The UCLA study of Predictors of Cognitive Functioning Following Moderate/Severe Pediatric Traumatic Brain Injury

Evidence Suggesting Prolonged Neuroinflammation in a Subset of Children after Moderate/Severe TBI: A UCLA RAPBI Study

Traumatic brain injury (TBI) presents a public health concern as a leading cause of death and disability in children. Pediatric populations are particularly vulnerable to adverse outcomes following TBI due to periods of rapid growth, synaptic pruning, and myelination. Pediatric patients with moderate-severe TBI (msTBI) and healthy controls were evaluated from the post-acute (2-5 months) to chronic phase (13-19 months) of recovery using diffusion magnetic resonance imaging (dMRI) and interhemispheric transfer time (IHTT), which is an event-related potential measure the speed of information transfer across the corpus callosum. We previously identified two subgroups of patients based on IHTT, with one group showing a significantly slower IHTT (TBI-slow), poorer cognitive performance, and progressive structural damage. In contrast, the other group (TBI-normal) did not differ from controls on IHTT or cognitive performance and showed relative structural recovery over time. Here, we examined group differences in restricted diffusion imaging (RDI), which is a dMRI metric sensitive to inflammation. Comparing TBI-slow, TBI-normal, and controls on RDI cross-sectionally, dMRI connectometry analysis revealed higher RDI across the white matter in the TBI-slow group compared to both the control and TBI-normal groups. Longitudinal analyses indicated that while both TBI groups exhibited a decrease in RDI over time, suggesting resolution of neuroinflammation and recovery, the decreases in the TBI-slow group were smaller. The differences in RDI between TBI-slow and TBI-normal suggest that inflammation may play a key role in the prolonged recovery, including brain structure, cognitive performance, and symptom reports, of pediatric patients with msTBI.

The neurocognitive correlates of DTI indicators of white matter disorganization in pediatric moderate-to-severe traumatic brain injury

Introduction

Neuroimaging has expanded our understanding of pediatric brain disorders in which white matter organization and connectivity are crucial to functioning. Paralleling the known pathobiology of many neurodevelopmental disorders, traumatic brain injury (TBI) in childhood can alter trajectories of brain development. Specifically, diffusion tensor imaging (DTI) studies in TBI have demonstrated white matter (WM) abnormalities that suggest microstructural disruptions that may underlie atypical neurodevelopment. The neurocognitive correlates of these previous findings will be explored in this study.

Methods

Indicators of WM organization were collected in 44 pediatric patients with moderate/severe TBI and 76 controls over two post-injury time points: T1 (8-20 weeks) and T2 (54-96 weeks). Our previous work identified two TBI subgroups based on information processing differences: one with slower interhemispheric transfer times (IHTT) of visual information than controls and another with comparable IHTT. We extend this prior work by evaluating neurocognitive trajectories associated with divergent WM structure post-injury in slow and normal IHTT TBI subgroups.

Results

At T1, both TBI subgroups performed significantly worse than controls on a norm-referenced working memory index (WMI), but only the Normal IHTT TBI subgroup significantly improved over the 12-month follow-up period (p = 0.014) to match controls (p = 0.119). In contrast, the Slow IHTT TBI subgroup did not show any recovery in working memory performance over time and performed more poorly than the control group (p < 0.001) at T2. Improvement in one of the two WMI subtests was associated with DTI indicators of WM disorganization in CC tracts to the precentral, postcentral, frontal, and parietal cortices. IHTT and WM mean diffusivity predicted 79% of the variance in cognitive recovery from T1 to T2 when also accounting for other known predictors of TBI recovery.

Discussion

In the year following TBI, some pediatric patients experienced persisting working memory disturbance while others exhibited recovery; stratification was based on an event-related potential marker. More or less improvement in neurocognition was also associated with the degree of WM disorganization. IHTT, measured post-acutely after TBI, and progression of WM disorganization over time predicted neurocognitive trajectories at the chronic timeframe - potentially representing a prognostic biomarker.

Processing speed and its association with working memory and episodic memory 3-6 months after pediatric mild traumatic brain injury

OBJECTIVE

Following mild traumatic brain injury (mTBI), children show reduced processing speed (PS). Evidence suggests that slowed PS after TBI is associated with working memory deficits. Our aim was to investigate several forms of PS and to examine its impact on working and episodic memory performance in children after mTBI.

