Magnetic resonance imaging in relation to functional outcome of pediatric closed head injury: a test of the Ommaya-Gennarelli model

Magnetic Resonance Imaging Findings Are Associated with Long-Term Global Neurological Function or Death after Traumatic Brain Injury in Critically Ill Children

The identification of children with traumatic brain injury (TBI) who are at risk of death or poor global neurological functional outcome remains a challenge. Magnetic resonance imaging (MRI) can detect several brain pathologies that are a result of TBI; however, the types and locations of pathology that are the most predictive remain to be determined. Forty-two critically ill children with TBI were recruited prospectively from pediatric intensive care units at five Canadian children's hospitals. Pathologies detected on subacute phase MRIs included cerebral hematoma, herniation, cerebral laceration, cerebral edema, midline shift, and the presence and location of cerebral contusion or diffuse axonal injury (DAI) in 28 regions of interest were assessed. Global functional outcome or death more than 12 months post-injury was assessed using the Pediatric Cerebral Performance Category score. Linear modeling was employed to evaluate the utility of an MRI composite score for predicting long-term global neurological function or death after injury, and nonlinear Random Forest modeling was used to identify which MRI features have the most predictive utility. A linear predictive model of favorable versus unfavorable long-term outcomes was significantly improved when an MRI composite score was added to clinical variables. Nonlinear Random Forest modeling identified five MRI variables as stable predictors of poor outcomes: presence of herniation, DAI in the parietal lobe, DAI in the subcortical white matter, DAI in the posterior corpus callosum, and cerebral contusion in the anterior temporal lobe. Clinical MRI has prognostic value to identify children with TBI at risk of long-term unfavorable outcomes.

Acute Imaging Findings Predict Recovery of Cognitive and Motor Function after Inpatient Rehabilitation for Pediatric Traumatic Brain Injury: A Pediatric Brain Injury Consortium Study

Traumatic brain injury (TBI) is a major cause of morbidity and mortality in children; survivors experience long-term cognitive and motor deficits. To date, studies predicting outcome following pediatric TBI have primarily focused on acute behavioral responses and proxy measures of injury severity; unsurprisingly, these measures explain very little of the variance following heterogenous injury. In adults, certain acute imaging biomarkers help predict cognitive and motor recovery following moderate to severe TBI. This multi-center, retrospective study, characterizes the day-of-injury computed tomographic (CT) reports of pediatric, adolescent, and young adult patients (2 months to 21 years old) who received inpatient rehabilitation services for TBI (n = 247). The study also determines the prognostic utility of CT findings for cognitive and motor outcomes assessed by the Pediatric Functional Independence Measure, converted to age-appropriate developmental functional quotient (DFQ), at discharge from rehabilitation. Subdural hematomas (66%), contusions (63%), and subarachnoid hemorrhages (59%) were the most common lesions; the majority of subjects had less severe Rotterdam CT scores (88%, ≤ 3). After controlling for age, gender, mechanism of injury, length of acute hospital stay, and admission DFQ in multivariate regression analyses, the highest Rotterdam score (β = -25.2, p < 0.01) and complete cisternal effacement (β = -19.4, p < 0.05) were associated with lower motor DFQ, and intraventricular hemorrhage was associated with lower motor (β = -3.7, p < 0.05) and cognitive DFQ (β = -4.9, p < 0.05). These results suggest that direct detection of intracranial injury provides valuable information to aid in prediction of recovery after pediatric TBI, and needs to be accounted for in future studies of prognosis and intervention.

Two Coarse Spatial Patterns of Altered Brain Microstructure Predict Post-traumatic Amnesia in the Subacute Stage of Severe Traumatic Brain Injury

Introduction: Diffuse traumatic axonal injury (TAI) is one of the key mechanisms leading to impaired consciousness after severe traumatic brain injury (TBI). In addition, preferential regional expression of TAI in the brain may also influence clinical outcome. Aim: We addressed the question whether the regional expression of microstructural changes as revealed by whole-brain diffusion tensor imaging (DTI) in the subacute stage after severe TBI may predict the duration of post-traumatic amnesia (PTA). Method: Fourteen patients underwent whole-brain DTI in the subacute stage after severe TBI. Mean fractional anisotropy (FA) and mean diffusivity (MD) were calculated for five bilateral brain regions: fronto-temporal, parieto-occipital, and midsagittal hemispheric white matter, as well as brainstem and basal ganglia. Region-specific calculation of mean FA and MD only considered voxels that showed no tissue damage, using an exclusive mask with all voxels that belonged to local brain lesions or microbleeds. Mean FA or MD of the five brain regions were entered in separate partial least squares (PLS) regression analyses to identify patterns of regional microstructural changes that account for inter-individual variations in PTA. Results: For FA, PLS analysis revealed two spatial patterns that significantly correlated with individual PTA. The lower the mean FA values in all five brain regions, the longer that PTA lasted. A pattern characterized by lower FA values in the deeper brain regions relative to the FA values in the hemispheric regions also correlated with longer PTA. Similar trends were found for MD, but opposite in sign. The spatial FA changes as revealed by PLS components predicted the duration of PTA. Individual PTA duration, as predicted by a leave-one-out cross-validation analysis, correlated with true PTA values (Spearman r = 0.68, p permutation = 0.008). Conclusion: Two coarse spatial patterns of microstructural damage, indexed as reduction in FA, were relevant to recovery of consciousness after TBI. One pattern expressed was consistent with diffuse microstructural damage across the entire brain. A second pattern was indicative of a preferential damage of deep midline brain structures.

Abnormal Motor Response Associated With Concussive Injuries: Biomechanical Comparison Between Impact Seizures and Loss of Consciousness

CONTEXT

Loss of consciousness (LOC) and impact seizures associated with concussion represent different clinical presentations of concussion; however, they are often investigated and treated similarly. The biomechanical parameters differentiating these 2 distinct signs of injury are poorly described.

OBJECTIVE

To differentiate between cases of concussions with LOC and those with impact seizures by comparing the impact velocity, peak linear and peak rotational acceleration, as well as brain tissue deformation in the cerebral cortex, white matter, brainstem, cerebellum, thalamus, and corpus callosum.

DESIGN

Descriptive laboratory study.

PATIENTS OR OTHER PARTICIPANTS

Elite American football players who sustained an LOC (n = 20) or impact seizures (n = 21).

MAIN OUTCOME MEASURE(S)

Impact velocity, peak linear and peak rotational acceleration, maximum principal strain, cumulative strain damage measure at 10%, and strain rate (SR).

RESULTS

The SR in the cerebral white matter was greater in the LOC group than in the impact-seizure group. Similar trends were observed for SRs in the cerebral cortex, brainstem, and corpus callosum. No differences were present between groups for the other variables in this study.

