In patients with severe brain injury, the neurological wake-up test—a brief interruption of sedation to check responsiveness—often yields ambiguous or absent behavioral responses, limiting its prognostic value. Recording 128-channel EEG from 41 such patients during propofol sedation interruption revealed that brain responses, measured by EEG power, spatial ratios, and the spectral exponent, can show signs of waking even when behavior does not. Combining EEG with behavioral assessment improved predictions of survival, recovery of consciousness, and long-term functional outcomes, outperforming the predictions of attending physicians. EEG can complement the wake-up test to better inform clinicians, families, and treatment planning.
Consciousness depends on the brain and has two main aspects: wakefulness and awareness. Awareness includes perception, abstract thought, selection, judgment, motivation, and emotion. The brain can process information and influence behavior without conscious awareness. Advances in science and technology have deepened understanding of the neural functions and brain region interactions underlying conscious experience. Studies of disorders from brain death to delirium have shaped knowledge of regional and global brain functions. Behavioral responses alone are insufficient to determine conscious level; some unresponsive-wakeful patients retain cognitive capacity detectable by fMRI and electrophysiology. Much remains unknown about how full awareness and self-awareness arise and how best to assess and manage disorders of consciousness.