METHOD

We included data of 64 children after mTBI and 57 healthy control children aged 8-16 years. PS (Color Naming, Coding, Symbol Search, Alertness) was compared between groups 1 week (T1) and 3-6 months (T2) after the injury; working and episodic memory outcome was compared between groups at T2.

RESULTS

Alertness at T1 and Color Naming at T1 and T2 were significantly reduced following mTBI compared to controls, although most group differences in PS disappeared when patients with previous impairments and mTBI were excluded. PS was predictive for episodic and working memory performance 3-6 months after injury, whereas group was a significant predictor of working memory.

CONCLUSIONS

Compared to healthy controls, children after mTBI showed reduced performance in verbal PS, which was associated with working memory. In children who are symptomatic after mTBI, diagnostic screening of PS could be helpful in identifying patients that could profit from speed-improving strategies.

Impaired episodic verbal memory recall after 1 week and elevated forgetting in children after mild traumatic brain injury - results from a short-term longitudinal study

Objective

There is preliminary evidence that children after traumatic brain injury (TBI) have accelerated long-term forgetting (ALF), i.e., an adequate learning and memory performance in standardized memory tests, but an excessive rate of forgetting over delays of days or weeks. The main aim of this study was to investigate episodic memory performance, including delayed retrieval 1 week after learning, in children after mild TBI (mTBI).

Methods

This prospective study with two time-points (T1: 1 week after injury and T2: 3-6 months after injury), included data of 64 children after mTBI and 57 healthy control children aged between 8 and 16 years. We assessed episodic learning and memory using an auditory word learning test and compared executive functions (interference control, working memory, semantic fluency and flexibility) and divided attention between groups. We explored correlations between memory performance and executive functions. Furthermore, we examined predictive factors for delayed memory retrieval 1 week after learning as well as for forgetting over time.

Results

Compared to healthy controls, patients showed an impaired delayed recall and recognition performance 3-6 months after injury. Executive functions, but not divided attention, were reduced in children after mTBI. Furthermore, parents rated episodic memory as impaired 3-6 months after injury. Additionally, verbal learning and group, but not executive functions, were predictive for delayed recall performance at both time-points, whereas forgetting was predicted by group.

Discussion

Delayed recall and forgetting over time were significantly different between groups, both post-acutely and in the chronic phase after pediatric mTBI, even in a very mildly injured patient sample. Delayed memory performance should be included in clinical evaluations of episodic memory and further research is needed to understand the mechanisms of ALF.

Exposure to Sedation and Analgesia Medications: Short-term Cognitive Outcomes in Pediatric Critical Care Survivors With Acquired Brain Injury

Background/Objective: Pediatric intensive care unit (PICU) survivors risk significant cognitive morbidity, particularly those with acquired brain injury (ABI) diagnoses. Studies show sedative and analgesic medication may potentiate neurologic injury, but few studies evaluate impact on survivor outcomes. This study aimed to evaluate whether exposures to analgesic and sedative medications are associated with worse neurocognitive outcome. Methods: A retrospective cohort study was conducted of 91 patients aged 8 to 18 years, undergoing clinical neurocognitive evaluation approximately 1 to 3 months after PICU discharge. Electronic health data was queried for sedative and analgesic medication exposures, including opioids, benzodiazepines, propofol, ketamine, and dexmedetomidine. Doses were converted to class equivalents, evaluated by any exposure and cumulative dose exposure per patient weight. Cognitive outcome was derived from 8 objective cognitive assessments with an emphasis on executive function skills using Principal Components Analysis. Then, linear regression was used to control for baseline cognitive function estimates to calculate a standardized residualized neurocognitive index (rNCI) z-score. Multivariable linear regression evaluated the association between rNCI and medication exposure controlling for covariates. Significance was defined as P < .05. Results: Most (n = 80; 88%) patients received 1 or more study medications. Any exposure and higher cumulative doses of benzodiazepine and ketamine were significantly associated with worse rNCI in bivariate analyses. When controlling for Medicaid, preadmission comorbid conditions, length of stay, delirium, and receipt of other medication classes, receipt of benzodiazepine was associated with significantly worse rNCI (β-coefficient = -0.48, 95% confidence interval = -0.88, -0.08). Conclusions: Exposure to benzodiazepines was independently associated with worse acute phase cognitive outcome using objective assessments focused on executive function skills when controlling for demographic and illness characteristics. Clinician decisions regarding medication regimens in the PICU may serve as a modifiable factor to improve outcomes. Additional inquiry into associations with long-term cognitive outcome and optimal medication regimens is needed.

