Comparison of three measures of injury severity in children with traumatic brain injury

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

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

Effects of nicotinamide on spatial memory and inflammation after juvenile traumatic brain injury

Age is a consistent predictor of outcome following traumatic brain injury (TBI). Although children and adolescents have the highest rate of hospitalizations and long-term disabilities, few preclinical studies have attempted to model and treat TBI in this population. Studies using nicotinamide (NAM), a soluble B-group vitamin, in older animals (3-6 months) have shown improved functional recovery in experimental models of TBI. The purpose of this study was two-fold: to examine the preclinical efficacy of NAM at different doses on behavioral outcomes in juvenile rats and examine the microglial response over time. Groups of juvenile rats (PND 28-60) were assigned to sham, NAM (125 mg/kg, 500 mg/kg, or 1000 mg/kg) or saline (1 mL/kg) and received unilateral cortical contusion injuries (CCI) and received injections at 15 min, 24 h, and 72 h after injury. Animals treated with NAM demonstrated no significant behavioral improvements over saline treatments. NAM treatments did however show slowed cortical loss and reduced microglia compared to saline treated animals. In summary, the preclinical efficacy of NAM as a treatment following CCI in juvenile animals differs from that previously documented in older rat models. While NAM treatments did reduce microglial activity and slowed progression of cortical loss, it did not reduce the total cortical volume lost nor did it improve behavioral outcomes. The findings of this study emphasize the need to examine potential treatments for TBI utilizing juvenile populations and may explain why so many treatments have failed in clinical trials.

Systematic review and need assessment of pediatric trauma outcome benchmarking tools for low-resource settings

INTRODUCTION

Trauma is a leading cause of mortality and disability in children worldwide. The World Health Organization reports that 95% of all childhood injury deaths occur in Low-Middle-Income Countries (LMIC). Injury scores have been developed to facilitate risk stratification, clinical decision making, and research. Trauma registries in LMIC depend on adapted trauma scores that do not rely on investigations that require unavailable material or human resources. We sought to review and assess the existing trauma scores used in pediatric patients. Our objective is to determine their wideness of use, validity, setting of use, outcome measures, and criticisms. We believe that there is a need for an adapted trauma score developed specifically for pediatric patients in low-resource settings.

MATERIALS AND METHODS

A systematic review of the literature was conducted to identify and compare existing injury scores used in pediatric patients. We constructed a search strategy in collaboration with a senior hospital librarian. Multiple databases were searched, including Embase, Medline, and the Cochrane Central Register of Controlled Trials. Articles were selected based on predefined inclusion criteria by two reviewers and underwent qualitative analysis.

RESULTS

The scores identified are suboptimal for use in pediatric patients in low-resource settings due to various factors, including reliance on precise anatomic diagnosis, physiologic parameters maladapted to pediatric patients, or laboratory data with inconsistent accessibility in LMIC.

CONCLUSION

An important gap exists in our ability to simply and reliably estimate injury severity in pediatric patients and predict their associated probability of outcomes in settings, where resources are limited. An ideal score should be easy to calculate using point-of-care data that are readily available in LMIC, and can be easily adapted to the specific physiologic variations of different age groups.

Blast injury in children: an analysis from Afghanistan and Iraq, 2002-2010

BACKGROUND

Throughout history, children have been victims of armed conflict, including the blast injury complex, however, the pattern of injury, physiologic impact, and treatment needs of children with this injury are not well documented.

METHODS

The Joint Theatre Trauma Registry provides data on all civilians admitted to US military treatment facilities from 2002 to 2010 with injuries from an explosive device. The data were stratified by age and analyzed for differences in anatomic injury patterns, Injury Severity Score (ISS), Revised Trauma Score (RTS), mortality, intensive care unit days, and length of hospitalization. Multivariate logistic regression was done to determine independent predictors of mortality. All operative procedures with a specified site were tabulated and categorized by body region and age.

RESULTS

A total of 4,983 civilian patients were admitted, 25% of whom were younger than 15 years. Pediatric patients aged 8 to 14 years had a higher ISS and hospital stay than other age groups, and children younger than 15 years had a longer intensive care unit stay. Injuries in children were more likely to occur in the head and neck and less likely in the bony pelvis and extremities. Children had a lower RTS than the other age groups. Mortality correlated highly with burns, head injury, transfusion, and RTS. Adolescent patients had a lower mortality rate than the other age groups. Improvised explosive devices were the most common cause of injury in all age groups.

