Correlation of atrophy measures on MRI with neuropsychological sequelae in children and adolescents with traumatic brain injury

Diffuse axonal injury on magnetic resonance imaging and its relation to neurological outcomes in pediatric traumatic brain injury

OBJECTIVE

Diffuse axonal injury (DAI), a frequent consequence of pediatric traumatic brain injury (TBI), presents challenges in predicting long-term recovery. This study investigates the relationship between the severity of DAI and neurological outcomes in children.

METHODS

We conducted a retrospective analysis of 51 pediatric TBI patients diagnosed with DAI using Adam's classification. Neurological function was assessed at 2, 3, and 6 weeks, and 12 months post-injury using the Pediatric Glasgow Outcome Scale-Extended (PGOSE).

RESULTS

PGOSE scores significantly improved over time across all DAI grades, suggesting substantial recovery potential even in initially severe cases. Despite indicating extensive injury, patients with DAI grades II and III demonstrated significant improvement, achieving a good recovery by 12 months. Although the initial Glasgow Coma Scale (GCS) score did not show a statistically significant association with long-term outcomes in our limited sample, these findings suggest that the severity of DAI alone may not fully predict eventual recovery.

CONCLUSIONS

Our study highlights the potential for significant neurological recovery in pediatric patients with DAI, emphasizing the importance of long-term follow-up and individualized rehabilitation programs. Further research with larger cohorts and extended follow-up periods is crucial to refine our understanding of the complex relationships between DAI severity, injury mechanisms, and long-term neurological outcomes in children.

Processing Speed in Children with Traumatic Brain Injury

Abstract: Traumatic brain injury (TBI) is a common cause of childhood morbidity and mortality. Information processing speed (IPS) is a central construct of neuropsychology and a mediator for a range of cognitive functions. In adults, the negative effects of TBI on IPS are well documented. This review qualitatively describes the impact of TBI on IPS in children and adolescents and examines various influencing factors. We included a total of 37 studies in the review that explored IPS using various clinical assessments. These clinical assessments often examine other neuropsychological functions besides IPS. In 29 of these studies, we found a negative effect of TBI on IPS. While injury severity has small but consistent effects on IPS, the effects of age at injury, time since injury, and gender were less evident. Because it is a central construct of neuropsychological functions, IPS should be assessed after TBI.

Topology of diffusion changes in corpus callosum in Alzheimer's disease: An exploratory case-control study

Aim

This study aims to assess the integrity of white matter in various segments of the corpus callosum in Alzheimer's disease (AD) by using metrics derived from diffusion tensor imaging (DTI), diffusion kurtosis imaging (DKI) and white matter tract integrity model (WMTI) and compare these findings to healthy controls (HC).

Methods

The study was approved by the institutional ethics board. 12 AD patients and 12 HC formed the study population. All AD patients were recruited from a tertiary neurology memory clinic. A standardized battery of neuropsychological assessments was administered to the study participants by a trained rater. MRI scans were performed with a Philips Ingenia 3.0T scanner equipped with a 32-channel head coil. The protocol included a T1-weighted sequence, FLAIR and a dMRI acquisition. The dMRI scan included a total of 71 volumes, 8 at b = 0 s/mm2, 15 at b = 1,000 s/mm2 and 48 at b = 2,000 s/mm2. Diffusion data fit was performed using DKI REKINDLE and WMTI models.

Results and discussion

We detected changes suggesting demyelination and axonal degeneration throughout the corpus callosum of patients with AD, most prominent in the mid-anterior and mid-posterior segments of CC. Axial kurtosis was the most significantly altered metric, being reduced in AD patients in almost all segments of corpus callosum. Reduced axial kurtosis in the CC segments correlated with poor cognition scores in AD patients in the visuospatial, language and attention domains.

GABAergic circuits of the basolateral amygdala and generation of anxiety after traumatic brain injury

Traumatic brain injury (TBI) has reached epidemic proportions around the world and is a major public health concern in the United States. Approximately 2.8 million individuals sustain a traumatic brain injury and are treated in an Emergency Department yearly in the U.S., and about 50,000 of them die. Persistent symptoms develop in 10-15% of the cases including neuropsychiatric disorders. Anxiety is the second most common neuropsychiatric disorder that develops in those with persistent neuropsychiatric symptoms after TBI. Abnormalities or atrophy in the temporal lobe has been shown in the overwhelming number of TBI cases. The basolateral amygdala (BLA), a temporal lobe structure that consolidates, stores and generates fear and anxiety-based behavioral outputs, is a critical brain region in the anxiety circuitry. In this review, we sought to capture studies that characterized the relationship between human post-traumatic anxiety and structural/functional alterations in the amygdala. We compared the human findings with results obtained with a reproducible mild TBI animal model that demonstrated a direct relationship between the alterations in the BLA and an anxiety-like phenotype. From this analysis, both preliminary insights, and gaps in knowledge, have emerged which may open new directions for the development of rational and more efficacious treatments.

Disturbed Interhemispheric Functional and Structural Connectivity in Type 2 Diabetes

BACKGROUND

Type 2 diabetes mellitus (T2DM) is associated with cognitive decline and altered brain structure and function. However, the interhemispheric coordination of T2DM patients is unclear.

PURPOSE

To investigate interhemispheric functional and anatomic connectivity in T2DM, and their associations with cognitive performance and endocrine parameters.

STUDY TYPE

Prospective.

SUBJECTS

38 T2DM patients and 42 matched controls.

FIELD STRENGTH/SEQUENCES

3.0 T magnetic resonance imaging (MRI) scanner; magnetization-prepared rapid acquisition gradient echo sequence; fluid-attenuated inversion recovery sequence; single-shot, gradient-recalled echo-planar imaging sequence (resting-state functional MRI); and diffusion-weighted spin-echo-based echo-planar sequence (diffusion tensor imaging).

ASSESSMENT

Voxel-mirrored homotopic connectivity (VMHC) value was calculated based on the functional images. Fibers passing through the regions with significant VMHC differences were identified using an atlas-guided track recognition. The mean fractional anisotropy (FA), mean diffusivity (MD), and fiber length were extracted and compared between the two groups. Finally, correlational analyses were performed to examine the relationships between abnormal interhemispheric connectivity, cognitive performances, and endocrine parameters.