CARE4Kids Study: Endophenotypes of Persistent Post-Concussive Symptoms in Adolescents: Study Rationale and Protocol

Treatment of youth concussion during the acute phase continues to evolve, and this has led to the emergence of guidelines to direct care. While symptoms after concussion typically resolve in 14-28 days, a portion (∼20%) of adolescents endorse persistent post-concussive symptoms (PPCS) beyond normal resolution. This report outlines a study implemented in response to the National Institute of Neurological Diseases and Stroke call for the development and initial clinical validation of objective biological measures to predict risk of PPCS in adolescents. We describe our plans for recruitment of a Development cohort of 11- to 17-year-old youth with concussion, and collection of autonomic, neurocognitive, biofluid, and imaging biomarkers. The most promising of these measures will then be validated in a separate Validation cohort of youth with concussion, and a final, clinically useful algorithm will be developed and disseminated. Upon completion of this study, we will have generated a battery of measures predictive of high risk for PPCS, which will allow for identification and testing of interventions to prevent PPCS in the most high-risk youth.

Prolonged duration of post-traumatic amnesia: A sensitive classification for predicting cognitive outcomes in children recovering from traumatic brain injury

OBJECTIVE

A paucity of data exists regarding the duration of post-traumatic amnesia (PTA) as a predictor of cognitive functioning among children after traumatic brain injury (TBI). The study aimed to assess the relationship between PTA duration and areas of neurocognitive function among the pediatric population in the sub-acute phase of recovery and rehabilitation.

METHODS

Data were collected from medical files on 103 children aged 5.5-16.5 hospitalized at a pediatric rehabilitation department with a diagnosis of moderate-severe TBI (msTBI) between the years 2004-2019. The Children Orientation and Amnesia Test was used to evaluate PTA duration. Measures of high-order cognitive abilities of attention and executive function were collected using the Test of Everyday Attention-Child version (TEA-Ch).

RESULTS

Three PTA duration groups were assembled out of a cluster analysis: "Long PTA" (M = 21 days), "Very Long PTA" (M = 47 days), and "Extremely Long PTA" (M = 94 days). Analyses revealed that the "Long PTA" group preformed significantly better than the "Very Long PTA" and "Extremely Long PTA" groups on all TEA-Ch measures, that is, Selective Attention, Attentional Control Switching, and Sustained Attention.

CONCLUSIONS

This study is the first to demonstrate that PTA duration is a useful predictor of high-order cognitive functions among children with msTBI in the sub-acute phase of recovery and rehabilitation. The findings emphasize the importance of using a more sensitive classification of prolonged PTA durations to improve outcome prediction and allocation of resources to those who can benefit most after severe brain injuries.

Post-Intensive Care Syndrome in a Cohort of School-Aged Children and Adolescent ICU Survivors: The Importance of Follow-up in the Acute Recovery Phase

Pediatric intensive care unit (PICU) survivors experience a collection of physical, cognitive, emotional, and social symptoms named post-intensive care syndrome (PICS). We aimed to quantify PICS morbidities from multiple stakeholder perspectives across domains. Using physician, neuropsychologist, and parent/caregiver-completed outcome measures across domains in a cross-sectional analysis of 186 children between the ages of 8 and 19 years with data from a PICU follow-up clinic 1 to 3 months after PICU discharge, we quantified PICS morbidities and used Spearman correlation to evaluate interdependence of PICS domains. Compared with pre-hospitalization functioning, new PICS-related morbidities were observed and significant correlations were identified between the PICS domains. Results highlight the need to identify and support patients and families for multiple morbidities simultaneously across all relevant PICS domains; moreover, an important divergence between caregiver report, physician, and neuropsychologist assessment was also found, showcasing the importance of multiple assessments and perspectives. New PICS morbidities across domains are common after discharge from the PICU, and timely follow-up care is needed that involves collaboration/integration of physicians, neuropsychologists, youth, and families to effectively identify and treat PICS-related issues.