CONCLUSIONS

A lower SR in certain brain regions helps to explain why motor function is preserved and can be observed in patients with impact seizures versus LOC from concussive injuries.

Spectrum and outcome of traumatic brain injury in children <15 years: A tertiary level experience in India

BACKGROUND

Though, traumatic brain injury (TBI) has been documented as the single most common cause of morbidity and mortality in infancy and childhood, the exact incidence is unavailable in India. Moreover, modes of injury, mechanisms of damage, and management differ significantly from that of an adult.

AIMS AND OBJECTIVES

To analyze the epidemiological factors, the spectrum of TBI, modes of injury, types of injury, and the outcome in the children <15 years with TBI.

MATERIALS AND METHODS

This is a retrospective study from August 2012 to May 2013 at Department of Neurosurgery, S.C.B. Medical College, Cuttack, Odisha, India. All the pertinent details from case records of hundred and forty-seven children <15 years with TBI were analyzed. Follow-up was done for 6 months at outpatients department.

RESULTS

Age wise, incidence and severity of TBI is more common in 10-15 years. Males outnumber females with a male: female ratio 2.19:1. Overall, road traffic accident (RTA) is the commonest mode of injury. Assault is not uncommon (7.48% cases). Falls is common in <5 years while RTA is common in 5-15 years. The extradural hematoma was the most common injury pattern; however, surgical consideration was maximal for fracture skull. Overall mortality was 7.48%. Diffuse axonal injury has the maximum individual potential for mortality. We noticed excellent recovery in 68.7%, disabilities in 17.68%, and persistent vegetative state in 5.45% cases.

CONCLUSION

TBI in children carries good outcome, if resuscitated and referred early to a neurotrauma center, and managed subsequently on an individualized basis with a well-organized team approach. Severe TBI in children has a poor outcome.

Establishing a Clinically Relevant Large Animal Model Platform for TBI Therapy Development: Using Cyclosporin A as a Case Study

We have developed the first immature large animal translational treatment trial of a pharmacologic intervention for traumatic brain injury (TBI) in children. The preclinical trial design includes multiple doses of the intervention in two different injury types (focal and diffuse) to bracket the range seen in clinical injury and uses two post-TBI delays to drug administration. Cyclosporin A (CsA) was used as a case study in our first implementation of the platform because of its success in multiple preclinical adult rodent TBI models and its current use in children for other indications. Tier 1 of the therapy development platform assessed the short-term treatment efficacy after 24 h of agent administration. Positive responses to treatment were compared with injured controls using an objective effect threshold established prior to the study. Effective CsA doses were identified to study in Tier 2. In the Tier 2 paradigm, agent is administered in a porcine intensive care unit utilizing neurological monitoring and clinically relevant management strategies, and intervention efficacy is defined as improvement in longer term behavioral endpoints above untreated injured animals. In summary, this innovative large animal preclinical study design can be applied to future evaluations of other agents that promote recovery or repair after TBI.

Predicting Outcome after Pediatric Traumatic Brain Injury by Early Magnetic Resonance Imaging Lesion Location and Volume

Brain lesions after traumatic brain injury (TBI) are heterogeneous, rendering outcome prognostication difficult. The aim of this study is to investigate whether early magnetic resonance imaging (MRI) of lesion location and lesion volume within discrete brain anatomical zones can accurately predict long-term neurological outcome in children post-TBI. Fluid-attenuated inversion recovery (FLAIR) MRI hyperintense lesions in 63 children obtained 6.2±5.6 days postinjury were correlated with the Glasgow Outcome Scale Extended-Pediatrics (GOS-E Peds) score at 13.5±8.6 months. FLAIR lesion volume was expressed as hyperintensity lesion volume index (HLVI)=(hyperintensity lesion volume / whole brain volume)×100 measured within three brain zones: zone A (cortical structures); zone B (basal ganglia, corpus callosum, internal capsule, and thalamus); and zone C (brainstem). HLVI-total and HLVI-zone C predicted good and poor outcome groups (p<0.05). GOS-E Peds correlated with HLVI-total (r=0.39; p=0.002) and HLVI in all three zones: zone A (r=0.31; p<0.02); zone B (r=0.35; p=0.004); and zone C (r=0.37; p=0.003). In adolescents ages 13-17 years, HLVI-total correlated best with outcome (r=0.5; p=0.007), whereas in younger children under the age of 13, HLVI-zone B correlated best (r=0.52; p=0.001). Compared to patients with lesions in zone A alone or in zones A and B, patients with lesions in all three zones had a significantly higher odds ratio (4.38; 95% confidence interval, 1.19-16.0) for developing an unfavorable outcome.

Epidemiology and treatment outcome of head injury in children: A prospective study

Summary:

Head injury in children is a major concern all over the world. The increasing level of poverty in the world is exposing more children to trauma situations. The future consequences of trauma in these children are enormous, hence prevention they say, is better than cure.

Aim of the Study:

The study was designed to determine the etiological pattern, age group affectation and treatment outcome in children managed for head injury in our center.

Methods:

It was a prospective, descriptive and cross-sectional study of children with head injuries managed in our center from July 2010 to December 2013. Data were collected using structured proforma that was part of our prospective Data Bank approved by our hospital Research and Ethics Committee. Data were collected in accident and emergency unit, Intensive Care Unit, wards and out-patient clinic. The data was analyzed using Epi Info 7 software.

Results:

Total of 76 children managed by the unit and followed-up to a minimum of 3 months qualified for the study. There were 42 males. The age ranged from 7 months to 18 years with a mean of 8.66 years. There were 30 adolescent/teenagers. Road traffic accident formed 63.15%. Pedestrian accident was more among preschool and school children. Thirty-seven patients had mild head injury. Sixty-six patients were managed conservatively. The commonest posttraumatic effect was seizure (15.79%). Good functional outcome (≥4) was seen in 92.1%. Mode of accident and severity of injury affected the outcome.

Conclusions:

The etiologies of traumatic brain injury, from our study, were age dependent with falls commonest in toddlers and pedestrian accident commonest in pre-school and school ages. The outcome of treatment was related to severity of injury.

Attentional control ten years post-childhood traumatic brain injury: the impact of lesion presence, location, and severity in adolescence and early adulthood

The relationship between brain injury and attentional control (AC) long after a childhood traumatic brain injury (TBI) has received limited investigation. The aim of this article was to investigate the impact that lesion presence, location, and severity has on AC in a group of young persons who had sustained a moderate to severe TBI 10 years earlier during childhood. The participants in this study were a subset of a larger 10-year, follow-up assessment comprised of 31 persons in late adolescence and early adulthood (21 males), with a mean age at testing of 15.4 years (standard error 0.6; range 10.7-21.2 years). Analyses revealed that in regard to AC abilities, the presence of a lesion(s) appears to have a differential effect depending on the testing measure used. When using standardized testing with subtests of the TEA-ch, no differences in performance between those with and those without a lesion at 10 years post-TBI were found. On standardized behavioral measures such as parental reports of perceived AC (Behavior Rating Inventory of Executive Function), however, the presence of a lesion was found to have a detrimental effect on the ability to self-regulate and monitor behavior in late adolescence and the early stages of adulthood. We discuss these results and propose that there is a network of brain regions associated with AC, and generalized lesions have the greatest influence on such abilities.

