Hidden Consciousness Detected with EEG Predicts Recovery of Unresponsive Patients

A new study finds that signs of covert consciousness subtle brainwaves detectable with EEG--are the strongest predictor of eventual recovery for brain-injured patients who otherwise appear completely unresponsive.

The findings suggest brainwave analysis has the potential to completely change how unresponsive patients with acute brain injury are managed. The study was published online in Lancet Neurology.

Standard bedside assessments alone do not always predict clinical outcomes. In the intensive care unit, doctors routinely assess the prognosis of brain-injured patients by asking them to respond to a simple verbal command, such as "move your hand" or "stick out your tongue." Those who do not respond to these commands are thought to be unconscious. In the absence of any other explanations for this unresponsiveness, injuries may be considered so severe that patients are unlikely to regain consciousness.

Researchers found that covert consciousness is an independent predictor of recovery, stronger than any other established factor we looked at, including the patient's age, initial Glasgow Coma Scale score (a standard measure of the extent of neurological injury), or the cause of the brain injury. In the future, cognitive-motor dissociation may be another factor to consider when assessing a patient's prognosis.

The researchers are investigating the underlying mechanisms of covert consciousness to better understand why a patient who has brainwave activity in response to different motor commands and is not paralyzed cannot physically act on these commands. They also are interested in studying how degrees of covert consciousness are linked to clinical outcomes.

Researchers concluded that in some rare cases, unresponsive patients do eventually regain consciousness and may make meaningful progress toward recovering many day-to-day functions many months later.

Reference: "Hidden Consciousness Detected with EEG Predicts Recovery of Unresponsive Patients"; COLUMBIA UNIVERSITY IRVING MEDICAL CENTER, JOURNAL-The Lancet Neurology.