Effect of parental education and household poverty on recovery after traumatic brain injury in school-aged children

OBJECTIVE

While prior studies have found parental socioeconomic status (SES) affects the outcomes of pediatric traumatic brain injury (TBI), the longitudinal trajectory of this effect is not well understood.

METHODS

This prospective cohort study included children 8-18 years of age admitted to six sites with a complicated mild (n = 123) or moderate-severe TBI (n = 47). We used caregiver education and household poverty level as predictors, and multiple quality of life and health behavior domains as outcomes. Differences at 6, 12, and 24 months from baseline ratings of pre-injury functioning were compared by SES. We examined the association between measures of SES and domains of functioning over the 24 months post-injury in children with a complicated mild or moderate- severe TBI, and determined how this association varied over time.

RESULTS

Parental education was associated with recovery among children with complicated mild TBI; outcomes at 6, 12, and 24 months were substantially poorer than at baseline for children with the least educated parents. After moderate-severe TBI, children in households with lower incomes had poorer outcomes compared to baseline across time.

IMPLICATIONS

Parental education and household income were associated with recovery trajectories for children with TBI of varying severity.

Memory functioning 7 years after severe childhood traumatic brain injury: Results of the Traumatisme Grave de l'Enfant study

OBJECTIVE

To explore memory functioning 7 years after severe paediatric traumatic brain injury (TBI), associated factors, and relationships with other outcomes.

METHOD

Children aged 0-15 years (n = 65), consecutively admitted over a 3-year period in a single trauma centre, who survived after severe non-inflicted TBI, were included in a prospective longitudinal study. Memory assessments were performed 7 years post-injury using the Children's Memory Scale or the Wechsler Memory Scale (WMS IV), according to age. The General Memory Score (GMS-7) was the primary outcome.

RESULTS

Thirty-seven patients were available for assessment at 7 years post-injury. Mean GMS-7 was in the low average range (M = 84.9, SD = 12.1). Lower GMS-7 was significantly associated with markers of higher injury severity, such as length of coma. One year post-injury functional and disability outcomes explained 74% of the variance of GMS-7. Concurrent intellectual ability and type of ongoing education correlated strongly with GMS-7. Age at injury and parental education were not associated with memory outcome.

CONCLUSIONS

Memory functioning is variable but often strongly impaired several years after severe paediatric TBI, and is mostly related to injury severity, functional outcomes measured 1 year post-injury, and concomitant cognitive and educational outcomes. GMS-7 was lower at 7 years than one year post-injury, supporting the importance of long term follow-up.

Cognitive recovery of children and adolescents with moderate to severe TBI during inpatient rehabilitation

OBJECTIVE

Traumatic brain injury (TBI) is the leading cause of morbidity and mortality in children and adolescents. This study examines the early cognitive-linguistic recovery of pediatric patients who sustained TBI and required inpatient rehabilitation and investigates the contribution of various demographic, clinical, and preinjury factors to recovery.

METHODS

A retrospective chart review of children and adolescents, ages 3-20 years, admitted to an inpatient rehabilitation unit. Acute outcomes were assessed at admission and discharge using the WeeFIM and CALS. Premorbid measures of behavioral and emotional functioning were also collected.

RESULTS

One hundred and one children and adolescents (mean age = 12.31, SD = 4.46) diagnosed with TBI requiring inpatient rehabilitation were included. Patients displayed significant improvements on cognitive-linguistic skills and functional independence between admission and discharge, with medium to large effect sizes. Premorbid behavioral-emotional functioning was not found to be associated with early cognitive recovery.

CONCLUSION

Results suggest that significant functional improvements can be expected for pediatric patients with TBI during inpatient rehabilitation. Consistent with previous literature, injury severity was significantly related to acute outcomes. In conjunction with the WeeFIM, the CALS appears to be a meaningful complement for assessing and monitoring cognitive-linguistic skills during inpatient rehabilitation.Implications for RehabiliationOur study provides support for the utility of the CALS to assess cognitive recovery during inpatient rehabilitation following moderate to severe TBI.Injury severity and not pre-injury functioning or demographic variables was related to worse scores on the CALS at discharge.Using a measure sensitive to change over admission, such as the CALS, can inform treatment planning.