Outcome of patients with traumatic head injury in infants: An institutional experience at level 1 trauma center

Background:

Traumatic head injury is a common cause of mortality and acquired disability in infants and children. However, patterns and outcome of head injury in infants are different from other age groups.

Aims and Objectives:

Aim of our study was to find out epidemiological factors, characteristics of injury, and outcome in infants with traumatic brain injury.

Materials and Methods:

This is a retrospective study from March 2009 through Feb 2012, at JPNATC, AIIMS, New Delhi. The clinical records of all patients, admitted with head injury were evaluated. Twenty-nine infants with traumatic brain injury were followed up and outcome was analyzed.

Results:

Twenty-nine infants with traumatic brain injury were included in the study. Of these 17 (59%) were boys and 12 (41%) were girls. Fall from height was recorded in 27 (93%) patients and road traffic accident was the mode of injury in 2 (7%). Mild head injury (GCS 14-15) was found in 18 (62%) patients, moderate in 4 (14%) patients (GCS 9-13), severe (GCS 3-8) in 7 (24%) patients. SDH was the most common injury in 8 (27%) patients. Out of these 4 (14%) were immediately operated, 25 (86%) were managed conservatively. Overall mortality was 11% (3 patients). Glasgow Outcome Scale was 5 in 20 (69%) patients and 3 (10.3%) patients each had GOS 3 or 4.

Conclusion:

Infants suffered significant brain injury due to fall. Traumatic brain injury in infants generally carries good outcome. Severe head injury was observed to be a predictor of poor outcome.

Planning Ability Following Moderate to Severe Traumatic Brain Injury: Performance on a 4-Disk Version of the Tower of London

This study aimed to assess planning ability in adults with traumatic brain injury (TBI) using a 4-disk version of the Tower of London (TOL). Thirty three individuals with TBI were compared with equivalent numbers of matched controls. Overall, the TOL4 was shown to be sensitive to the effects of brain injury, with the TBI group performing significantly more poorly on this version of the planning test than the matched controls. More specifically, group differences were found to be related to the complexity of the planning problems, particularly among a TBI subgroup with localised prefrontal damage. Results of the study provide support for the adverse effects of TBI on planning ability, and the important role of the prefrontal cortex in planning.

The effects of pediatric traumatic brain injury on verbal and visual-spatial working memory

The purpose of this study was to investigate the effects of pediatric traumatic brain injury (TBI) on verbal and visual-spatial working memory (WM). WM tasks examined memory span through recall of the last item of a series of stimuli. Additionally, both verbal and visual-spatial tests had a dual-task condition assessing the effect of increasing demands on the central executive (CE). Inhibitory control processes in verbal WM were examined through intrusion errors. The TBI group (n = 73) performed more poorly on verbal and visual-spatial WM tasks than orthopedic-injured children (n = 30) and non-injured children (n = 40). All groups performed more poorly on the dual-task conditions, reflecting an effect of increasing CE load. This effect was not greater for the TBI group. There were no group differences in intrusion errors on the verbal WM task, suggesting that problems in WM experienced by children with TBI were not primarily due to difficulties in inhibitory control. Finally, injury-related characteristics, namely days to follow commands, accounted for significant variance in WM performance, after controlling for relevant demographic variables. Findings suggest that WM impairments in TBI are general rather than modality-specific and that severity indices measured over time are better predictors of WM performance than those taken at a single time point.

The relationship of resting cerebral blood flow and brain activation during a social cognition task in adolescents with chronic moderate to severe traumatic brain injury: a preliminary investigation

Alterations in cerebrovascular function are evident acutely in moderate to severe traumatic brain injury (TBI), although less is known about their chronic effects. Adolescent and adult patients with moderate to severe TBI have been reported to demonstrate diffuse activation throughout the brain during functional magnetic resonance imaging (fMRI). Because fMRI is a measure related to blood flow, it is possible that any deficits in blood flow may alter activation. An arterial spin labeling (ASL) perfusion sequence was performed on seven adolescents with chronic moderate to severe TBI and seven typically developing (TD) adolescents during the same session in which they had performed a social cognition task during fMRI. In the TD group, prefrontal CBF was positively related to prefrontal activation and negatively related to non-prefrontal, posterior, brain activation. This relationship was not seen in the TBI group, who demonstrated a greater positive relationship between prefrontal CBF and non-prefrontal activation than the TD group. An analysis of CBF data independent of fMRI showed reduced CBF in the right non-prefrontal region (p<.055) in the TBI group. To understand any role reduced CBF may play in diffuse extra-activation, we then related the right non-prefrontal CBF to activation. CBF in the right non-prefrontal region in the TD group was positively associated with prefrontal activation, suggesting an interactive role of non-prefrontal and prefrontal blood flow throughout the right hemisphere in healthy brains. However, the TBI group demonstrated a positive association with activation constrained to the right non-prefrontal region. These data suggest a relationship between impaired non-prefrontal CBF and the presence of non-prefrontal extra-activation, where the region with more limited blood flow is associated with activation limited to that region. In a secondary analysis, pathology associated with hyperintensities on T2-weighted FLAIR imaging over the whole brain was related to whole brain activation, revealing a negative relationship between lesion volume and frontal activation, and a positive relationship between lesion volume and posterior activation. These preliminary data, albeit collected with small sample sizes, suggest that reduced non-prefrontal CBF, and possibly pathological tissue associated with T2-hyperintensities, may provide contributions to the diffuse, primarily posterior extra-activation observed in adolescents following moderate to severe TBI.

Neurobiological consequences of traumatic brain injury

Traumatic brain injury (TBI) is a worldwide public health problem typically caused by contact and inertial forces acting on the brain. Recent attention has also focused on the mechanisms of injury associated with exposure to blast events or explosions. Advances in the understanding of the neuropathophysiology of TBI suggest that these forces initiate an elaborate and complex array of cellular and subcellular events related to alterations in Ca⁺⁺ homeostasis and signaling. Furthermore, there is a fairly predictable profile of brain regions that are impacted by neurotrauma and the related events. This profile of brain damage accurately predicts the acute and chronic sequelae that TBI survivors suffer from, although there is enough variation to suggest that individual differences such as genetic polymorphisms and factors governing resiliency play a role in modulating outcome. This paper reviews our current understanding of the neuropathophysiology of TBI and how this relates to the common clinical presentation of neurobehavioral difficulties seen after an injury.

