Current concepts: Diffuse axonal injury–associated traumatic brain injury

Using diffusion tensor imaging (DTI), we assessed the relationship of white matter integrity and performance on the Boston Naming Test (BNT) in a group of retired professional football players and a control group. We examined correlations between fractional anisotropy (FA) and mean diffusivity (MD) with BNT T-scores in an unbiased voxelwise analysis processed with tract-based spatial statistics (TBSS). We also analyzed the DTI data by grouping voxels together as white matter tracts and testing each tract's association with BNT T-scores. Significant voxelwise correlations between FA and BNT performance were only seen in the retired football players ( p < 0.02). Two tracts had mean FA values that significantly correlated with BNT performance: forceps minor and forceps major. White matter integrity is important for distributed cognitive processes, and disruption correlates with diminished performance in athletes exposed to concussive and subconcussive brain injuries, but not in controls without such exposure.

Section: Introductionmentioning

confidence: 99%

White Matter Changes and Confrontation Naming in Retired Aging National Football League Athletes

Strain

Didehbani

Spence

et al. 2017

“…Therefore, there is increasing interest in developing and applying new functional neuroimaging techniques that are specifically designed for the detection of DAI. [4][5] The integrity of cerebral cortico-subcortical connectivity is essential for maintaining normal brain function. [6][7] This connectivity is particularly vulnerable to the effects of traumatic injuries that can alter not only the individual components of the network (focal lesions) but also the connections between brain-nodes (DAI).…”

Section: Introductionmentioning

confidence: 99%

A Voxel-Based Analysis of FDG-PET in Traumatic Brain Injury: Regional Metabolism and Relationship between the Thalamus and Cortical Areas

García-Panach

Lull

et al. 2011

patients with different neurological outcomes. Methods: We studied 49 patients who had suffered a severe TBI and 10 healthy control subjects using 18F-FDG-PET. The patients were divided into three groups: the MCS&VS group (n=17), which included patients who were in a vegetative or a minimally conscious state; the In-PTA group (n=12), which included patients in post-traumatic amnesia (PTA); and the Out-PTA group (n=20), which included patients who had recovered from PTA. SPM5 software was used to determine the metabolic differences between the groups. FDG-PET images were normalized and four regions of interest were generated around the thalamus, precuneus and the frontal and temporal lobes. The groups were parameterized using the Student's T-test. Principal component analysis was used to obtain an intensityestimated-value per subject to correlate the function between the structures.Results: Differences in glucose metabolism in all structures were related to the neurological outcome, and the most severe patients showed the most severe hypometabolism. We also found a significant correlation between the cortico-thalamocortical metabolism in all groups. Conclusions: Voxel-based analysis suggests a functional correlation between these four areas and decreased metabolism was associated with less favorable outcome. Higher levels of activation of the corticocortical connections appear to be related to better neurological conditions. Differences in the thalamo-cortical correlations between patients and controls may be related to traumatic dysfunction due to focal or diffuse lesions.3

“…Conventional diagnostic computed tomography and magnetic resonance imaging (MRI), however, often do not detect subtle DAI, and therefore do not provide an explanation for lingering neurological or neurobehavioral symptoms (Ashwal et al, 2006b;Meythaler et al, 2001;Tasker et al, 2006). Consequently, more sensitive imaging techniques are needed to not only improve prognostic ability (Ashwal et al, 2006a), but also to elucidate the underlying neural mechanisms that explain neurological and neurocognitive deficits, and the restorative and repair processes that follow.…”

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confidence: 99%

“…Histopathologically, DAI is characterized by widespread damage to the axons of the brainstem, parasagittal white matter of the cerebrum, corpus callosum (CC), and the graywhite junctions of the cerebral cortex (Meythaler et al, 2001), with greatest involvement in the frontal white matter, brainstem, diencephalon, and the CC (Tong et al, 2004). As the largest white matter tract in the brain, the CC is particularly vulnerable to DAI.…”

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confidence: 99%

Metabolic Levels in the Corpus Callosum and Their Structural and Behavioral Correlates after Moderate to Severe Pediatric TBI

Babikian

Marion

Copeland

et al. 2010

Diffuse axonal injury (DAI) secondary to traumatic brain injury (TBI) contributes to long-term functional morbidity. The corpus callosum (CC) is particularly vulnerable to this type of injury. Magnetic resonance spectroscopy (MRS) was used to characterize the metabolic status of two CC regions of interest (ROIs) (anterior and posterior), and their structural (diffusion tensor imaging; DTI) and neurobehavioral (neurocognitive functioning, bimanual coordination, and interhemispheric transfer time [IHTT]) correlates. Two groups of moderate=severe TBI patients (ages 12-18 years) were studied: post-acute (5 months post-injury; n ¼ 10), and chronic (14.7 months post-injury; n ¼ 8), in addition to 10 age-matched healthy controls. Creatine (energy metabolism) did not differ between groups across both ROIs and time points. In the TBI group, choline (membrane degeneration=in-inflammation) was elevated for both ROIs at the post-acute but not chronic period. N-acetyl aspartate (NAA) (neuronal=axonal integrity) was reduced initially for both ROIs, with partial normalization at the chronic time point. Posterior, not anterior, NAA was positively correlated with DTI fractional anisotropy (FA) (r ¼ 0.88), and most domains of neurocognition (r range 0.22-0.65), and negatively correlated with IHTT (r ¼ À0.89). Inverse corerlations were noted between creatine and posterior FA (r ¼ À0.76), neurocognition (r range À0.22 to À0.71), and IHTT (r ¼ 0.76). Multimodal studies at distinct time points in specific brain structures are necessary to delineate the course of the degenerative and reparative processes following TBI, which allows for preliminary hypotheses about the nature and course of the neural mechanisms of subsequent functional morbidity. This will help guide the future development of targeted therapeutic agents.