Implementation of an attention training programme with a sample of children who have sustained traumatic brain injuries in South Africa: A pilot study

This pilot study evaluated the feasibility of implementing an attention-training programme for children who have sustained moderate-to-severe traumatic brain injuries (TBIs) in a South African context. We compared the performance on the programme of children with TBI (TBI Intervention Group) to children who had been diagnosed with Attention Deficit Hyperactivity Disorder (ADHD Intervention Group), a TBI Art group and a TBI No-intervention Group (n=5 in each group) in this preliminary study. Children in the two Intervention Groups participated in the "Pay Attention!" programme for 45 minutes twice a week for 12 weeks. All children were aged 6-8 years and underwent neuropsychological testing pre- and post-intervention. Behavioural data were collected from parents. Children in the ADHD Intervention Group showed individual clinically significant attentional improvements on measures of the Conners' Continuous Performance Test II using the Reliable Change Index (≥ 2.58 SD). Despite mixed results, the pilot study demonstrates that implementing a cognitive rehabilitation programme in South Africa is feasible and necessary, despite limited infrastructure and access to resources.

Functional Brain Hyperactivations Are Linked to an Electrophysiological Measure of Slow Interhemispheric Transfer Time after Pediatric Moderate/Severe Traumatic Brain Injury

Increased task-related blood oxygen level dependent (BOLD) activation is commonly observed in functional magnetic resonance imaging (fMRI) studies of moderate/severe traumatic brain injury (msTBI), but the functional relevance of these hyperactivations and how they are linked to more direct measures of neuronal function remain largely unknown. Here, we investigated how working memory load (WML)-dependent BOLD activation was related to an electrophysiological measure of interhemispheric transfer time (IHTT) in a sample of 18 msTBI patients and 26 demographically matched controls from the UCLA RAPBI (Recovery after Pediatric Brain Injury) study. In the context of highly similar fMRI task performance, a subgroup of TBI patients with slow IHTT had greater BOLD activation with higher WML than both healthy control children and a subgroup of msTBI patients with normal IHTT. Slower IHTT treated as a continuous variable was also associated with BOLD hyperactivation in the full TBI sample and in controls. Higher WML-dependent BOLD activation was related to better performance on a clinical cognitive performance index, an association that was more pronounced within the patient group with slow IHTT. Our previous work has shown that a subgroup of children with slow IHTT after pediatric msTBI has increased risk for poor white matter organization, long-term neurodegeneration, and poor cognitive outcome. BOLD hyperactivations after msTBI may reflect neuronal compensatory processes supporting higher-order capacity demanding cognitive functions in the context of inefficient neuronal transfer of information. The link between BOLD hyperactivations and slow IHTT adds to the multi-modal validation of this electrophysiological measure as a promising biomarker.

Factors Predicting Outcomes in Surgically Treated Pediatric Traumatic Brain Injury

Introduction

Traumatic brain injury (TBI) is a common presentation to the pediatric emergency department. Understanding factors that predict outcomes will be useful in clinical decision-making and prognostication. The objective of this study was to identify important clinical parameters predictive of outcomes in pediatric TBI patients who underwent surgery.

Materials and Methods

This retrospective study included 43 pediatric TBI patients who underwent surgery from January 2011 to January 2017. Clinical parameters, including presenting signs and symptoms, mechanism of injury, intracranial pressure (ICP), need for inotropes, and computed tomography findings were collected. Outcomes were assessed using the Glasgow outcome score (GOS) based on the latest follow-up. Outcomes were divided into favorable (GOS 4-5) and unfavorable (GOS 1-3).

Results

Surgery was performed in 43 patients. The mean age was 9.6 ± 4.9. The mean follow-up period was 31 weeks. Thirty (70%) patients had favorable outcome and 13 (30%) had unfavorable outcome. On univariate analysis, mechanism of injury, vomiting, Glasgow coma scale score, pupil size and reactivity, hypotension, inotropic use, need for blood transfusion, and raised ICP (all P < 0.005) were significantly associated with outcomes. On step-wise logistic regression, only raised ICP (odds ratio [OR] = 35.6, P = 0.008) and hypotension (OR = 26.1, P = 0.01) were found to be statistically significant.

Conclusion

The present study suggests that the majority of pediatric TBI patients who required neurosurgical intervention have favorable outcomes. Closer attention should be paid to raised ICP and hypotension as they were strong predictors of unfavorable outcomes. These findings also help manage expectations of patients' family and clinicians.