STATISTICAL TESTS

Two-sample t-tests were performed controlling for confounding factors, with partial correlation analysis. False discovery rate (FDR) correction was used for multiple comparisons. A P value <0.05 was considered statistically significant.

RESULTS

T2DM patients exhibited significantly decreased VMHC between bilateral lingual gyrus and sensorimotor cortex. The fibers connecting lingual gyrus in patients showed significantly lower FA (P = 0.011) and shorter fiber length (P < 0.001), while the differences in sensorimotor fibers were insignificant (P = 0.096 for FA, P = 0.739 for fiber length and P = 0.150 for MD). The FA value in the lingual fibers was negatively correlated with insulin resistance (IR) level in T2DM group after FDR correction (R = -0.635).

DATA CONCLUSION

We noted disruptions in interhemispheric coordination in T2DM patients, involving both functional and anatomical connectivities. IR might be a promising therapeutic target in the intervention of T2DM-related cognitive impairment.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY STAGE: 2.

Brain Magnetic Resonance Imaging Volumetric Measures of Functional Outcome after Severe Traumatic Brain Injury in Adolescents

Adolescent traumatic brain injury (TBI) is a major public health concern, resulting in >35,000 hospitalizations in the United States each year. Although neuroimaging is a primary diagnostic tool in the clinical assessment of TBI, our understanding of how specific neuroimaging findings relate to outcome remains limited. Our study aims to identify imaging biomarkers of long-term neurocognitive outcome after severe adolescent TBI. Twenty-four adolescents with severe TBI (Glasgow Coma Scale ≤8) enrolled in the ADAPT (Approaches and Decisions after Pediatric TBI) study were recruited for magnetic resonance imaging (MRI) scanning 1-2 years post-injury at 13 participating sites. Subjects underwent outcome assessments ∼1-year post-injury, including the Wechsler Abbreviated Scale of Intelligence (IQ) and the Pediatric Glasgow Outcome Scale-Extended (GOSE-Peds). A typically developing control cohort of 38 age-matched adolescents also underwent scanning and neurocognitive assessment. Brain-image segmentation was performed on T1-weighted images using Freesurfer. Brain and ventricular cerebrospinal fluid volumes were used to compute a ventricle-to-brain ratio (VBR) for each subject, and the corpus callosum cross-sectional area was determined in the midline for each subject. The TBI group demonstrated higher VBR and lower corpus callosum area compared to the control cohort. After adjusting for age and sex, VBR was significantly related with GOSE-Peds score in the TBI group (n = 24, p = 0.01, cumulative odds ratio = 2.18). After adjusting for age, sex, intracranial volume, and brain volume, corpus callosum cross-sectional area correlated significantly with IQ score in the TBI group (partial cor = 0.68, n = 18, p = 0.007) and with PSI (partial cor = 0.33, p = 0.02). No association was found between VBR and IQ or between corpus callosum and GOSE-Peds. After severe adolescent TBI, quantitative MRI measures of VBR and corpus callosum cross-sectional area are associated with global functional outcome and neurocognitive outcomes, respectively.

The mentalizing network and theory of mind mediate adjustment after childhood traumatic brain injury

Childhood traumatic brain injury (TBI) affects over 600 000 children per year in the United States. Following TBI, children are vulnerable to deficits in psychosocial adjustment and neurocognition, including social cognition, which persist long-term. They are also susceptible to direct and secondary damage to related brain networks. In this study, we examine whether brain morphometry of the mentalizing network (MN) and theory of mind (ToM; one component of social cognition) mediates the effects of TBI on adjustment. Children with severe TBI (n = 15, M_age = 10.32), complicated mild/moderate TBI (n = 30, M_age = 10.81) and orthopedic injury (OI; n = 42, M_age = 10.65) completed measures of ToM and executive function and underwent MRI; parents rated children’s psychosocial adjustment. Children with severe TBI demonstrated reduced right-hemisphere MN volume, and poorer ToM, vs children with OI. Ordinary least-squares path analysis indicated that right-hemisphere MN volume and ToM mediated the association between severe TBI and adjustment. Parallel analyses substituting the central executive network and executive function were not significant, suggesting some model specificity. Children at greatest risk of poor adjustment after TBI could be identified based in part on neuroimaging of social brain networks and assessment of social cognition and thereby more effectively allocate limited intervention resources.

Traumatic brain injury and frontal lobe plasticity

Over 1.4 million people in the United States experience traumatic brain injury (TBI) each year and approximately 52,000 people die annually due to complications related to TBI. Traditionally, TBI has been viewed as a static injury with significant consequences for frontal lobe functioning that plateaus after some window of recovery, remaining relatively stable thereafter. However, over the past decade there has been growing consensus that the consequences of TBI are dynamic, with unique characteristics expressed at the individual level and over the life span. This chapter first discusses the pathophysiology of TBI in order to understand its dynamic process and then describes the behavioral changes that are the result of injury with focus on frontal lobe functions. It integrates a historical perspective on structural and functional brain-imaging approaches used to understand how TBI impacts the frontal lobes, as well as more recent approaches to examine large-scale network changes after TBI. The factors most useful for outcome prediction are surveyed, along with how the theoretical frameworks used to predict recovery have developed over time. In this chapter, the authors argue for the need to understand outcome after TBI as a dynamic process with individual trajectories, taking a network theory perspective to understand the consequences of disrupting frontal systems in TBI. Within this framework, understanding frontal lobe dysfunction within a larger coordinated neural network to study TBI may provide a novel perspective in outcome prediction and in developing individualized treatments.

Therapeutic strategies to target acute and long-term sequelae of pediatric traumatic brain injury

Pediatric traumatic brain injury (TBI) remains one of the leading causes of morbidity and mortality in children. Experimental and clinical studies demonstrate that the developmental age, the type of injury (diffuse vs. focal) and sex may play important roles in the response of the developing brain to a traumatic injury. Advancements in acute neurosurgical interventions and neurocritical care have improved and led to a decrease in mortality rates over the past decades. However, survivors are left with life-long behavioral deficits underscoring the need to better define the cellular mechanisms underlying these functional changes. A better understanding of these mechanisms some of which begin in the acute post-traumatic period may likely lead to targeted treatment strategies. Key considerations in designing pre-clinical experiments to test therapeutic strategies in pediatric TBI include the use of age-appropriate and pathologically-relevant models, functional outcomes that are tested as animals age into adolescence and beyond, sex as a biological variable and the recognition that doses and dosing strategies that have been demonstrated to be effective in animal models of adult TBI may not be effective in the developing brain. This article is part of the Special Issue entitled "Novel Treatments for Traumatic Brain Injury".

