Injury Severity and Free-Water Volume Fraction Predict Regional White Matter Atrophy During the First Year Following...

Area of Science:

• Neuroscience
• Radiology
• Neuropathology

Background:

• Traumatic axonal injury is a key feature of traumatic brain injury (TBI).
• Previous studies show white matter (WM) volume reduction and altered diffusion metrics post-TBI.
• The spatiotemporal progression of WM degeneration and its predictors require further characterization.

Purpose of the Study:

• To map WM atrophy in moderate-to-severe TBI (msTBI) patients over the first year post-injury.
• To correlate WM atrophy patterns with the duration of post-traumatic amnesia (PTA).
• To assess if baseline free-water (FW) or FW-corrected fractional anisotropy (F-FA) predicts subsequent WM atrophy.

Main Methods:

• Longitudinal analysis of brain imaging data from 33 msTBI patients.
• Estimation of WM atrophy spatial distribution and correlation with PTA duration.
• Assessment of baseline FW and F-FA as predictors of WM atrophy.

Main Results:

• WM atrophy was widespread, most pronounced in the splenium of the corpus callosum, corona radiata, and brainstem.
• Central WM atrophy correlated with longer PTA duration.
• Elevated baseline FW predicted greater subsequent WM atrophy; F-FA did not show a significant association.

Conclusions:

• Early elevation in FW may indicate progressive WM neurodegeneration after msTBI.
• Neuroinflammatory processes could underlie the observed FW-related neuropathology.
• FW elevation shows potential as a biomarker for predicting TBI-induced WM degeneration.