Hitting a moving target: Basic mechanisms of recovery from acquired developmental brain injury

Executive functioning, behavior, and white matter microstructure in the chronic phase after pediatric mild traumatic brain injury: results from the adolescent brain cognitive development study

BACKGROUND

Mild traumatic brain injury (mTBI) is common in children. Long-term cognitive and behavioral outcomes as well as underlying structural brain alterations following pediatric mTBI have yet to be determined. In addition, the effect of age-at-injury on long-term outcomes is largely unknown.

METHODS

Children with a history of mTBI (n = 406; Mage = 10 years, SDage = 0.63 years) who participated in the Adolescent Brain Cognitive Development (ABCD) study were matched (1:2 ratio) with typically developing children (TDC; n = 812) and orthopedic injury (OI) controls (n = 812). Task-based executive functioning, parent-rated executive functioning and emotion-regulation, and self-reported impulsivity were assessed cross-sectionally. Regression models were used to examine the effect of mTBI on these domains. The effect of age-at-injury was assessed by comparing children with their first mTBI at either 0-3, 4-7, or 8-10 years to the respective matched TDC controls. Fractional anisotropy (FA) and mean diffusivity (MD), both MRI-based measures of white matter microstructure, were compared between children with mTBI and controls.

RESULTS

Children with a history of mTBI displayed higher parent-rated executive dysfunction, higher impulsivity, and poorer self-regulation compared to both control groups. At closer investigation, these differences to TDC were only present in one respective age-at-injury group. No alterations were found in task-based executive functioning or white matter microstructure.

CONCLUSIONS

Findings suggest that everyday executive function, impulsivity, and emotion-regulation are affected years after pediatric mTBI. Outcomes were specific to the age at which the injury occurred, suggesting that functioning is differently affected by pediatric mTBI during vulnerable periods. Groups did not differ in white matter microstructure.

Do astrocytes act as immune cells after pediatric TBI?

Astrocytes are in contact with the vasculature, neurons, oligodendrocytes and microglia, forming a local network with various functions critical for brain homeostasis. One of the primary responders to brain injury are astrocytes as they detect neuronal and vascular damage, change their phenotype with morphological, proteomic and transcriptomic transformations for an adaptive response. The role of astrocytic responses in brain dysfunction is not fully elucidated in adult, and even less described in the developing brain. Children are vulnerable to traumatic brain injury (TBI), which represents a leading cause of death and disability in the pediatric population. Pediatric brain trauma, even with mild severity, can lead to long-term health complications, such as cognitive impairments, emotional disorders and social dysfunction later in life. To date, the underlying pathophysiology is still not fully understood. In this review, we focus on the astrocytic response in pediatric TBI and propose a potential immune role of the astrocyte in response to trauma. We discuss the contribution of astrocytes in the local inflammatory cascades and secretion of various immunomodulatory factors involved in the recruitment of local microglial cells and peripheral immune cells through cerebral blood vessels. Taken together, we propose that early changes in the astrocytic phenotype can alter normal development of the brain, with long-term consequences on neurological outcomes, as described in preclinical models and patients.

Growth Hormone Deficiency following Traumatic Brain Injury in Pediatric and Adolescent Patients: Presentation, Treatment, and Challenges of Transitioning from Pediatric to Adult Services

Traumatic brain injury (TBI) is increasingly recognized, with an incidence of approximately 110 per 100,000 in pediatric populations and 618 per 100,000 in adolescent and adult populations. TBI often leads to cognitive, behavioral, and physical consequences, including endocrinopathies. Deficiencies in anterior pituitary hormones (e.g., adrenocorticotropic hormone, thyroid-stimulating hormone, gonadotropins, and growth hormone [GH]) can negatively impact health outcomes and quality of life post-TBI. This review focuses on GH deficiency (GHD), the most common post-TBI pituitary hormone deficiency. GHD is associated with abnormal body composition, lipid metabolism, bone mineral density, executive brain functions, behavior, and height outcomes in pediatric, adolescent, and transition-age patients. Despite its relatively frequent occurrence, post-TBI GHD has not been well studied in these patients; hence, diagnostic and treatment recommendations are limited. Here, we examine the occurrence and diagnosis of TBI, retrospectively analyze post-TBI hypopituitarism and GHD prevalence rates in pediatric and adolescent patients, and discuss appropriate GHD testing strategies and GH dosage recommendations for these patients. We place particular emphasis on the ways in which testing and dosage recommendations may change during the transition phase. We conclude with a review of the challenges faced by transition-age patients and how these may be addressed to improve access to adequate healthcare. Little information is currently available to help guide patients with TBI and GHD through the transition phase and there is a risk of interrupted care; therefore, a strength of this review is its emphasis on this critical period in a patient's healthcare journey.

Family-centred service in paediatric acquired brain injury rehabilitation: Bridging the gaps

Background

Children and adolescents who sustain an acquired brain injury (ABI) can experience acute and ongoing difficulties in a range of cognitive and functional domains, and their families often experience significant life changes and challenges. Family-centred service is therefore considered best practice in paediatric ABI rehabilitation. Despite widespread acceptance of family-centred service in this context, recent literature indicates that family needs are often unrecognised and unmet following paediatric ABI. Although family-centred service was introduced in the field of developmental disability over five decades ago, there remains a lack of clarity about how this approach is implemented in practice. Additionally, limited literature has discussed the implementation of family-centred service in paediatric ABI rehabilitation despite key differences between ABI and developmental disability, including nature and timing of onset, rehabilitation foci, and impacts on families.

Aims

In this review, we aim to: (i) outline common sequelae of paediatric ABI with a focus on family outcomes; (ii) summarise paediatric rehabilitation and highlight opportunities for family support and involvement; (iii) discuss and synthesise literature across paediatric ABI rehabilitation and family-centred service to highlight gaps in knowledge and practice; and (v) identify clinical implications and future research directions.

Conclusions

There is a clear need for greater clarity and consensus regarding the implementation of family-centred service in paediatric ABI rehabilitation. This review highlights the importance of providing professional development opportunities for clinicians to increase competency in practising in a family-centred manner, and opportunities to actively involve, empower and support families within rehabilitation. This review also emphasises the importance of services implementing relevant supports to address family needs where possible and developing clear referral pathways so that families can access further support elsewhere when needed.