Neuropsychological outcome of children with traumatic brain injury and its association with late magnetic resonance imaging findings: A cohort study

OBJECTIVES

To evaluate neuropsychological outcome after traumatic brain injury (TBI) and its association with trauma severity and late magnetic resonance imaging (MRI) findings.

METHODS

Prospective cohort study of patients with TBI admitted to the paediatric intensive care unit over 5 years. Trauma severity was determined by Glasgow Coma Scale (GCS), neurological outcome by King's Outcome Scale for Childhood Head Injury (KOSCHI) and neuropsychological outcome by Wechsler Intelligence Scale for Children - Fourth Edition.

RESULTS

Twenty-five children (median age 6 years at trauma) were included. Patients were divided into Disability (DIS)(n = 10) and Good Recovery (GR)(n = 15) groups. Initial GCS score was not significantly different in both groups (median 6 vs. 10; p = 0.34). DIS group had lower values ​​of working memory index (WMI)(median 74 vs. 94; p = 0.004), perceptual reasoning index (PRI)(75 vs. 96; p = 0.03), verbal comprehension index (VCI)(65 vs. 84; p = 0.02), processing speed index (PSI)(74 vs. 97; p = 0.01) and full-scale intelligence quotient (FSIQ)(65 vs. 87; p = 0.008). In the GR group, 60% of patients had normal or minimally altered MRI versus 10% of patients in the DIS group (p = 0.018). Fractional anisotropy positively correlated with WMI(r = 0.65; p = 0.005), PRI(r = 0.52; p = 0.03) and FSIQ(r = 0.50; p = 0.04).

CONCLUSIONS

Neuropsychological impairment was observed in 40% of children who suffered a TBI and was associated with late MRI abnormalities.

Cognitive impairment after traumatic brain injury: The role of MRI and possible pathological basis

Traumatic brain injury (TBI) is closely related to increased incidence of cognitive impairment from the acute phase to chronic phase. At present, the pathological mechanism leading to cognitive impairment after TBI is still not fully understood. We hypothesize that neuron loss, diffuse axonal injury, microbleed, and blood-brain barrier (BBB) disruption altogether contribute to the development of cognitive impairment. Furthermore, the disruption of structural and functional neural network related to the cognitive function might bring about the final step in the occurrence of cognitive impairment after TBI. In this review, we summarize the role of different MRI techniques in the assessment of the pathological changes related to cognitive impairment after TBI. These MRI techniques include T1-MPRAGE sequence reflecting neuron loss, diffusion tensor imaging reflecting diffuse axonal injury, diffusion kurtosis imaging reflecting diffuse axonal injury and reactive gliosis, susceptibility weighted imaging showing microbleed, arterial spin labeling showing blood flow and dynamic contrast enhanced MRI showing BBB disruption. In the future, correlational study of multi-MRI sequences scan, pathological examination, and cognitive tests will provide valuable information for understanding the mechanism of cognitive impairment after TBI and manage TBI patients.

Recovering two languages with the right hemisphere

Converging evidence suggests that the right hemisphere (RH) plays an important role in language recovery from aphasia after a left hemisphere (LH) lesion. In this longitudinal study we describe the neurological, cognitive, and linguistic profile of A.C., a bilingual who, after a severe traumatic brain injury, developed a form of fluent aphasia that affected his two languages (i.e., Romanian and Italian). The trauma-induced parenchymal atrophy led to an exceptional ventricular dilation that, gradually, affected the whole left hemisphere. A.C. is now recovering both languages relying only on his right hemisphere. An fMRI experiment employing a bilingual covert verb generation task documented the involvement of the right middle temporal gyrus in processes of lexical selection and access. This case supports the hypothesis that the RH plays a role in language recovery from aphasia when the LH has suffered massive lesions.

Tensor-Based Morphometry Reveals Volumetric Deficits in Moderate=Severe Pediatric Traumatic Brain Injury

Traumatic brain injury (TBI) can cause widespread and prolonged brain degeneration. TBI can affect cognitive function and brain integrity for many years after injury, often with lasting effects in children, whose brains are still immature. Although TBI varies in how it affects different individuals, image analysis methods such as tensor-based morphometry (TBM) can reveal common areas of brain atrophy on magnetic resonance imaging (MRI), secondary effects of the initial injury, which will differ between subjects. Here we studied 36 pediatric moderate to severe TBI (msTBI) participants in the post-acute phase (1-6 months post-injury) and 18 msTBI participants who returned for their chronic assessment, along with well-matched controls at both time-points. Participants completed a battery of cognitive tests that we used to create a global cognitive performance score. Using TBM, we created three-dimensional (3D) maps of individual and group differences in regional brain volumes. At both the post-acute and chronic time-points, the greatest group differences were expansion of the lateral ventricles and reduction of the lingual gyrus in the TBI group. We found a number of smaller clusters of volume reduction in the cingulate gyrus, thalamus, and fusiform gyrus, and throughout the frontal, temporal, and parietal cortices. Additionally, we found extensive associations between our cognitive performance measure and regional brain volume. Our results indicate a pattern of atrophy still detectable 1-year post-injury, which may partially underlie the cognitive deficits frequently found in TBI.

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.

The UCLA Study of Children with Moderate-to-Severe Traumatic Brain Injury: Event-Related Potential Measure of Interhemispheric Transfer Time

Traumatic brain injury (TBI) frequently results in diffuse axonal injury and other white matter damage. The corpus callosum (CC) is particularly vulnerable to injury following TBI. Damage to this white matter tract has been associated with impaired neurocognitive functioning in children with TBI. Event-related potentials can identify stimulus-locked neural activity with high temporal resolution. They were used in this study to measure interhemispheric transfer time (IHTT) as an indicator of CC integrity in 44 children with moderate/severe TBI at 3-5 months post-injury, compared with 39 healthy control children. Neurocognitive performance also was examined in these groups. Nearly half of the children with TBI had IHTTs that were outside the range of the healthy control group children. This subgroup of TBI children with slow IHTT also had significantly poorer neurocognitive functioning than healthy controls-even after correction for premorbid intellectual functioning. We discuss alternative models for the relationship between IHTT and neurocognitive functioning following TBI. Slow IHTT may be a biomarker that identifies children at risk for poor cognitive functioning following moderate/severe TBI.

