London researchers develop technique to test consciousness of comatose patients

A group of London-based researchers is heralding a new bedside brain imaging technique they say can detect conscious awareness in ICU patients left comatose with a severe brain injury.

Researchers from Lawson Health Research Institute and Western University say the technique, called functional near infrared spectroscopy, or fNIRS, "opens the door" for improving the accuracy of an unresponsive patient's prognosis. 

The study identify a patient who, despite appearing unresponsive, was actually entirely conscious, said Dr. Karnig Kazazian, the study's co-lead author and research scientist at London Health Sciences Centre. 

"If you knew a patient was conscious, that's really going to influence a decision about continuing aggressive life-sustaining care, versus transitioning to comfort-focused care and having them pass away peacefully," Kazazian said. 

"If we know they're in there, and if we know they're aware, then we may be able to ask them some simple questions so they can have the autonomy to make decisions about their own care."

For their study, published in The Proceedings of the National Academy of Sciences (PNAS) journal, the researchers were able to use the portable technique to detect consciousness in an ICU patient who appeared to be in a coma.

The aim was to see if patients could feel pain, hear their surroundings and retain consciousness awareness.

The tests, which took place at patient's bedside at London Health Sciences Centre (LHSC), showed activity in the part of their brain that imagines movement after they were given a command to imagine themselves playing tennis.

"In order to imagine playing a game of tennis, you have to hear the instructions, you have to remember the instructions, and then you have to do it consistently over and over again," said Kazazian.

"By reading activity over the specific part of your brain responsible for imagining doing movements, we know that the person was aware."

Kazazian said they also plan to look at using technique for a brain-computer interface to make it possible to communicate with select ICU patients.

It's portability also allows ICU doctors to avoid moving a patient, and their life support machines, for similar diagnostics, and would make it easier for researchers to study the brain function of healthy participants in real-life settings, he said.

With the fNIRS technique, a cap worn on the head emits light waves which bounce off of the brain, said Dr. Derek Debicki, a neurologist at LHSC and one of the authors of the study. Researchers are then able to measure different properties of blood going through the brain, and determine which parts are active at a given point in time.

A major finding of the study, he said, is that the technology could be used at a patient's bedside.

For the study, the technique was tested on more than 100 healthy participants before it was tested on three patients from LHSC's intensive care unit, including the one asked to imagine themselves playing tennis. All three were deemed clinically unresponsive.

One of the other ICU patients had no brain activity recorded by fNIRS, while another showed activity in response to auditory stimuli in parts of the brain responsible for hearing and comprehension.

The hope, researchers say, is that the technology could be made more commonplace over the next few years and become a part of the medical toolkit in intensive care units.

Debicki said they're recruiting additional patients from the ICU for studies with a larger sample size as the research continues.