Metabolism of Exogenous [2,4-13C]β-Hydroxybutyrate following Traumatic Brain Injury in 21-22-Day-Old Rats: An Ex Vivo NMR Study

Traumatic brain injury (TBI) is leading cause of morbidity in young children. Acute dysregulation of oxidative glucose metabolism within the first hours after injury is a hallmark of TBI. The developing brain relies on ketones as well as glucose for energy. Thus, the aim of this study was to determine the metabolism of ketones early after TBI injury in the developing brain. Following the controlled cortical impact injury model of TBI, 21-22-day-old rats were infused with [2,4-¹³C]β-hydroxybutyrate during the acute (4 h) period after injury. Using ex vivo ¹³C-NMR spectroscopy, we determined that ¹³C-β-hydroxybutyrate (¹³C-BHB) metabolism was increased in both the ipsilateral and contralateral sides of the brain after TBI. Incorporation of the label was significantly higher in glutamate than glutamine, indicating that ¹³C-BHB metabolism was higher in neurons than astrocytes in both sham and injured brains. Our results show that (i) ketone metabolism was significantly higher in both the ipsilateral and contralateral sides of the injured brain after TBI; (ii) ketones were extensively metabolized by both astrocytes and neurons, albeit higher in neurons; (iii) the pyruvate recycling pathway determined by incorporation of the label from the metabolism of ¹³C-BHB into lactate was upregulated in the immature brain after TBI.

Risk factors for development of long-term mood and anxiety disorder after pediatric traumatic brain injury: a population-based, birth cohort analysis

OBJECTIVES

The objective of this study was to identify characteristics associated with an increased risk of anxiety and mood disorder prior to 25 years of age, in children who sustained a traumatic brain injury (TBI) prior to age 10.

METHODS

This population-based study identified 562 TBI cases from a 1976-1982 birth cohort in Olmsted County, Minnesota. TBI cases were manually confirmed and classified by injury severity. Separate Cox proportional hazards regression models were fit to estimate the association of TBI and secondary non-TBI related characteristics with the risk of a subsequent clinically determined anxiety or mood disorder. Multivariable-adjusted population attributable risk (PAR) estimates were calculated for TBI characteristics.

RESULTS

Older age at initial TBI and extracranial injury at time of initial TBI were significantly associated with an increased risk of anxiety (adjusted HR [95% CI]: 1.33 [1.16, 1.52] per 1-year increase and 2.41 [1.26, 4.59]), respectively. Older age at initial TBI was significantly associated with an increased risk of a mood disorder (adjusted HR 1.17 [1.08-1.27]).

CONCLUSION

In individuals sustaining a TBI prior to age 10, age at injury greater than 5 years old was the largest contributor to development of a mood or anxiety disorder.

Pediatric Traumatic Brain Injury: An Update on Preclinical Models, Clinical Biomarkers, and the Implications of Cerebrovascular Dysfunction

Traumatic brain injury (TBI) is a leading cause of pediatric morbidity and mortality. Recent studies suggest that children and adolescents have worse post-TBI outcomes and take longer to recover than adults. However, the pathophysiology and progression of TBI in the pediatric population are studied to a far lesser extent compared to the adult population. Common causes of TBI in children are falls, sports/recreation-related injuries, non-accidental trauma, and motor vehicle-related injuries. A fundamental understanding of TBI pathophysiology is crucial in preventing long-term brain injury sequelae. Animal models of TBI have played an essential role in addressing the knowledge gaps relating to pTBI pathophysiology. Moreover, a better understanding of clinical biomarkers is crucial to diagnose pTBI and accurately predict long-term outcomes. This review examines the current preclinical models of pTBI, the implications of pTBI on the brain’s vasculature, and clinical pTBI biomarkers. Finally, we conclude the review by speculating on the emerging role of the gut-brain axis in pTBI pathophysiology.

A population-based study of global outcome after moderate to severe traumatic brain injury in children and adolescents

OBJECTIVE

The primary aim of this study was to evaluate the global outcome longitudinally over 5 years in children and adolescents surviving moderate to severe traumatic brain injury (msTBI) to investigate changes in outcome over time. The secondary aim was to explore how age at the time of injury affected outcome.

METHODS

All children and adolescents (aged 0-17 years; subdivided into children aged 0-10 years and adolescents aged 11-17 years) with moderate (Glasgow Coma Scale [GCS] score 9-13) or severe (GCS score ≤ 8) TBI who were admitted to a level I trauma center in Norway over a 10-year period (2004-2014) were prospectively included. In addition, young adults (aged 18-24 years) with msTBI were included for comparison. Outcome was assessed with the Glasgow Outcome Scale-Extended (GOS-E) at 6 months, 12 months, and 5 years after injury. The effect of time since injury and age at injury on the probability of good outcome was estimated by the method of generalized estimating equations.

RESULTS

A total of 30 children, 39 adolescents, and 97 young adults were included, among which 24 children, 38 adolescents, and 76 young adults survived and were planned for follow-up. In-hospital mortality from TBI was 7% for children, 3% for adolescents, and 18% for young adults. In surviving patients at the 5-year follow-up, good recovery (GOS-E score 7 or 8) was observed in 87% of children and all adolescents with moderate TBI, as well as in 44% of children and 59% of adolescents with severe TBI. No patient remained in a persistent vegetative state. For all patients, the odds for good recovery increased from 6 to 12 months (OR 1.79, 95% CI 1.15-2.80; p = 0.010), although not from 12 months to 5 years (OR 0.98, 95% CI 0.62-1.55; p = 0.940). Children/adolescents (aged 0-17 years) had higher odds for good recovery than young adults (OR 2.86, 95% CI 1.26-6.48; p = 0.012).

CONCLUSIONS

In this population-based study of pediatric msTBI, surprisingly high rates of good recovery over 5 years were found, including good recovery for a large majority of children and all adolescents with moderate TBI. Less than half of the children and more than half of the adolescents with severe TBI had good outcomes. The odds for good recovery increased from 6 to 12 months and were higher in children/adolescents (aged 0-17 years) than in young adults.

Functional status 1 year after severe childhood traumatic brain injury predicts 7-year outcome: Results of the TGE study

BACKGROUND

Childhood severe traumatic brain injury (TBI) is a leading cause of long-lasting acquired disability, but predicting long-term functional outcome remains difficult.

OBJECTIVES

This study aimed to 1) describe the functional outcome at 1 and 7 years post-TBI; 2) determine the initial and concurrent factors associated with long-term outcome; and 3) evaluate the predictive value of functional status, overall disability level and intellectual ability measured at 1 year post-injury to determine 7-year clinically meaningful outcomes.

METHODS

Among the children (<16 years) consecutively included over 3 years in the Traumatisme Grave de l'Enfant (TGE) prospective longitudinal cohort study after accidental severe TBI, we studied the outcomes of 39 survivors at 1 and 7 years post-injury. Overall outcome included disability level (Glasgow Outcome Scale), functional status (Pediatric Injury Functional Outcome Scale), intellectual ability (Wechsler scales), executive functions (Behavior Rating Inventory of Executive Functions), behavior (Child Behavior Checklist) as well as neurological impairments and academic status.

RESULTS

Mean (SD) age of the 39 survivors at injury was 7.6 (4.6) years, and long-term evaluation was conducted at a mean of 7.8 years post-injury (range 5.9-9.3); 36% of participants were adults (≥18 years old). Most of the neurological impairments remained stable beyond 1 year after TBI, whereas overall disability level improved significantly from 1 to 7 years but remained highly variable, with almost half of participants presenting significant disability levels (moderate: 26%, or severe: 21%). Almost half of participants had significant cognitive, behavior and/or academic difficulties at 7 years post-TBI. On multivariate regression analysis, functional impairment at 1 year was the best predictor of severe disability at 7 years (F_(3,31)=13.18, p < 0.001, sensitivity=100%, specificity=78%).

