Clinical Trial: Assessing Covert Consciousness in Unresponsive Patients

Study Status: Not yet recruiting
Recruit Status: Not yet recruiting
Study Type: Interventional

Official Title: Assessing the Potential for 'Covert Consciousness' in Unresponsive Patients

Brief Summary: In this study, the investigators explore anesthesia as a tool for providing further insight into the level of consciousness of individuals with a clinical diagnosis of unresponsive wakefulness syndrome (UWS), but who possess some neurophysiological signatures of conscious awareness. This group, who could potentially be conscious, will herein be referred to as the target population. Our goal is to assess whether or not neurological patterns of consciousness in the target population respond to anesthesia in a similar manner to neurologically compromised individuals with known consciousness (e.g. those in minimally conscious state (MCS). In healthy controls, propofol-induced unconsciousness results in an elimination of the mismatch negativity event-related brain potential (ERP) and a diminished directed connectivity. The investigators hypothesize that at doses well below those required for surgery, anesthesia will have similar effects on these neural patterns in neurologically compromised patients with the potential for conscious awareness, but will not affect these patterns in those who lack consciousness.

Detailed Summary:
Sponsor: University of Michigan

Current Primary Outcome: Asymmetry in feedback vs. feedforward network connectivity [ Time Frame: 3 hours ]

EEG networks will be monitored pre, during and post anesthesia. Directed connectivity will be calculated using phase lag index (PLI) and symbolic transfer entropy (STE) between all combinations of EEG sensors. Average values of feedback connectivity (e.g. from the frontal regions to parietal and occipital regions) will be compared to average values of feedforward connectivity (e.g. from parietal and occipital regions to frontal regions). Positive asymmetry will be correlated to the presence of conscious awareness and negative asymmetry will be correlated to the absence of conscious awareness.


Original Primary Outcome: Same as current

Current Secondary Outcome: Presence of P300 and N400 event-related potentials [ Time Frame: 3 hours ]

EEG signals will be processed to extract the event-related EEG reactions to the auditory stimulation paradigm. Signals will be average 300 ms post-stimuli and 400 ms post-stimuli to assess the presence of the P300 and N400 event-related potentials. Presence of these event-related potentials will be correlated to the presence of conscious awareness and absence of these event-related potentials will be correlated to the absence of conscious awareness.


Original Secondary Outcome: Same as current

Information By: University of Michigan

Dates:
Date Received: January 8, 2016
Date Started: December 2016
Date Completion:
Last Updated: October 25, 2016
Last Verified: October 2016