Prognostic value of magnetic resonance imaging in moderate and severe head injury: a prospective study of early MRI findings and one-year outcome

The clinical benefit of early magnetic resonance imaging (MRI) in severe and moderate head injury is unclear. We sought to explore the prognostic value of the depth of lesions depicted with early MRI, and also to describe the prevalence and impact of traumatic brainstem lesions. In a cohort of 159 consecutive patients with moderate to severe head injury (age 5-65 years and surviving the acute phase) admitted to a regional level 1 trauma center, 106 (67%) were examined with MRI within 4 weeks post-injury. Depth of lesions in MRI was categorized as: hemisphere level, central level, and brainstem injury (BSI). The outcome measure was Glasgow Outcome Scale Extended (GOSE) 12 months post-injury. Forty-six percent of patients with severe injuries and 14% of patients with moderate injuries had BSI. In severe head injury, central or brainstem lesions in MRI, together with higher Rotterdam CT score, pupillary dilation, and secondary adverse events were significantly associated with a worse outcome in age-adjusted analyses. Bilateral BSI was strongly associated with a poor outcome in severe injury, with positive and negative predictive values of 0.86 and 0.88, respectively. In moderate injury, only age was significantly associated with outcome in multivariable analyses. Limitations of the current study include lack of blinded outcome evaluations and insufficient statistical power to assess the added prognostic value of MRI when combined with clinical information. We conclude that in patients with severe head injury surviving the acute phase, depth of lesion on the MRI was associated with outcome, and in particular, bilateral brainstem injury was strongly associated with poor outcomes. In moderate head injury, surprisingly, there was no association between MRI findings and outcome when using the GOSE score as outcome measure.

Brain-behavior relationships in young traumatic brain injury patients: DTI metrics are highly correlated with postural control

Traumatic brain injury (TBI) is a major cause of impairment and functional disability in children and adolescents, including deterioration in fine as well as gross motor skills. The aim of this study was to assess deficits in sensory organization and postural ability in a young group of TBI patients versus controls by using quantitative force-platform recordings, and to test whether balance deficits are related to variation in structural properties of the motor and sensory white matter pathways. Twelve patients with TBI and 14 controls (aged 8-20 years) performed the Sensory Organisation Test (SOT) protocol of the EquiTest (Neurocom). All participants were scanned using Diffusion Tensor Imaging (DTI) along with standard anatomical scans. Quantitative comparisons of DTI parameters (fractional anisotropy, axial and radial diffusivity) between TBI patients and controls were performed. Correlations between DTI parameters and SOT balance scores were determined. Findings revealed that the TBI group scored generally lower than the control group on the SOT, indicative of deficits in postural control. In the TBI group, reductions in fractional anisotropy were noted in the cerebellum, posterior thalamic radiation, and corticospinal tract. Degree of white matter deterioration was highly correlated with balance deficits. This study supports the view that DTI is a valuable tool for assessing the integrity of white matter structures and for selectively predicting functional motor deficits in TBI patients.

Predicting outcomes of traumatic brain injury by imaging modality and injury distribution

Early prediction of outcomes after traumatic brain injury (TBI) is often difficult. To improve prognostic accuracy soon after trauma, we compared different radiological modalities and anatomical injury distribution in a group of adult TBI patients. The four methods studied were computed tomography (CT), magnetic resonance imaging (MRI) with T2-weighted imaging (T2WI), fluid-attenuated inversion recovery (FLAIR) imaging, and susceptibility weighted imaging (SWI). The objective of this study was to identify which modality and anatomic model best predict outcome. The patient population consisted of 38 adults admitted between February 2001 and May 2003. Early CT, T2WI, FLAIR, and SWI were obtained for each patient as well as a Glasgow Outcome Score (GOS) between 0.1 and 22 months (mean 9.2 months) after injury. Using a semi-automated computer method, intraparenchymal lesions were traced, measured, and converted to lesion volumes based on slice thickness and pixel size. Lesions were assigned to zones and regions. Outcomes were dichotomized into good (GOS 4-5) and poor (GOS 1-3) outcome groups. Brain injury detected by imaging was analyzed by median total lesion volume, median volume per lesion, and median number of lesions per outcome group. T2WI and FLAIR imaging most consistently discriminated between good and poor outcomes by median total lesion volume, median volume per lesion, and median number of lesions. In addition, T2WI and FLAIR imaging most consistently discriminated between good and poor outcomes by zonal distribution. While SWI rarely discriminated by outcome, it was very sensitive to intraparenchymal injury and its optimal use in evaluating TBI is unclear. SWI and other new imaging modalities should be further studied to fully evaluate their prognostic utility in TBI evaluation.

Deficits in analogical reasoning in adolescents with traumatic brain injury

Individuals with traumatic brain injury (TBI) exhibit deficits in executive control, which may impact their reasoning abilities. Analogical reasoning requires working memory and inhibitory abilities. In this study, we tested adolescents with moderate to severe TBI and typically developing (TD) controls on a set of picture analogy problems. Three factors were varied: complexity (number of relations in the problems), distraction (distractor item present or absent), and animacy (living or non-living items in the problems). We found that TD adolescents performed significantly better overall than TBI adolescents. There was also an age effect present in the TBI group where older participants performed better than younger ones. This age effect was not observed in the TD group. Performance was affected by complexity and distraction. Further, TBI participants exhibited lower performance with distractors present than TD participants. The reasoning deficits exhibited by the TBI participants were correlated with measures of executive function that required working memory updating, attention, and attentional screening. Using MRI-derived measures of cortical thickness, correlations were carried out between task accuracy and cortical thickness. The TD adolescents showed negative correlations between thickness and task accuracy in frontal and temporal regions consistent with cortical maturation in these regions. This study demonstrates that adolescent TBI results in impairments in analogical reasoning ability. Further, TBI youth have difficulty effectively screening out distraction, which may lead to failures in comprehension of the relations among items in visual scenes. Lastly, TBI youth fail to show robust cortical–behavior correlations as observed in TD individuals.

Assessment of thalamic perfusion in patients with mild traumatic brain injury by true FISP arterial spin labelling MR imaging at 3T

OBJECTIVE

To assess cerebral blood flow (CBF) changes in patients with mild traumatic brain injury (MTBI) using an arterial spin labelling (ASL) perfusion MRI and to investigate the severity of neuropsychological functional impairment with respect to haemodynamic changes.

MATERIALS AND METHODS

Twenty-one patients with MTBI and 20 healthy controls were studied at 3T MR. The median time since the onset of brain injury in patients was 24.6 months. Both patients and controls underwent a traditional consensus battery of neurocognitive tests. ASL was performed using true fast imaging with steady state precession and a flow-sensitive alternating inversion recovery preparation. Regional CBF were measured in both deep and cortical gray matter as well as white matter at the level of basal ganglia.