CONCLUSIONS

Our results confirm the significant long-term impact of childhood severe TBI. All children with TBI should benefit from systematic follow-up, especially those with persistent functional deficits at 1 year post-injury, because the severity of functional impairment at 1 year seems the best predictor of long-term significant disability up to 7 years post-TBI.

Use of Motor Learning Strategies in Occupational Therapy for Children and Youth with Acquired Brain Injury

Motor learning strategies (MLS) can be used to promote motor skills acquisition in children and youth with acquired brain injury (ABI). While occupational therapists (OTs) likely use MLS in clinical practice, research has not investigated the extent and variety of their application.Aims: This study explored MLS use by OTs in pediatric ABI and factors influencing their application.Method: Individual video-recorded occupational therapy sessions for a sample of eight children/youth (ages 4-16) with ABI were evaluated via mixed methods approach. The Motor Learning Strategies Rating Instrument (MLSRI-22) quantified the extent of MLS use in each video. Directed content analysis of the videos explored the factors influencing how and when MLS were applied.Results: The most frequently used MLS were promoting problem solving, encouragement, directing attention to the body, permitting errors as part of learning, repetitive practice, and whole practice. Three themes described how and when the OTs used MLS: 1) Getting buy-in, 2) Going with the flow, and 3) Movement and thinking go hand-in-hand.Conclusions: The OTs frequently used MLS with children with ABI, appearing to select MLS based on factors related to the child, task, and environment. These findings are fundamental to future exploration of OT decision-making and evaluation of MLS effectiveness.

A Pro-social Pill? The Potential of Pharmacological Treatments to Improve Social Outcomes After Pediatric Traumatic Brain Injury

Traumatic brain injury (TBI) is a leading cause of injury-induced disability in young children worldwide, and social behavior impairments in this population are a significant challenge for affected patients and their families. The protracted trajectory of secondary injury processes triggered by a TBI during early life-alongside ongoing developmental maturation-offers an extended time window when therapeutic interventions may yield functional benefits. This mini-review explores the scarce but promising pre-clinical literature to date demonstrating that social behavior impairments after early life brain injuries can be modified by drug therapies. Compounds that provide broad neuroprotection, such as those targeting neuroinflammation, oxidative stress, axonal injury and/or myelination, may prevent social behavior impairments by reducing secondary neuropathology. Alternatively, targeted treatments that promote affiliative behaviors, exemplified by the neuropeptide oxytocin, may reduce the impact of social dysfunction after pediatric TBI. Complementary literature from other early life neurodevelopmental conditions such as hypoxic ischemic encephalopathy also provides avenues for future research in neurotrauma. Knowledge gaps in this emerging field are highlighted throughout, toward the goal of accelerating translational research to support optimal social functioning after a TBI during early childhood.

The Impact of Traumatic Injury to the Immature Human Brain: A Scoping Review with Insights from Advanced Structural Neuroimaging

Traumatic brain injury (TBI) during critical periods of early-life brain development can affect the normal formation of brain networks responsible for a range of complex social behaviors. Because of the protracted nature of brain and behavioral development, deficits in cognitive and socioaffective behaviors may not become evident until late adolescence and early adulthood, when such skills are expected to reach maturity. In addition, multiple pre- and post-injury factors can interact with the effects of early brain insult to influence long-term outcomes. In recent years, with advancements in magnetic-resonance-based neuroimaging techniques and analysis, studies of the pediatric population have revealed a link between neurobehavioral deficits, such as social dysfunction, with white matter damage. In this review, in which we focus on contributions from Australian researchers to the field, we have highlighted pioneering longitudinal studies in pediatric TBI, in relation to social deficits specifically. We also discuss the use of advanced neuroimaging and novel behavioral assays in animal models of TBI in the immature brain. Together, this research aims to understand the relationship between injury consequences and ongoing brain development after pediatric TBI, which promises to improve prediction of the behavioral deficits that emerge in the years subsequent to early-life injury.

Neutrophil-specific deletion of Syk results in recruitment-independent stabilization of the barrier and a long-term improvement in cognitive function after traumatic injury to the developing brain

While traumatic brain injury (TBI) is the leading cause of death and disability in children, we have yet to identify those pathogenic events that determine the extent of recovery. Neutrophils are best known as "first responders" to sites of infection and trauma where they become fully activated, killing pathogens via proteases that are released during degranulation. However, this activational state may generate substantial toxicity in the young brain after TBI that is partially due to developmentally regulated inadequate antioxidant reserves. Neutrophil degranulation is triggered via a downstream signaling pathway that is dependent on spleen tyrosine kinase (Syk). To test the hypothesis that the activational state of neutrophils is a determinant of early pathogenesis and long-term recovery, we compared young, brain-injured conditional knockouts of Syk (syk^f/fMRP8-cre⁺) to congenic littermates (syk^f/f). Based upon flow cytometry, there was an extended recruitment of distinct leukocyte subsets, including Ly6G⁺/Ly6C^- and Ly6G⁺/Ly6C^int, over the first several weeks post-injury which was similar between genotypes. Subsequent assessment of the acutely injured brain revealed a reduction in blood-brain barrier disruption to both high and low molecular weight dextrans and reactive oxygen species in syk^f/fMRP8-cre⁺ mice compared to congenic littermates, and this was associated with greater preservation of claudin 5 and neuronal integrity, as determined by Western blot analyses. At adulthood, motor learning was less affected in brain-injured syk^f/fMRP8-cre⁺ mice as compared to syk^f/f mice. Performance in the Morris Water Maze revealed a robust improvement in hippocampal-dependent acquisition and short and long-term spatial memory retention in syk^f/fMRP8-cre⁺ mice. Subsequent analyses of swim path lengths during hidden platform training and probe trials showed greater thigmotaxis in brain-injured syk^f/f mice than sham syk^f/f mice and injured syk^f/fMRP8-cre⁺ mice. Our results establish the first mechanistic link between the activation state of neutrophils and long-term functional recovery after traumatic injury to the developing brain. These results also highlight Syk kinase as a novel therapeutic target that could be further developed for the brain-injured child.

Endocrine Insights into the Pathophysiology of Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a class of neurodevelopmental disorders that affects males more frequently than females. Numerous genetic and environmental risk factors have been suggested to contribute to the development of ASD. However, no one factor can adequately explain either the frequency of the disorder or the male bias in its prevalence. Gonadal, thyroid, and glucocorticoid hormones all contribute to normal development of the brain, hence perturbations in either their patterns of secretion or their actions may constitute risk factors for ASD. Environmental factors may contribute to ASD etiology by influencing the development of neuroendocrine and neuroimmune systems during early life. Emerging evidence suggests that the placenta may be particularly important as a mediator of the actions of environmental and endocrine risk factors on the developing brain, with the male being particularly sensitive to these effects. Understanding how various risk factors integrate to influence neural development may facilitate a clearer understanding of the etiology of ASD.

