate models to predict outcome, MEA values did not independently correlate to outcome or lesion progression in multivariable analyses. Further prospective studies to monitor coagulation in TBI patients are warranted, in particular the interpretation of pathological MEA values in patients without antiplatelet therapies.

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.

Traumatic Intracerebral Hemorrhage: Risk Factors Associated with Progression

The increase in the volume of a traumatic intracerebral hemorrhage (TICH) is a widely studied phenomenon that has a direct impact on the prognosis of patients. The objective of this study was to identify the risk factors associated with the progression of TICH. We retrospectively analyzed the records of 1970 adult patients >15 years of age who were consecutively admitted after sustaining a closed severe traumatic brain injury (TBI) between January 1987 and November 2013 at a single center. Beginning in 2007, patients with moderate TBIs were also included. A total of 782 patients exhibited one or more TICH on the initial CT scan, and met the selection criteria. The main outcome variable was the presence or absence of progression of the TICH. Univariate and multivariate statistical analyses were performed. Factors independently associated with the growth of TICH obtained through logistic regression included the following: an initial volume <5 cc (odds ratio [OR] 2.42, p<0.001), cisternal compression (OR 1.95, p<0.001), decompressive craniectomy (OR 2.18, p<0.001), age (mean 37.67 vs. 42.95 years; OR 1.01, p<0.001), falls as mechanism of trauma (OR 1.72, p=0.001), multiple TICHs (OR 1.56, p=0.007), and hypoxia (OR 1.56, p=0.02). TICH progression occurred with a frequency of 63% in our study. We showed that there was a correlation between TICH growth and some variables, such as multiple TICHs, a lower initial volume, acute subdural hematoma, cisternal compression, older patient age, hypoxia, falls, and decompressive craniectomy.

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.

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.

Predicting progressive hemorrhagic injury after traumatic brain injury: derivation and validation of a risk score based on admission characteristics

Previous studies have demonstrated that patients with traumatic brain injury (TBI) who also have progressive hemorrhagic injury (PHI), have a higher risk of clinical deterioration and worse outcomes than do TBI patients without PHI. Therefore, the early prediction of PHI occurrence is useful to evaluate the status of patients with TBI and to improve outcomes. The objective of this study was to develop and validate a prognostic model that uses information available at admission to determine the likelihood of PHI after TBI. Retrospectively collected data were used to develop a PHI prognostic model with a logistic regression analysis. The prediction model was validated in 114 patients from a separate hospital. Eight independent prognostic factors were identified: age ≥ 57 years (5 points), intra-axial bleeding/brain contusion (4 points), midline shift ≥ 5 mm (6 points), platelet (PLT) count<100×10⁹/L (10 points), PLT count ≥ 100 but <150×10⁹/L (4 points), prothrombin time>14 sec (7 points), D-dimer ≥ 5 mg/L (12 points), and glucose ≥ 10 mmol/L (10 points). Each patient was assigned a number of points proportional to the regression coefficient. We calculated risk scores for each patient and defined three risk groups: low risk (0-13 points), intermediate risk (14-22 points), and high risk (23-54 points). In the development cohort, the PHI rates after TBI for these three groups were 10.3%, 47.3%, and 85.2%, respectively. In the validation cohort, the corresponding PHI rates were 10.9%, 47.3%, and 86.9%. The C-statistic for the point system was 0.864 (p=0.509 by the Hosmer-Lemeshow test) in the development cohort, and 0.862 (p=0.589 by the Hosmer-Lemeshow test) in the validation cohort. In conclusion, a relatively simple risk score using admission predictors accurately predicted the risk for PHI after TBI.