RESULTS

The mean regional CBF was significantly lower in patients with MTBI (45.9 +/- 9.8 ml/100 g min(-1)) as compared to normal controls (57.1 +/- 8.1 ml/100 g min(-1); p = 0.002) in both sides of thalamus. The decrease of thalamic CBF was significantly correlated with several neurocognitive measures including processing and response speed, memory/learning, verbal fluency and executive function in patients.

CONCLUSIONS

Haemodynamic impairment can occur and persist in patients with MTBI, the extent of which is more severe in thalamic regions and correlate with neurocognitive dysfunction during the extended course of disease.

Brain activation while thinking about the self from another person's perspective after traumatic brain injury in adolescents

Deficits in self awareness and taking the perspective of others are often observed following traumatic brain injury (TBI). Nine adolescents (ages 12-19 years) who had sustained moderate to severe TBI after an average interval of 2.6 years and nine typically developing (TD) adolescents underwent functional MRI (fMRI) while performing a perspective taking task (D'Argembeau et al., 2007). Participants made trait attributions either from their own perspective or from that of the significant other. The groups did not differ in reaction time or on a consistency criterion. When thinking of the self from a third-person perspective, adolescents with TBI demonstrated greater activation in posterior brain regions implicated in social cognition, the left lingual gyrus (BA 18) and posterior cingulate (BA 31), extending into neighboring regions not generally associated with social cognition, that is, cuneus (BA 31) and parahippocampal gyrus, relative to TD adolescents. We postulate that adolescents with moderate to severe TBI recruited alternative neural pathways during perspective-taking because traumatic axonal injury disrupted their fronto-parietal networks mediating social cognition.

Emotion recognition following pediatric traumatic brain injury: longitudinal analysis of emotional prosody and facial emotion recognition

Children with closed head injuries often experience significant and persistent disruptions in their social and behavioral functioning. Studies with adults sustaining a traumatic brain injury (TBI) indicate deficits in emotion recognition and suggest that these difficulties may underlie some of the social deficits. The goal of the current study was to examine if children sustaining a TBI exhibit difficulties with emotion recognition in terms of emotional prosody and face emotion recognition and to determine (1) how these abilities change over time and (2) what, if any, additional factors such as sex, age, and socioeconomic status (SES) affected the findings. Results provide general support for the idea that children sustaining a TBI exhibit deficits in emotional prosody and face emotion recognition performance. Further, although some gains were noted in the TBI group over the two-years following injury, factors such as SES and age at injury influenced the trajectory of recovery. The current findings indicate the relationship between TBI and emotion recognition is complex and may be influenced by a number of developmental and environmental factors. Results are discussed in terms of their similarity to previous investigations demonstrating the influence of environmental factors on behavioral recovery following pediatric TBI, and with regard to future investigations that can further explore the link between emotion recognition deficits and long-term behavioral and psychosocial recovery.

Neuroimaging after coma

Following coma, some patients will recover wakefulness without signs of consciousness (only showing reflex movements, i.e., the vegetative state) or may show non-reflex movements but remain without functional communication (i.e., the minimally conscious state). Currently, there remains a high rate of misdiagnosis of the vegetative state (Schnakers et. al. BMC Neurol, 9:35, 8) and the clinical and electrophysiological markers of outcome from the vegetative and minimally conscious states remain unsatisfactory. This should incite clinicians to use multimodal assessment to detect objective signs of consciousness and validate para-clinical prognostic markers in these challenging patients. This review will focus on advanced magnetic resonance imaging (MRI) techniques such as magnetic resonance spectroscopy, diffusion tensor imaging, and functional MRI (fMRI studies in both "activation" and "resting state" conditions) that were recently introduced in the assessment of patients with chronic disorders of consciousness.

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.

Diffusion tensor imaging in relation to cognitive and functional outcome of traumatic brain injury in children

OBJECTIVE

To investigate the relation of white matter integrity using diffusion tensor imaging (DTI) to cognitive and functional outcome of moderate to severe traumatic brain injury (TBI) in children.

DESIGN

Prospective observational study of children who had sustained moderate to severe TBI and a comparison group of children who had sustained orthopedic injury (OI).

PARTICIPANTS

Thirty-two children who had sustained moderate to severe TBI and 36 children with OI were studied.

METHODS

Fiber tracking analysis of DTI acquired at 3-month postinjury and assessment of global outcome and cognitive function within 2 weeks of brain imaging. Global outcome was assessed using the Glasgow Outcome Scale and the Flanker task was used to measure cognitive processing speed and resistance to interference.

RESULTS

Fractional anisotropy and apparent diffusion coefficient values differentiated the groups and both cognitive and functional outcome measures were related to the DTI findings. Dissociations were present wherein the relation of Fractional anisotropy to cognitive performance differed between the TBI and OI groups. A DTI composite measure of white matter integrity was related to global outcome in the children with TBI.

CONCLUSIONS

DTI is sensitive to white matter injury at 3 months following moderate to severe TBI in children, including brain regions that appear normal on conventional magnetic resonance imaging. DTI measures reflecting diffusion of water parallel and perpendicular to white matter tracts as calculated by fiber tracking analysis are related to global outcome, cognitive processing speed, and speed of resolving interference in children with moderate to severe TBI. Longitudinal data are needed to determine whether these relations between DTI and neurobehavioral outcome of TBI in children persist at longer follow-up intervals.

Traumatic brain injury in young children: postacute effects on cognitive and school readiness skills

Previous studies have documented weaknesses in cognitive ability and early academic readiness in young children with traumatic brain injury (TBI). However, few of these studies have rigorously controlled for demographic characteristics, examined the effects of TBI severity on a wide range of skills, or explored moderating influences of environmental factors on outcomes. To meet these objectives, each of three groups of children with TBI (20 with severe, 64 with moderate, and 15 with mild) were compared with a group of 117 children with orthopedic injuries (OI group). The children were hospitalized for their injuries between 3 and 6 years of age and were assessed an average of 1 1/2 months post injury. Analysis revealed generalized weaknesses in cognitive and school readiness skills in the severe TBI group and less pervasive effects of moderate TBI. Indices of TBI severity predicted outcomes within the TBI sample and environmental factors moderated the effects of TBI on some measures. The findings document adverse effects of TBI in early childhood on postacute cognitive and school readiness skills and indicate that these effects are related to both injury severity and the family environment.

