Brain networks
October 20, 2014

Cambridge Scientists Devise Possible New Way To Test For Brain Activity In Vegetative Patients

Chuck Bednar for redOrbit.com - Your Universe Online

The discovery of hidden signs of consciousness in vegetative-state patients could help doctors determine if people are aware even if they appear to be unresponsive, according to research published in the journal PLOS Computational Biology.

According to BBC News health reporter Smitha Mundasad, doctors typically consider patients who have suffered severe brain trauma to be unaware of their surroundings, even if they appear to be awake. The new study could lead to a test that would allow doctors to detect which non-responsive patients are actually conscious, even if they can’t respond to commands or make purposeful movements.

As part of their research, scientists from the University of Cambridge and the MRC Cognition and Brain Sciences Unit, Cambridge studied the brains of 32 patients that had been diagnosed as vegetative and minimally conscious. They used high-density electroencephalographs (EEG) and a type of mathematics known as “graph theory” to analyze networks of activity in their brains, then compared their results to those of healthy adult brains.

While the study authors found “rich and diversely connected networks” of brain activity in healthy men and women, International Business Times reporter Mary-Ann Russon noted that they also discovered similar brain activity patterns in some of the vegetative patients. The latter group of patients was unable to show physical movement or respond to questions, she added, but were apparently able to imagine performing a task such as playing tennis.

“The researchers showed that the rich and diversely connected networks that support awareness in the healthy brain are typically – but importantly, not always – impaired in patients in a vegetative state,” the university explained in a statement. “Some vegetative patients had well-preserved brain networks that look similar to those of healthy adults – these patients were those who had shown signs of hidden awareness by following commands such as imagining playing tennis.”

“Understanding how consciousness arises from the interactions between networks of brain regions is an elusive but fascinating scientific question,” added Dr. Srivas Chennu from the Department of Clinical Neurosciences at the University of Cambridge. “But for patients diagnosed as vegetative and minimally conscious, and their families, this is far more than just an academic question – it takes on a very real significance. Our research could improve clinical assessment and help identify patients who might be covertly aware despite being uncommunicative.”

Dr. Chennu and his colleagues believe their findings could result in the development of a relatively simple way of identifying which patients are aware while in a vegetative state and which are not. While the so-called ‘tennis test’ is a difficult task for patients to complete and requires difficult-to-obtain functional MRI scanners, their new method uses electroencephalography (EEG) and could be administered at the patient’s bedside.

“On a practical note,” the researchers wrote, “it is worth highlighting that short EEG recordings” such as the ones they analyzed in non-responsive or vegetative patients “are commonly measured… in hospitals around the world, and clinically interpreted by eye by electrophysiologists. These could potentially become much more clinically informative if powerful analytical tools are used to unveil the capacity of cortical integration and differentiation.”

“Combining easy-to-administer and inexpensive EEG with developments in network science could allow us to make inferences about information transfer across multiple scales of brain dynamics, and ultimately aid diagnosis and prognosis in this challenging group of patients,” added the authors, whose research was funded primarily by the Wellcome Trust, the National Institute of Health Research Cambridge Biomedical Research Centre and the Medical Research Council (MRC).

While the researchers pointed out that there are limitations as to how successful their test would be when used by itself, when used along with other trials – including the ‘tennis test’ – it could help assess the awareness and brain activity of unresponsive patients. They added that if the examinations indicate the patients’ so-called awareness networks remain active and intact, those individuals are likely to be cognizant of what it going on around them.

“This type of information might be helpful for families and the healthcare team looking after the patient,” Dr. Chennu told BBC News. “We have heard anecdotally that carers change their level of interaction with patients once they know there may be some hope of awareness.”

Related Reading:

> Researchers Advocate For More Scientific Research On Consciousness
> Scientists Discover On-Off Switch To A Person’s Consciousness
> Some Apparently Vegetative Patients Are Aware And Can Follow Commands
> Patients In A Vegetative State May One Day Interact With The Outside World

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