Hemorrhagic progression of a contusion after traumatic brain injury: a review

The magnitude of damage to cerebral tissues following head trauma is determined by the primary injury, caused by the kinetic energy delivered at the time of impact, plus numerous secondary injury responses that almost inevitably worsen the primary injury. When head trauma results in a cerebral contusion, the hemorrhagic lesion often progresses during the first several hours after impact, either expanding or developing new, non-contiguous hemorrhagic lesions, a phenomenon termed hemorrhagic progression of a contusion (HPC). Because a hemorrhagic contusion marks tissues with essentially total unrecoverable loss of function, and because blood is one of the most toxic substances to which the brain can be exposed, HPC is one of the most severe types of secondary injury encountered following traumatic brain injury (TBI). Historically, HPC has been attributed to continued bleeding of microvessels fractured at the time of primary injury. This concept has given rise to the notion that continued bleeding might be due to overt or latent coagulopathy, prompting attempts to normalize coagulation with agents such as recombinant factor VIIa. Recently, a novel mechanism was postulated to account for HPC that involves delayed, progressive microvascular failure initiated by the impact. Here we review the topic of HPC, we examine data relevant to the concept of a coagulopathy, and we detail emerging data elucidating the mechanism of progressive microvascular failure that predisposes to HPC after head trauma.

Ethanol intoxication is associated with a lower incidence of admission coagulopathy in severe traumatic brain injury patients

The aim of this study was to determine the impact of ethanol (ETOH) on the incidence of severe traumatic brain injury (sTBI)-associated coagulopathy and to examine the effect of ETOH on in-hospital outcomes in patients sustaining sTBI. Patients admitted to the surgical intensive care unit from June 2005 through December 2008 following sTBI, defined as a head Abbreviated Injury Scale (AIS) score ≥3, were retrospectively identified. Patients with a chest, abdomen, or extremity AIS score >3 were excluded to minimize the impact of extracranial injuries. Criteria for sTBI-associated coagulopathy included thrombocytopenia and/or elevated International Normalized Ratio (INR) and/or prolonged activated partial thromboplastin time (aPTT). The incidence of admission coagulopathy, in-hospital complications, and mortality were compared between patients who were ETOH positive [ETOH (+)] and ETOH negative [ETOH (-)]. During the study period, there were 439 patients with ETOH levels available for analysis. Overall, 46.5% (n=204) of these patients were ETOH (+), while 53.5% (n=235) were ETOH (-). Coagulopathy was significantly less frequent in the ETOH (+) patients compared to their ETOH (-) counterparts (5.4% versus 15.3%; adjusted p<0.001). In the forward logistic regression analysis, a positive ETOH level proved to be an independent protective factor for admission coagulopathy [OR (95% CI)=0.24 (0.10,0.54; p=0.001]. ETOH (+) patients had a significantly lower in-hospital mortality rate than ETOH (-) patients [9.8% versus 16.6%; adjusted p=0.011; adjusted OR (95% CI)=0.39 (0.19,0.81)]. For brain-injured patients arriving alive to the hospital, ETOH intoxication is associated with a significantly lower incidence of early coagulopathy and in-hospital mortality. Further research to establish the pathophysiologic mechanisms underlying any potential beneficial effect of ETOH on the coagulation system following sTBI is warranted.

Key role of sulfonylurea receptor 1 in progressive secondary hemorrhage after brain contusion

An important but poorly understood feature of traumatic brain injury (TBI) is the clinically serious problem of spatiotemporal progression ("blossoming") of a hemorrhagic contusion, a phenomenon we term progressive secondary hemorrhage (PSH). Molecular mechanisms of PSH are unknown and efforts to reduce it by promoting coagulation have met with equivocal results. We hypothesized that PSH might be due to upregulation and activation of sulfonylurea receptor 1 (SUR1)-regulated NC(Ca-ATP) channels in capillary endothelial cells, predisposing to oncotic death of endothelial cells and catastrophic failure of capillary integrity. Anesthetized adult male rats underwent left parietal craniectomy for induction of a focal cortical contusion. The regulatory subunit of the channel, SUR1, was prominently upregulated in capillaries of penumbral tissues surrounding the contusion. In untreated rats, PSH was characterized by progressive enlargement of the contusion deep into the site of cortical impact, including corpus callosum, hippocampus, and thalamus, by progressive accumulation of extravasated blood, with a doubling of the volume during the first 12 h after injury, and by capillary fragmentation in penumbral tissues. Block of SUR1 using low-dose (non-hypoglycemogenic) glibenclamide largely eliminated PSH and capillary fragmentation, and was associated with a significant reduction in the size of the necrotic lesion and in preservation of neurobehavioral function. Antisense oligodeoxynucleotide against SUR1, administered after injury, reduced both SUR1 expression and PSH, consistent with a requirement for transcriptional upregulation of SUR1. Our findings provide novel insights into molecular mechanisms responsible for PSH associated with hemorrhagic contusions, and point to SUR1 as a potential therapeutic target in TBI.