Is there evidence for neurodegenerative change following traumatic brain injury in children and youth? A scoping review

While generalized cerebral atrophy and neurodegenerative change following traumatic brain injury (TBI) is well recognized in adults, it remains comparatively understudied in the pediatric population, suggesting that research should address the potential for neurodegenerative change in children and youth following TBI. This focused review examines original research findings documenting evidence for neurodegenerative change following TBI of all severities in children and youth. Our relevant inclusion and exclusion criteria identified a total of 16 articles for review. Taken together, the studies reviewed suggest there is evidence for long-term neurodegenerative change following TBI in children and youth. In particular both cross-sectional and longitudinal studies revealed volume loss in selected brain regions including the hippocampus, amygdala, globus pallidus, thalamus, periventricular white matter, cerebellum, and brain stem as well as overall decreased whole brain volume and increased CSF and ventricular space. Diffusion Tensor Imaging (DTI) studies also report evidence for decreased cellular integrity, particularly in the corpus callosum. Sensitivity of the hippocampus and deep limbic structures in pediatric populations are similar to findings in the adult literature and we consider the data supporting these changes as well as the need to investigate the possibility of neurodegenerative onset in childhood associated with mild traumatic brain injury (mTBI).

Cavum septum pellucidum in pediatric traumatic brain injury

The cavum septum pellucidum (CSP) is a fluid-filled cavity in the thin midline structure of the septum pellucidum. The CSP has been linked to several neurodevelopmental disorders, but it also occurs as a result of head injury. The aims were to assess the presence and characterization of the CSP in youth with traumatic brain injury (TBI), to assess whether injury severity or IQ measures were related to CSP size, and to examine brain morphometry changes associated with the CSP size. Ninety-eight survivors of TBI and 34 control children underwent magnetic resonance imaging (MRI). Numerous methods were used to define the presence and characterization of the CSP including length, classification of abnormally large CSP, rating of the CSP, and volume. There was no difference in presence of CSP between TBI patients and controls; however, there was larger and more severely graded CSP in the patient group. Size of the CSP correlated positively with injury severity, and regions that correlated most significantly with CSP size were the right entorhinal cortex and bilateral hippocampus. Characterizing the CSP and related brain changes may provide important information concerning disturbances seen after a TBI.

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.

Cognitive reserve as a moderator of responsiveness to an online problem-solving intervention for adolescents with complicated mild-to-severe traumatic brain injury

Children and adolescents with traumatic brain injury (TBI) often experience behavior difficulties that may arise from problem-solving deficits and impaired self-regulation. However, little is known about the relationship of neurocognitive ability to post-TBI behavioral recovery. To address this question, we examined whether verbal intelligence, as estimated by Vocabulary scores from the Wechsler Abbreviated Scale of Intelligence, predicted improvements in behavior and executive functioning following a problem-solving intervention for adolescents with TBI. One hundred and thirty-two adolescents with complicated mild-to-severe TBI were randomly assigned to a six-month Web-based problem-solving intervention (CAPS; n = 65) or to an Internet resource comparison (IRC; n = 67) group. Vocabulary moderated the association between treatment group and improvements in metacognitive abilities. Examination of the mean estimates indicated that for those with lower Vocabulary scores, pre-intervention Metacognition Index scores from the Behavior Rating Inventory of Executive Function (BRIEF) did not differ between the groups, but post-intervention scores were significantly lower (more improved) for those in the CAPS group. These findings suggest that low verbal intelligence was associated with greater improvements in executive functioning following the CAPS intervention and that verbal intelligence may have an important role in response to intervention for TBI. Understanding predictors of responsiveness to interventions allows clinicians to tailor treatments to individuals, thus improving efficacy.

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.

Cognitive proficiency in pediatric epilepsy

Cognitive proficiency (CP) is a sensitive gauge of neurological status, but it is not typically viewed in relation to focal cerebral function. We examined CP and its relationship to general intellectual ability and seizure focus in 90 patients with pediatric epilepsy. CP was significantly lower than general ability (GA) in the overall sample. In particular, it was more deficient than GA in patients with right- than left-lateralized epilepsy onset, and in patients with frontal- than temporal-onset epilepsy. The discrepancy between CP and GA varied with participants' overall intelligence, being more pronounced (i.e., GA-CP difference larger) in individuals of lower overall ability. Deficits in CP are a defining characteristic of pediatric epilepsy and serve as an important marker of neurocognitive status, especially when seizures originate from a primary epileptogenic focus within the right hemisphere or the frontal lobe.

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.

Hippocampus, amygdala and global brain changes 10 years after childhood traumatic brain injury

Traumatic brain injury (TBI) in children results in damage to the developing brain, particularly in severely injured individuals. Little is known, however, of the long-term structural aspects of the brain following childhood TBI. This study investigated the integrity of the brain 10 years post-TBI using magnetic resonance imaging volumetrics in a sample of 49 participants with mild, moderate and severe TBI, evaluated against a normative sample of 20 individuals from a pediatric database with comparable age and gender distribution. Structural integrity was investigated in gray and white matter, and by manually segmenting two regions of interest (hippocampus, amygdala), potentially vulnerable to the effects of childhood TBI. The results indicate that more severe injuries caused a reduction in gray and white brain matter, while all TBI severity levels resulted in increased volumes of cerebrospinal fluid and smaller hippocampal volumes. In addition, enlarged amygdala volumes were detected in severely injured patients compared to their mild and moderate counterparts, suggesting that childhood TBI may disrupt the development of certain brain regions through diffuse pathological changes. The findings highlight the lasting impact of childhood TBI on the brain and the importance of monitoring brain structure in the long-term after early injury.

Corpus callosum anatomy in chronically treated and stimulant naïve ADHD

OBJECTIVE

To determine the effect of chronic stimulant treatment on corpus callosum (CC) size in children with ADHD using volumetric and area measurements. Previously published research indicated possible medication effects on specific areas of the CC.

