Bedside EEG Detects Awareness in Vegetative Patients

EEG detects residual cognitive function, conscious awareness in patients in vegetative state

THURSDAY, Nov. 10 (HealthDay News) -- Electroencephalography (EEG) performed at the bedside of patients in a vegetative state can detect residual cognitive function and conscious awareness, according to a study published online Nov. 10 in The Lancet.

Damian Cruse, Ph.D., from the University of Western Ontario in London, Canada, and colleagues assessed whether EEG could be used for bedside detection of awareness among patients in a vegetative state. A total of 16 patients with traumatic and non-traumatic brain injury, who met the Coma Recovery Scale-Revised definition of vegetative state, were compared with 12 healthy controls. Patients were asked to imagine their right-hand and toes moving to command. Robust evidence of appropriate, consistent, and statistically reliable markers of motor imagery was identified by comparing command-specific EEG responses of each patient with those of healthy controls.

The investigators found that appropriate EEG responses to two distinct commands could be repeatedly and reliably generated in 19 percent of patients who were otherwise behaviorally entirely unresponsive (classification accuracy ranged from 61 to 78 percent). There was no significant correlation noted between patients' clinical histories and their ability to follow commands. On separating by cause, 20 percent of the traumatic patients and 9 percent of the non-traumatic patients successfully completed the task.

"The EEG method that we developed is cheap, portable, widely available, and objective. It could allow the widespread use of this bedside technique for the rediagnosis of patients who behaviorally seem to be entirely vegetative, but who might have residual cognitive function and conscious awareness," the authors write.

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