Engaging children and adolescents with acquired brain injury and their families in goal setting: The clinician perspective

This paper explored clinicians' experiences of the goal setting process with children and adolescents with acquired brain injuries (ABI) and their families in paediatric neurorehabilitation. Semi-structured interviews were conducted with 13 clinicians, all members of an interdisciplinary paediatric rehabilitation service, who work with children and adolescents with ABI and their families. Interview transcripts and additional data were analysed using constructivist grounded theory methods. Three main themes and sub-themes were developed: (1) Seeing the bigger picture: Goals change over time; Families set bigger picture goals; Need-to-dos: Goals that the child/adolescent needs to achieve; and Want-to-dos: Goals that the child/adolescent wants to achieve; (2) Collaborating as a team: Everyone needs to be on the same page; Hearing the child's/adolescent's voice; and Parents as advocates; and (3) Recognizing and navigating challenges: Child-/adolescent- and family-related challenges and Time as a service-related challenge. Participants perceived the clinician's role during goal setting as that of an active collaborator, enabling children and adolescents with ABI and their families to generate meaningful goals. These findings demonstrate insights into goal setting in paediatric ABI neurorehabilitation from clinicians' perspectives, and highlight the importance of collaboration, flexibility and anticipation of challenges in facilitating children's, adolescents' and families' involvement in this process.

Examining the Effects of Anabolic-Androgenic Steroids on Repetitive Mild Traumatic Brain Injury (RmTBI) Outcomes in Adolescent Rats

Background: Repetitive mild traumatic brain injury (RmTBI) is increasingly common in adolescents. Anabolic–androgenic steroid (AAS) consumption among younger professional athletes is a significant risk factor for impaired neurodevelopment. Given the increased rates and overlapping symptomology of RmTBI and AAS use, we sought to investigate the behavioural and neuropathological outcomes associated with the AAS Metandienone (Met) and RmTBI on rats. Methods: Rats received either Met or placebo and were then administered RmTBIs or sham injuries, followed by a behavioural test battery. Post-mortem MRI was conducted to examine markers of brain integrity and qRT-PCR assessed mRNA expression of markers for neurodevelopment, neuroinflammation, stress responses, and repair processes. Results: Although AAS and RmTBI did not produce cumulative deficits, AAS use was associated with detrimental outcomes including changes to depression, aggression, and memory; prefrontal cortex (PFC) atrophy and amygdala (AMYG) enlargement; damaged white matter integrity in the corpus callosum; and altered mRNA expression in the PFC and AMYG. RmTBI affected general activity and contributed to PFC atrophy. Conclusions: Findings corroborate previous results indicating that RmTBI negatively impacts neurodevelopment but also demonstrates that AAS results in significant neuropathological insult to the developing brain.

Is Pediatric Traumatic Brain Injury Associated with Adult Alcohol Misuse?

Evidence suggests that pediatric traumatic brain injury (TBI) may be causally related to alcohol misuse later in life; however, the nature and extent of the association has not been well described. This study examined the relationship between pediatric TBI and adult alcohol misuse in a population sample ≥20 years of age. We sought to determine (1) whether first self-reported incidence of TBI with loss of consciousness (LOC) before the age of 20 increased the risk for alcohol misuse later in life; and (2) whether sex, injury severity, and age at time of injury modified the association. We found a greater likelihood of binge but not heavy drinking for those whose first self-reported TBI with LOC occurred before the age of 20 when compared with those whose first self-reported TBI with LOC occurred later in life (28.5% vs. 20.4%, p = 0.003). When limited to those with only mild TBI, the relationship to binge drinking remained significant (31.9% vs. 19.3%, p < 0.001) and was evident for both males (38.4% vs. 25.6%, p = 0.016) and females (20.9% vs. 12.4%, p = 0.044). When controlling for sex, age, and race/ethnicity, reporting a first TBI with LOC before age 20 was associated with binge drinking only for those with mild TBI (adjusted odds ratio [AOR] = 1.32; 95% confidence interval [CI] = 1.00-1.74). Results also showed that those with first TBI with LOC occurring between the ages of 10 and 19 years were more likely to binge drink as adults than those first injured earlier in life, regardless of TBI severity. Further research is needed at both the epidemiological and pre-clinical levels to better understand this relationship.

Treatment of Pediatric Concussion

Concussions have gained attention in medical literature, legal literature, and lay media over the past several years as a public health affecting children, particularly those who do not improve in the first few days after an injury. We discuss strategies for acute management immediately after a concussion and an introduction to medical and non-medical options for treatment of the complex symptoms that persist in some patients with concussions. We examine the role of rest and exercise during recovery. We briefly discuss the role of the multidisciplinary approach to concussion in a setting that engages multiple specialists. Finally, we address policy changes related to sport-concussions and their efficacy in improving long term outcomes.

Bridging the gap: Mechanisms of plasticity and repair after pediatric TBI

Traumatic brain injury is the leading cause of death and disability in the United States, and may be associated with long lasting impairments into adulthood. The multitude of ongoing neurobiological processes that occur during brain maturation confer both considerable vulnerability to TBI but may also provide adaptability and potential for recovery. This review will examine and synthesize our current understanding of developmental neurobiology in the context of pediatric TBI. Delineating this biology will facilitate more targeted initial care, mechanism-based therapeutic interventions and better long-term prognostication and follow-up.

Emotion regulation after acquired brain injury: a study of heart rate variability, attentional control, and psychophysiology

Primary objective: To examine the efficacy of heart rate variability biofeedback (HRV-BF) to treat emotional dysregulation in persons with acquired brain injury. Design: A secondary analysis of a quasi-experimental study which enrolled 13 individuals with severe chronic acquired brain injury participating in a community-based programme. Response-to-treatment was measured with two HRV resonance indices (low frequency activity [LF] and low frequency/high frequency ratio [LF/HF]). Main outcome: Behavior Rating Inventory of Executive Function-informant report (emotional control subscale [EC]). Results: Results show significant correlation between LF and EC with higher LF activity associated with greater emotional control; the association between LF/HF pre-post-change score and EC is not statistically significant. A moderation model, however, demonstrates a significant influence of attention on the relation between LF/HF change and EC when attention level is high, with an increase in LF/HF activity associated with greater emotional control. Conclusions: HRV-BF is associated with large increases in HRV, and it appears to be useful for the treatment of emotional dysregulation in individuals with severe acquired brain injury. Attention training may enhance an individual's emotional control.

