Electrical brain activity can predict the likelihood of recovery in patients who are otherwise unresponsive after acute brain injury, research suggests.
“Covert consciousness” shown in response to verbal motor commands anticipated the recovery trajectory in these patients, who had experienced acute brain injury due to trauma, stroke or cardiac arrest or as a result of meningitis.
Also known as cognitive-motor dissociation, this type of brain activation detected using a bedside electroencephalogram (EEG) independently predicted earlier time to good functional recovery.
Indeed, it was a stronger predictor of recovery than any other established factor examined, including the patient’s age, the extent of neurological injury, or the cause of brain injury.
“These findings could provide clinicians with information that helps them better explain possible recovery trajectories to families of patients who are clinically unresponsive from an acute brain injury,” suggest Jan Claassen, associate professor of neurology at Columbia University Vagelos College of Physicians and Surgeons, New York, USA, and co-workers in The Lancet Neurology.
The team screened 598 patients with acute brain injury for their study, all of whom were admitted to the neurological intensive care unit at Columbia University Irving Medical Center, New York Presbyterian Hospital, USA, and spoke English or Spanish as their primary language.
A total of 193 ultimately took part in the study, after excluding the rest for reasons such as age, confounding neurological conditions, or prior deafness. A control group of 15 healthy volunteers were also recruited to examine brain activation to the motor commands.
Participants were fitted with single-use headphones and given commands including “keep opening and closing your right hand” and “stop opening and closing your right hand” in three blocks, with eight consecutive trials each for the left and right hand, during which a digital bedside EEG was recorded.
Covert consciousness was detected in 14 per cent of participants on at least one bedside EEG recording, and those with this brain activity had higher and faster recovery rates than others.
Within a year, 41 percent of these 27 patients with cognitive-motor dissociation had met the primary outcome of a Glasgow Outcome Scale-Extended (GOS-E) score of at least four, indicating functional recovery to the extent that they could be left alone for up to 8 hours without assistance. This compared with just 10 per cent of 166 participants without cognitive-motor dissociation.
Similar findings were observed at the three- and six-month timepoints.
Among patients alive at discharge, cognitive-motor dissociation (odds ratio [OR]=7·2), discharge to home or a rehabilitation setting (OR=5·6), and the interaction between time and discharge disposition (OR=1·3) independently predicted improvement in GOS-E score over time.
For those patients discharged home or to a rehabilitation setting, cognitive-motor dissociation diagnosed in an ICU setting was associated with improved functional outcomes, seen as early as three months after injury.
The researchers suggest: “A diagnosis of cognitive-motor dissociation could enable clinicians to identify patients who have a high potential to benefit from rehabilitation interventions, possibly even among individuals who do not meet current criteria to be discharged into a rehabilitation setting.”