Dataset Information

Abnormal White Matter Blood-Oxygen-Level-Dependent Signals in Chronic Mild Traumatic Brain Injury.

ABSTRACT: Concussion, or mild traumatic brain injury (mTBI), can cause persistent behavioral symptoms and cognitive impairment, but it is unclear if this condition is associated with detectable structural or functional brain changes. At two sites, chronic mTBI human subjects with persistent post-concussive symptoms (three months to five years after injury) and age- and education-matched healthy human control subjects underwent extensive neuropsychological and visual tracking eye movement tests. At one site, patients and controls also performed the visual tracking tasks while blood-oxygen-level-dependent (BOLD) signals were measured with functional magnetic resonance imaging. Although neither neuropsychological nor visual tracking measures distinguished patients from controls at the level of individual subjects, abnormal BOLD signals were reliably detected in patients. The most consistent changes were localized in white matter regions: anterior internal capsule and superior longitudinal fasciculus. In contrast, BOLD signals were normal in cortical regions, such as the frontal eye field and intraparietal sulcus, that mediate oculomotor and attention functions necessary for visual tracking. The abnormal BOLD signals accurately differentiated chronic mTBI patients from healthy controls at the single-subject level, although they did not correlate with symptoms or neuropsychological performance. We conclude that subjects with persistent post-concussive symptoms can be identified years after their TBI using fMRI and an eye movement task despite showing normal structural MRI and DTI.

SUBMITTER: Astafiev SV

PROVIDER: S-EPMC4601555 | biostudies-literature | 2015 Aug

REPOSITORIES: biostudies-literature

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Abnormal White Matter Blood-Oxygen-Level-Dependent Signals in Chronic Mild Traumatic Brain Injury.

Astafiev Serguei V SV Shulman Gordon L GL Metcalf Nicholas V NV Rengachary Jennifer J MacDonald Christine L CL Harrington Deborah L DL Maruta Jun J Shimony Joshua S JS Ghajar Jamshid J Diwakar Mithun M Huang Ming-Xiong MX Lee Roland R RR Corbetta Maurizio M

Journal of neurotrauma 20150506 16

Concussion, or mild traumatic brain injury (mTBI), can cause persistent behavioral symptoms and cognitive impairment, but it is unclear if this condition is associated with detectable structural or functional brain changes. At two sites, chronic mTBI human subjects with persistent post-concussive symptoms (three months to five years after injury) and age- and education-matched healthy human control subjects underwent extensive neuropsychological and visual tracking eye movement tests. At one sit ...[more]

PMID: 25758167

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Project description:Blast-related traumatic brain injury (TBI) has been a common injury among returning troops due to the widespread use of improvised explosive devices in the Iraq and Afghanistan Wars. As most of the TBIs sustained are in the mild range, brain changes may not be detected by standard clinical imaging techniques such as CT. Furthermore, the functional significance of these types of injuries is currently being debated. However, accumulating evidence suggests that diffusion tensor imaging (DTI) is sensitive to subtle white matter abnormalities and may be especially useful in detecting mild TBI (mTBI). The primary aim of this study was to use DTI to characterize the nature of white matter abnormalities following blast-related mTBI, and in particular, examine the extent to which mTBI-related white matter abnormalities are region-specific or spatially heterogeneous. In addition, we examined whether mTBI with loss of consciousness (LOC) was associated with more extensive white matter abnormality than mTBI without LOC, as well as the potential moderating effect of number of blast exposures. A second aim was to examine the relationship between white matter integrity and neurocognitive function. Finally, a third aim was to examine the contribution of PTSD symptom severity to observed white matter alterations. One hundred fourteen OEF/OIF veterans underwent DTI and neuropsychological examination and were divided into three groups including a control group, blast-related mTBI without LOC (mTBI - LOC) group, and blast-related mTBI with LOC (mTBI + LOC) group. Hierarchical regression models were used to examine the extent to which mTBI and PTSD predicted white matter abnormalities using two approaches: 1) a region-specific analysis and 2) a measure of spatial heterogeneity. Neurocognitive composite scores were calculated for executive functions, attention, memory, and psychomotor speed. Results showed that blast-related mTBI + LOC was associated with greater odds of having spatially heterogeneous white matter abnormalities. Region-specific reduction in fractional anisotropy (FA) in the left retrolenticular part of the internal capsule was observed in the mTBI + LOC group as the number of blast exposures increased. A mediation analysis revealed that mTBI + LOC indirectly influenced verbal memory performance through its effect on white matter integrity. PTSD was not associated with spatially heterogeneous white matter abnormalities. However, there was a suggestion that at higher levels of PTSD symptom severity, LOC was associated with reduced FA in the left retrolenticular part of the internal capsule. These results support postmortem reports of diffuse axonal injury following mTBI and suggest that injuries with LOC involvement may be particularly detrimental to white matter integrity. Furthermore, these results suggest that LOC-associated white matter abnormalities in turn influence neurocognitive function.

Dataset Information

Abnormal White Matter Blood-Oxygen-Level-Dependent Signals in Chronic Mild Traumatic Brain Injury.

Publications

Abnormal White Matter Blood-Oxygen-Level-Dependent Signals in Chronic Mild Traumatic Brain Injury.

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