Determinants of social behavior deficits and recovery after pediatric traumatic brain injury

Traumatic brain injury (TBI) during early childhood is associated with a particularly high risk of developing social behavior impairments, including deficits in social cognition that manifest as reduced social interactions, with profound consequences for the individuals' quality of life. A number of pre-injury, post-injury, and injury-related factors have been identified or hypothesized to determine the extent of social behavior problems after childhood TBI. These include variables associated with the individual themselves (e.g. age, genetics, the injury severity, and extent of white matter damage), proximal environmental factors (e.g. family functioning, parental mental health), and more distal environmental factors (e.g. socioeconomic status, access to resources). In this review, we synthesize the available evidence demonstrating which of these determinants influence risk versus resilience to social behavior deficits after pediatric TBI, drawing upon the available clinical and preclinical literature. Injury-related pathology in neuroanatomical regions associated with social cognition and behaviors will also be described, with a focus on findings from magnetic resonance imaging and diffusion tensor imaging. Finally, study limitations and suggested future directions are highlighted. In summary, while no single variable can alone accurately predict the manifestation of social behavior problems after TBI during early childhood, an increased understanding of how both injury and environmental factors can influence social outcomes provides a useful framework for the development of more effective rehabilitation strategies aiming to optimize recovery for young brain-injured patients.

Bell Ringers: Factors Related to Concussive Events in Children Playing Tackle Football

INTRODUCTION

Sports-related concussion is a significant pediatric health risk, given the number of children involved in sports and the vulnerability of developing brains. Although most research has focused on high school/college athletes, these findings may not be applicable to younger athletes.

METHOD

A mixed-methods analysis examined concussion incidence and sequelae in a cohort of 8- to 13-year-old males (N = 31) playing youth football and their parents. Parents provided background information and completed mood/behavioral questionnaires, and each athlete completed a neuropsychological battery.

RESULTS

Eight athletes (26%) had a history of concussion before assessment. Concussion risk was related to lack of medical evaluation in prior concussions, tackling exposure (in both offensive and defensive positions), and multisport participation. There were no cognitive or psychological differences based on concussion history.

DISCUSSION

Findings identify factors that may contribute to concussion risk in children and show the need for further research in this understudied population.

Identifying dyslexia risk for sport-related concussion management: Sensitivity and specificity of self-report and rapid naming

BACKGROUND

Dyslexia is the most common type of learning disability and studies have shown that student-athletes with learning disabilities sustain more concussions than their non-affected peers. However, current methods of dyslexia identification in college students are potentially invalid because they rely on students to self-report formal dyslexia diagnoses.

METHODS

To test the accuracy of self-report against two alternative methods of dyslexia screening, 94 college students completed three dyslexia symptom inventories, two rapid naming (RAN) tasks, and a standard word reading measure.

RESULTS

Reliability was acceptable for screening purposes on the inventories (α =.70, -.72), and excellent for RAN (α = .91, -.94). Specificity was acceptable (82.5%), but sensitivity was low (14.3%) when students self-reported suspected diagnoses of reading impairment. Sensitivity and specificity were higher for the digit RAN task (71 and 98%, respectively) compared to the letter RAN task (57 and 90%). Sensitivity (92.7%) and specificity (92.5%) were optimal when a cut-score of ≥27 seconds was used. A binary logistic regression showed digit RAN alone significantly predicted whether students were classified as typical or inefficient readers, p< .001, whereas the most reliable dyslexia inventory alone did not, p=.284. Including inventories along with RAN provided no additional predictive value.

CONCLUSION

Self-report inventories missed many cases of inefficient word reading. The digit RAN task classified 93.6% of the cases correctly compared to 72.3% for self-report inventory. Thus, we recommend that neuropsychologists working with college concussion management programs add to their baseline screening protocols the digit RAN task, which can be completed in less than one minute.

Longitudinal diffusion tensor imaging after pediatric traumatic brain injury: Impact of age at injury and time since injury on pathway integrity

Following pediatric traumatic brain injury (TBI), longitudinal diffusion tensor imaging may characterize alterations in initial recovery and subsequent trajectory of white matter development. Our primary aim examined effects of age at injury and time since injury on pathway microstructure in children ages 6-15 scanned 3 and 24 months after TBI. Microstructural values generated using tract-based spatial statistics extracted from core association, limbic, and projection pathways were analyzed using general linear mixed models. Relative to children with orthopedic injury, the TBI group had lower fractional anisotropy (FA) bilaterally in all seven pathways. In left-hemisphere association pathways, school-aged children with TBI had the lowest initial pathway integrity and showed the greatest increase in FA over time suggesting continued development despite incomplete recovery. Adolescents showed limited change in FA and radial diffusivity and had the greatest residual deficit suggesting relatively arrested development. Radial diffusivity was persistently elevated in the TBI group, implicating dysmyelination as a core contributor to chronic post-traumatic neurodegenerative changes. The secondary aim compared FA values over time in the total sample, including participants contributing either one or two scans to the analysis, to the longitudinal cases contributing two scans. For each pathway, FA values and effect sizes were very similar and indicated extremely small differences in measurement of change over time in the total and longitudinal samples. Statistical approaches incorporating missing data may reliably estimate the effects of TBI and provide increased power to identify whether pathways show neurodegeneration, arrested development, or continued growth following pediatric TBI. Hum Brain Mapp 37:3929-3945, 2016. © 2016 Wiley Periodicals, Inc.

Psychosocial and Executive Function Recovery Trajectories One Year after Pediatric Traumatic Brain Injury: The Influence of Age and Injury Severity

Time since traumatic brain injury (TBI) and developmental stage at injury may affect the trajectory of outcomes associated with adjustment and school success. We prospectively enrolled a cohort of 519 children with either TBI or orthopedic injury (OI) age 2.5-15 years to examine children's psychosocial and executive function outcomes at 3- and 12-months post-injury. Outcome measures included the Child Behavior Checklist (CBCL), Strengths and Difficulties Questionnaire (SDQ), and Behavior Rating Inventory of Executive Function (BRIEF) ratings. Controlling for pre-injury ratings and using the OI group as the reference, children with TBI, regardless of age or injury severity, had affective, anxiety, and attention-deficit/hyperactivity disorder (ADHD) problems on the CBCL. Symptom trajectories differed both by injury severity and age at injury. Children with mild and complicated mild TBI had a decreasing anxiety trajectory, whereas children with severe TBI had increasing symptoms. Children 6-11 years of age had high ADHD and affective scores; however, the youngest children had increasing symptoms over time. On the SDQ, peer relationships and prosocial behaviors were not significantly affected by TBI but were associated with family environment. Children with severe TBI had the worst executive function scores; however, mild and complicated mild/moderate TBI groups had clinically important working memory deficits. Hispanic ethnicity and strong social capital were positively associated with multiple outcomes. Children's recovery trajectories differed by injury severity, time since injury, and developmental stage when injured. Schools need to reassess children's skills over time as new problems in behavior and learning may emerge.

