They don’t speak and they don’t move. Completely cut off from everything around them. Apparently in a coma and with no obvious signs of recovery. In most cases what is seen on the outside reflects exactly what happens inside too, in the conscience, i.e. nothing.
One in five patients is conscious even if unresponsive
But in 15 to 20 percent of cases, patients who appear to be in a coma or other unresponsive state are conscious. That is, they are present to themselves without being able to prove it. Unless advanced brain imaging methods or sophisticated monitoring of the brain’s electrical activity are used. These techniques have only recently been perfected, but they are already revolutionizing our understanding of coma and other disorders of consciousness.
At what stage are the studies on the “hidden consciousness”
Among the pioneers in the search for forms of “hidden consciousness” are John Claassenassociate professor of neurology at Columbia University and neurologist at Columbia University’s New York-Presbyterian Hospital, e Brian L. Edlowan associate professor of neurology at Harvard Medical School and a neurologist at Massachusetts General Hospital.
In an article recently published on Scientific Americanthe two scientists have attempted to shed light on a field, that of the consciousness of people in a coma, which is still very mysterious.
The case of Maria Mazurkevich
To do so they told the case of Maria Mazurkevich, 30-year-old pharmacist, admitted to New York-Presbyterian Hospital after a ruptured brain aneurysm. The woman was placed on a ventilator and her vital signs were stable. However, she showed no signs of consciousness. She didn’t respond to any commands. Or at least not on the outside.
The doctors decided to do an EEG to monitor the electrical activity of the brain. During the examination, the patient was asked to open and close her right hand and the result left the doctors and family members speechless: even if the woman’s hands did not move even a millimeter, the brain activity clearly showed a response to the two commands.
In practice, the cerebral reactions clearly indicated that Maria was there, she was conscious and was able to distinguish the two commands, the one to open and the one to close her hands. After about a week the patient’s body started following the brain. Slowly Mazurkevich started to wake up and in less than a year she made a full recovery without major limitations on her physical or cognitive abilities. She currently works as a pharmacist.
Scientists were therefore able to find the hidden consciousness of the patient. “Columbia University researchers have demonstrated that, in some cases, even comatose and clinically unresponsive patients may have evidence of brain electrical activation in response to voice commands, which can be detected through advanced neuromonitoring systems such as electroencephalography or functional magnetic resonance imaging,” he explains Clare Robbamedical director of the Policlinico San Martino, IRCCS for Oncology and Neuroscience of Genoa.
Identifying cases is essential to better manage care
Indeed, it seems that at least a proportion of chronically unresponsive patients after brain damage – he continues – may have a dissociation between behavior and activation, and that patients who present this response to vocal commands more often have a better neurological recovery than the others. This implication becomes of fundamental importance for the management of the patient’s care, for the family, and can have an effect on decisions relating to the suspension of life-sustaining therapies”.
It is evident that our understanding of the coma is changing and that it becomes essential to learn to recognize this hidden state of consciousness and to develop ways to communicate with the people in it.
“Detecting and predicting early recovery of consciousness in the intensive care unit is often a matter of life and death,” write Claassen and Edlow. “Families typically make decisions about whether to continue or stop life-support therapy within 10 to 14 days of the injury, at which time surgical procedures become necessary to support long-term breathing and feeding. It’s a conscientious diagnosis. could influence clinical decisions about goals of care, pain management, bedside behavior of physicians and family members, and management of depression and anxiety.
Brain activation comparable to that of healthy volunteers
In 2006 the neuroscientist Adrian M. Owennow at Western University in Ontario, and his research team examined a young woman who had suffered a severe traumatic brain injury and was believed to be in a vegetative state.
The patient underwent a functional MRI scan, which traces blood flow through the brain to reveal active areas. During this scan, the clinicians asked the woman to imagine she was playing tennis and to imagine walking through the rooms in her house.
To the surprise of Owen and his colleagues, the woman showed brain activation comparable to that seen in healthy volunteers. Furthermore, the brain activation patterns while the patient imagined playing tennis were distinct from those of her while she imagined walking. This indicated to scholars that the woman could deliberately change her brain activity. Subsequently there have been other cases of hidden consciousness identified, following various types of brain injuries.
The limits of diagnostic tools
EEG and functional magnetic resonance have been instrumental, but they have limitations: they take pictures of a given moment, but they cannot detect brain activity of patients who recover later, i.e. when they are not monitored. Furthermore, they are complex exams that are difficult to repeat many times in patients who cannot be easily transported from one department to another. However, the evidence for their utility is strong enough for them to be approved for the diagnosis of hidden consciousness in clinical guidelines in the United States (2018) and Europe (2020).
The importance of early diagnosis
Early detection of hidden consciousness, soon after a patient’s injury, predicts behavioral recovery of consciousness, long-term functional recovery, and the speed of that recovery, as demonstrated by research that Claassen and Edlow’s research team published. in 2019 and then confirmed this year.
Building on the momentum of these studies, scientists came together in 2019 to launch the “Curing Coma” campaign, an international collaboration led by the Neurocritical Care Society to direct medical resources and public attention to the condition, with the goal of develop new therapies that promote recovery of consciousness.
Neurologists are trying to develop a test that can identify which patients may be in a state of hidden consciousness and therefore should undergo advanced EEG and MRI assessments.
Structural and functional mechanisms yet to be discovered
Laboratories around the world are working to develop such screening methods, but progress has been slow because the structural and functional mechanisms underlying hidden consciousness are uncertain, so doctors don’t know exactly what to look for.
Recent studies suggest that brain injuries disconnecting the thalamus — a region that transmits movement signals and sensory information between the body and the brain — from the cerebral cortex, which is responsible for higher-level cognitive functioning, may be responsible for the condition. However it is likely that not a single type of injury but rather various combinations of injuries in different areas could cause motor dysfunction while still allowing for hidden consciousness.
The brain-computer interfaces
Building on recent discoveries about the presence of hidden consciousness, researchers are trying to reconnect and communicate with these patients using brain-computer interfaces. These devices typically record the brain’s electrical activity as it asks the patient to move the mouse cursor on a computer screen.
The computer “learns” to identify the physiological signals related to the patient’s attempts to move the cursor, left, right, up or down. Once training is complete, these brain patterns allow the patient to take control of the cursor and then they can use it to select letters and spell words.