METHOD

Measurements of the CC from anatomical MRIs were obtained from children aged 9-16 in three diagnostic groups (a) chronically treated ADHD, (b) stimulant-naïve ADHD, and (c) typically developing children.

RESULTS

The three groups did not differ in overall CC volume. Additional analyses found differences in the area of the splenium, with the treatment-naïve group exhibiting the smallest area.

CONCLUSIONS

Previously reported reductions of CC size in ADHD samples do not appear to be a result of chronic stimulant treatment. The current study suggested a trend toward normalization of splenium size for participants treated with stimulant medication.

Corpus callosum and inferior forebrain white matter microstructure are related to functional outcome from raised intracranial pressure in child traumatic brain injury

In severe paediatric traumatic brain injury (TBI), a common focus of treatment is raised intracranial pressure (ICP). We have previously reported frontal cerebral vulnerability with executive deficits from raised ICP in paediatric TBI. Now, using diffusion tensor imaging (DTI) in a different population, we have examined fractional anisotropy (FA), and mean, axial and radial diffusivity (MD, AD, RD) in 4 regions of the corpus callosum (CC) and in both inferior frontal regions. Our aim was to examine during the chronic phase of TBI whether the CC cross-sectional area correlated with regional DTI metrics of white matter microstructure, with global outcome ratings of function (Functional Independence Measure and Multiattribute Health Status Classification) and with performance in the Rey-Osterrieth Complex Figure (ROCF) test. We examined 33 paediatric TBI cases who were followed, on average, 4.9 years after severe injury. All cases had received mechanical ventilation during their acute treatment and, a priori, they were assigned to a non-ICP or a raised ICP group. Twenty-two participants had mainly right-sided injury at the time of acute ictus. The findings confirm that severe TBI in childhood, complicated by intracranial hypertension, results in CC vulnerability. In the chronic phase of recovery, it is reduced in the cross-sectional area, it is more compact and thinned, and the anterior region is disproportionately small. Late after raised ICP, we have also found that individuals exhibit regional microstructural abnormality with combined reduced FA and increased MD, AD and RD. Smaller size and such microstructural changes in the anterior CC were associated with similar right-sided (rather than left-sided) frontal microstructural changes in the ICP group. Taken together, this evidence points to an interaction between raised ICP-related brain tissue perturbation and focal frontal extracallosal injury, leading to anterior CC regional vulnerability, most likely wallerian degeneration. At long-term follow-up, this lack of white matter integrity in the anterior CC is correlated with functional outcome, particularly in aspects of social interaction and the copy component of the ROCF test, which suggests that the CC-to-forebrain function warrants further study in chronic TBI.

Early nonischemic oxidative metabolic dysfunction leads to chronic brain atrophy in traumatic brain injury

Chronic brain atrophy after traumatic brain injury (TBI) is a well-known phenomenon, the causes of which are unknown. Early nonischemic reduction in oxidative metabolism is regionally associated with chronic brain atrophy after TBI. A total of 32 patients with moderate-to-severe TBI prospectively underwent positron emission tomography (PET) and volumetric magnetic resonance imaging (MRI) within the first week and at 6 months after injury. Regional lobar assessments comprised oxidative metabolism and glucose metabolism. Acute MRI showed a preponderance of hemorrhagic lesions with few irreversible ischemic lesions. Global and regional chronic brain atrophy occurred in all patients by 6 months, with the temporal and frontal lobes exhibiting the most atrophy compared with the occipital lobe. Global and regional reduction in cerebral metabolic rate of oxygen (CMRO(2)), cerebral blood flow (CBF), oxygen extraction fraction (OEF), and cerebral metabolic rate of glucose were observed. The extent of metabolic dysfunction was correlated with the total hemorrhage burden on initial MRI (r=0.62, P=0.01). The extent of regional brain atrophy correlated best with CMRO(2) and CBF. Lobar values of OEF were not in the ischemic range and did not correlate with chronic brain atrophy. Chronic brain atrophy is regionally specific and associated with regional reductions in oxidative brain metabolism in the absence of irreversible ischemia.

The relation between Glasgow Coma Scale score and later cerebral atrophy in paediatric traumatic brain injury

PRIMARY OBJECTIVE

To examine initial Glasgow Coma Scale (GCS) score and its relationship with later cerebral atrophy in children with traumatic brain injury (TBI) using Quantitative Magnetic Resonance Imaging (QMRI) at 4 months post-injury. It was hypothesized that a lower GCS score would predict later generalized atrophy. As a guide in assessing paediatric TBI patients, the probability of developing chronic cerebral atrophy was determined based on the initial GCS score.

METHODS AND PROCEDURES

The probability model used data from 45 paediatric patients (mean age = 13.6) with mild-to-severe TBI and 41 paediatric (mean age = 12.4) orthopaedically-injured children.

RESULTS

This study found a 24% increase in the odds of developing an abnormal ventricle-to-brain ratio (VBR) and a 27% increase in the odds of developing reduced white matter percentage on neuroimaging with each numerical drop in GCS score. Logistic regression models with cut-offs determined by normative QMRI data confirmed that a lower initial GCS score predicts later atrophy.

CONCLUSION

GCS is a commonly used measure of injury severity. It has proven to be a prognostic indicator of cognitive recovery and functional outcome and is also predictive of later parenchymal change.

Neuroimaging in pediatric traumatic brain injury: current and future predictors of functional outcome

Although neuroimaging has long played a role in the acute management of pediatric traumatic brain injury (TBI), until recently, its use as a tool for understanding and predicting long-term brain-behavior relationships after TBI has been limited by the relatively poor sensitivity of routine clinical imaging for detecting diffuse axonal injury (DAI). Newer magnetic resonance-based imaging techniques demonstrate improved sensitivity to DAI. Early research suggests that these techniques hold promise for identifying imaging predictors and correlates of chronic function, both globally and within specific neuropsychological domains. In this review, we describe the principles of new, advanced imaging techniques including diffusion weighted and diffusion tensor imaging, susceptibility weighted imaging, and (1)H-magnetic resonance spectroscopy. In addition, we summarize current research demonstrating their early success in establishing relationships between imaging measures and functional outcomes after TBI. With the ongoing research, these imaging techniques may allow earlier identification of possible chronic sequelae of tissue injury for each child with TBI, thereby facilitating efficacy and efficiency in delivering successful rehabilitation services.

