Longitudinal changes in brain morphology from 4 weeks to 12 months after mild traumatic brain injury: Associations with cognitive functions and clinical variables

Objective: To investigate longitudinal changes in cortical and subcortical volumes in patients with mild traumatic brain injury (MTBI) and to evaluate whether such changes were associated with self-reported post-concussive symptoms, global functional outcomes and neuropsychological functioning.Methods: This was a prospecitve, longitudinal cohort study of patients with complicated (i.e presence of intracranial abnormalities on the day of injury CT) and uncomplicated MTBI (i.e, absence of intracranial abnormalities). Magnetic resonance imaging (MRI) was performed at approximately 4 weeks and 12 months. We utilized a 3T MRI system, cortical reconstruction and volumetric segmentation by FreeSurfer software. We included 33 patients with uncomplicated and 29 with complicated MTBI, who were aged 16-65 years.Results: 12 months after MTBI, significant within-group volume reductions were detected in the left accumbens area and right caudate nucleus for both patients groups, but no significant differences between the groups were revealed. No associations between volumetric variables and post-concussive symptoms or global functioning were found. The left temporal thickness was significantly associated with executive functioning.Conclusion: Structural subcortical alterations occur after complicated and uncomplicated MTBIs but these findings were not associated with symptoms burden or functional outcomes. Nonetheless, worse executive functioning was found in patients with shrinkage of the left temporal lobe.