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


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.

Download full-text


Available from: Ronald Yeo, May 02, 2014
    • "remain in need of further exploration . One such area concerns the nature of the white abnormalities in the acute and subacute phase following mTBI . Of note , several studies have shown abnormalities in DTI metrics in the opposite direction of what is typically seen , namely reporting increased FA or decreased MD / ADC ( Bazarian et al . , 2007 ; Mayer et al . , 2010 ; Wäljas et al . , 2014"
    [Show abstract] [Hide abstract]
    ABSTRACT: Recent advances in neuroimaging methodologies sensitive to axonal injury have made it possible to assess in vivo the extent of traumatic brain injury (TBI) -related disruption in neural structures and their connections. The objective of this paper is to review studies examining connectivity in TBI with an emphasis on structural and functional MRI methods that have proven to be valuable in uncovering neural abnormalities associated with this condition. We review studies that have examined white matter integrity in TBI of varying etiology and levels of severity, and consider how findings at different times post-injury may inform underlying mechanisms of post-injury progression and recovery. Moreover, in light of recent advances in neuroimaging methods to study the functional connectivity among brain regions that form integrated networks, we review TBI studies that use resting-state functional connectivity MRI methodology to examine neural networks disrupted by putative axonal injury. The findings suggest that TBI is associated with altered structural and functional connectivity, characterized by decreased integrity of white matter pathways and imbalance and inefficiency of functional networks. These structural and functional alterations are often associated with neurocognitive dysfunction and poor functional outcomes. TBI has a negative impact on distributed brain networks that lead to behavioral disturbance.
    No preview · Article · Nov 2015 · Journal of the International Neuropsychological Society
  • Source
    • ") 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"
    [Show abstract] [Hide abstract]
    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.
    Full-text · Article · Dec 2014 · Developmental Neuropsychology
  • Source
    • " 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 ) ."
    [Show abstract] [Hide abstract]
    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
    Full-text · Article · Nov 2014 · Glia
Show more