Clinical review: Prognostic value of magnetic resonance imaging in acute brain injury and coma

Progress in management of critically ill neurological patients has led to improved survival rates. However, severe residual neurological impairment, such as persistent coma, occurs in some survivors. This raises concerns about whether it is ethically appropriate to apply aggressive care routinely, which is also associated with burdensome long-term management costs. Adapting the management approach based on long-term neurological prognosis represents a major challenge to intensive care. Magnetic resonance imaging (MRI) can show brain lesions that are not visible by computed tomography, including early cytotoxic oedema after ischaemic stroke, diffuse axonal injury after traumatic brain injury and cortical laminar necrosis after cardiac arrest. Thus, MRI increases the accuracy of neurological diagnosis in critically ill patients. In addition, there is some evidence that MRI may have potential in terms of predicting outcome. Following a brief description of the sequences used, this review focuses on the prognostic value of MRI in patients with traumatic brain injury, anoxic/hypoxic encephalopathy and stroke. Finally, the roles played by the main anatomical structures involved in arousal and awareness are discussed and avenues for future research suggested.

A combined clinical and MRI approach for outcome assessment of traumatic head injured comatose patients

Traumatic brain injury (TBI) is associated with substantial consumption of health care resources. No clinical or paraclinical examination can reliably predict neurological evolution. In this study, we evaluated the ability of a combined clinical and MRI approach to predict outcome.

METHODS

This prospective study took place between June 2001 and March 2005 in a Neurosurgical Intensive Care Unit in Paris, France. Inclusion criteria were TBI patients still mechanically ventilated and without clinical signs of awareness after 2 weeks. Four clinical signs were assessed after cessation of sedation: grasping, yawning, chewing and paroxysmal sympathetic storm. FLAIR and T2* acquisitions on MRI were used in order to localize brain lesions. Statistically linked regions (clusters) were defined. Outcome was assessed at one year by Glasgow Outcome Scale (GOS).

FINDINGS

73 patients were included: 41 had poor outcome (GOS 1-3) and 32 had good outcome (GOS 4-5). Lesions in the clusters "right upper pons and right lower midbrain"," hypothalamus and basal forebrain","left parietal, left temporal, left occipital lobes and left insula" and the presence of grasping or chewing were associated with poor outcome in multivariate analysis. This combined clinical and MRI approach gives a much better prediction than MRI approach only (P < 0.009), with an area under the ROC curve of 0.94 (95 % CI, 0.89-1.00).

INTERPRETATION

These data suggest that MRI associated with clinical assessment improves outcome prediction in severe TBI patients.

Susceptibility-weighted MR imaging: a review of clinical applications in children

Susceptibility-weighted imaging (SWI) is a high-spatial-resolution 3D gradient-echo MR imaging technique with phase postprocessing that accentuates the paramagnetic properties of blood products such as deoxyhemoglobin, intracellular methemoglobin, and hemosiderin. It is particularly useful for detecting intravascular venous deoxygenated blood as well as extravascular blood products. It is also quite sensitive to the presence of other substances such as iron, some forms of calcification, and air. We have used this technique in the past several years to study a wide variety of pediatric neurologic disorders. We present a review with selected case histories to demonstrate its clinical usefulness in the improvement of the following: 1) detection of hemorrhagic lesions seen in various conditions, including traumatic brain injury and coagulopathic or other hemorrhagic disorders; 2) detection of vascular malformations such as cavernous angiomas, telangiectasias, or pial angiomas associated with Sturge-Weber syndrome; 3) demonstration of venous thrombosis and/or increased oxygen extraction in the setting of infarction, hypoxic/anoxic injury, or brain death; 4) delineation of neoplasms with hemorrhage, calcification, or increased vascularity; and 5) depiction of calcium or iron deposition in neurodegenerative disorders. SWI has provided new understanding of some of these disease processes. It is hoped that as SWI becomes more widely available, it will provide additional diagnostic and prognostic information that will improve the care and outcome of affected children.

Diffusion-weighted magnetic resonance imaging improves outcome prediction in adult traumatic brain injury

In patients with traumatic brain injury (TBI), diffuse axonal injury (DAI) accounts for a significant amount of parenchymal injury. Diffusion weighted magnetic resonance imaging (DWI) is known to be sensitive for detecting visible DAI lesions. We focused on detection of non-visible, quantifiable diffusion changes in specific normal-appearing brain regions, using apparent diffusion coefficient (ADC) maps. Thirty-seven adults with TBI were compared to 35 age-matched control patients. DWI was performed and ADC maps were generated. Thirty-one regions of interest (ROI) were manually drawn on ADC maps and ADC values extracted. Brain ROIs were categorized into five zones: peripheral gray matter, peripheral white matter, deep gray matter, deep white matter, and posterior fossa. ADC results were compared with the severity of injury based on the admission Glasgow Coma Scale (GCS 3-8; severe; GSC 9-15 mild/moderate) and with long-term outcome (6-12 months after injury) using the Glasgow Outcome Scale (GOS 1-3, unfavorable; GOS: 4-5, favorable) score. Mean ADC values in all five brain zones were significantly different between TBI subjects and controls (p<or=0.05). Patients with more severe injury (i.e., GCS 3-8) had significantly different mean ADC values than control patients (p<or=0.05) and patients with unfavorable outcomes had significantly higher mean deep gray and white matter ADC values compared to those with favorable outcomes and to controls (p<or=0.05). Thus, ADC maps can be used to detect non-visible DAI lesions. In addition, injuries in the deep gray and white matter may be useful to predict outcome in adult TBI patients.

The neurocognitive basis of compromised autonomy after traumatic brain injury: clinical and ethical considerations

It is widely accepted, based on the principle of respect for autonomy, that there are ethical constraints on the range of tactics that persons may use to influence the decisions and behaviors of others. However, accurate ascriptions of autonomy to either persons or acts may vary considerably, depending on properties of the person, the situation, or both. Traumatic brain injury affects cognitive domains that are critical for the effective exercise of autonomy, and so offers a context for further examination of this variability. Analysis of the neuropathology of traumatic brain injury and its neurocognitive consequences provides a foundation for understanding cases in which autonomy is compromised even though legal competency may be preserved. Respecting autonomy in these cases is not always straightforward; it may entail both special ethical obligations and consideration of tactics that would not be morally permissible under other circumstances.

Mechanisms, clinical presentations, injuries, and outcomes from inflicted versus noninflicted head trauma during infancy: results of a prospective, multicentered, comparative study

OBJECTIVE

Our goal was to conduct a prospective, multicentered, comparative study that would objectively verify and explain observed differences in short-term neurodevelopmental outcomes after inflicted versus noninflicted head trauma.

METHODS

Children <36 months of age who were hospitalized with acute head trauma confirmed by computed tomography imaging were recruited at multiple sites. Extensive clinical data were captured prospectively, subjects were examined, cranial imaging studies were blindly reviewed, and caregivers underwent scripted interviews. Follow-up neurodevelopmental evaluations were completed 6 months after injury. Head-trauma etiology and mechanisms were categorized by using objective a priori criteria. Thereafter, subject groups with inflicted versus noninflicted etiologies were compared.