Assessment of memory functioning over two years following severe childhood traumatic brain injury: results of the TGE cohort

The aims of this study were (1) to prospectively measure memory functioning following severe childhood Traumatic Brain Injury (TBI), and its evolution over 2 years; (2) to assess demographic and medical factors associated with memory function and recovery; (3) to explore relations between memory and other TBI outcomes. Methods: Children (aged 0-15 years; n= 65) consecutively admitted in a single trauma center over a 3-year period, who survived severe non-inflicted TBI, were included in a prospective longitudinal study. Memory was assessed in 38 children aged 5-15 years at injury, using the Children's Memory Scale at 3, 12, and 24 months post-injury. Results: Mean general memory score was low at 3 months (M = 90.2, SD = 20.3) but within the normal range at 12 and 24 months (M = 100.6, SD = 23.1 and M = 108.6, SD = 24.1, respectively), with high variability. Improvement was stronger for immediate visual memory than for other memory indices. Lower general memory score was associated with higher injury severity, lower intellectual ability and functional status, higher overall disability, and ongoing education. Conclusion: Memory functioning is highly variable following severe childhood TBI, related to injury severity and functional, cognitive and educational outcomes; improvement is significant during the first-year post-injury, but varies according to the type of memory.

Age and Mortality in Pediatric Severe Traumatic Brain Injury: Results from an International Study

BACKGROUND

Although small series have suggested that younger age is associated with less favorable outcome after severe traumatic brain injury (TBI), confounders and biases have limited our understanding of this relationship. We hypothesized that there would be an association between age and mortality in children within an ongoing observational, cohort study.

METHODS

The first 200 subjects from the Approaches and Decisions for Acute Pediatric TBI trial were eligible for this analysis (inclusion criteria: severe TBI (Glasgow Coma Scale [GCS] score ≤ 8], age 18 years, and intracranial pressure (ICP) monitor placed; exclusion: pregnancy). Children with suspected abusive head trauma (AHT) were excluded to avoid bias related to the association between AHT and mortality. Demographics, and prehospital and resuscitation events were collected/analyzed, and children were stratified based on age at time of injury (< 5, 5-< 11, 11-18 years) and presented as mean ± standard error of the mean (SEM). Analyses of variance were used to test the equality of the means across the group for continuous variable, and Chi-square tests were used to compare percentages for discrete variables (post hoc comparisons were made using t test and Bonferroni corrections, as needed). Kaplan-Meier curves were generated for each age subgroup describing the time of death, and log-rank was used to compare the curves. Cox proportional hazards regression models were used to assess the effect of age on time to death while controlling for covariates.

RESULTS

In the final cohort (n = 155, 45 excluded for AHT), overall age was 9.2 years ± 0.4 and GCS was 5.3 ± 0.1. Mortality was similar between strata (14.0, 20.0, 20.9%, respectively, p = 0.58). Motor vehicle accidents were the most common mechanism across all strata, while falls tended to be more common in the youngest stratum (p = 0.08). The youngest stratum demonstrated increased incidence of spontaneous hypothermia at presentation and decreased hemoglobin concentrations and coagulopathies, while the oldest demonstrated lower platelet counts.

CONCLUSIONS

In contrast to previous reports, we failed to detect mortality differences across age strata in children with severe TBI. We have discerned novel associations between age and various markers of injury-unrelated to AHT-that may lead to testable hypotheses in the future.

Whole Brain Magnetic Resonance Spectroscopic Determinants of Functional Outcomes in Pediatric Moderate/Severe Traumatic Brain Injury