Progression of traumatic intracerebral hemorrhage: a prospective observational study

ABSTRACT Preliminary evidence has shown that intracerebral hemorrhages, either spontaneous (sICH) or traumatic (tICH) often expand over time. An association between hemorrhage expansion and clinical outcomes has been described for sICH. The intent of this prospective, observational study was to characterize the temporal profile of hemorrhage progression, as measured by serial computed tomography (CT) scanning, with the aim of better understanding the natural course of hemorrhage progression in tICH. There was also a desire to document the baseline adverse event (AE) profile in this patient group. An important motive for performing this study was to set the stage for subsequent studies that will examine the role of a new systemic hemostatic agent in tICH. Subjects were enrolled if they had tICH lesions of at least 2 mL on a baseline CT scan obtained within 6 h of a head injury. CT scans were repeated at 24 and 72 h. Clinical outcomes and pre-defined AEs were documented. The data showed that 51% of the subjects demonstrated an increase in tICH volume, and that most of the increase occurred early. In addition, larger hematomas exhibited the greatest expansion. Thromboembolic complications were identified in 13% of subjects. This study demonstrates that tICH expansion between the baseline and 24-h CT scans occurred in approximately half of the subjects. The earlier after injury that the initial CT scan is obtained, the greater is the likelihood that the hematoma will expand on subsequent scans. The time frame during which hemorrhagic expansion occurs provides an opportunity for early intervention to limit a process with adverse prognostic implications.

Correlation of a high D-dimer level with poor outcome in traumatic intracranial hemorrhage

The correlations between D-dimer and Glasgow Coma Scale (GCS), pupillary light reflex, distance of midline shift on brain computed tomography (CT), and Glasgow Outcome Score (GOS) in patients with trauma/non-trauma intracranial hemorrhage (ICH) are not consistent in studies. Ninety-eight traumatic and 59 non-traumatic ICH patients were studied. Pre-existing venous thrombosis, recent surgery, drug use (aspirin or coumadin), or malignancy, were excluded. D-dimer level was estimated within hours after acute insult, and statistical analyses were used for comparisons between groups. Traumatic ICH patients had higher D-dimer levels than controls (2984 vs. 256 microg/l; P = 0.001). The GCS, midline shift on brain CT, pupillary reflex, and GOS at 3 months were significantly correlated with high D-dimer value in traumatic patients (individual P < 0.001), but not in the non-traumatic group. Using receiver-operating characteristic curve (ROC), the cutoff point was 1496 microg/l, with sensitivity and specificity of 100% and 83%, respectively. D-dimer > or =1496 microg/l predicted a poor outcome [adjusted odds ratio (OR) 14.44, 95% CI 1.16-179.27; P = 0.038]. A high D-dimer level is associated with a poor outcome in patients with traumatic ICH. It can be used in addition to neurological assessment to predict the outcome.

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.

