Lasting effects of pediatric traumatic brain injury

Pathophysiology of Pediatric Traumatic Brain Injury

The national incidence of traumatic brain injury (TBI) exceeds that of any other disease in the pediatric population. In the United States the Centers for Disease Control and Prevention (CDC) reports 697,347 annual TBIs in children ages 0–19 that result in emergency room visits, hospitalization or deaths. There is a bimodal distribution within the pediatric TBI population, with peaks in both toddlers and adolescents. Preclinical TBI research provides evidence for age differences in acute pathophysiology that likely contribute to long-term outcome differences between age groups. This review will examine the timecourse of acute pathophysiological processes during cerebral maturation, including calcium accumulation, glucose metabolism and cerebral blood flow. Consequences of pediatric TBI are complicated by the ongoing maturational changes allowing for substantial plasticity and windows of vulnerabilities. This review will also examine the timecourse of later outcomes after mild, repeat mild and more severe TBI to establish developmental windows of susceptibility and altered maturational trajectories. Research progress for pediatric TBI is critically important to reveal age-associated mechanisms and to determine knowledge gaps for future studies.

Behavioral consequences of mild traumatic brain injury in preschoolers

BACKGROUND

Pediatric traumatic brain injury (TBI) is a leading cause of long-term disability in children and adolescents worldwide. Amongst the wide array of consequences known to occur after pediatric TBI, behavioral impairments are among the most widespread and may particularly affect children who sustain injury early in the course of development. The aim of this study was to investigate the presence of internalizing and externalizing behavioral problems 6 months after preschool (i.e. 18-60 months old) mild TBI.

METHODS

This work is part of a prospective, longitudinal cohort study of preschool TBI. Participants (N = 229) were recruited to one of three groups: children with mild TBI, typically developing children and orthopedic injured (OI) children. Mothers of children in all three groups completed the Child Behavior Checklist as a measure of behavioral outcomes 6-month post-injury. Demographics, injury-related characteristics, level of parental distress, and estimates of pre-injury behavioral problems were also documented.

RESULTS

The three groups did not differ on baseline characteristics (e.g. demographics and pre-injury behavioral problems for the mild TBI and OI groups) and level of parental distress. Mothers' ratings of internalizing and externalizing behaviors were higher in the mild TBI group compared with the two control groups. Pre-injury behavioral problems and maternal distress were found to be significant predictors of outcome.

CONCLUSION

Our results show that even in its mildest form, preschool TBI may cause disruption to the immature brain serious enough to result in behavioral changes, which persist for several months post-injury.

Delayed and progressive damages to juvenile mice after moderate traumatic brain injury

Symptoms are commonly more severe in pediatric traumatic brain injury (TBI) patients than in young adult TBI patients. To understand the mechanism, juvenile mice received a controlled cortical impact (CCI) injury at moderate level. Tissue lesion and cell death were measured and compared to our previous reports on brain injury in the young adult mice that received same level of impact using same injury device. Tissue lesion and cell death in the cortex was much less in the juvenile mouse brain in the first few hours after injury. However, once the injury occurred, it developed more rapidly, lasted much longer, and eventually led to exaggerated cell death and a 32.7% larger tissue lesion cavity in the cortex of juvenile mouse brain than of young adult mouse brain. Moreover, we found significant cell death in the thalamus of juvenile brains at 72 h, which was not commonly seen in the young adult mice. In summary, cell death in juvenile mice was delayed, lasted longer, and finally resulted in more severe brain injury than in the young adult mice. The results suggest that pediatric TBI patients may have a longer therapeutic window, but they also need longer intensive clinical care after injury.

Pediatric gunshot penetrating head injury: a case report with 2-year follow-up

Gunshot is a rare subset of penetrating head injury, and generally the victim dies before arriving at the hospital. This paper reported a case of an intracranial gunshot injury in a 12 year-old boy that was shot by his friend, whose primary intention was to play around, using a revolver. A missile projectile penetrated from mid frontal and came out from right occipital. Vital signs were stable with GCS 8 from physical examination. A rational management strategy should permit a good outcome. The only complications that occured were hydrocephalus, yet it was managed by VP–shunt. Skull defect was closed using titanium mesh. A two-year follow-up showed a good result. The patient was able to do daily activity and back to school again.

