Self-processing in coma, unresponsive wakefulness syndrome and minimally conscious state

Area of Science:

• Neuroscience
• Cognitive Science

Background:

• Disorders of Consciousness (DoC) present a significant challenge in assessing cognitive function, particularly in the acute stage.
• Previous research has focused on high-level cognitive markers, neglecting fundamental abilities like self-recognition crucial for consciousness emergence.
• The hypothesis posits that preserved self-recognition is independent of behavioral impairment and may indicate potential for consciousness recovery.

Purpose of the Study:

• To investigate the preservation of self-recognition in patients with acquired DoC.
• To determine if self-recognition, assessed via auditory stimuli, correlates with behavioral outcomes and consciousness recovery.
• To explore the potential of electrophysiological markers for predicting recovery in DoC patients.

Main Methods:

• Utilized bedside Electroencephalography (EEG) to record brain responses in 129 severely brain-damaged patients.
• Administered auditory stimuli including the patient's own name (SON) and unfamiliar first names (OFN).
• Analyzed for a significant P3 event-related brain response (the 'SON effect') indicative of self-recognition, comparing outcomes across coma, unresponsive wakefulness syndrome (UWS), and minimally conscious state (MCS) patients.

Main Results:

• 29% of DoC patients exhibited a 'SON effect', with no significant difference across coma (29%), UWS (34%), and MCS (23%) groups.
• Patients in MCS at enrollment were more likely to emerge from MCS (EMCS) at 6 months compared to coma and UWS patients.
• Among survivors, 75% of those with a 'SON effect' (n=16) emerged to EMCS, versus 59% without the effect (n=56), suggesting a predictive value.

Conclusions:

• A significant subset of DoC patients demonstrate covert self-recognition abilities, even without observable behavioral signs of consciousness.
• The 'SON effect' identified through EEG may serve as a valuable electrophysiological marker for predicting consciousness recovery.
• This finding highlights the potential of assessing lower-level cognitive functions to better understand and predict outcomes in patients with disorders of consciousness.