Diffuse axonal injury contributes to the long-term functional morbidity observed after pediatric moderate/severe traumatic brain injury (msTBI). Whole-brain proton magnetic resonance echo-planar spectroscopic imaging was used to measure the neurometabolite levels in the brain to delineate the course of disruption/repair during the first year post-msTBI. The association between metabolite biomarkers and functional measures (cognitive functioning and corpus callosum [CC] function assessed by interhemispheric transfer time [IHTT] using an event related potential paradigm) was also explored. Pediatric patients with msTBI underwent assessments at two times (post-acutely at a mean of three months post-injury, n = 31, and chronically at a mean of 16 months post-injury, n = 24). Healthy controls also underwent two evaluations, approximately 12 months apart. Post-acutely, in patients with msTBI, there were elevations in choline (Cho; marker for inflammation and/or altered membrane metabolism) in all four brain lobes and the CC and decreases in N-acetylaspartate (NAA; marker for neuronal and axonal integrity) in the CC compared with controls, all of which normalized by the chronic time point. Subgroups of TBI showed variable patterns chronically. Patients with slow IHTT had lower lobar Cho chronically than those with normal IHTT; they also did not show normalization in CC NAA whereas those with normal IHTT showed significantly higher levels of CC NAA relative to controls. In the normal IHTT group only, chronic CC Cho and NAA together explained 70% of the variance in long-term cognitive functioning. MR based whole brain metabolic evaluations show different patterns of neurochemistry after msTBI in two subgroups with different outcomes. There is a dynamic relationship between prolonged inflammatory responses to brain damage, reparative processes/remyelination, and subsequent neurobehavioral outcomes. Multimodal studies allow us to test hypotheses about degenerative and reparative processes in patient groups that have divergent functional outcome, with the ultimate goal of developing targeted therapeutic agents.

Magnetic resonance spectroscopy of fiber tracts in children with traumatic brain injury: A combined MRS - Diffusion MRI study

Traumatic brain injury can cause extensive damage to the white matter (WM) of the brain. These disruptions can be especially damaging in children, whose brains are still maturing. Diffusion magnetic resonance imaging (dMRI) is the most commonly used method to assess WM organization, but it has limited resolution to differentiate causes of WM disruption. Magnetic resonance spectroscopy (MRS) yields spectra showing the levels of neurometabolites that can indicate neuronal/axonal health, inflammation, membrane proliferation/turnover, and other cellular processes that are on-going post-injury. Previous analyses on this dataset revealed a significant division within the msTBI patient group, based on interhemispheric transfer time (IHTT); one subgroup of patients (TBI-normal) showed evidence of recovery over time, while the other showed continuing degeneration (TBI-slow). We combined dMRI with MRS to better understand WM disruptions in children with moderate-severe traumatic brain injury (msTBI). Tracts with poorer WM organization, as shown by lower FA and higher MD and RD, also showed lower N-acetylaspartate (NAA), a marker of neuronal and axonal health and myelination. We did not find lower NAA in tracts with normal WM organization. Choline, a marker of inflammation, membrane turnover, or gliosis, did not show such associations. We further show that multi-modal imaging can improve outcome prediction over a single modality, as well as over earlier cognitive function measures. Our results suggest that demyelination plays an important role in WM disruption post-injury in a subgroup of msTBI children and indicate the utility of multi-modal imaging.

Neuroimaging of the Injured Pediatric Brain: Methods and New Lessons

Traumatic brain injury (TBI) is a significant public health problem in the United States, especially for children and adolescents. Current epidemiological data estimate over 600,000 patients younger than 20 years are treated for TBI in emergency rooms annually. While many patients experience a full recovery, for others there can be long-lasting cognitive, neurological, psychological, and behavioral disruptions. TBI in youth can disrupt ongoing brain development and create added family stress during a formative period. The neuroimaging methods used to assess brain injury improve each year, providing researchers a more detailed characterization of the injury and recovery process. In this review, we cover current imaging methods used to quantify brain disruption post-injury, including structural magnetic resonance imaging (MRI), diffusion MRI, functional MRI, resting state fMRI, and magnetic resonance spectroscopy (MRS), with brief coverage of other methods, including electroencephalography (EEG), single-photon emission computed tomography (SPECT), and positron emission tomography (PET). We include studies focusing on pediatric moderate-severe TBI from 2 months post-injury and beyond. While the morbidity of pediatric TBI is considerable, continuing advances in imaging methods have the potential to identify new treatment targets that can lead to significant improvements in outcome.

Prevalence of low test scores in a pediatric psychiatric inpatient population: Applying multivariate base rate analyses

The understanding of neuropsychological functioning in pediatric psychiatric inpatient populations is growing, but limited, resulting in interpretive challenges. This study examined the application of multivariate base rate (MVBR) analysis in a clinical sample to appraise its utility in characterizing the frequency of low scores, as well as predictors of low scores, when using a flexible test battery. Participants included 99 children from a psychiatric inpatient unit referred for neuropsychological testing. Children hospitalized with psychiatric disorders exhibited high rates of low scores at varying criteria across the battery of tests. Hierarchical multiple regression analyses revealed that after accounting for demographic and psychiatric factors, intellectual functioning accounted for approximately 26% of the variance in observed low scores. The results suggest that a substantial percentage of this population produces low scores on neuropsychological testing and, consistent with prior research, intellectual functioning is strongly associated with low score frequency. To our knowledge, this is the first study to examine the clinical application of MVBR analysis in a pediatric psychiatric inpatient population using a flexible test battery. Taken together, this investigation highlights the potential clinical utility of MVBR analysis when interpreting neuropsychological performance in clinical pediatric populations.

