Journal of neurotrauma
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Journal of neurotrauma · Jun 2011
ReviewMechanisms of primary blast-induced traumatic brain injury: insights from shock-wave research.
Traumatic brain injury caused by explosive or blast events is traditionally divided into four phases: primary, secondary, tertiary, and quaternary blast injury. These phases of blast-induced traumatic brain injury (bTBI) are biomechanically distinct and can be modeled in both in vivo and in vitro systems. The primary bTBI injury phase represents the response of brain tissue to the initial blast wave. ⋯ These are well-described pathological findings within the SW literature. Acoustic impedance mismatch, penetration of tissue by shock/bubble interaction, geometry of the skull, shear stress, tensile stress, and subsequent cavitation formation, are all important factors in determining the extent of SW-induced tissue and cellular injury. Herein we describe the requirements for the adequate experimental set-up when investigating blast-induced tissue and cellular injury; review SW physics, research, and the importance of engineering validation (visualization/pressure measurement/numerical simulation); and, based upon our findings of SW-induced injury, discuss the potential underlying mechanisms of primary bTBI.
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Journal of neurotrauma · Jun 2011
Acute serum hormone levels: characterization and prognosis after severe traumatic brain injury.
Experimental traumatic brain injury (TBI) studies report the neuroprotective effects of female sex steroids on multiple mechanisms of injury, with the clinical assumption that women have hormonally mediated neuroprotection because of the endogenous presence of these hormones. Other literature indicates that testosterone may exacerbate injury. Further, stress hormone abnormalities that accompany critical illness may both amplify or blunt sex steroid levels. ⋯ Changes in the post-TBI adrenal response and peripheral aromatization influenced hormone TRAJ profiles and contributed to the abnormalities, including increased estradiol in men and increased testosterone in women. In addition to older age and greater injury severity, increased estradiol and testosterone levels over time were associated with increased mortality and worse global outcome for both men and women. These findings represent a paradigm shift when thinking about the role of sex steroids in neuroprotection clinically after TBI.
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Journal of neurotrauma · Jun 2011
Bimanual coordination and corpus callosum microstructure in young adults with traumatic brain injury: a diffusion tensor imaging study.
Bimanual actions are ubiquitous in daily life. Many coordinated movements of the upper extremities rely on precise timing, which requires efficient interhemispheric communication via the corpus callosum (CC). As the CC in particular is known to be vulnerable to traumatic brain injury (TBI), furthering our understanding of its structure-function association is highly valuable for TBI diagnostics and prognosis. ⋯ Finally, multiple regression analyses showed evidence of the high specificity of callosal subregions accounting for the variance associated with performance of the different bimanual coordination tasks. Whereas disruption in commissural pathways between occipital areas played a role in performance on the clinical tests of bimanual coordination, deficits in the switching task were related to disrupted interhemispheric communication in prefrontal, sensory, and parietal regions. This study provides evidence that structural alterations of several subregional callosal fibers in adults with TBI are associated with differential behavioral manifestations of bimanual motor functioning.
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Journal of neurotrauma · Jun 2011
Comparative StudyLong-term outcomes after uncomplicated mild traumatic brain injury: a comparison with trauma controls.
The question as to whether mild traumatic brain injury (mTBI) results in persisting sequelae over and above those experienced by individuals sustaining general trauma remains controversial. This prospective study aimed to document outcomes 1 week and 3 months post-injury following mTBI assessed in the emergency department (ED) of a major adult trauma center. One hundred and twenty-three patients presenting with uncomplicated mTBI and 100 matched trauma controls completed measures of post-concussive symptoms and cognitive performance (Immediate Post-Concussion Assessment and Cognitive Testing battery; ImPACT) and pre-injury health-related quality of life (SF-36) in the ED. ⋯ There were no significant group differences in psychiatric function. However, the group with mild TBI was more likely to report ongoing memory and concentration problems in daily activities. Further investigation of factors associated with these ongoing problems is warranted.
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Journal of neurotrauma · Jun 2011
Interaction between brain chemistry and physiology after traumatic brain injury: impact of autoregulation and microdialysis catheter location.
Bedside monitoring of cerebral metabolism in traumatic brain injury (TBI) with microdialysis is gaining wider clinical acceptance. The objective of this study was to examine the relationship between the fundamental physiological neuromonitoring modalities intracranial pressure (ICP), cerebral perfusion pressure (CPP), brain tissue oxygen (P(bt)O(2)), and cerebrovascular pressure reactivity index (PRx), and cerebral chemistry assessed with microdialysis, with particular focus on the lactate/pyruvate (LP) ratio as a marker of energy metabolism. Prospectively collected observational neuromonitoring data from 97 patients with TBI, requiring neurointensive care management and invasive cerebral monitoring, were analyzed. ⋯ These differences remained significant following adjustment for the influences of other important physiological parameters (ICP, CPP, P(bt)O(2), P(bt)CO(2), PRx, and brain temperature; mixed linear model), suggesting that they may reflect inherent tissue properties related to the initial injury. Despite inherent biochemical differences between less-injured brain and "perilesional" cerebral tissue, both tissue types exhibited relationships between established physiological variables and biochemistry. Decreases in perfusion and oxygenation were associated with deteriorating neurochemistry and these effects were more pronounced in perilesional tissue and when cerebrovascular reactivity was impaired.