Volumetric alterations following severe traumatic brain injury even in the absence of focal lesions

Introduction Traumatic brain injury (TBI) frequently leads to cognitive and behavioural disorders interfering with everyday life and work, despite the absence of focal lesions on clinical images acquired after injury. The aim of this study is to use magnetic resonance imaging (MRI) to examine whether volumetric alterations measured voxel by voxel in the whole brain could explain these cognitive and behavioural disorders. Methods Eight adults with severe TBI (GCS ≤ 8) but without focal lesions on the CT scan were included. Patients had normal intellectual abilities (PM38) but abnormal behaviour (Lhermitte's scale). These 8 patients and 17 age-matched controls performed an episodic memory task (RL-RI-16 items) as well as classical and ecological executive tasks. All participants also underwent a volumetric T1-weighted MRI at 1.5 T. Grey and white matter volumes were compared between patients and controls using the Voxel Based Morphometry (VBM5) toolbox in the Statistical Parametric Mapping (SPM) software. Results Patients exhibited abnormal results on both the episodic memory and executive tasks. Regarding brain volume, between-group comparisons ( P Discussion Despite the absence of cerebral brain lesions on CT scans, TBI patients with behavioural disorders show episodic memory disorders and executive dysfunctions associated with grey and white matter atrophy in subcortical and cerebellar regions. Alterations of nodes and connections of the frontal-subcortical circuits (but not systematically of the frontal cortex) following severe TBI may thus explain subsequent behavioural dysexecutive disorders.