CONCLUSION

Children experiencing blast injury complex have an anatomic pattern that is unique and an RTS that reflects more severe physiologic derangement. Injuries requiring transfusion or involving the head and neck and burns were predictive of mortality, and this persisted across all age groups. The mortality rate of children with blast injury is significant (7%), and treatment is resource intensive, requiring many surgical subspecialties.

LEVEL OF EVIDENCE

Epidemiologic study, level III.

Diffuse brain injury in the immature rat: evidence for an age-at-injury effect on cognitive function and histopathologic damage

Diffuse axonal injury is a significant component of the pathology of moderate-severe pediatric traumatic brain injury in children less than 4 years of age, and is associated with poor cognitive outcome. However, cognitive deficits or gross histopathologic abnormalities are typically not observed following moderate-severe diffuse brain injury in the immature (17-day-old) rat. In order to test whether the age of the immature animal may influence post-traumatic outcome, non-contusive brain trauma was induced in post-natal day (PND) 11 or 17 rats. Brain injury in the PND11 rat, but not in the PND17 rat, was associated with a significant acquisition deficit at 28 days post-injury (p<0.0005 compared with age-matched sham rats, and with brain-injured PND17 rats). All brain-injured animals exhibited a retention deficit in the probe trial (p<0.001), but also demonstrated a significant visual deficit in the visible platform trial (p<0.05 compared to sham animals). Although significantly longer times of apnea and loss of righting reflex were observed in brain-injured PND17 rats compared to PND11 rats (p<0.05), overt cytoarchitectural alterations and reactive gliosis were not observed in the older age group. No focal pathology was observed in the cortex below the impact site in the PND11 rat but by 28 days, the brain-injured PND11 rat exhibited atrophy in multiple brain regions and an enlarged lateral ventricle in the impact hemisphere. Quantitative analysis revealed a time-dependent increase in tissue loss in the injured hemisphere (7-10%) in the younger animals, and a modest extent of tissue loss in the older animals (3-4%). Traumatic axonal injury was observed to similar extents in the white matter and thalamus below the impact site in both brain-injured PND11 and 17 rats. These data demonstrate that non-contusive (diffuse) brain injury of moderate severity in the immature rat is associated with chronic cognitive deficits and long-term histopathologic alterations and suggest that the age-at-injury is an important parameter of behavioral and pathologic outcome following closed head injury in the immature age group.

Brain tissue oxygen monitoring in pediatric patients with severe traumatic brain injury

OBJECT

Intracranial pressure (ICP) and cerebral perfusion pressure (CPP) monitoring are fundamental to the management of severe traumatic brain injury (TBI). In adults, brain tissue oxygen monitoring (specifically PO2) and treatment have been shown to be safe additions to conventional neurocritical care and are associated with improved outcome. Brain tissue oxygen monitoring, however, has not been described in pediatric patients with TBI. In this report, the authors present preliminary experience with the use of ICP and PO2 monitoring in this population.

METHODS

Pediatric patients (age <18 years) with severe TBI (Glasgow Coma Scale score <8) admitted to a Level 1 trauma center who underwent ICP and PO2 monitoring were evaluated. Therapy was directed at maintaining ICP below 20 mm Hg and age-appropriate CPP (> or =40 mm Hg). Data obtained in six patients (two girls and four boys ranging in age from 6-16 years) were analyzed. Brain tissue oxygen levels were significantly higher (p < 0.01) at an ICP of less than 20 mm Hg (PO2 29.29 +/- 7.17 mm Hg) than at an ICP of greater than or equal to 20 mm Hg (PO2 22.83 +/- 13.85 mm Hg). Significant differences (p < 0.01) were also measured when CPP was less than 40 mm Hg (PO2 2.53 +/- 7.98 mm Hg) and greater than or equal to 40 mm Hg (PO2 28.97 +/- 7.85 mm Hg).

CONCLUSIONS

Brain tissue oxygen monitoring may be a safe and useful addition to ICP monitoring in the treatment of pediatric patients with severe TBI.

Functional status after childhood traumatic brain injury

BACKGROUND

Identification of children after traumatic brain injury (TBI) likely to have functional deficits at trauma center discharge will facilitate care.

METHODS

Two logistic regression models were derived from data on 4,439 children after TBI 7 to 14 years old enrolled in the National Pediatric Trauma Registry between 1994 and 2001 to predict physical and cognitive disabilities.

