A prospective diffusion tensor imaging study in mild traumatic brain injury

The Mind Research Network, Pete & Nancy Domenici Hall, 1101 Yale Blvd. NE, Albuquerque, NM 87106, USA.
Neurology (Impact Factor: 8.29). 02/2010; 74(8):643-50. DOI: 10.1212/WNL.0b013e3181d0ccdd
Source: PubMed

ABSTRACT Only a handful of studies have investigated the nature, functional significance, and course of white matter abnormalities associated with mild traumatic brain injury (mTBI) during the semi-acute stage of injury. The present study used diffusion tensor imaging (DTI) to investigate white matter integrity and compared the accuracy of traditional anatomic scans, neuropsychological testing, and DTI for objectively classifying mTBI patients from controls.
Twenty-two patients with semi-acute mTBI (mean = 12 days postinjury), 21 matched healthy controls, and a larger sample (n = 32) of healthy controls were studied with an extensive imaging and clinical battery. A subset of participants was examined longitudinally 3-5 months after their initial visit.
mTBI patients did not differ from controls on clinical imaging scans or neuropsychological performance, although effect sizes were consistent with literature values. In contrast, mTBI patients demonstrated significantly greater fractional anisotropy as a result of reduced radial diffusivity in the corpus callosum and several left hemisphere tracts. DTI measures were more accurate than traditional clinical measures in classifying patients from controls. Longitudinal data provided preliminary evidence of partial normalization of DTI values in several white matter tracts.
Current findings of white matter abnormalities suggest that cytotoxic edema may be present during the semi-acute phase of mild traumatic brain injury (mTBI). Initial mechanical damage to axons disrupts ionic homeostasis and the ratio of intracellular and extracellular water, primarily affecting diffusion perpendicular to axons. Diffusion tensor imaging measurement may have utility for objectively classifying mTBI, and may serve as a potential biomarker of recovery.

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Available from: Ronald Yeo, May 02, 2014
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    • ") TBIs (N studies = 11) and, on average, were scanned approximately one year after their injury (mean = 14.4 months, SD = 18 months). Five studies examined injuries that ranged from complicated– mild (GCS = 13–15 plus visible brain lesions) to severe, three investigated mild TBIs (GCS = 13–15) (one reported in multiple papers: Borich et al., 2013; Mayer et al,. 2012; Yallampalli et al., 2010) and another examined mild to severe TBI (Wozniak et al., 2007). Four studies performed scans on children with mild TBI at 1-, 2-, or 4-weeks post-TBI and were labeled 'short-term'. The other 16 studies performed scans 3 or more months post-TBI, and included children with all levels of TBI; these were grouped into a 'medium to long-term"
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    ABSTRACT: This study meta-analyzed research examining Diffusion Tensor Imaging following pediatric non-penetrating traumatic brain injury to identify the location and extent of white matter changes. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) data from 20 studies were analyzed. FA increased and ADC decreased in most white matter tracts in the short-term (moderate-to-large effects), and FA decreased and ADC increased in the medium- to long-term (moderate-to-very-large effects). Whole brain (short-term), cerebellum and corpus callosum (medium- to long-term) FA values have diagnostic potential, but the impact of age/developmental stage and injury severity on FA/ADC, and the predictive value, is unclear.
    Developmental Neuropsychology 12/2014; 39(8):600-37. DOI:10.1080/87565641.2014.973958 · 2.24 Impact Factor
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    • " reported increased FA , reduced ADC , and reduced radial ( perpendicular axis ) diffu - sivity in WM regions and left thalamus . Similarly , Bazarian et al . ( 2007 ) studied six mTBI patients within 72 h of injury and reported increased FA in the posterior CC and reduced ADC in the anterior limb of the internal capsule ( IC ) . Addi - tionally , Mayer et al . ( 2010 ) studied 22 mTBI patients within 12 days of injury and reported increased FA and reduced radial diffusivity in the CC and left hemisphere tracts . However , Inglese et al . ( 2005 ) found reduced FA in the splenium of CC and posterior limb of IC in 20 mTBI patients imaged up to 10 days after injury ( mean 5 4 days ) ."
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    ABSTRACT: An improved understanding and characterization of glial activation and its relationship with white matter injury will likely serve as a novel treatment target to curb post injury inflammation and promote axonal remyelination after brain trauma. Traumatic brain injury (TBI) is a significant public healthcare burden and a leading cause of death and disability in the United States. Particularly, traumatic white matter (WM) injury or traumatic axonal injury has been reported as being associated with patients' poor outcomes. However, there is very limited data reporting the importance of glial activation after TBI and its interaction with WM injury. This article presents a systematic review of traumatic WM injury and the associated glial activation, from basic science to clinical diagnosis and prognosis, from advanced neuroimaging perspective. It concludes that there is a disconnection between WM injury research and the essential role of glia which serve to restore a healthy environment for axonal regeneration following WM injury. Particularly, there is a significant lack of non-invasive means to characterize the complex pathophysiology of WM injury and glial activation in both animal models and in humans. An improved understanding and characterization of the relationship between glia and WM injury will likely serve as a novel treatment target to curb post injury inflammation and promote axonal remyelination. GLIA 2014
    Glia 11/2014; 62(11). DOI:10.1002/glia.22690 · 6.03 Impact Factor
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    • "Recently, diffusion tensor imaging (DTI) has shown great promise in characterizing the structural damage to white matter tracts induced by DAI. Commonly damaged regions following mild TBI include the corpus callosum (Bazarian et al. 2007; Kumar et al. 2009; Mayer et al. 2010; Warner et al. 2010), internal and external capsule (Arfanakis et al. 2002; Bazarian et al. 2007), and cingulum bundles (Mac Donald et al. 2011) (See (Aoki et al. 2012) for a meta-analysis of DTI studies in mTBI). Therefore since many previous studies have reported damage to the corpus callosum following mTBI, our goal was to specifically assess if this reported damage to structural connections between the two hemispheres would have an effect on the large-scale functional networks involved in cognitive and sensory processing. "
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    ABSTRACT: This study investigates cognitive deficits and alterations in resting state functional connectivity in civilian mild traumatic brain injury (mTBI) participants with high and low symptoms. Forty-one mTBI participants completed a resting state fMRI scan and the Automated Neuropsychological Assessment Metrics (ANAM) during initial testing (<10 days of injury) and a 1 month follow up. Data were compared to 30 healthy control subjects. Results from the ANAM demonstrate that mTBI participants performed significantly worse than controls on the code substitution delayed subtest (p = 0.032) and weighted throughput score (p = 0.001). Among the mTBI patients, high symptom mTBI participants performed worse than those with low symptoms on the code substitution delayed (p = 0.017), code substitution (p = 0.012), repeated simple reaction time (p = 0.031), and weighted throughput score (p = 0.009). Imaging results reveal that during the initial visit, low symptom mTBI participants had reduced interhemispheric functional connectivity (IH-FC) within the lateral parietal lobe (p = 0.020); however, during follow up, high symptom mTBI participants showed reduced IH-FC compared to the control group within the dorsolateral prefrontal cortex (DLPFC) (p = 0.013). Reduced IH-FC within the DLPFC during the follow-up was associated with reduced cognitive performance. Together, these findings suggest that reduced rs-FC may contribute to the subtle cognitive deficits noted in high symptom mTBI participants compared to control subjects and low symptom mTBI participants.
    Brain Imaging and Behavior 02/2014; 9(2). DOI:10.1007/s11682-014-9295-y · 4.60 Impact Factor
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