Repetitive mild traumatic brain injury induces ventriculomegaly and cortical thinning in juvenile rats

Traumatic brain injury (TBI) most frequently occurs in pediatric patients and remains a leading cause of childhood death and disability. Mild TBI (mTBI) accounts for nearly 75% of all TBI cases, yet its neuropathophysiology is still poorly understood. While even a single mTBI injury can lead to persistent deficits, repeat injuries increase the severity and duration of both acute symptoms and long-term deficits. In this study, to model pediatric repetitive mTBI (rmTBI) we subjected unrestrained juvenile animals (postnatal day 20) to repeat weight-drop impacts. Animals were anesthetized and subjected to sham injury or rmTBI once per day for 5 days. Magnetic resonance imaging (MRI) performed 14 days after injury revealed marked cortical atrophy and ventriculomegaly in rmTBI animals. Specifically, beneath the impact zone the thickness of the cortex was reduced by up to 46% and the area of the ventricles increased by up to 970%. Immunostaining with the neuron-specific marker NeuN revealed an overall loss of neurons within the motor cortex but no change in neuronal density. Examination of intrinsic and synaptic properties of layer II/III pyramidal neurons revealed no significant difference between sham-injured and rmTBI animals at rest or under convulsant challenge with the potassium channel blocker 4-aminopyridine. Overall, our findings indicate that the neuropathological changes reported after pediatric rmTBI can be effectively modeled by repeat weight drop in juvenile animals. Developing a better understanding of how rmTBI alters the pediatric brain may help improve patient care and direct "return to game" decision making in adolescents.

A neurovascular perspective for long-term changes after brain trauma

Traumatic brain injury (TBI) affects all age groups in a population and is an injury generating scientific interest not only as an acute event, but also as a complex brain disease with several underlying neurobehavioral and neuropathological characteristics. We review early and long-term alterations after juvenile and adult TBI with a focus on changes in the neurovascular unit (NVU), including neuronal interactions with glia and blood vessels at the blood-brain barrier (BBB). Post-traumatic changes in cerebral blood-flow, BBB structures and function, as well as mechanistic pathways associated with brain aging and neurodegeneration are presented from clinical and experimental reports. Based on the literature, increased attention on BBB changes should be integrated in studies characterizing TBI outcome and may provide a meaningful therapeutic target to resolve detrimental post-traumatic dysfunction.

Evolution of the cognitive profile in school-aged patients with severe TBI during the first 2 years of neurorehabilitation

OBJECTIVE

Persistent post-injury cognitive, academic and behavioural deficits have been documented in children who sustained severe TBI during the school-age years. The major aim of this study was to examine and follow-up for 2 years the cognitive profile of a sample of post-injured patients (aged 6-16.11), in order to verify to what extent they recovered their intellectual functions after rehabilitation.

METHOD

Twenty-six patients who received a specific neuropsychological treatment and three cognitive evaluations with WISC-III were selected from a pool of 77.

RESULTS

This group of patients showed a mild cognitive deficit at baseline, which improved over the 2 years to a borderline level. Despite the improvement in intellectual quotients and single sub-test scores achieved through rehabilitation, different recovery times were seen according to the function under study. The most common deficits are in processing speed, inferential and lexical-semantic skills.

CONCLUSIONS

Detailed analysis of the WISC-III sub-tests allows for an accurate description of single cognitive functions after TBI. This allows one to make differential diagnoses between functional profiles and plan individualized rehabilitation treatments. Post-injured school-aged patients should receive rehabilitation for a period of at least 2 years, which is the time necessary for an at-least partial reorganization of basic cognitive functions.

Juvenile traumatic brain injury evolves into a chronic brain disorder: behavioral and histological changes over 6months

Traumatic brain injury (TBI) refers to physical trauma to the brain that can lead to motor and cognitive dysfunctions. TBI is particularly serious in infants and young children, often leading to long-term functional impairments. Although clinical research is useful for quantifying and observing the effects of these injuries, few studies have empirically assessed the long-term effects of juvenile TBI (jTBI) on behavior and histology. After a controlled cortical impact delivered to postnatal 17day old rats, functional abilities were measured after 3, 5, and 6months using open field (activity levels), zero maze (anxiety-like behaviors), rotarod (sensorimotor abilities, coordination, and balance), and water maze (spatial learning and memory, swim speed, turn bias). Sensorimotor function was impaired for up to 6months in jTBI animals, which showed no improvement from repeated test exposure. Although spatial learning was not impaired, spatial memory deficits were observed in jTBI animals starting at 3months after injury. Magnetic resonance imaging and histological data revealed that the effects of jTBI were evolving for up to 6months post-injury, with reduced cortical thickness, decreased corpus callosum area and CA1 neuronal cell death in jTBI animals distant to the impact site. These findings suggest that this model of jTBI produces long-term impairments comparable to those reported clinically. Although some deficits were stable over time, the variable nature of other deficits (e.g., memory) as well as changing properties of the lesion itself, suggest that the effects of a single jTBI produce a chronic brain disorder with long-term complications.