Coagulation Abnormalities Associated with Severe Isolated Traumatic Brain Injury: Cerebral Arterio-Venous Differences in Coagulation and Inflammatory Markers

Although coagulopathy is known to be the major contributor to a poor outcome of traumatic brain injury (TBI), the mechanisms that trigger coagulation abnormalities have not been studied in detail. We undertook a prospective observational study at a neurosurgical ICU (NICU) in a university hospital. We examined 11 patients with severe isolated TBI, at admittance to the hospital and during the next 3 days. We collected cerebrovenous blood samples from a jugular bulb catheter, arterial blood, and cerebrospinal fluid (CSF) samples. We measured concentrations of thrombin-antithrombin complex (TAT), fibrin D-dimer (DD), prothrombin fragment 1 + 2 (F1 + 2), interleukin-6 (IL-6), and complement complex (C5b-9). All patients had some degree of consumption coagulopathy at the study start and a tendency to thrombocytopenia during the next few days. Levels of DD (3.6 +/- 2.7 mg/L), TAT (86 +/- 72 microg/L) and F1 + 2 (5.9 +/- 6.8 nmol/L) were significantly increased shortly after the trauma compared to reference values, with considerable transcranial gradients for TAT (49 microg/L) and F1 + 2 (3.2 nmol/L). Compared to controls, IL-6 levels were increased more than a hundredfold in both blood (283 +/- 192 ng/L) and CSF (424 +/- 355 ng/L) samples, with a transcranial gradient at the study start (107 ng/L). C5b-9 levels were moderately increased in blood samples, 270 +/- 114 microg/L, versus controls, 184 +/- 39 (p < 0.05). We conclude that activation of the coagulation system takes place during the passage of blood through the damaged brain, and is already evident hours after the trauma. IL-6 and activation of the complement system (C5b-9) co-vary with hemostatic parameters in TBI patients.

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.

Thrombocytopenia Predicts Progressive Hemorrhage after Head Trauma

Patients with traumatic brain injury (TBI) often show progression of hemorrhagic injuries (PHI) after admission to the hospital. This progression is correlated with poor outcome. In this study, we have investigated if thrombocytopenia was a risk factor for PHI. The study was performed on patients admitted to the hospital with severe TBI during year 2000. In total, 50 patients were admitted with severe TBI. Twenty-seven out of these had complete platelet counts at admission and 24 hours thereafter and were included for further study. We found thrombocytopenia at admission to be a risk factor for PHI (p=0.008). We also found that the platelet count decreased more significantly during the first 24 h after injury in patients with PHI compared to patients without PHI (p=0.009). A trend towards longer periods of mechanical ventilation in patients with PHI compared to patients without PHI was identified. These findings support a causal relationship between thrombocytopenia and PHI. The findings provide a rationale for future studies of hemostatic agents in the treatment of TBI in order to minimise complications caused by PHI.

Delayed Thrombosis after Traumatic Brain Injury in Rats

Secondary thrombosis may contribute to cerebral ischemia caused by traumatic brain injury (TBI). In this study, we sought to investigate the temporal and spatial profiles of intravascular thrombosis and to evaluate the effect of atorvastatin, a beta-hydroxy-beta-methylglutaryl coenzyme-A (HMG-CoA) reductase inhibitor, on thrombosis after TBI. Young male Wistar rats weighing 350-400 g were subjected to controlled cortical impact injury, and were sacrificed at 1 and 4 h, and 1, 3, 8, and 15 days after TBI (5 rats/time point), respectively. For the evaluation of the effects of atorvastatin on intravascular thrombosis, rats were subjected to TBI, and subsequently atorvastatin (1 mg/kg) was orally administered starting 1 day after TBI and then daily until sacrifice at 3, 8, and 15 days after TBI (5 rats/time point). Before sacrifice of animals, blood was withdrawn and employed for the measurement of von Willibrand factor and platelet activity using enzyme-linked immunoabsorbant assay (ELISA). Brain tissues were prepared for histological analysis. The data show that (1) delayed thrombosis is present in the lesion boundary zone and in the hippocampal CA3 region, starting at 1-4 h, peaking at 1-3 days, and then declining at 8 and 15 days after TBI; (2) intravascular thrombosis also occurs in the other areas of cortex, striatum, and corpus callosum, but with a scattered distribution; (3) delayed thrombi are composed of platelets, fibrin, and vWF; and (4) reduction of the plasma vWF level and platelet activity by atorvastatin decreases delayed thrombosis after TBI. These data suggest that atorvastatin reduces intravascular thrombosis attributed to hemostatic disturbances caused by TBI.