Arrested development and disrupted callosal microstructure following pediatric traumatic brain injury: relation to neurobehavioral outcomes

Chronic pediatric traumatic brain injury (TBI) is associated with significant and persistent neurobehavioral deficits. Using diffusion tensor imaging (DTI), we examined area, fractional anisotropy (FA), radial diffusion, and axial diffusion from six regions of the corpus callosum (CC) in 41 children and adolescents with TBI and 31 comparison children. Midsagittal cross-sectional area of the posterior body and isthmus was similar in younger children irrespective of injury status; however, increased area was evident in the older comparison children but was obviated in older children with TBI, suggesting arrested development. Similarly, age was correlated significantly with indices of tissue microstructure only for the comparison group. TBI was associated with significant reduction in FA and increased radial diffusivity in the posterior third of the CC and in the genu. The axial diffusivity did not differ by either age or group. Logistic regression analyses revealed that FA and radial diffusivity were equally sensitive to post-traumatic changes in 4 of 6 callosal regions; radial diffusivity was more sensitive for the rostral midbody and splenium. IQ, working memory, motor, and academic skills were correlated significantly with radial diffusion and/or FA from the isthmus and splenium only in the TBI group. Reduced size and microstructural changes in posterior callosal regions after TBI suggest arrested development, decreased organization, and disrupted myelination. Increased radial diffusivity was the most sensitive DTI-based surrogate marker of the extent of neuronal damage following TBI; FA was most strongly correlated with neuropsychological outcomes.

Persistent metabolic crisis as measured by elevated cerebral microdialysis lactate-pyruvate ratio predicts chronic frontal lobe brain atrophy after traumatic brain injury

OBJECTIVE

To determine whether persistent metabolic dysfunction in normal-appearing frontal lobe tissue is correlated with long-term tissue atrophy.

DESIGN

Prospective monitoring with retrospective data analysis.

SETTING

Single-center academic neurointensive care unit.

PATIENTS

Fifteen patients with moderate to severe traumatic brain injury (Glasgow Coma Scale score 3-12).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Hourly cerebral microdialysis was performed for the initial 96 hrs after trauma to determine extracellular levels of glucose, glutamate, glycerol, lactate, and pyruvate in normal appearing frontal lobes. Six months after injury, the anatomical outcome was assessed by measures of global and regional cerebral atrophy using volumetric brain magnetic resonance imaging. The lactate/pyruvate ratio was elevated >40 after traumatic brain injury in most patients, with a mean percent time of 32 +/- 29% of hours monitored. At 6 months after traumatic brain injury, there was a mean frontal lobe atrophy of 12 +/- 11% and global brain atrophy of 8.5 +/- 4.5%. The percentage of time of elevated lactate/pyruvate ratio correlated with the extent of frontal lobe brain atrophy (r = -.56, p < 0.01), but not global brain atrophy (r = -.31, p = 0.20). The predictive effect of lactate/pyruvate ratio was independent of patient age, Glasgow Coma Scale score, and volume of frontal lobe contusion.

CONCLUSION

Persistent metabolic crisis, as reflected by an elevated lactate/pyruvate ratio, in normal appearing posttraumatic frontal lobe, is predictive of the degree of tissue atrophy at 6 months.

Ventral frontal cortex functions and quantified MRI in traumatic brain injury

Ventral frontal cortex is commonly involved in traumatic brain injury (TBI). The smell identification test (SIT), object alternation (OA), and the Iowa gambling task (IGT) are associated with this brain region in experimental and neuropsychological research. We examined the relationship of performance on these tests to residual structural brain integrity quantified from MRI in 58 TBI patients, including 18 patients with focal cortical contusions and 40 patients with diffuse injury only. Image analysis yielded regional volumetric measures of gray matter, white matter and cerebrospinal fluid. Multivariate analyses identified distributed patterns of regional volume loss associated with test performance across all three behavioral measures. The tasks were sensitive to effects of TBI. In multivariate analyses, performance in all three tasks was related to gray matter loss including ventral frontal cortex, but the SIT was most sensitive to ventral frontal cortex damage, even in patients without focal lesions. The SIT was further related to temporal lobe and posterior cingulate/retrosplenial volumes. OA and the IGT were associated with superior medial frontal volumes. Complex tasks, such as OA and the IGT, do not consistently localize to a single cortical region. The SIT is associated with the integrity of ventral frontal regions, but it is also affected by distributed damage, although the contribution of undetected olfactory tract or bulb damage could not be ruled out. This study illustrates the scope and limitations of functional localization in human ventral frontal cortex.

Magnetic resonance imaging (MRI) findings and neuropsychological sequelae in children after severe traumatic brain injury: the role of cerebellar lesion

We studied the relationships between magnetic resonance imaging (MRI) findings and neuropsychological sequelae in children after severe traumatic brain injury. Twenty-three children ages 7-13 years underwent MRI assessment of brain lesion topography and volume and neuropsychological evaluations, more than 1 year after sustaining severe traumatic brain injury. Most children had lesions to the corpus callosum and frontal lobes. Total lesion volume and extent of cerebral atrophy did not impact on the neuropsychological evaluation. Additional relationships were observed: left frontal lesions with lower semantic verbal fluency, right occipital lesions with lower visual recognition task scores, dyscalculia with cerebellar lesions, and cerebellar damage with lower cognitive performances and lower visual recognition memory. This study demonstrates the significance of the cerebellum's role in neuropsychological outcomes after traumatic brain injury and the importance of the lesion depth classification in predicting functional results.

Neurocognitive and neuroimaging correlates of pediatric traumatic brain injury: a diffusion tensor imaging (DTI) study

This study examined the sensitivity of diffusion tensor imaging (DTI) to microstructural white matter (WM) damage in mild and moderate pediatric traumatic brain injury (TBI). Fourteen children with TBI and 14 controls ages 10-18 had DTI scans and neurocognitive evaluations at 6-12 months post-injury. Groups did not differ in intelligence, but children with TBI showed slower processing speed, working memory and executive deficits, and greater behavioral dysregulation. The TBI group had lower fractional anisotropy (FA) in three WM regions: inferior frontal, superior frontal, and supracallosal. There were no group differences in corpus callosum. FA in the frontal and supracallosal regions was correlated with executive functioning. Supracallosal FA was also correlated with motor speed. Behavior ratings showed correlations with supracallosal FA. Parent-reported executive deficits were inversely correlated with FA. Results suggest that DTI measures are sensitive to long-term WM changes and associated with cognitive functioning following pediatric TBI.

