Mild Traumatic Brain Injury: Longitudinal Regional Brain Volume Changes

Abstract

Purpose:To investigate longitudinal changes in global and regional brain volume in patients 1 year after mild traumatic brain injury (MTBI) and to correlate such changes with clinical and neurocognitive metrics. Materials and Methods:This institutional review board-approved study was HIPAA compliant. Twenty-eight patients with MTBI (with 19 followed up at 1 year) with posttraumatic symptoms after injury and 22 matched control subjects (with 12 followed up at 1 year) were enrolled. Automated segmentation of brain regions to compute regional gray matter (GM) and white matter (WM) volumes was performed by using three-dimensional T1-weighted 3.0-T magnetic resonance imaging, and results were correlated with clinical metrics. Pearson and Spearman rank correlation coefficients were computed between longitudinal brain volume and neurocognitive scores, as well as clinical metrics, over the course of the follow-up period. Results:One year after MTBI, there was measurable global brain atrophy, larger than that in control subjects. The anterior cingulate WM bilaterally and the left cingulate gyrus isthmus WM, as well as the right precuneal GM, showed significant decreases in regional volume in patients with MTBI over the 1st year after injury (corrected P , .05); this was confirmed by means of cross-sectional comparison with data in control subjects (corrected P , .05). Left and right rostral anterior cingulum WM volume loss correlated with changes in neurocognitive measures of memory (r = 0.65, P = .005) and attention (r = 0.60, P = .01). At 1-year follow-up, WM volume in the left cingulate gyrus isthmus correlated with clinical scores of anxiety (Spearman rank correlation r = 20.68, P = .007) and postconcussive symptoms (Spearman rank correlation r = 20.65, P = .01). Conclusion:These observations demonstrate structural changes to the brain 1 year after injury after a single concussive episode. Regional brain atrophy is not exclusive to moderate and severe traumatic brain injury but may be seen after mild injury. In particular, the anterior part of the cingulum and the cingulate gyrus isthmus, as well as the precuneal GM, may be distinctively vulnerable 1 year after MTBI.q RSNA, 2013

Early Cortical Thickness Change after Mild Traumatic Brain Injury following Motor Vehicle Collision

“…It is possible that the timing of the measures could influence these relationships, because progressive atrophic changes in this region would be suggested by decreased gray matter volume and density of precuneus from 1 month to 1 year after mTBI. 26 Interestingly, the increased cortical thickness of mTBI survivors at initial days after MVC was significantly correlated with the number of reduced usual activity days over the initial 3 months after MVC. An MVC can impair the quality of life of injured survivors, and a prolonged reduction in usual activities may reflect poor health.…”

“…23 The functional relevance of progressive structural cortical changes in adults soon after mTBI is still unclear, however. 26 Progressive thickness changes in left rMFG may affect working memory activation in mTBI survivors, as evidenced by colocalization of abnormal working memory in this region soon after mTBI. This possibility needs to be tested by future studies that concurrently examine progressive structural and functional changes after mTBI.…”

“…Another study did find reductions of gray matter volume (measured based on cortical thickness and surface area) and density (volume-based morphometry) in the right precuneus 1 month to 1 year post-injury, raising the possibility that duration of recovery may be a factor contributing to these differences in findings. 26 The reported low resolution T2*-weighted echo planar images are only suitable clinically for the diagnosis of large hematomas. Detecting micro-hemorrhaging and edema underlying subtle cortical thickness changes may necessitate quantitative vertex-based analyses of concurrent high-resolution and sensitive diffusion-and susceptibility-weighted images.…”

“…16 Finally, a study using thickness-based measures of gray matter volume (thickness times surface area) reported no volumetric difference in the initial weeks (average 23 days) after heterogeneous head traumas, while finding a significant decrease in the gray matter volume of right precuneus cortex from initial weeks to a year after mTBI, compared with healthy controls. 26 Currently, cortical thickness studies conducted shortly after an mTBI remain inconclusive, with several factors potentially contributing to differences in findings. The animal study cited above suggests that detecting dynamic changes in cortical thickness after mTBI may depend on the timing of the investigation.…”

Strategy‐based reasoning training modulates cortical thickness and resting‐state functional connectivity in adults with chronic traumatic brain injury

“…MRI‐based morphometry has revealed altered cortical thickness and volume within individuals who have sustained a TBI (Bendlin et al., 2008; Gale, Baxter, Roundy, & Johnson, 2005; Kim et al., 2008; Sidaros et al., 2009; Spitz et al., 2013; Tate et al., 2014; Turken et al., 2009; Warner et al., 2010; Zhou et al., 2013). These altered cortical morphometric properties are frequently associated with functional deficits (Gale et al., 2005; Palacios et al., 2013; Sidaros et al., 2009; Spitz et al., 2013; Warner et al., 2010; Zhou et al., 2013), and correspondences between MRI‐based and histological morphometric data of TBI individuals have been reported (Maxwell, MacKinnon, Stewart, & Graham, 2009). RsFC MRI measures the temporal coherency of blood oxygenation level‐dependent (BOLD) signal at rest and it allows us to identify how the brain's intrinsic functional networks are organized (see van Dijk et al., 2010 for review).…”