Implications of fibrinogenolysis in patients with closed head injury

The objective of this study was to determine the clinical significance of fibrinogenolysis in patients with isolated closed head injury. We correlated indices of fibrinolytic activity, fibrinogen degradation products (FgDP), and fibrin degradation products (FbDP) with outcome in order to accomplish this. This study consisted of 40 patients with isolated closed head trauma in whom blood sampling could be initiated within 3 h after injury. Patients were divided into two groups according to Glasgow Outcome Scale status at 3 months after injury, characterized as good recovery or moderate disability (group 1, n = 21); and severe disability, vegetative, or death (group 2, n = 19). The plasma fibrinogen concentration correlated with the Glasgow Coma Scale score on admission (r2 = 0.201, p < 0.01), and plasma fibrinogen concentrations in group 2 were lower than in group 1 (p < 0.05). Plasma concentrations of fibrin/fibrinogen degradation products (FDP) and plasmin-alpha2-plasmin inhibitor complex (PIC), molecular markers of activation of fibrinolysis, were higher in group 2 than in group 1 (p < 0.001), and both FgDP and FbDP concentrations in group 2 also were higher than in group 1 (p < 0.001). Both the FgDP and FbDP concentrations correlated with the PIC concentration. Moreover, the plasma FgDP concentrations correlated inversely with alpha2-plasmin inhibitor activity, a potent inhibitor of the fibrinolytic sysytem, as did the FbDP concentration. This study reveals that both fibrinolysis and fibrinogenolysis are involved in the coagulopathy that develops during the acute phase of head injury and correlate with fibrinolytic activity. Decreased activity of alpha2-plasmin inhibitor may contribute to fibrinogenolysis.

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

Thrombomodulin (TM), which is located in the surface of the endothelium in the arteries, veins, and capillaries of major organs such as the brain, lungs, liver, kidneys, skeletal muscles, and gastrointestinal tract, is one of several indicators of endothelial injury. Von Willebrand factor (vWf), which is synthesized by endothelial cells, is also an endothelial specific glycoprotein. The serum level of vWf increases in response to various stimuli without endothelial injury. An elevated serum level of vWf may suggest endothelial activation in severe head injury. We hypothesize that the degree of cerebral endothelial activation or injury depends on the type of head injury and that measuring the TM and vWf is useful for predicting delayed traumatic intracerebral hematoma (DTICH), produced by weakness of the vessel wall, occuring either as a direct or indirect effect of head injury. The values of vWf in focal brain injury (ranging from 332.5 +/- 52.8% to 361.7 +/- 86.2%) were significantly higher than those in diffuse axonal injury from 2 h to 7 days after the injury occurred (ranging from 201.6 +/- 59.5% to 242.5 +/- 51.7%). The serum level of TM in focal brain injury (ranging from 3.84 +/- 1.54 to 4.12 +/- 1.46 U/mL) was higher than that in diffuse axonal injury (ranging from 2.96 +/- 0.63 to 3.67 +/- 1.70 U/mL), but these differences were not statistically significant. In patients with DTICH, TM was significantly higher than in patients without DTICH (p < 0.01). The results of our study demonstrate that the degree of endothelial activation in focal brain injury was significantly higher than in diffuse brain injury. In addition, the serum level of TM in patients with DTICH was significantly higher than in patients without DTICH. These findings suggest that cerebral tissue injury is often accompanied by cerebral endothelial activation, and that these two phenomena should be distinguished from each other. The levels of serum TM and vWf appear to be good indicators of the cerebral endothelial injury and of endothelial activation in severe head injury.