RESULTS

Fifty-four subjects who met the eligibility criteria were enrolled at 9 sites. Of 52 surviving subjects, 27 underwent follow-up assessment 6 months after injury. Etiology was categorized as noninflicted in 30 subjects, inflicted in 11, and undetermined in 13. Compared with subjects with noninflicted head trauma, subjects with inflicted head trauma (1) more frequently experienced noncontact injury mechanisms, (2) sustained greater injury depth, (3) more frequently manifested acute cardiorespiratory compromise, (4) had lower initial Glasgow Coma Scale scores, (5) experienced more frequent and prolonged impairments of consciousness, (6) more frequently demonstrated bilateral, hypoxic-ischemic brain injury, (7) had lower mental developmental index scores 6 months postinjury, and (8) had lower gross motor quotient scores 6 months postinjury.

CONCLUSIONS

Compared with infants with noninflicted head trauma, young victims of inflicted head trauma experience more frequent noncontact injury mechanisms that result in deeper brain injuries, cardiorespiratory compromise, diffuse cerebral hypoxia-ischemia, and worse outcomes.

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.

Brain activation during working memory after traumatic brain injury in children

Eight children with moderate to severe traumatic brain injury (TBI) and eight matched, uninjured control children underwent fMRI during an N-back task to test effects of TBI on working memory performance and brain activation. Two patterns in the TBI group were observed. Patients whose criterion performance was reached at lower memory loads than control children demonstrated less extensive frontal and extrafrontal brain activation than controls. Patients who performed the same, highest (3-back) memory load as controls demonstrated more frontal and extrafrontal activation than controls. Our findings of performance and brain activation changes in children after TBI await longitudinal investigation.

Decision-making after traumatic brain injury in children: a preliminary study

Decision-making under conditions of uncertainty was studied in 11 children with moderate to severe post-acute traumatic brain injury (TBI) using a modification of the Iowa Gambling Task (Bechara et al., 1994). We hypothesized that decision-making would be compromised in children with TBI. The results revealed that when divided into subgroups by lesion location, children with lesions in the amygdala (AM) were impaired on modified gambling task performance, but children with ventromedial (VM) lesions did not appear to be impaired on the task. These results are in contrast to studies of decision-making in adults with focal lesions of vascular etiology.

Plastic reorganization of hippocampal and neocortical circuitry in experimental traumatic brain injury in the immature rat

The reorganization of circuitry in the immature forebrain resulting from controlled cortical impact was examined with viral transneuronal tracing. Animals injured on postnatal day (PND) 17 and sham controls from the same litters received an intracerebral injection of a recombinant strain of pseudorabies virus (PRV) into the entorhinal cortex on PND 45. Fifty hours following injection of virus the animals were perfused and infected neurons were localized immunohistochemically with antisera specific for PRV. Prior studies have demonstrated that the PRV recombinant used in this analysis moves exclusively in the retrograde direction through synaptically linked neurons. CCI induced a necrotic loss of cortex at the site of impact and variable damage to the underlying corpus callosum and rostral (dorsal) hippocampus that was not present in sham controls. Analysis of viral transport in sham controls revealed retrograde transport of virus through hippocampal and neocortical circuitry in a pattern consistent with established patterns of connectivity and topography. Injured animals exhibited preservation of topographically organized connections in both the hippocampus and neocortex. However, the magnitude of labeling in the injured hemisphere was significantly increased relative to control animals and correlated with the magnitude of the injury. The distribution of infected neurons in the contralateral uninjured hemisphere also conformed to known connections. However differences in the involvement of the corpus callosum in the injury resulted in greater variability in the number of infected neurons among cases. These data provide novel insights into trauma induced reorganization of the developing brain and add to the experimental tools that can be used to assess the basis for functional recovery in animal models of developmental traumatic brain injury.

Coma duration prediction in diffuse axonal injury: analyses of apparent diffusion coefficient and clinical prognostic factors

The purpose of this paper is to evaluate the hypothesis that the Apparent Diffusion Coefficient (ADC) values combined with initial clinical factors indicates the depth of shearing lesions in the brain structure and therefore relates to coma duration of diffuse axonal injury (DAI). Seventy-four adult patients (48 male and 26 female patients) with diffuse axonal injury were examined with convention MR imaging and diffusion weighted MR imaging between 2 hours and 20 days after injury. Apparent diffusion coefficient (ADC) maps were obtained and the mean ADC values of each Region of Interest (ROI) were measured using MRI console software. The lesions involvement of brainstem, deep gray matter, and corpus callosum were determined for each sequence separately as well as for the combination of all sequences. The correlations between magnetic resonance (MR) imaging findings of presence of apparent brain injury combined with initial clinical factors were investigated. Clinical characteristics, such as initial score on the Glasgow Coma Scale (GCS), age, and the number of all lesions, ADC scores of the patient in MR findings were predictive of the duration of coma. Post-traumatic coma duration of DAI could be predicted by cerebral MRI findings in the acute to subacute stage after head injury combined with clinical prognostic factors. Age, ADC scores, GCS, number of lesions are highly significant in predicting coma duration. The technique presented herein might provide a tool for in vivo detection of DAI for the coma duration at the early stages in patients with traumatic brain injury.

Response Inhibition After Traumatic Brain Injury (TBI) in Children: Impairment and Recovery

Children who experience traumatic brain injury (TBI) often show cognitive impairments postinjury, some of which recover over time. We examined the recovery of motor response inhibition immediately following TBI and over 2 years. We assessed the role of injury severity, age at injury, and lesion characteristics on initial impairment and recovery while considering the role of pre-injury psychiatric disorder. Participants were 136 children with TBI aged 5-16 years. Latency of motor response inhibition was measured with the stop-signal task within 1 month of the injury and again at 3, 6, 12, and 24 months. The performance of the TBI participants at each measurement occasion was standardized with 117 children of similar age, but without injury. Residualized latency scores were calculated. Growth curve analyses showed an initial impairment in response inhibition and improvement over the 2 years following injury. Younger TBI patients were initially more impaired although they exhibited greater recovery of response inhibition than did older TBI patients. Longer duration of coma, but not reactivity of pupils or Glasgow Coma Scale score, predicted initial deficit. Lesion characteristics or pre-injury attention deficit hyperactivity disorder did not predict initial impairment or recovery. Replication with longitudinal testing of a comparison group of children sustaining extracranial injury is necessary to confirm our findings.

Traumatic brain injury and grey matter concentration: a preliminary voxel based morphometry study

BACKGROUND

Magnetic resonance imaging (MRI) studies have shown diffuse cerebral atrophy following traumatic brain injury. In the past, quantitative volumetric analysis of these changes was carried out by manually tracing specific regions of interest. In contrast, voxel based morphometry (VBM) is a fully automated technique that allows examination of the whole brain on a voxel by voxel basis.

OBJECTIVE

To use VBM to evaluate changes in grey matter concentration following traumatic brain injury.

