Abstract
Predicting outcome in comatose patients after successful cardiopulmonary resuscitation is challenging. Our primary aim was to assess the potential contribution of resting-state-functional magnetic resonance imaging (RS-fMRI) in predicting neurological outcome. RS-fMRI was used to evaluate functional and effective connectivity within the default mode network in a cohort of 90 comatose patients and their impact on functional neurological outcome after 3 months. The RS-fMRI processing protocol comprises the evaluation of functional and effective connectivity within the default mode network. Seed-to-voxel and ROI-to-ROI feature analysis was performed as starting point for a supervised machine-learning approach. Classification of the Cerebral Performance Category (CPC) 1–3 (good to acceptable outcome) versus CPC 4–5 (adverse outcome) achieved a positive predictive value of 91.7%, sensitivity of 90.2%, and accuracy of 87.8%. A direct link to the level of consciousness and outcome after 3 months was identified for measures of segregation in the precuneus, in medial and right frontal regions. Thalamic connectivity appeared significantly reduced in patients without conscious response. Decreased within-network connectivity in the default mode network and within cortico-thalamic circuits correlated with clinical outcome after 3 months. Our results indicate a potential role of these markers for decision-making in comatose patients early after cardiac arrest.
Highlights
Predicting outcome in comatose patients after successful cardiopulmonary resuscitation is challenging
There were no significant differences in age between the healthy control group and the survivors (t = 1.01; p = 0.32) but the age of the non-survivors compared to controls was significantly higher (t = 2.85; p = 0.005)
The authors found that default mode network (DMN) activation and connectivity was preserved in the two patients who had regained consciousness at the 3-month reevaluation, whereas DMN activity could not be identified by the initial fMRI scanning in the 11 patients who remained unconscious after 3 months
Summary
Predicting outcome in comatose patients after successful cardiopulmonary resuscitation is challenging. RS-fMRI was used to evaluate functional and effective connectivity within the default mode network in a cohort of 90 comatose patients and their impact on functional neurological outcome after 3 months. External awareness correlates with BOLD fluctuations within the frontoparietal network (FPN), known as the task-positive network The latter encompasses mainly lateral frontoparietal hemispheric r egions[16] reflecting the brain activations during goal-directed behavior and it has been linked to cognitive processes of external sensory input, such as somatosensory17 visual[18] and auditory[19]. The presence of functional DMN connectivity in patients with reversible coma is supported by previous studies and case reports across a range of altered states of consciousness including light[30] and deep[31] anesthesia, minimal consciousness32 VS32–35, and c oma[32,36]. The finding of altered connectivity in the DMN along various states of altered consciousness suggests that the DMN represents a fundamental or intrinsic property of functional brain o rganization[31]
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