Head trauma

Acute pediatric traumatic brain injury severity predicts long-term verbal memory performance through suppression by white matter integrity on diffusion tensor imaging

Mediation analysis was used to investigate the role of white matter integrity in the relationship between injury severity and verbal memory performance in participants with chronic pediatric traumatic brain injury (TBI). DTI tractography was used to measure fractional anisotropy (FA) within the corpus callosum, fornix, cingulum bundles, perforant pathways, and uncinate fasciculi. Injury severity was indexed using Glasgow Coma Scale (GCS) scores obtained at the time of the injury. Verbal memory was measured by performance on the long-delay free recall (LDFR) trial of the California Verbal Learning Test-Children's version. Participants were between the ages of 10-18 and included 21 children with TBI (injured before age 9) and 19 typically-developing children (TDC). Children with TBI showed lower FA across all pathways and poorer LDFR performance relative to TDC. Within the TBI group, mediation analysis revealed neither a significant total effect of GCS on LDFR nor significant direct effects of GCS on LDFR across pathways; however, the indirect effects of GCS on LDFR through FA of the corpus callosum, left perforant pathway, and left uncinate fasciculus were significant and opposite in sign to their respective direct effects. These results suggests that the predictive validity of GCS for LDFR is initially suppressed by the substantial variance accounted for by FA, which is uncorrelated with GCS, and the predictive validity of GCS increases only when FA is considered, and the opposing path is controlled. These findings illustrate the complex associations between acute injury severity, white matter pathways, and verbal memory several years following pediatric TBI.

Predicting behavioral deficits in pediatric traumatic brain injury through uncinate fasciculus integrity

Behavioral dysregulation is a common and detrimental consequence of traumatic brain injury (TBI) in children that contributes to poor academic achievement and deficits in social development. Unfortunately, behavioral dysregulation is difficult to predict from either injury severity or early neuropsychological evaluation. The uncinate fasciculus (UF) connects orbitofrontal and anterior temporal lobes, which are commonly implicated in emotional and behavioral regulation. Using probabilistic diffusion tensor tractography (DTT), we examined the relationship between the integrity of the UF 3 months post-injury and ratings of executive functions 12 months post-injury in children with moderate to severe TBI and a comparison group with orthopedic injuries. As expected, fractional anisotropy of the UF was lower in the TBI group relative to the orthopedic injury group. DTT metrics from the UF served as a biomarker and predicted ratings of emotional and behavior regulation, but not metacognition. In contrast, the Glasgow Coma Scale score was not related to either UF integrity or to executive function outcomes. Neuroanatomical biomarkers like the uncinate fasciculus may allow for early identification of behavioral problems and allow for investigation into the relationship of frontotemporal networks to brain-behavior relationships.

MR diffusion tensor imaging: a window into white matter integrity of the working brain

As Norman Geschwind asserted in 1965, syndromes resulting from white matter lesions could produce deficits in higher-order functions and "disconnexion" or the interruption of connection between gray matter regions could be as disruptive as trauma to those regions per se. The advent of in vivo diffusion tensor imaging, which allows quantitative characterization of white matter fiber integrity in health and disease, has served to strengthen Geschwind's proposal. Here we present an overview of the principles of diffusion tensor imaging (DTI) and its contribution to progress in our current understanding of normal and pathological brain function.

Small orbitofrontal traumatic lesions detected by high resolution MRI in a patient with major behavioural changes

We report a case of a male patient who showed personality changes and marked social problems after a traumatic brain injury. Although suspected to have lesions in the orbitofrontal cortex because of the typical characteristics of his behavioural change, lesions were not apparent using conventional imaging techniques. However, investigation using high-resolution MRI revealed lesions in the orbitofrontal cortex. Our case suggests that standard MRI scanning techniques may have only limited power. Hence, we stress the important role played by qualitative assessments of emotion, personality, and social behaviour in evaluating sequelae of traumatic orbitofrontal injuries.

Practitioner review: early adversity and developmental disorders

BACKGROUND

Knowledge of genetic influences, on developmental disorders such as autism spectrum, attention deficit/hyperactivity disorder and learning disabilities, has increased the opportunities for understanding the influences of the early environment.

METHODS

This paper provides a selective, narrative review for clinicians of the effects of factors such as exposure to toxins and stresses in utero and in postnatal life; brain injuries and perinatal compromise; neglect, malnutrition and selective food deficiencies. It also considers what is known about the mechanisms through which early adversities operate.

