Thalamic atrophy and dysfunction in patients with mild-to-moderate traumatic diffuse axonal injury

Abstract

Disrupted white matter structure has been established in patients with diffuse axonal injury (DAI), but morphological changes in gray matter and local intrinsic activity in the short and midterm (before 6 months) have not been documented in DAI patients. We hypothesized that regionally selective atrophy observed in deep gray matter in the short-term and mid-term periods in patients with mild-to-moderate DAI, local atrophy, and/or dysfunction would be related to clinical characteristics. We evaluated the changes in regional density and synchronization in 18 DAI patients separately using Diffeomorphic Anatomical Registration through Exponentiated Lie algebra-enhanced voxel-based morphometry and regional homogeneity (ReHo). Compared with the controls, DAI patients showed a decreased density in the bilateral thalami and decreased ReHo values in the ventral anterior and ventral lateral nuclei of the bilateral thalami. Pearson’s correlation analysis showed that decreased density in the bilateral thalami was correlated negatively with time since injury and decreased ReHo values in the ventral anterior and ventral lateral nuclei of the bilateral thalami were associated with a worsened motor assessment scale. These findings suggest that mild-to-moderate traumatic DAI within the short and midterm could lead to thalamic atrophy and that dysfunction in the bilateral thalami is associated with declining motor function. This study could potentially provide complementary evidence as an important element in longitudinal studies.

Longitudinal change in regional brain volumes with exposure to repetitive head impacts

“…Previous studies, including our own work, have reported differences compared to controls in thalamic and corpus callosum volumes in disorders that affect the white matter, including traumatic brain injury and multiple sclerosis. 5,[14][15][16] Animal studies of head trauma indicate that blows to the head can result in physical injury to axons. 17 Because the thalamus has abundant afferent and efferent fibers, the progressive loss of volume seen may reflect Wallerian degeneration of the axons with subsequent neuronal dropout, though other mechanisms that may reduce thalamic volume are also possible.…”

Characterizing Static and Dynamic Fractional Amplitude of Low-Frequency Fluctuation and its Prediction of Clinical Dysfunction in Patients with Diffuse Axonal Injury

“…In recent years, increasing numbers of studies have revealed compensatory activation (7) or engagement (8) in working memory performance task, disrupted regional (9) and long-distance connectivity (10,11), and even network dysconnectivity (12). However, these studies relied on the assumption of the 'static' temporal strength or inter-region relationship in temporal pattern, neglecting to investigate the dynamic brain alterations or time-varying of the blood oxygen level dependent (BOLD) signal in resting-state scanning (13).…”

Spatiotemporal profile of atrophy in the first year following moderate‐severe traumatic brain injury

“…The thalamus, while traditionally considered a relay station for the cortex, has an active role in many higher‐level cognitive processes including memory, attention, and processing speed, and is specifically implicated in cognitive effects of aging (Fama & Sullivan, 2015). Thalamic atrophy has been reported in the short term after mild‐to‐moderate TBI, with implications for post‐traumatic symptoms (Wu et al, 2018) and in mild TBI, thalamic damage accounts for many neurocognitive impairments (Grossman & Inglese, 2016). The ubiquity and unique trajectory of thalamic atrophy positions this structure as a promising biomarker for injury severity and prognosis; yet, much work is needed to relate thalamic atrophy to its connected structures (e.g., anterior and posterior cerebral cortex) and examine its role in functional outcomes following injury.…”