RESULTS

Children with open or multiple fractures or closed fractures or injured by motor vehicles were 8.2, 3.5, or 2.5 times more likely, respectively, than those without those circumstances to have discharge physical disabilities. Likelihood of cognitive impairment was increased by factors of 3.2 and 5.8 in children obtunded or comatose on arrival. Preexisting cognitive deficits, injury severity, and intubation predicted physical and cognitive disabilities. The C statistic was 0.862 for the motor model and 0.860 for the cognitive model.

CONCLUSION

Predicting the likelihood of morbidity after acute management of childhood TBI can provide information pertinent to providing effective care.

Progesterone Differentially Regulates Pro- and Anti-Apoptotic Gene Expression in Cerebral Cortex Following Traumatic Brain Injury in Rats

Although the administration of progesterone has been shown to be neuroprotective in experimental models of traumatic brain injury (TBI), the mechanisms for this beneficial effect are still poorly understood. The present study examined the effects of progesterone on mRNA and protein levels of the Bcl-2 apoptosis regulatory genes, bax, bad, bcl-2, and bcl-x(L), in cerebral cortex after TBI. Male Sprague-Dawley rats were subjected to either sham surgery or lateral fluid percussion brain injury of moderate severity (2.4-2.6 atm). Within 1 h post-surgery, progesterone (4 mg/kg) or vehicle (corn oil) administration was initiated for 1-7 days postoperatively. Our results indicate that bax and bad mRNA levels and Bax and Bad protein expression in the ipsilateral, injured cerebral cortex were significantly elevated post-TBI, while mRNA levels of bcl-2 and bcl-x(L) or Bcl-2 and Bcl-x(L) protein expression were not changed. Under the sham-treated condition, progesterone significantly increased mRNA levels of the anti-apoptotic gene, bcl-2, but down-regulated pro-apoptotic gene expression (bax and bad) in cerebral cortex. After TBI, progesterone treatment reduced bax and bad mRNA levels in the ipsilateral cerebral cortex of TBI rats, and decreased Bax and Bad protein levels. In addition, bcl-2 and bcl-x(L) mRNA levels, as well as Bcl-2 and Bcl-x(L) protein expression, were increased by progesterone in TBI injured cortex. These data indicate that one of the neuroprotective mechanisms of progesterone may be related to its differential regulation of apoptotic signals.

Developing experimental models to address traumatic brain injury in children

Traumatic brain injury (TBI) is the leading cause of injury-related death and disability among children under the age of 15 years in the United States. Epidemiological studies have revealed that even within the pediatric population there are differences in incidence, gender differences, causes, types of injuries sustained, and mortality within age subdivisions. This heterogeneity must be taken into account when developing appropriate models to address TBI in children. This review explores the current developmental TBI models, including fluid percussion, weight drop, and controlled cortical impact. It also addresses unique considerations to modeling pediatric brain injury that require special attention when modeling and designing studies: age appropriateness, injury severity, evaluation of recovery, plasticity, and anesthesia.

Age-dependency of 45calcium accumulation following lateral fluid percussion: acute and delayed patterns

This study was designed to determine the regional and temporal profile of 45calcium (45Ca2+) accumulation following mild lateral fluid percussion (LFP) injury and how this profile differs when traumatic brain injury occurs early in life. Thirty-six postnatal day (P) 17, thirty-four P28, and 17 adult rats were subjected to a mild (approximately 2.75 atm) LFP or sham injury and processed for 45Ca2+ autoradiography immediately, 6 h, and 1, 2, 4, 7, and 14 days after injury. Optical densities were measured bilaterally within 16 regions of interest. 45Ca2+ accumulation was evident diffusely within the ipsilateral cerebral cortex immediately after injury (18-64% increase) in all ages, returning to sham levels by 2-4 days in P17s, 1 day in P28s, and 4 days in adults. While P17s showed no further 45Ca2+ accumulation, P28 and adult rats showed an additional delayed, focal accumulation in the ipsilateral thalamus beginning 2-4 days postinjury (12-49% increase) and progressing out to 14 days (26-64% increase). Histological analysis of cresyl violet-stained, fresh frozen tissue indicated little evidence of neuronal loss acutely (in all ages), but considerable delayed cell death in the ipsilateral thalamus of the P28 and adult animals. These data suggest that two temporal patterns of 45Ca2+ accumulation exist following LFP: acute, diffuse calcium flux associated with the injury-induced ionic cascade and blood brain barrier breakdown and delayed, focal calcium accumulation associated with secondary cell death. The age-dependency of posttraumatic 45Ca2+ accumulation may be attributed to differential biomechanical consequences of the LFP injury and/or the presence or lack of secondary cell death.