Electrical stimulation of the vagus nerve helped scientists "wake up" a man who has been in a coma for 15 years after a severe traumatic brain injury, according to an article published in the journal Current Biology.
“By stimulating the vagus nerve, we were able to show that we can improve the patient's condition and return him to 'our world' even when it seems that everything is lost. The brain retains the ability to form new connections and repair itself even in such a critical situation,”said Angela Serigu from the Institute of Cognitive Sciences in Lyon (France).
Strokes and various head injuries often lead a person into a condition that doctors call "brain death." In such cases, the patient's body is still alive, if it is supported by artificial respiration and the removal of waste products, but the brain is no longer functioning. In fact, a person in this state can be considered dead, since he can no longer live independently.
Today, scientists believe that people who have lain in a similar state or in a coma for more than a month lose their chances of regaining consciousness forever, but many patients live in this state for decades before they die or their relatives decide to disconnect them from life support systems.
Serigu and her colleagues worked with a patient in a Lyon clinic who had a car accident at the age of 20 and spent more than 15 years in a coma. Like many other people in a similar state, he cannot get out of a coma due to damage to special areas in the brain that connect his lower parts, which control life, with the cortex and other parts of the nervous system that are responsible for the work of the mind.
All these parts of the brain, the researchers say, are connected by the so-called vagus nerve - one of the longest and most complex ligaments of neurons in the human body, connecting dozens of individual organs to the brain. This connection, as scientists suggested, can be used to stimulate "isolated" parts of the nervous system in the brain of comatose patients and the formation of new connections between them.
Guided by this idea, scientists installed a special electrical stimulator in the patient's abdominal cavity, which was connected to one of the endings of the vagus nerve in his neck and constantly sent special sets of impulses to it, the frequency and power of which changed over time.
As noted by Serigu, the results of this experiment significantly exceeded the relatively pessimistic expectations of scientists - the man came out of a coma and began to respond to the words and actions of others and to execute simple commands from nurses and relatives. For example, he regained the ability to follow objects with his eyes, learned to move his neck, and stopped falling asleep when the nurse or his mother read him a book. In addition, the man began to react to sudden movements and to show other reactions that are not typical for people in a coma.
Promotional video:
All these positive changes, according to biologists, were manifested at the level of electrical activity of the brain. The patient's EEG showed the so-called theta rhythms, indicating the presence of rudimentary consciousness, and the number of active connections between different parts of the brain increased markedly.
Scientists are now preparing to conduct new clinical trials with a large number of volunteers, which Serigu and her colleagues hope will confirm their findings and help understand what needs to be done to further improve the condition of people in coma.
