Coming out of a coma

Artificial nerve stimulation brought a person back from a vegetative state

Sergey Vasiliev, Naked Science

Severe trauma or too long a break in the supply of oxygen to the brain can lead to the development of a vegetative state. A gross violation of the function of the large hemispheres while maintaining the work of the "lower" parts of the brain leaves the patient with basic and sometimes even motor reflexes and alternation of sleep and wakefulness. He can yawn and blink at the light, but he is not aware of himself or his surroundings. In some cases, a person returns from a vegetative state to minimal consciousness, but if this does not happen within 12 months after the injury, there is practically no hope for this.

With such a patient – a 35-year-old man who has been in a vegetative state for 15 years – doctors led by Angela Sirigu from the French Institute of Cognitive Research in Brona worked. A miniature implanted device stimulated the vagus nerve of the patient. This is one of the most important pathways connecting the brain to the periphery, and its artificial stimulation (Vagus Nerve Stimulation, VNS) is sometimes used to combat epileptic seizures.

The vagus nerve performs mixed functions, responsible for the innervation of the muscles of the pharynx, lungs, esophagus, intestines and heart, and for the work of the glands of the stomach and pancreas, and for the transmission of many sensory signals back to the brain. In an article published by the journal Current Biology, French doctors report on the results of monitoring the patient before and after implantation. In addition to recording the behavior and reactions of the patient, data from electroencephalography and positron emission tomography were studied. Finally, stimulation was turned on.

Over the course of a month, the intensity of exposure gradually increased, reaching the level of 1 milliampere, and by this time the patient began to show significant improvements, was able to respond to some requests, follow objects with his eyes and turn his head slightly. For the first time in 15 years, he showed "stable, measurable signs of consciousness," moving from vegetative to a state of minimal consciousness.

Activity of higher brain regions before and after VNS.
A drawing from an article in Current Biology.

Improvements were also visible on the EEG and tomography data: stable activity was recorded in previously "silenced" areas of the brain, primarily in the thalamus, which is involved in processing a variety of sensory information and receives signals, including from the vagus nerve. "Plastic recovery of the brain is possible even when all hope has disappeared," the scientists add. Now they intend to repeat the experiments on other patients in order to move on to creating a full-fledged therapy for patients in a vegetative state.

Portal "Eternal youth" http://vechnayamolodost.ru  26.09.2017