Vascular impairment as a pathological mechanism underlying long-lasting cognitive dysfunction after pediatric traumatic brain injury

Traumatic brain injury (TBI) is the leading cause of death and disability in children. Indeed, the acute mechanical injury often evolves to a chronic brain disorder with long-term cognitive, emotional and social dysfunction even in the case of mild TBI. Contrary to the commonly held idea that children show better recovery from injuries than adults, pediatric TBI patients actually have worse outcome than adults for the same injury severity. Acute trauma to the young brain likely interferes with the fine-tuned developmental processes and may give rise to long-lasting consequences on brain's function. This review will focus on cerebrovascular dysfunction as an important early event that may lead to long-term phenotypic changes in the brain after pediatric TBI. These, in turn may be associated with accelerated brain aging and cognitive dysfunction. Finally, since no effective treatments are currently available, understanding the unique pathophysiological mechanisms of pediatric TBI is crucial for the development of new therapeutic options.

Targeting the Epidemic: Interventions and Follow-up Are Necessary in the Pediatric Traumatic Brain Injury Clinic

Traumatic brain injury is a major public health problem in the pediatric population. Previously, management was acute emergency department/primary care evaluation with follow-up by primary care. However, persistent symptoms after traumatic brain injury are common, and many do not have access to a specialized traumatic brain injury clinic to manage chronic issues. The goal of this study was to determine the factors related to outcomes, and identify the interventions provided in this subspecialty clinic. Data were extracted from medical records of 151 retrospective and 403 prospective patients. Relationships between sequelae, injury characteristics, and clinical interventions were analyzed. Most patients returning to clinic were not fully recovered from their injury. Headaches were more common after milder injuries, and seizures were more common after severe. The majority of patients received clinical intervention. The presence of persistent sequelae for traumatic brain injury patients can be evaluated and managed by a specialty concussion/traumatic brain injury clinic ensuring that medical needs are met.

Pathophysiology and Management of Moderate and Severe Traumatic Brain Injury in Children

Traumatic brain injury remains a leading cause of morbidity and mortality in children. Key pathophysiologic processes of traumatic brain injury are initiated by mechanical forces at the time of trauma, followed by complex excitotoxic cascades associated with compromised cerebral autoregulation and progressive edema. Acute care focuses on avoiding secondary insults, including hypoxia, hypotension, and hyperthermia. Children with moderate or severe traumatic brain injury often require intensive monitoring and treatment of multiple parameters, including intracranial pressure, blood pressure, metabolism, and seizures, to minimize secondary brain injury. Child neurologists can play an important role in acute and long-term care. Acutely, as members of a multidisciplinary team in the intensive care unit, child neurologists monitor for early signs of neurological change, guide neuroprotective therapies, and transition patients to long-term recovery. In the longer term, neurologists are uniquely positioned to treat complications of moderate and severe traumatic brain injury, including epilepsy and cognitive and behavioral issues.

Pediatric Rodent Models of Traumatic Brain Injury

Due to a high incidence of traumatic brain injury (TBI) in children and adolescents, age-specific studies are necessary to fully understand the long-term consequences of injuries to the immature brain. Preclinical and translational research can help elucidate the vulnerabilities of the developing brain to insult, and provide model systems to formulate and evaluate potential treatments aimed at minimizing the adverse effects of TBI. Several experimental TBI models have therefore been scaled down from adult rodents for use in juvenile animals. The following chapter discusses these adapted models for pediatric TBI, and the importance of age equivalence across species during model development and interpretation. Many neurodevelopmental processes are ongoing throughout childhood and adolescence, such that neuropathological mechanisms secondary to a brain insult, including oxidative stress, metabolic dysfunction and inflammation, may be influenced by the age at the time of insult. The long-term evaluation of clinically relevant functional outcomes is imperative to better understand the persistence and evolution of behavioral deficits over time after injury to the developing brain. Strategies to modify or protect against the chronic consequences of pediatric TBI, by supporting the trajectory of normal brain development, have the potential to improve quality of life for brain-injured children.

Repetitive Mild Traumatic Brain Injury in the Developing Brain: Effects on Long-Term Functional Outcome and Neuropathology

Although accumulating evidence suggests that repetitive mild TBI (rmTBI) may cause long-term cognitive dysfunction in adults, whether rmTBI causes similar deficits in the immature brain is unknown. Here we used an experimental model of rmTBI in the immature brain to answer this question. Post-natal day (PND) 18 rats were subjected to either one, two, or three mild TBIs (mTBI) or an equivalent number of sham insults 24 h apart. After one or two mTBIs or sham insults, histology was evaluated at 7 days. After three mTBIs or sham insults, motor (d1-5), cognitive (d11-92), and histological (d21-92) outcome was evaluated. At 7 days, silver degeneration staining revealed axonal argyrophilia in the external capsule and corpus callosum after a single mTBI, with a second impact increasing axonal injury. Iba-1 immunohistochemistry showed amoeboid shaped microglia within the amygdalae bilaterally after mTBI. After three mTBI, there were no differences in beam balance, Morris water maze, and elevated plus maze performance versus sham. The rmTBI rats, however, showed impairment in novel object recognition and fear conditioning. Axonal silver staining was observed only in the external capsule on d21. Iba-1 staining did not reveal activated microglia on d21 or d92. In conclusion, mTBI results in traumatic axonal injury and microglial activation in the immature brain with repeated impact exacerbating axonal injury. The rmTBI in the immature brain leads to long-term associative learning deficit in adulthood. Defining the mechanisms damage from rmTBI in the developing brain could be vital for identification of therapies for children.

Metabolic Alterations in Developing Brain After Injury: Knowns and Unknowns

Brain development is a highly orchestrated complex process. The developing brain utilizes many substrates including glucose, ketone bodies, lactate, fatty acids and amino acids for energy, cell division and the biosynthesis of nucleotides, proteins and lipids. Metabolism is crucial to provide energy for all cellular processes required for brain development and function including ATP formation, synaptogenesis, synthesis, release and uptake of neurotransmitters, maintaining ionic gradients and redox status, and myelination. The rapidly growing population of infants and children with neurodevelopmental and cognitive impairments and life-long disability resulting from developmental brain injury is a significant public health concern. Brain injury in infants and children can have devastating effects because the injury is superimposed on the high metabolic demands of the developing brain. Acute injury in the pediatric brain can derail, halt or lead to dysregulation of the complex and highly regulated normal developmental processes. This paper provides a brief review of metabolism in developing brain and alterations found clinically and in animal models of developmental brain injury. The metabolic changes observed in three major categories of injury that can result in life-long cognitive and neurological disabilities, including neonatal hypoxia-ischemia, pediatric traumatic brain injury, and brain injury secondary to prematurity are reviewed.

The regulatory roles of non-coding RNAs in nerve injury and regeneration

Non-coding RNAs (ncRNAs), especially microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), have attracted much attention since their regulatory roles in diverse cell processes were recognized. Emerging studies demonstrate that many ncRNAs are differentially expressed after injury to the nervous system, significantly affecting nerve regeneration. In this review, we compile the miRNAs and lncRNAs that have been reported to be dysregulated following a variety of central and peripheral nerve injuries, including acquired brain injury, spinal cord injury, and peripheral nerve injury. We also list investigations on how these miRNAs and lncRNAs exert the regulatory actions in neurodegenerative and neuroregenerative processes through different mechanisms involving their interaction with target coding genes. We believe that comprehension of the expression profiles and the possible functions of ncRNAs during the processes of nerve injury and regeneration will help understand the molecular mechanisms responsible for post-nerve-injury changes, and may contribute to the potential use of ncRNAs as a diagnostic marker and therapeutic target for nerve injury.

