Structural and functional connectivity of the ascending arousal network for prediction of outcome in patients with acute disorders of consciousness

Abstract

To determine the role of early acquisition of blood oxygen level-dependent (BOLD) signals and diffusion tensor imaging (DTI) for analysis of the connectivity of the ascending arousal network (AAN) in predicting neurological outcomes after acute traumatic brain injury (TBI), cardiopulmonary arrest (CPA), or stroke. A prospective analysis of 50 comatose patients was performed during their ICU stay. Image processing was conducted to assess structural and functional connectivity of the AAN. Outcomes were evaluated after 3 and 6 months. Nineteen patients (38%) had stroke, 18 (36%) CPA, and 13 (26%) TBI. Twenty-three patients were comatose (44%), 11 were in a minimally conscious state (20%), and 16 had unresponsive wakefulness syndrome (32%). Univariate analysis demonstrated that measurements of diffusivity, functional connectivity, and numbers of fibers in the gray matter, white matter, whole brain, midbrain reticular formation, and pontis oralis nucleus may serve as predictive biomarkers of outcome depending on the diagnosis. Multivariate analysis demonstrated a correlation of the predicted value and the real outcome for each separate diagnosis and for all the etiologies together. Findings suggest that the above imaging biomarkers may have a predictive role for the outcome of comatose patients after acute TBI, CPA, or stroke.

Disruption in structural–functional network repertoire and time-resolved subcortical fronto-temporoparietal connectivity in disorders of consciousness

“…Previous studies have already demonstrated a strong signature of the underlying structural network in functional networks in DoC. However, these previously described functional networks were mostly obtained using time-averaged estimation methods ( Annen et al, 2016 ; Enciso-Olivera et al, 2021 ; Kuceyeski et al, 2016 ; Lant et al, 2016 ), and have not provided insight into a stronger structural functional coupling in DoC. Using time-resolved functional connectivity and its relationship to eigenmodes, we shed light on this observation.…”

Electrophysiological correlates of thalamocortical function in acute severe traumatic brain injury

“…Our cohort also included a relatively low proportion of patients with an acute, behavioral diagnosis of VS (5%). Recent studies investigating patients with acute DoCs enrolled widely varying proportions of patients with behavioral VS diagnoses (range: 11–41%) ( Claassen et al, 2019 ; Enciso-Olivera et al, 2021 ; Kondziella et al, 2017 ; Othman et al, 2021 ; Seel et al, 2013 ). The timing of post-injury behavioral assessments in such studies is also often variable.…”

Disorder of consciousness: Structural integrity of brain networks for the clinical assessment

“…When assessing structural integrity, methodological considerations become critical due to the extent and heterogeneity of lesions in DoC patients. A variety of approaches have been used, broadly classified in quantitative approaches, using automated or semi‐automated algorithms, 11–13 and qualitative approaches, based on neuroradiologists' ratings 5,6,14–16 …”

“…6 When assessing structural integrity, methodological considerations become critical due to the extent and heterogeneity of lesions in DoC patients. A variety of approaches have been used, broadly classified in quantitative approaches, using automated or semi-automated algorithms, [11][12][13] and qualitative approaches, based on neuroradiologists' ratings. 5,6,[14][15][16] The quantitative methods are user-independent, providing an unbiased measure, but are sensitive to MRI artifacts or anatomical deformations that can determine the exclusion of a potentially high number of patients (up to 35%).…”

“…Another element to be considered in the characterization of DoC is etiology. In fact, the damage determined by the various etiologies 12,13 can affect the integrity of functional networks differently. 6,7,17 For example, in vascular injuries, the damage may be more localized along branches of the anterior, middle, or posterior cerebral arteries and the recognition of some networks can be more challenging.…”