Fiberoptic intraparenchymal brain pressure monitoring with the Camino V420 monitor: reflections on our experience in 163 severely head-injured patients

To assess the safety and accuracy of the Camino intraparenchymal sensor, we prospectively evaluated hemorrhagic complications, zero-drift, infection, and system malfunction in 163 patients monitored after a severe head injury. Mean duration of intracranial pressure (ICP) monitoring was 5 +/- 2.2 days (range: 12 h to 11 days). Of the 141 patients with a control CT scan, four showed a 1-2-cc collection of blood at the catheter's end. When removed, the sensors underread the true ICP value (negative zero-drift) in 80 of the 126 sensors evaluated (63.5%). Fourteen sensors showed no zero-drift, and 32 sensors overread the true ICP value (positive zero-drift) (median: -1 mm Hg; interquartile range: -4 to +1 mm Hg). No significant relationship was found between zero-drift, the surgeon who implanted the sensor, intracranial hypertension, or duration of ICP monitoring. No clinical infections could be attributed to the devices. Sixteen patients (9.8%) required more than one ICP sensor due to malfunctioning of the system. In conclusion, continuous ICP monitoring using the Camino intraparenchymal sensor has a low complication rate. However, this sensor may underread the real ICP values in a high number of patients. The lack of correlation between duration of ICP monitoring and zero-drift suggests that, contrary to the recommendations of other reports, the intraparenchymatous Camino sensor can provide reliable readings after the fifth day of use.

Utility of an initial D-dimer assay in screening for traumatic or spontaneous intracranial hemorrhage

OBJECTIVE

To evaluate the sensitivity of a D-dimer assay as a screening tool for possible traumatic or spontaneous intracranial hemorrhage. If adequately sensitive, the D-dimer assay may potentially permit omission of a more expensive computed tomography (CT) scan of the head when such hemorrhage is clinically suspected.

METHODS

Prospective, consecutive, blinded study of patients (age > 16 years) requiring a CT scan of the head for suspected intracranial hemorrhage over a five-month period at a university, Level I trauma center. All study patients had a serum D-dimer assay obtained prior to their CT scans. Sensitivity and specificity, with 95% confidence intervals (95% CIs), of the enzyme-linked immunosorbent assay (ELISA) D-dimer assay for the detection of intracranial hemorrhage were calculated.

RESULTS

Of the 319 patients entered in the study, 25 (7.8%) had a CT scan positive for intracranial hemorrhage. Patients with intracranial hemorrhage were more likely to have a positive D-dimer assay (chi-square = 13.075, p < 0.001). The D-dimer assay had 21 true-positive and four false-negative tests, resulting in a sensitivity of 84.0% (95% CI = 63.7% to 95.5%) and a specificity of 55.8% (95% CI = 55.5% to 55.9%). The four false-negative cases included one small intraparenchymal hemorrhage, one small subarachnoid hemorrhage, one moderate-sized intraparenchymal hemorrhage with mid-line shift, and one large subdural hematoma requiring emergent surgery.

CONCLUSIONS

Due to the catastrophic nature of missing an intracranial hemorrhage in the emergency department, the D-dimer assay is not adequately sensitive or predictive to use as a screening tool to allow routine omission of head CT scanning.

Indications for computed tomography in patients with minor head injury

BACKGROUND

Computed tomography (CT) is widely used as a screening test in patients with minor head injury, although the results are often normal. We performed a study to develop and validate a set of clinical criteria that could be used to identify patients with minor head injury who do not need to undergo CT.

METHODS

In the first phase of the study, we recorded clinical findings in 520 consecutive patients with minor head injury who had a normal score on the Glasgow Coma Scale and normal findings on a brief neurologic examination; the patients then underwent CT. Using recursive partitioning, we derived a set of criteria to identify all patients who had abnormalities on CT scanning. In the second phase, the sensitivity and specificity of the criteria for predicting a positive scan were evaluated in a group of 909 patients.

RESULTS

Of the 520 patients in the first phase, 36 (6.9 percent) had positive scans. All patients with positive CT scans had one or more of seven findings: headache, vomiting, an age over 60 years, drug or alcohol intoxication, deficits in short-term memory, physical evidence of trauma above the clavicles, and seizure. Among the 909 patients in the second phase, 57 (6.3 percent) had positive scans. In this group of patients, the sensitivity of the seven findings combined was 100 percent (95 percent confidence interval, 95 to 100 percent). All patients with positive CT scans had at least one of the findings.