Functional and magnetic resonance imaging correlates of corpus callosum in normal pressure hydrocephalus before and after shunting

BACKGROUND

Normal pressure hydrocephalus (NPH) is associated with corpus callosum abnormalities.

OBJECTIVES

To study the clinical and neuropsychological effect of callosal thinning in 18 patients with idiopathic NPH and to investigate the postsurgical callosal changes in 14 patients.

METHODS

Global corpus callosum size and seven callosal subdivisions were measured. Neuropsychological assessment included an extensive battery assessing memory, psychomotor speed, visuospatial and frontal lobe functioning.

RESULTS

After surgery, patients showed improvements in memory, visuospatial and frontal lobe functions, and psychomotor speed. Two frontal corpus callosum areas, the genu and the rostral body, were the regions most related to the clinical and neuropsychological dysfunction. After surgery, total corpus callosum and four of the seven subdivisions presented a significant increase in size, which was related to poorer neuropsychological and clinical outcome.

CONCLUSION

The postsurgical corpus callosum increase might be the result of decompression, re-expansion and increase of interstitial fluid, although it may also be caused by differences in shape due to cerebral reorganisation.

Cluster subtypes on the California verbal learning test-children's version after pediatric traumatic brain injury

The purpose of this study is to determine the presence of profile subtypes on the California Verbal Learning Test-Children's Version (CVLT-C; Delis, Kramer, Kaplan, and Ober, 1994) in 175 children with traumatic brain injury (TBI). Four key z score variables are used in a 2-stage cluster analysis that reveal 4 reliable subtypes. No meaningful differences among the clusters are found on demographic variables. In contrast, statistically significant differences among the 4 clusters in both level and pattern of performance are found on injury severity parameters and the 4 factor index scores from an independent measure of psychometric intelligence (Wechsler Intelligence Scale for Children-Third Edition; Wechsler, 1991). This study concludes that although no unique profile is found on the CVLT-C after TBI in children, performance on this test is affected strongly by injury severity, with a mediating contribution by speed of information processing.

In vivo characterization of traumatic brain injury neuropathology with structural and functional neuroimaging

Quantitative neuroimaging is increasingly used to study the effects of traumatic brain injury (TBI) on brain structure and function. This paper reviews quantitative structural and functional neuroimaging studies of patients with TBI, with an emphasis on the effects of diffuse axonal injury (DAI), the primary neuropathology in TBI. Quantitative structural neuroimaging has evolved from simple planometric measurements through targeted region-of-interest analyses to whole-brain analysis of quantified tissue compartments. Recent studies converge to indicate widespread volume loss of both gray and white matter in patients with moderate-to-severe TBI. These changes can be documented even when patients with focal lesions are excluded. Broadly speaking, performance on standard neuropsychological tests of speeded information processing are related to these changes, but demonstration of specific brain-behavior relationships requires more refined experimental behavioral measures. The functional consequences of these structural changes can be imaged with activation functional neuroimaging. Although this line of research is at an early stage, results indicate that TBI causes a more widely dispersed activation in frontal and posterior cortices. Further progress in analysis of the consequences of TBI on neural structure and function will require control of variability in neuropathology and behavior.

Changes in white matter late after severe traumatic brain injury in childhood

Severe traumatic brain injury in childhood, particularly that complicated by raised intracranial pressure, has significant long-term effects on the brain. Since magnetic resonance imaging provides a means of visualizing neuroanatomic structure in exquisite detail, the scope of this review is to revisit the pathology of traumatic brain injury described in recent clinical imaging studies. Acute imaging provides insight into the acute mechanism of focal and diffuse injury. There is some reduction in threshold for white matter pathology in the hemisphere ipsilateral to injury. After injury, there may be long-term effects on white matter architecture and the potential for brain growth. In this context, the pattern of hippocampal rather than parahippocampal gyrus tissue loss provides insight into the likely cause of white matter injury being cerebral hypoperfusion.

Focal Lesion in Splenium of Corpus Callosum on FLAIR MRI: Common Findings in Aged Patients

Focal high signal intensity in the splenium of the corpus callosum on fluid-attenuated inversion-recovery (FLAIR) images is generally considered an abnormal MR finding. The aim of this study was to determine the frequency of this finding in elderly patients and review the differentiation from other diseases with the similar findings. FLAIR images of 132 patients with suspect CNS disease were retrospectively reviewed. The changes in the splenium of corpus callosum, deep white matter lesions, periventricular matter lesions, infarcts, atrophy and age were analyzed, as well as history. Among the initial 132 patients, focal high signal intensity in the splenium was associated with aging, white matter changes, atrophy, and cognitive disorders. Focal high signal intensity in the splenium of the corpus callosum on FLAIR image is a common finding in elderly patients, especially in aged patients with cognitive disorders. The pathologic alterations were commonly described by the term of "leukoaraiosis". Knowledge of this finding and differentiation from other lesions focusing on the splenium of corpus callosum may help avoid unnecessary invasive diagnostic and therapeutic intervention.

Neuroanatomic correlates of CVLT-C performance following pediatric traumatic brain injury

Traumatic brain injury (TBI) frequently results in memory problems, and the degree of memory impairment is related to injury severity and is commonly associated with lesions in frontal and temporal brain areas. This study examined the relationship among injury severity, brain lesions, and memory in children with moderate to severe TBI using Donders' (1999) 5-factor model of performance on the California Verbal Learning Test-Children's Version (CVLT-C). Seventy-six children underwent magnetic resonance imaging (MRI) scans 3 months post-TBI and testing 1 year post-TBI. Results showed injury severity (Glasgow Coma Scale) was not predictive of performance on 4 of the 5 factors. Volume of frontal and/or temporal brain lesions was significantly predictive of performance on 3 of the 5 factors. Unexpectedly, lesion volume outside these areas (extra-frontotemporal) was predictive of performance on all 5 factors. In contrast, Verbal IQ at 1 year was most strongly associated with preinjury factors (socioeconomic status and special education involvement), although extra-frontotemporal lesions also contributed to the variability in this measure. Results suggest that in children with moderate to severe TBI, extra-frontal/temporal lesions are predictive of memory outcome 1 year postinjury above and beyond initial severity or frontal/temporal contusions. This finding may relate to widespread diffuse axonal injury, which potentially disconnects brain circuits mediating memory following moderate to severe TBI.