METHODS

Nine patients with a history of traumatic brain injury (ranging from mild to severe) about one year previously were compared with nine age and sex matched healthy volunteers. T1 weighted three dimensional MRI images were acquired and then analysed with statistical parametric mapping software (SPM2). The patients with traumatic brain injury also completed cognitive testing to determine whether regional grey matter concentration correlated with a measure of attention and initial injury severity.

RESULTS

Compared with controls, the brain injured patients had decreased grey matter concentration in multiple brain regions including frontal and temporal cortices, cingulate gyrus, subcortical grey matter, and the cerebellum. Decreased grey matter concentration correlated with lower scores on tests of attention and lower Glasgow coma scale scores.

CONCLUSIONS

Using VBM, regions of decreased grey matter concentration were observed in subjects with traumatic brain injury compared with well matched controls. In the brain injured patients, there was a relation between grey matter concentration and attentional ability.

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.

Psychosocial outcome of TBI in children with unilateral frontal lesions

To evaluate effects of unilateral frontal lesions on psychosocial and global outcome of traumatic brain injury (TBI) in children, Study 1 compared matched groups of 22 school aged children who had sustained TBI either with or without unilateral frontal lesions. Study 2 evaluated effects of unilateral extrafrontal lesions in 18 TBI patients as compared with 18 nonlesional TBI patients. Communication, Daily Living, and Socialization domains and the Maladaptive Behavior Scale of the Vineland Adaptive Behavior Scales (VABS) were used to assess psychosocial outcome, and the Glasgow Outcome Scale (GOS) measured global outcome. All patients underwent magnetic resonance imaging at least 3 months post injury. Children with frontal lesions had worse scores on the Daily Living and Socialization domains and a higher frequency of maladaptive behavior than those without frontal lesions, but there was no difference in cognitive function. Disability was twice as common in the frontal lesion group relative to children without frontal lesions. Volume of frontal lesion was related to the Socialization domain. Side of lesion had no effect, nor did presence of an extrafrontal lesion (Study 2). Unilateral frontal lesions adversely affect late psychosocial outcome of TBI in children.

Changes in Working Memory After Traumatic Brain Injury in Children

The impact of traumatic brain injury (TBI) on working memory (WM) was studied in 144 children (79 with mild, 23 with moderate, and 42 with severe injuries) who underwent magnetic resonance imaging (MRI) at 3 months and were tested at baseline and at 3, 6, 12, and 24 months postinjury. An n-back WM task for letter identity was administered with memory load ranging from 1- to 3-back and a 0-back condition. A TBI Severity x Quadratic Tune interaction showed that net percentage correct (correct detections of targets minus false alarms) was significantly lower in severe than in mild TBI groups. The Left Frontal Lesions x Age interaction approached significance. Mechanisms mediating late decline in WM and the effects of left frontal lesions are discussed.

Premorbid intellectual functioning, education, and brain size in traumatic brain injury: an investigation of the cognitive reserve hypothesis

Cognitive reserve theories have been postulated in an attempt to explain individual differences in functional outcome following cerebral insult or disease. These theories suggest that higher education and psychometric intelligence may preserve functional capacity regardless of injury or disease severity. This study investigated cognitive reserve in 25 participants with traumatic brain injury (TBI) using high-resolution magnetic resonance imaging (MRI) analyses. We examined the relationships between total intracranial volume (TICV), ventricle-tobrain ratio (VBR), education level, and standardized testing obtained prior to injury with post-injury cognitive outcome. Participants with lower post-injury IQ scores had significantly lower TICV values, irrespective of injury severity, and experienced significantly greater change in IQ from pre- to post-injury. TICV and education correctly predicted participants' post-injury IQ category ( Y 90 or < 90). However, premorbid standardized testing (PST) scores did not predict cognitive outcome. The results of this study suggest that larger premorbid brain volume and higher education level may decrease vulnerability to cognitive deficits following TBI, consistent with the notion of a cognitive reserve.

Tools for the measurement of outcome after minor head injury in children: summary from the Ambulatory Pediatric Association/EMSC Outcomes Research Conference

This article summarizes discussions held during a conference on outcomes research in emergency medical services for children. It provides detailed information on existing outcome measures for pediatric minor head injury. Benefits and/or limitations in their applicability for use in pediatric emergency medicine and pediatric minor head injury research are highlighted.

Semiquantitative analysis of corpus callosum injury using magnetic resonance imaging indicates clinical severity in patients with diffuse axonal injury

OBJECTIVE

To evaluate the hypothesis that the extent of corpus callosum injury indicates the depth of shearing lesions in the central brain structure and therefore relates to the clinical severity of diffuse axonal injury.

METHODS

A simple and objective procedure for semiquantitative analysis of magnetic resonance images (MRI)-the maximum signal intensity ratio (MSIR)-was employed prospectively in 21 patients with diffuse axonal injury but without apparent injury to the ventral pons. All were diagnosed using serial combination MRI scans of fluid attenuated inversion recovery (FLAIR) and T2* weighted gradient echo imaging during the initial two weeks after the injury. The signal intensity ratio between the two regions of interest-the corpus callosum and the normal appearing ventral pons-was calculated serially in mid-sagittal and parasagittal FLAIR image sections in each patient. The MSIR during the study period was determined as a semiquantitative index of corpus callosum injury in each patient. The correlations between MSIR and the duration of unconsciousness, Glasgow outcome scale at six months, and the presence of apparent midbrain injury were investigated.

RESULTS

The mean (SD) MSIR value was 1.12 (0.18) at 7.4 (3.1) days after the injury (n = 21). MSIR correlated strongly with the duration of unconsciousness (n = 19, R(2) = 0.74, p < 0.0001), and was higher in patients with both an unfavourable GOS outcome (p = 0.020) and apparent midbrain injury (p < 0.001).

CONCLUSIONS

MSIR, which is a simple and objective procedure for semiquantitative analysis of corpus callosum damage in diffuse axonal injury, correlated with clinical severity. A high MSIR value may indicate the presence of concomitant midbrain injury.

Metacognition following pediatric traumatic brain injury: a preliminary study

Metacognition is one of the cognitive processes included under the general term executive functions. The executive functions are widely held to be under the control of the prefrontal cortex, an area often damaged after severe traumatic brain injury (TBI). We examined the metacognitive processing of a group of 9 children with TBI, and a group of 9 healthy, age-matched control children. Children with TBI showed significant impairments in their accuracy of prediction of the ease with which an item would be learned and their ability to predict recall of an item after a 2-hr delay. No significant differences in recall performance between the TBI and control groups were exhibited. The results are interpreted as suggesting an impairment in metacognitive processing resulting from frontal lobe damage after TBI in children. Additional research is necessary to confirm the relation of frontal lobe pathology and severity of injury to metacognitive impairments.