Abstract
The chronic consequences of traumatic brain injury (TBI) may contribute to the increased risk for early cognitive decline and dementia, primarily due to diffusion axonal injury. Previous studies in mild TBI (mTBI) have been controversial in describing the white matter tract integrity changes occurring at acute and subacute post-injury. In this prospective longitudinal study, we aim to investigate the longitudinal changes of white matter (WM) using diffusion tensor imaging (DTI) and their correlations with neuropsychological tests. Thirty-three patients with subacute mTBI and 31 matched healthy controls were studied with an extensive imaging and clinical battery. Neuroimaging was obtained within 7 days post-injury for acute scans and repeated at 1 and 3 months post-injury. Using a region-of-interest-based approach, tract-based spatial statistics was used to conduct voxel-wise analysis on diffusion changes in mTBI and was compared to those of healthy matched controls, scanned during the same time period and rescanned with an interval similar to that of patients. We found decreased fractional anisotropy (FA) values in the left anterior limb of internal capsule (ALIC) and right inferior fronto-occipital fasciculus (IFOF) during the 7 days post-injury, which showed longitudinal evidence of recovery following 1 month post-injury. Increased FA values in these two tracts at 1 month post-injury were positively associated with better performance on cognitive information processing speed at initial assessment. By contrast, there were also some tracts (right anterior corona radiata, forceps major, and body of corpus callosum) exhibiting the continuing loss of integrity sustaining even beyond 3 months, which can predict the persisting post-concussion syndromes. Continuing loss of structural integrity in some tracts may contribute to the persistent post-concussion syndromes in mTBI patients, suggesting certain tracts providing an objective biomarker for tracking the pathological recovery process following mTBI.
Highlights
IntroductionDespite the negative findings in conventional imaging assessments, distinctive white matter tracts (WMTs), known as diffuse axonal injury (DAI), after mild TBI (mTBI) have been confirmed in both human biopsies (Bigler, 2010) and animal models (Mac Donald et al, 2007; Spain et al, 2010)
The United States Centers for Disease Control and Prevention estimates that mild traumatic brain injury (TBI) is experienced in 70–90% of TBI-related emergency department (ED) visits (Taylor et al, 2017)
Our results show that the majority of neuropsychological tests (NPTs) were sorted to the “most reliable” group, with the Healthy controls (HCs) having the most reliable change indices, given the relatively small practice effects (Supplementary Figure S1)
Summary
Despite the negative findings in conventional imaging assessments, distinctive white matter tracts (WMTs), known as diffuse axonal injury (DAI), after mTBI have been confirmed in both human biopsies (Bigler, 2010) and animal models (Mac Donald et al, 2007; Spain et al, 2010). Mayer et al (2010) investigated 22 adult patients with mTBI within weeks post-injury and found increased FA noted in the genu, left superior coronal radiation (CR), and left uncinate fasciculus (UF), while decreased radial diffusivity (RD) was noted only in the genu, left CR, and left UF. Another study presented decreased FA in the splenium and posterior CC in 20 adult mTBI patients between 1 and 10 days post-injury (Inglese et al, 2005). There were no significant differences between mTBI patients and controls in the CC
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