Disruption of the ascending arousal network in acute traumatic disorders of consciousness

Objective: To determine whether ascending arousal network (AAN) connectivity is reduced in patients presenting with traumatic coma.

Methods: We performed high angular resolution diffusion imaging (HARDI) in 16 patients with acute severe traumatic brain injury who were comatose on admission and in 16 matched controls. We used probabilistic tractography to measure the connectivity probability (CP) of AAN axonal pathways linking the brainstem tegmentum to the hypothalamus, thalamus and basal forebrain. To assess the spatial specificity of CP differences between patients and controls, we also measured CP within four subcortical pathways outside the AAN.

Results: Compared to controls, patients showed a reduction in AAN pathways connecting the brainstem tegmentum to a region of interest encompassing the hypothalamus, thalamus, and basal forebrain. Examining each pathway individually, brainstem-hypothalamus and brainstem-thalamus CPs, but not brainstem-forebrain CP, were significantly re...