Journal of neurotrauma
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Journal of neurotrauma · Mar 2014
An fMRI Study of Working Memory in Youth Following Sports-related Concussion: Is it Still Working?
Abstract In children, the importance of detecting deficits after mild traumatic brain injury (mTBI) or concussion has grown with the increasing popularity of leisure physical activities and contact sports. Whereas most postconcussive symptoms (PCS) are similar for children and adults, the breadth of consequences to children remains largely unknown. To investigate the effect of mTBI on brain function, we compared working memory performance and related brain activity using blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) in 15 concussed youths and 15 healthy age-matched control subjects. ⋯ However, significant differences were noted. In particular, the observation of reduced working memory accuracy suggests that youths may be unable to engage compensatory strategies to maintain cognitive performance after mTBI. This has significant implications for safe return to daily activities, including competitive sport.
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Journal of neurotrauma · Mar 2014
Neuroimaging, Behavioral, and Psychological Sequelae of Repetitive Combined Blast/Impact Mild Traumatic Brain Injury in Iraq and Afghanistan War Veterans.
Abstract Whether persisting cognitive complaints and postconcussive symptoms (PCS) reported by Iraq and Afghanistan war veterans with blast- and/or combined blast/impact-related mild traumatic brain injuries (mTBIs) are associated with enduring structural and/or functional brain abnormalities versus comorbid depression or posttraumatic stress disorder (PTSD) remains unclear. We sought to characterize relationships among these variables in a convenience sample of Iraq and Afghanistan-deployed veterans with (n=34) and without (n=18) a history of one or more combined blast/impact-related mTBIs. Participants underwent magnetic resonance imaging of fractional anisotropy (FA) and macromolecular proton fraction (MPF) to assess brain white matter (WM) integrity; [(18)F]-fluorodeoxyglucose positron emission tomography imaging of cerebral glucose metabolism (CMRglu); structured clinical assessments of blast exposure, psychiatric diagnoses, and PTSD symptoms; neurologic evaluations; and self-report scales of PCS, combat exposure, depression, sleep quality, and alcohol use. ⋯ Neuroimaging metrics did not differ between participants with versus without PTSD. Iraq and Afghanistan veterans with one or more blast-related mTBIs exhibit abnormalities of brain WM structural integrity and macromolecular organization and CMRglu that are not related to comorbid PTSD. These findings are congruent with recent neuropathological evidence of chronic brain injury in this cohort of veterans.
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Journal of neurotrauma · Mar 2014
Serial Atlas-based DTI Study of Uncomplicated Mild Traumatic Brain Injury in Adults.
Abstract In this report, we applied diffusion tensor imaging (DTI) methods in 36 patients with uncomplicated mild traumatic brain injury (mTBI) and a comparison group of 37 participants with orthopedic injury. Our aim was to characterize regional and global macro- and microstructural attributes of white matter (WM), gray matter (GM), in addition to volume and diffusivity of cerebrospinal fluid (CSF) to identify and differentiate patterns of acute and short-term recovery. Given that previous DTI reports on mTBI in adults using a region-of-interest approach implicated the corona radiata (CR), corpus callosum, and hippocampus, we analyzed and quantified DTI metrics of these regions using atlas-based methods. ⋯ CR radial diffusivity was found to be elevated in the between-group comparison at baseline (mTBI1 vs. OC1), but did not differ in the within-group comparison (mTBI1 vs. mTBI2; N=19), suggesting the possible resolution of edema. Our analysis of the cross-sectional and follow-up data, which is uncorrected for multiple comparisons, demonstrates dissociation between volumetric (macrostructural) and tissue integrity (microstructural) attributes and shows the potential utility of DTI to capture transient edema in the CR.
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The pathophysiology of blast-induced traumatic brain injury (TBI) and subsequent behavioral deficits are not well understood. Unraveling the mechanisms of injury is critical to derive effective countermeasures against this form of neurotrauma. Preservation of the integrity of cellular DNA is crucial for the function and survival of cells. ⋯ A positive correlation was observed between the righting reflex time and CFD level in plasma at 2 h after blast exposure. Brain DNA damage subsequent to repeated blast was associated with decreased mitochondrial membrane potential, increased release of cytochrome C, and up-regulation of caspase-3, all of which are indicative of cellular apoptosis. Shock-wave-induced DNA damage and initiation of mitochondrial-driven cellular apoptosis in the brain after repeated blast exposures indicate that therapeutic strategies directed toward inhibition of DNA damage or instigation of DNA repair may be effective countermeasures.