RESULTS

Gaps in the research are identified and suggestions made about clinical investigations. Several types of environmental adversity have associations with later disorders that suggest a causal role. The effects are often on a broad range of psychological processes, and are not always quickly reversible. Several adversities often coexist, calling for skilled judgement about priorities in treatment.

CONCLUSIONS

Individuals vary considerably in their exposure to adversity and their vulnerability to its effects, and genetic inheritance can influence both.

Pharmacologic Treatment of Cognitive Deficits and Hypersexuality Due to “Shaken-Baby Syndrome”

Objective:

To describe the clinical effects of amantadine and propranolol in an agitated pediatric patient with cognitive deficits, hyperactivity, and hypersexualism secondary to “shaken-baby syndrome.”

Background:

Patients with shaken-baby syndrome can present with cognitive and behavioral impairments.

Case:

A 9-year-old girl presented with cognitive impairments secondary to shaken-baby syndrome at 3 weeks of age. She was receiving many medications, including dextroamphetamine, methylphenidate, and clonidine, that were not effective in improving her cognitive status or decreasing her hypersexuality. She was weaned from stimulants and clonidine and prescribed amantadine 100 mg bid with improvement of attention, concentration, and cognition, although hypersexuality remained. She was then started on propranolol 10 mg tid and a gradual increase to 40 mg tid with amelioration of hypersexuality and hyperactivity and no unwanted effects noted. Self-weaning of propranolol was associated with the return of hypersexuality. The combination of amantadine and propranolol led to improvement of cognition and behavior, especially intellectual functioning and appropriate socialization with peers, respectively.

Conclusion:

Cognitive deficits and hypersexuality with hyperactive features due to shaken-baby syndrome may respond to the drug regimen of amantadine and propranolol.

Neurobehavioral recovery after pediatric head trauma: injury, pre-injury, and post-injury issues

This article reviews the most significant demographic, neurological, and psychosocial factors affecting the occurrence of and recovery from traumatic head injury (THI) in children and adolescents. Review of the available literature suggests that, as with adults, there is no compelling evidence for persistent neurobehavioral deficits after mild THI in children. In contrast, neurobehavioral deficits are common in children who have sustained moderate to severe THI. This article emphasizes that a long-term developmental perspective that considers in concert injury, pre-injury, and post-injury variables is needed for a proper appreciation of possible sequelae of pediatric THI. Specific pitfalls in forensic assessments of these children are reviewed. Empirical findings are presented to support the position that neuropsychological evaluations of children with THI that do not consider pre-injury status are likely to lead to misattribution errors. Clinical implications are illustrated with a case example.

Late sequelae of major trauma in children

Traumatic injuries represent the most important threat to the health of children in the United States and are the leading cause of death after the first year of life. More than 20,000 children and young adults will die this year as a result of injury. For every child that dies, another 40 will require hospitalization and 1000 more will be evaluated in emergency departments. Moreover, 50,000 children and adolescents will sustain some degree of permanent disability, the majority of victims of brain injury. This article focuses on several important long-term implications for children, their families and primary care physicians, following multisystem injuries.

Inability to restore resting intracellular calcium levels as an early indicator of delayed neuronal cell death

The hippocampus is especially vulnerable to excitotoxicity and delayed neuronal cell death. Chronic elevations in free intracellular calcium concentration ([Ca2+]i) following glutamate-induced excitotoxicity have been implicated in contributing to delayed neuronal cell death. However, no direct correlation between delayed cell death and prolonged increases in [Ca2+]i has been determined in mature hippocampal neurons in culture. This investigation was initiated to determine the statistical relationship between delayed neuronal cell death and prolonged increases in [Ca2+]i in mature hippocampal neurons in culture. Using indo-1 confocal fluorescence microscopy, we observed that glutamate induced a rapid increase in [Ca2+]i that persisted after the removal of glutamate. Following excitotoxic glutamate exposure, neurons exhibited prolonged increases in [Ca2+]i, and significant delayed neuronal cell death was observed. The N-methyl-D-aspartate (NMDA) channel antagonist MK-801 blocked the prolonged increases in [Ca2+]i and cell death. Depolarization of neurons with potassium chloride (KCl) resulted in increases in [Ca2+]i, but these increases were buffered immediately upon removal of the KCl, and no cell death occurred. Linear regression analysis revealed a strong correlation (R = 0.973) between glutamate-induced prolonged increases in [Ca2+]i and delayed cell death. These data suggest that excitotoxic glutamate exposure results in an NMDA-induced inability to restore resting [Ca2+]i (IRRC) that is a statistically significant indicator of delayed neuronal cell death.