- "There's limited understanding of the inner workings within the cranium."
Following a severe brain injury, individuals often find themselves in a coma, managed in an intensive care unit. This leads to the question among family and medical staff: Has the patient regained consciousness? To explore this, the patient might be asked to move a hand. Lack of response can often lead to assumptions that the person is still deeply comatose and unaware of their surroundings. However, recent research suggests otherwise.
Research has shown that some individuals who do not display external responses may still have cognitive brain activity. Previous studies conducted at individual research centers indicated such activity in approximately 15 to 20 percent of cases. A new study published in the prestigious journal "New England Journal of Medicine" now reports a higher figure of approximately 25 percent.
Lead author Yelena Bodien of the Center for Neurotechnology and Neurorehabilitation at Massachusetts General Hospital explains: "Patients with severe brain injuries may appear unresponsive to their external environment. However, when examined using advanced techniques such as functional magnetic resonance imaging (fMRI) and electroencephalography (EEG), we can detect brain activities suggesting otherwise."
The study involved participants from the USA and Europe who had suffered severe brain injuries, often months prior, such as a traffic accident with a traumatic brain injury, a stroke, or cardiac arrest. While their brains were scanned, they were given instructions, like "Imagine opening and closing your hand" or "Imagine performing a sport."
Of the 241 participants, 60 showed no visible reaction but followed the instructions internally for minutes at a time. These individuals were found to be attentive, understood language, and had short-term memory.
The study, conducted over many years and involving six medical centers, is significant as it is the largest patient group studied so far and has systematically captured the phenomenon, according to Julian Bösel, spokesperson for the Commission on Neurological Intensive Care of the German Society of Neurology (DGN). The study raises a central ethical question: whether to continue therapy or not.
Severe brain injuries often result in impaired consciousness. A coma is defined as a state of complete unconsciousness with no eye opening even in response to pain. If a person occasionally opens their eyes and has distinguishable sleep-wake phases but no signs of communication, it was previously referred to as a vegetative state, now known as the syndrome of unresponsive wakefulness (SUR). This is distinguished from a state with minimal consciousness, where eye following movements are present or simple commands are followed.
More investigations and time may be advisable. Bösel suggests that studies like the current one could provide grounds for examining more of these patients with EEG and observing them over longer periods. This could lead to giving selected patients more time in cases of doubt.
It remains unclear whether special therapies can help these people. Attempts have been made using behavioral therapies, medication, or other methods, but these have typically not resulted in significant or lasting success. A team at the Massachusetts General Hospital is also employing modern technology: Using brain-computer interfaces, they aim to establish a connection between the brains of these patients and computers, enabling them to communicate.
Brain activity does not necessarily mean consciousness
Frank Erbguth, President of the German Brain Foundation, however, believes that the new study does not say anything fundamentally new. "The phenomenon is known," he says. But measuring electrical patterns or active regions in the brain does not necessarily mean that these people have a higher form of consciousness. Such activity can also be found in the fMRI or EEG of anesthetized people.
Both experts agree on how to treat people who do not respond. "People on intensive care and rehabilitation units should always be treated as if they are aware," says Erbguth. "You talk to them and treat them respectfully. That's already the case today."
The number of affected people is uncertain
How high is the rate of people who show cognitive abilities but lack behavioral signs? Both the authors of the study and the German experts explain that making definitive statements is difficult. In the new study, the tests were not standardized and the patients were selected. "Moreover, the study combined completely different causes of brain damage," says Erbguth.
Nevertheless, emphasizes Bösing, the percentage figures from studies like this show: "We should be aware that perhaps more consciousness-disordered patients than thought are aware of what's going on around them." In his experience, it is still common in many places to speak at the bedside of comatose patients as if they are not there. "Many nursing staff do this very well by greeting the patient, introducing themselves, and telling them what they are doing."
Everyone should keep this in mind, including doctors during rounds or visitors, and avoid discussing frightening topics at the bedside. "We stand at the bedside and don't know much about what's really going on in the skull, we have to be honest about that."
Study from 2009 in "BMC Neurology" "German Medical Journal": Vegetative state and minimal consciousness state Meta-analysis from 2016 in "Journal of Neurology, Neurosurgery and Psychiatry" Meta-analysis from 2020 in "Brain Sciences" Current study
The use of advanced techniques like functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) can reveal brain activities in patients with severe brain injuries who appear unresponsive. Despite displaying no visible reaction, some individuals may follow internal instructions during scanning, indicating attentiveness, language understanding, and short-term memory.
