A five years longitudinal magnetic resonance imaging study of severe traumatic brain injury patients. Correlation with functional outcome

Abstract

International audienceIntroductionTraumatic brain injury (TBI) doesn't seem to be a single insult with amonophasic resolution. Recently, degenerative mechanisms havebeen suggested to occur in the chronic phase and could constituted"tertiary" lesions [1]. These degenerative phenomena can potentiallyhave a worsening impact on the long-term functional prognosis.ObjectivesThe objective of this prospective study was to longitudinally evaluate(1) white and grey matter structures volumes measured from Tlthree-dimensional (30) and (2) white matter integrity assessed fromdiffusion tensor imaging (DTI) in severe TBI.Method20 severe TBI (37 ± 16 yrs) and 12 healthy volunteers (HV; 42 ± 6 yrs)underwent multimodal magnetic resonance imaging in the subacutephase (within 21 ± 8 days after injury). A longitudinal follow-upwas obtained for all of them at the chronic phase of injury (median64 ± 16 months after injury) together with neuropsychological assessments.Longitudinal imaging changes were assessed using corticalvolumetric reconstruction and segmentation of white and deep greymatter structures with Freesurfer [2]; cortical sulci were automaticallyreconstructed and identified with Brainvisa software, and a voxelbasedDTI analysis was performed with Comasoft. The Extended GOS(GOSE) was used to classify at 5 years the TBI subjects into " good"(GOSE 6-7; n = 11) and "intermediate" (GOSE 3-5; n = 9) recovery.Cortical morphometry and fractional anisotropy (FA) derived fromDTI were used with linear mixed effects models to link changes to behaviour status.Results At baseline, there were no volumetric differences between the 3 groups (GOSE 3-5; GOSE 6-7; HV). At 5 years, patients with TBI demonstrated a significant volumetric reduction of the whole white matter (-10±4 %; PConclusions: We observed a strong correlation between neuropsychological scores and morphometric changes over time suggesting (1) occurrence of tertiary lesions and (2) that lesions location influence functional outcome. These data provide further insight into early and late pathophysiology of cognitive dysfunctions after TBI.[no other pdf