Long-term outcome after severe traumatic brain injury (TBI) and correlation with volumetry and fractional anisotropy

Objective To assess long-term outcome of severe TBI, then correlate it to initial severity criteria, and global volumetric measure and fractional anisotropy (FA). Material/patients and methods We included 101 TBI patients from a cohort of patients hospitalized between 2005 and 2011 in the neurotrauma intensive care unit of the Pitie-Salpetriere Hospital (Paris). Initial severity criteria including initial Glasgow Outcome Scale (GCSi), and duration of coma were collected from medical file. The global functional outcome was assessed with the Glasgow Outcome Scale Extended (GOSE). Volumetric measures and FA were measured on the same day as the clinical assessment, and analyzed in reference to Catani's Atlas. Results Patients were included at a mean delay of 63 months after TBI. Mean Glasgow Coma Score was 8 ± 4 [3–15] and mean duration of coma was 19 days ± 18 [0–120]. The mean age at time of the assessment was 37 years ± 16 [19–73]. Good recovery (GOSE 7–8) concerned 35 patients, moderate disability (GOSE 5–6) 51 patients and severe disability (GOSE 3–4) 15 patients. GOSE was significantly correlated to GCSi and coma duration ( P P  = 0.01), to white matter volume ( P  = 0.03) but not to global mean FA. After stepwise regression, based on the FA value, the tracts the most related to GOSE were left and right corticospinal tracts, internal capsule, left arcuate long segment, left inferior longitudinal fasciculus and left optic radiations. Discussion – conclusion Five years after severe TBI, GOSE is still correlated to a combination of initial GCS and coma duration. GOSE was correlated to brain atrophy, but at this delay, global decrease in FA was not related to global outcome. By observing more specifically 22 functional tracts described by Catani et al., tracts related to global outcome seem to be most distributed in the left hemisphere. Surprisingly, despite the fact that two third of patients had no motor difficulties, the tracts the most impacted in FA were corticospinal tracts and internal capsule.