Susceptibility weighted imaging: neuropsychologic outcome and pediatric head injury

Traumatic brain injury is among the most frequent pediatric neurologic disorders in the United States, affecting multiple aspects of neuropsychologic functioning. This study assessed the efficacy of susceptibility weighted imaging as a predictor of long-term neuropsychologic functioning after pediatric brain injury compared with magnetic resonance spectroscopic imaging. Susceptibility weighted imaging is a relatively new method that is considered superior to traditional magnetic resonance imaging sequences for detecting hemorrhagic diffuse axonal injury. In this study, imaging and spectroscopy were acquired 6 +/- 4 days after injury. Measures of neuropsychologic functioning were administered to 18 children and adolescents 1-4 years post injury. Negative correlations between lesion number and volume with neuropsychologic functioning were demonstrated. Lesion volume explained over 32% of the variance in cognitive performance, explaining at least an additional 20% beyond injury severity and age at injury alone and 19% beyond magnetic resonance spectroscopic metabolite variables. Exploratory analyses resulted in notable trends, with lesions in deeper brain regions more strongly associated with poorer neuropsychologic performance. Improved detection of the extent of diffuse axonal injury following a brain injury will allow for a better understanding of its association with long-term outcome, which in turn can improve prognostic efficacy for effective treatment planning.

Head circumference and brain and hippocampal volume after severe traumatic brain injury in childhood

Vulnerability of the hippocampus to traumatic brain injury (TBI) in adults is related to severity of injury and white matter atrophy. The objectives of this study were to determine features of anthropometry and cerebral morphometry late after TBI in childhood and to assess whether hippocampal volume is related to severity of initial ictus and changes in white matter at follow-up. Thirty-three patients underwent magnetic resonance imaging 4.9 y after severe TBI that necessitated intensive care; 23 had mechanical ventilation and intracranial pressure monitoring longer than 3 d. Magnetic resonance imaging analyses included volume of brain, hemisphere, ventricles, and hippocampal and perihippocampal regions; spatial distribution of voxel-based morphometry differences in white matter; and eigenvalues of diffusion tensor imaging diffusivity. Patients with longer intensive care ictus had smaller-than-expected occipitofrontal head circumference. Eight of these, identified by voxel-based morphometry, had periventricular white matter loss and smaller-than-expected brain volume for OFC, suggesting "atrophy"; the remainder had expected volume for a smaller OFC, suggesting "growth disturbance." Ninety-three percent of the variation in right hippocampal volume was accounted for by factors related to severity of injury and white matter atrophy. It is concluded that anthropometry and cerebral morphometric measurements late after severe TBI in childhood provides useful outcome data and indicate that, despite adequate growth in stature, effects of TBI on brain growth and hippocampal volume may extend into adulthood.

A quantitative computed tomography assessment of brain weight, volume, and specific gravity in severe head trauma

BACKGROUND

Computed tomography DICOM images analysis allows a quantitative measurement of organ weight, volume and specific gravity in humans.

METHODS

The brain weight, volume and specific gravity of 15 traumatic brain-injury patients (3+/-2 days after trauma) were computed using a specially designed software (BrainView). Data were compared with those obtained from 15 healthy subjects paired for age and overall intracranial volume.

RESULTS

Hemisphere weight were 91 g higher in patients than in controls (1167+/-101 vs 1076+/-112 g; p<0.05). Specific gravity of hemispheres (1.0367+/-0.0017 vs 1.0335+/-0.0012 g/ml; p<0.001), brainstem (1.0302+/-0.0016 vs 1.0277+/-0.0015 g/ml; p<0.001) and cerebellum (1.0396+/-0.0020 vs 1.0375+/-0.0015 g/ml; p<0.05) was significantly higher in traumatic brain injury (TBI) patients than in controls (all p<0.0001 without interaction). This increase in specific gravity was evenly distributed between the hemispheres, the brainstem and the cerebellum, and the grey and white matter. It was more pronounced in the rostral than in the caudal areas of the hemispheres. It was independent of the volume of brain contusion, of the mechanism of head injury, of natremia and of initial Glasgow coma score.

CONCLUSION

Human TBI patients present a diffuse increase in specific gravity. This observation is in sharp opposition with the data derived from the experimental literature.

Frontal and temporal morphometric findings on MRI in children after moderate to severe traumatic brain injury

In vivo MRI volumetric analysis enables investigators to evaluate the extent of tissue loss following traumatic brain injury (TBI). However, volumetric studies of pediatric TBI are sparse, and there have been no volumetric studies to date in children examining specific subregions of the prefrontal and temporal lobes. In this study, MRI volumetry was used to evaluate brain volume differences in the whole brain, and prefrontal, temporal, and posterior regions of children following moderate to severe TBI as compared to uninjured children of similar age and demographic characteristics. The TBI group had significantly reduced whole brain, and prefrontal and temporal regional tissue volumes as well as increased cerebrospinal fluid (CSF). Confidence interval testing further revealed group differences on gray matter (GM) and white matter (WM) in the superior medial and ventromedial prefrontal regions, WM in the lateral frontal region, and GM, WM, and CSF in the temporal region. Whole brain volume and total brain GM were reduced, and total ventricular volume, total CSF volume, and ventricle-to-brain ratio (VBR) were increased in the TBI group. Additional analyses comparing volumetric data from typically developing children and subgroups of TBI patients with and without regional focal lesions suggested that GM loss in the frontal areas was primarily attributable to focal injury, while WM loss in the frontal and temporal lobes was related to both diffuse and focal injury. Finally, volumetric measures of preserved frontotemporal tissue were related to functional recovery as measured by the Glasgow Outcome Scale (adapted for children) with greater tissue preservation predicting better recovery.