Questions about how aware brain-injured patients might be have always been wrenching for loved ones.
A new study, while shedding light on the unconscious, unfortunately won’t make those questions any easier to handle.
An international research team found that about 1 in 4 patients who appear completely unresponsive might, in fact, be conscious but unable to physically show that awareness.
The phenomenon is called cognitive motor dissociation.
The researchers used two techniques to study more than 350 patients with brain injuries of varying degree.
In the first, called functional magnetic resonance imaging, they measured brain activity by tracking changes in blood flow.
Patients were asked to imagine doing tasks, such as walking inside their home or playing tennis. If the appropriate brain areas activated in response to the commands, it meant the patient could understand the instructions, despite no outward response.
In the second test, called electroencephalography, electrodes were placed on a patient’s scalp. The electrodes measured brain wave patterns for signs of intentional response to similar commands.
Twenty-five percent of patients tested showed brain activity consistent with being able to understand and follow commands.
In a curious plot twist, among patients who could follow commands, more than 60 percent showed no signs of it on the brain activity tests.
The researchers say the techniques are not yet widely used.
For now, we’re left to question what we thought we knew about consciousness and end-of-life decisions. And the troubling reminder that we can’t always trust our own eyes.
