To describe the changes in fractional anisotropy (FA) measured with Diffusion Tensor Imaging (DTI) and the changes in Regional Homogeneity (ReHo) signal measured with resting state functional MRI on patients with visuo-spatial working memory deficit, 5 years after a severe TBI.

We included TBI patients from a neurosurgical intensive care cohort of the Pitié-Salpêtrière Parisian Hospital. Patients were hospitalized between 2005 and 2011. A French version of the Glasgow Outcome Scale Extended (GOSE) assessed the global functional outcome. A large neuropsychological assessment including working memory tests was performed. We present here the results of the backward visuo-spatial span as standard notes. FA were measured on DTI and ReHo were extracted from resting state functional MRI acquisition on a voxel-based approach.

Fifty-four patients were included 65 months after their TBI. The median age at evaluation time was 34 years [19–71]. Median Glasgow Coma Score was 8 [3–15]. Seventeen patients had a GOSE score below 6, 18 had a GOSE at 6 and 19 had a GOSE higher than 6. Thirty patients had a standard note on backward visuo-spatial span inferior to 7, which corresponds to a deficit. In this group, FA was lower in the left hemisphere, in the anterior limb of the internal capsule and in the external capsule. Patients also had an increased ReHo in the right hemisphere in the superior temporal gyrus, Heschl's gyrus, putamen, medium frontal gyrus and inferior frontal gyrus triangularis.

Despite the fact that axonal lesions observed after TBI are diffuse, decreased FA was predominant in the left hemisphere of patients with the most severe working memory deficits and in whom ReHo appeared higher in the right hemisphere. These observations should open the discussion about contralateral inhibition of hemispheres.