In the month since a vagus nerve stimulator was put into his chest, the man, who was injured in a car accident, has begun responding to simple orders.
The findings, which were reported in Current Biology, may help to show that by stimulating the vagus nerve, “it is possible to improve a patient’s presence in the world”, said lead researcher Angela Sirigu of Institut des Sciences Cognitives Marc Jeannerod, in Lyon, France.
The researchers say it may challenge the view that a vegetative state which lasts for more than 12 months is irreversible.
“Other scientists have hailed it as “a potentially very exciting finding”, but have also urged caution.
After treatment, it was reported the patient could follow an object with his eyes and turn his head on request, and his mother said there was an improved ability to stay awake, when listening to his therapist reading a book.
The vagus nerve connects the brain to many other parts of the body, including the gut. It is known to be important in waking, alertness, and many other essential functions.
The patient, who was picked because he had been lying in a vegetative state for more than a decade with no sign of improvement also appeared to react to a “threat”.
Researchers spotted that he reacted with surprise by opening his eyes wide when the examiner suddenly moved their head towards his face.
Changes in brain activity may show that he had shifted from being in a vegetative state to being in a state of minimal consciousness.
An important signal in distinguishing between these conditions increased significantly in areas of the brain that are involved in movement, sensation, and awareness, according to the scientists.
Gains were also spotted in the brain’s functional connectivity, and metabolic activity in both cortical and subcortical regions of the brain.
The researchers are now planning a large, collaborative study.
Tom Manly of Cambridge University’s MRC Cognition and Brain Sciences Unit described it as a “potentially very exciting finding”.