Metabolic Alterations in Developing Brain After Injury: Knowns and Unknowns

Brain development is a highly orchestrated complex process. The developing brain utilizes many substrates including glucose, ketone bodies, lactate, fatty acids and amino acids for energy, cell division and the biosynthesis of nucleotides, proteins and lipids. Metabolism is crucial to provide energy for all cellular processes required for brain development and function including ATP formation, synaptogenesis, synthesis, release and uptake of neurotransmitters, maintaining ionic gradients and redox status, and myelination. The rapidly growing population of infants and children with neurodevelopmental and cognitive impairments and life-long disability resulting from developmental brain injury is a significant public health concern. Brain injury in infants and children can have devastating effects because the injury is superimposed on the high metabolic demands of the developing brain. Acute injury in the pediatric brain can derail, halt or lead to dysregulation of the complex and highly regulated normal developmental processes. This paper provides a brief review of metabolism in developing brain and alterations found clinically and in animal models of developmental brain injury. The metabolic changes observed in three major categories of injury that can result in life-long cognitive and neurological disabilities, including neonatal hypoxia-ischemia, pediatric traumatic brain injury, and brain injury secondary to prematurity are reviewed.

Noninvasive brain stimulation: the potential for use in the rehabilitation of pediatric acquired brain injury

Noninvasive brain stimulation (NIBS) offers the potential to modulate neural activity and recovery after acquired brain injury. There are few studies of NIBS in children, but a survey of those studies might provide insight into the potential for NIBS to modulate motor rehabilitation, seizures, and behavior in children. We surveyed the published literature prior to July 2014 for articles pertaining to children and NIBS with a focus on case series or trials. We also reviewed selected articles involving adults to illustrate specific points where the literature in children is lacking. A limited number of articles suggest that NIBS can transiently improve motor function. The evidence for an effect on seizures is mixed. Two open-label studies reported improvement of mood in adolescents with depression. NIBS may serve as a tool for pediatric neurorehabilitation, but many gaps in our knowledge must be filled before NIBS can be adopted as a clinical intervention. To move forward, the field needs adequately powered trials that can answer these questions. Such trials will be challenging to perform, will likely require multicenter collaboration, and may need to adopt novel trial designs that have been used with rare disorders.

Brain development in rodents and humans: Identifying benchmarks of maturation and vulnerability to injury across species

Hypoxic-ischemic and traumatic brain injuries are leading causes of long-term mortality and disability in infants and children. Although several preclinical models using rodents of different ages have been developed, species differences in the timing of key brain maturation events can render comparisons of vulnerability and regenerative capacities difficult to interpret. Traditional models of developmental brain injury have utilized rodents at postnatal day 7-10 as being roughly equivalent to a term human infant, based historically on the measurement of post-mortem brain weights during the 1970s. Here we will examine fundamental brain development processes that occur in both rodents and humans, to delineate a comparable time course of postnatal brain development across species. We consider the timing of neurogenesis, synaptogenesis, gliogenesis, oligodendrocyte maturation and age-dependent behaviors that coincide with developmentally regulated molecular and biochemical changes. In general, while the time scale is considerably different, the sequence of key events in brain maturation is largely consistent between humans and rodents. Further, there are distinct parallels in regional vulnerability as well as functional consequences in response to brain injuries. With a focus on developmental hypoxic-ischemic encephalopathy and traumatic brain injury, this review offers guidelines for researchers when considering the most appropriate rodent age for the developmental stage or process of interest to approximate human brain development.

Animal models of traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of mortality and morbidity both in civilian life and on the battlefield worldwide. Survivors of TBI frequently experience long-term disabling changes in cognition, sensorimotor function and personality. Over the past three decades, animal models have been developed to replicate the various aspects of human TBI, to better understand the underlying pathophysiology and to explore potential treatments. Nevertheless, promising neuroprotective drugs that were identified as being effective in animal TBI models have all failed in Phase II or Phase III clinical trials. This failure in clinical translation of preclinical studies highlights a compelling need to revisit the current status of animal models of TBI and therapeutic strategies.

The motor learning strategy instrument: interrater reliability within usual and virtual reality physical therapy interventions

PURPOSE

To evaluate and compare the interrater reliability of the Motor Learning Strategy Rating Instrument (MLSRI) within usual and virtual reality (VR) interventions for children with acquired brain injury.

METHODS

Two intervention sessions for each of 11 children (total, 22) were videotaped; sessions were provided by 4 physical therapists. Videotapes were divided into usual and VR components and rated by 2 observers using the MLSRI. A generalizability theory approach was used to determine interrater reliability for each intervention.

RESULTS

Interrater reliability for usual interventions was high for the MLSRI total score (g-coefficient, 0.81), whereas it was low for the VR total score (g-coefficient, 0.28); MLSRI category g-coefficients varied from 0.35 to 0.65 for usual and from 0.17 to 0.72 for VR interventions.

CONCLUSION

Adequate reliability was achieved within ratings of usual interventions; however, challenges related to MLSRI use to rate VR-based interventions require further evaluation.

Deficits in social behavior emerge during development after pediatric traumatic brain injury in mice

The pediatric brain may be particularly vulnerable to social deficits after traumatic brain injury (TBI) due to the protracted nature of psychosocial development through adolescence. However, the majority of pre-clinical studies fail to assess social outcomes in experimental pediatric TBI. The current study evaluated social behavior in mice subjected to TBI at post-natal day (p)21. Social behaviors were assessed by a partition test, resident-intruder, three-chamber, and tube dominance tasks during adolescence (p35-42) and again during early adulthood (p60-70), during encounters with unfamiliar, naïve stimulus mice. Despite normal olfactory function and normal social behaviors during adolescence, brain-injured mice showed impaired social investigation by adulthood, evidenced by reduced ano-genital sniffing and reduced following of stimulus mice in the resident-intruder task, as well as a loss of preference for sociability in the three-chamber task. TBI mice also lacked a preference for social novelty, suggestive of a deficit in social recognition or memory. By adulthood, brain-injured mice exerted more frequent dominance in the tube task compared to sham-operated controls, a finding suggestive of aggressive tendencies. Together these findings reveal reduced social interaction and a tendency towards increased aggression, which evolves across development to adulthood. This emergence of aberrant social behavior, which parallels the development of other cognitive deficits in this model and behaviors seen in brain-injured children, is consistent with the hypothesis that the full extent of deficits is not realized until the associated skills reach maturity. Thus, efficacy of therapeutics for pediatric TBI should take into account the time-dependent emergence of abnormal behavioral patterns.