Local and global challenges in pediatric traumatic brain injury outcome and rehabilitation assessment

Traumatic brain injury (TBI) is a major public health problem associated with high morbidity and mortality rates in children in both high- and low- and middle-income countries. Predicting outcome after pediatric TBI is challenging given the wide range of injury and non-injury-related factors which may have an impact. Some of these factors are relevant globally (like heterogeneity in patient and injury-related factors and research methodology) and others are more specific to local contexts (like sociodemographic and cultural factors). The assessment of rehabilitation outcomes post-TBI are similarly challenging given the various methodological limitations, disparities in access to rehabilitation, and limited awareness of deficits, which are encountered globally, as well as the lack of services in the local settings. In this article, we discuss these global and local challenges to outcome and rehabilitation assessment following pediatric TBI.

Diverging volumetric trajectories following pediatric traumatic brain injury

Traumatic brain injury (TBI) is a significant public health concern, and can be especially disruptive in children, derailing on-going neuronal maturation in periods critical for cognitive development. There is considerable heterogeneity in post-injury outcomes, only partially explained by injury severity. Understanding the time course of recovery, and what factors may delay or promote recovery, will aid clinicians in decision-making and provide avenues for future mechanism-based therapeutics. We examined regional changes in brain volume in a pediatric/adolescent moderate-severe TBI (msTBI) cohort, assessed at two time points. Children were first assessed 2-5 months post-injury, and again 12 months later. We used tensor-based morphometry (TBM) to localize longitudinal volume expansion and reduction. We studied 21 msTBI patients (5 F, 8-18 years old) and 26 well-matched healthy control children, also assessed twice over the same interval. In a prior paper, we identified a subgroup of msTBI patients, based on interhemispheric transfer time (IHTT), with significant structural disruption of the white matter (WM) at 2-5 months post injury. We investigated how this subgroup (TBI-slow, N = 11) differed in longitudinal regional volume changes from msTBI patients (TBI-normal, N = 10) with normal WM structure and function. The TBI-slow group had longitudinal decreases in brain volume in several WM clusters, including the corpus callosum and hypothalamus, while the TBI-normal group showed increased volume in WM areas. Our results show prolonged atrophy of the WM over the first 18 months post-injury in the TBI-slow group. The TBI-normal group shows a different pattern that could indicate a return to a healthy trajectory.

Diverging white matter trajectories in children after traumatic brain injury: The RAPBI study

OBJECTIVE

To examine longitudinal trajectories of white matter organization in pediatric moderate/severe traumatic brain injury (msTBI) over a 12-month period.

METHODS

We studied 21 children (16 M/5 F) with msTBI, assessed 2-5 months postinjury and again 13-19 months postinjury, as well as 20 well-matched healthy control children. We assessed corpus callosum function through interhemispheric transfer time (IHTT), measured using event-related potentials, and related this to diffusion-weighted MRI measures of white matter (WM) microstructure. At the first time point, half of the patients with TBI had significantly slower IHTT (TBI-slow-IHTT, n = 11) and half were in the normal range (TBI-normal-IHTT, n = 10).

RESULTS

The TBI-normal-IHTT group did not differ significantly from healthy controls, either in WM organization in the chronic phase or in the longitudinal trajectory of WM organization between the 2 evaluations. In contrast, the WM organization of the TBI-slow-IHTT group was significantly lower than in healthy controls across a large portion of the WM. Longitudinal analyses showed that the TBI-slow-IHTT group experienced a progressive decline between the 2 evaluations in WM organization throughout the brain.

CONCLUSIONS

We present preliminary evidence suggesting a potential biomarker that identifies a subset of patients with impaired callosal organization in the first months postinjury who subsequently experience widespread continuing and progressive degeneration in the first year postinjury.