CONCLUSIONS

For the evaluation of patients with minor head injury, the use of CT can be safely limited to those who have certain clinical findings.

Scandinavian guidelines for initial management of minimal, mild, and moderate head injuries. The Scandinavian Neurotrauma Committee

BACKGROUND

The Scandinavian Neurotrauma Committee was initiated by the Scandinavian Neurosurgical Society to develop evidence-based guidelines for improved care of neurotrauma patients.

METHODS

A MEDLINE search identified 475 papers dealing with the management of minimal, mild, and moderate head injuries. Forty-two studies presenting class II evidence on the initial management of such injuries were reviewed and management guidelines were developed.

RESULTS

Implementation of the Head Injury Severity Scale is advocated. Patients with minimal injuries (no loss of consciousness, Glasgow Coma Scale score of 15) can be safely discharged. Routine early computed tomographic scan is recommended in cases with mild injuries (history of loss of consciousness, Glasgow Coma Scale score = 14-15) and patients with normal scans may be discharged. Computed tomographic scan and admission is mandatory in moderate injuries (Glasgow Coma Scale score = 13). All patients harboring additional risk factors should be scanned and admitted. A flow-chart for clinical decision making and a Head Injury Instruction card is introduced.

CONCLUSIONS

The Scandinavian Neurotrauma Committee suggests guidelines that should be safe and cost-effective for the initial management of minimal, mild, and moderate head injuries.

Traumatic brain injury: patterns of failure of nonoperative management

OBJECTIVE

The circumstances of failure for nonoperative management of blunt traumatic brain injury have been poorly defined. In this study, all trauma patients identified over a 12-year period with progression of neurologic injury requiring craniotomy were retrospectively reviewed.

METHODS

Data collected included demographic information, mechanism of injury, field and admission vital signs, and Glasgow Coma Scale score, medications, associated injuries, and coagulopathy. Head computed tomographic scans were reviewed, and anatomic findings were correlated with clinical changes (change in mental status or elevation of intracranial pressure) that led to subsequent CT scan and craniotomy.

RESULTS

Of 20,100 patients, there were 852 who had computed tomographic scans with acute intracranial injuries on admission; 462 patients were managed nonoperatively. Fifty-seven patients had progression of neurologic injury (34 < 24 hours = early; 23 > 24 hours = late) that required surgery.

CONCLUSION

Of the variables investigated, only anatomic location of injury was found to be predictive of early failure of nonoperative management. Frontal intraparenchymal hematomas are particularly prone to early failure. Clinical examination and intracranial pressure monitoring are equally important in detecting failure and should be an integral part of nonoperative management.

Alcohol and head injury: an issue revisited

The pathophysiologic changes associated with acute and chronic alcohol exposure in the setting of traumatic brain injury are complex. Experimental data indicate that ethanol intoxication can exacerbate brain injury through several mechanisms including hemodynamic and respiratory depression, blood-brain barrier disruption, and derangements in hemostasis. Alcohol, however, is also a potent inhibitor of N-methyl-D-aspartate (NMDA) receptor-mediated excitotoxicity, and thus is neuroprotective. In contrast to the effects of acute intoxication, chronic alcohol exposure appears to result in upregulation of NMDA receptor activity and downregulation of gamma-aminobutyric acid (GABA) receptor function. This imbalance, it is hypothesized, can result in a surge of excitotoxicity following alcohol withdrawal. Trauma-related excitotoxic cell damage may be significantly potentiated by this alcohol-induced receptor imbalance that is unmasked as withdrawal occurs. Clinical and epidemiologic investigations of alcohol and outcome after head injury have not consistently demonstrated a measurable effect from either acute or chronic alcohol use. Multiple factors including the timing of intoxication in relation to time of injury, the degree and chronicity of intoxication, as well as the influence of other secondary injury processes appear to determine the net effect of alcohol in a given individual. Further clinical and experimental investigations aimed at defining the impact of alcohol use on outcome after head injury are warranted.