Use of the King's Outcome Scale for Childhood Head Injury in the evaluation of outcome in childhood traumatic brain injury

OBJECTIVE

To examine the inter-rater reliability of The King's Outcome Scale for Childhood Head Injury (KOSCHI) with clinicians of varying experience in paediatric traumatic brain injury (TBI); and to examine change in outcome during long-term follow-up of children following traumatic brain injury (TBI) using KOSCHI.

METHOD

Retrospective assessment of detailed clinic reports of 97 children followed-up by a tertiary specialist paediatric brain injury service. Investigators were blinded to each other's scores.

RESULTS

Inter-rater reliability was substantial (weighted kappa 0.71) and similar for investigators of varying experience. KOSCHI outcome was strongly associated with markers of injury severity (p = 0.028). In longitudinal follow-up, KOSCHI score worsened in 7 (23%) children who were injured under 8 years but in no older children (p = 0.02).

CONCLUSION

KOSCHI has high inter-rater reliability for investigators of different experience. Long-term KOSCHI outcome is associated with injury severity. Some young children may develop worse disability over time.

Usual and virtual reality video game-based physiotherapy for children and youth with acquired brain injuries

Little is known about how therapists promote learning of functional motor skills for children with acquired brain injuries. This study explores physiotherapists' description of these interventions in comparison to virtual reality (VR) video game-based therapy. Six physiotherapists employed at a children's rehabilitation center participated in semi-structured interviews, which were transcribed and analyzed using thematic analysis. Physiotherapists describe using interventions that motivate children to challenge performance quality and optimize real-life functioning. Intervention strategies are influenced by characteristics of the child, parent availability to practice skills outside therapy, and therapist experience. VR use motivates children to participate, but can influence therapist use of verbal strategies and complicate interventions. Physiotherapists consider unique characteristics of this population when providing interventions that promote learning of motor skills. The VR technology has advantageous features but its use with this population can be challenging; further research is recommended.

Mechanisms and consequences of acquired brain injury during development

The brain of the infant and young child is a developing, dynamic, structure subject to functional remodelling under the influence of factors responsible for optimal neuronal development and synaptogenesis. It exhibits age dependent variation in metabolic rate, blood flow, and ability to tolerate oxidative stress. It is also characterized by an exuberance of neurotransmitter activity, particularly in the first few years of life. The dynamic evolution and adaptability of early brain function permits the organization of neuronal networks to be influenced by environmental stimulation, and, to reduce the functional impact of injury. However, these same processes may also exacerbate the harm sustained by the brain following an acquired brain injury (ABI). The developing neurons are susceptible to excitotoxicity, oxidative stress, and, inflammation, often leading to cellular necrosis and apoptosis. Despite being immunologically privileged via the blood brain barrier, the developing brain is susceptible to injury from systemic inflammation through alteration of normally protective cerebrovascular endothelial cell function. Finally, many of the therapeutic agents currently employed in post-ABI hospital care may also compromise ABI outcome via non-intended pharmacological effects. These agents include analgesic, sedative and anti-convulsant medications. This review emphasizes those physiological considerations in the developing brain which may impact the outcome after ABI, including, the cellular mechanisms of neuronal and cerebrovascular endothelial cell injury, ABI outcome and future therapeutic directions.

Social communication in young children with traumatic brain injury: relations with corpus callosum morphometry

The purpose of the present investigation was to characterize the relations of specific social communication behaviors, including joint attention, gestures, and verbalization, with surface area of midsagittal corpus callosum (CC) subregions in children who sustained traumatic brain injury (TBI) before 7 years of age. Participants sustained mild (n=10) or moderate-severe (n=26) noninflicted TBI. The mean age at injury was 33.6 months; mean age at MRI was 44.4 months. The CC was divided into seven subregions. Relative to young children with mild TBI, those with moderate-severe TBI had smaller surface area of the isthmus. A semi-structured sequence of social interactions between the child and an examiner was videotaped and coded for specific social initiation and response behaviors. Social responses were similar across severity groups. Even though the complexity of their language was similar, children with moderate-severe TBI used more gestures than those with mild TBI to initiate social overtures; this may indicate a developmental lag or deficit as the use of gestural communication typically diminishes after age 2. After controlling for age at scan and for total brain volume, the correlation of social interaction response and initiation scores with the midsagittal surface area of the CC regions was examined. For the total group, responding to a social overture using joint attention was significantly and positively correlated with surface area of all regions, except the rostrum. Initiating joint attention was specifically and negatively correlated with surface area of the anterior midbody. Use of gestures to initiate a social interaction correlated significantly and positively with surface area of the anterior and posterior midbody. Social response and initiation behaviors were selectively related to regional callosal surface areas in young children with TBI. Specific brainbehavior relations indicate early regional specialization of anterior and posterior CC for social communication.

Repeat traumatic brain injury in the developing brain

The Center for Disease Control estimates that there are 1.7 million brain injuries in the US each year with 51% of these injuries occurring during periods of cerebral development. Among this population there is a growing population of individuals with repeat traumatic brain injury (RTBI). While the exact incidence is unknown, estimates range from 5.6 to 36% of the TBI population. This review summarizes the clinical problems/challenges and experimental research models that currently exist. It is intended to reveal the critical areas that need to be addressed so that age-relevant clinical management guidelines can be established to protect this population.

Documenting the content of physical therapy for children with acquired brain injury: development and validation of the motor learning strategy rating instrument

BACKGROUND

A goal of physical therapy interventions for children and youth with acquired brain injury (ABI) is the learning and relearning of motor skills. Therapists can apply theoretically derived and evidence-based motor learning strategies (MLSs) to structure the presentation of a task and organize the environment in ways that may promote effective, transfer-oriented practice. However, little is known about how MLSs are used in physical therapy interventions for children with ABI.

OBJECTIVE

The purpose of this study was to develop and validate an observer-rated Motor Learning Strategy Rating Instrument (MLSRI) quantifying the application of MLSs in physical therapy interventions for children with ABI.

DESIGN

A multi-stage, iterative, item generation and reduction approach was used.

METHODS

An initial list of MLS items was generated through literature review. Seven experts participated in face validation to confirm item comprehensiveness. In a content validation process, 12 physical therapists with pediatric ABI experience responded to a questionnaire evaluating feasibility and importance of items. Six physical therapy sessions with clients with ABI were videotaped at a children's rehabilitation center. The 12 physical therapists participated in a session where they: (1) rated session videos to test the MLSRI and (2) provided verbal feedback.

RESULTS

Revisions were made sequentially to the MLSRI based on these processes.

LIMITATIONS

The MLSRI was scored during videotape observation rather than being given a live rating, which may be onerous in certain settings and may influence therapist or child behavior.

CONCLUSIONS

Further reliability investigations will determine whether the 33-item MLSRI is of help in documenting strategy use during intervention, as an evaluation tool in research, and as a knowledge transfer resource in clinical practice.