Ms Sirigu and her team now hope to apply the technique more widely to patients with less serious brain injuries, where the gains could be even greater.
French researchers say they restored some signs of consciousness in a brain-injured man who hadn't shown any awareness in 15 years. The vagus nerve serves many roles in the anatomy: it controls the slowing of the heartbeat and the muscles of the small intestine. For example, he could follow an object with his eyes and turn his head upon request. In the case presented, after a month of nerve stimulation, the patient showed significant improvements in attention, movement, and brain activity, according to the researchers.
The 35-year-old, left severely brain damaged by a vehicle crash, had shown minimal signs he was aware of the outside world following the accident. To ensure that any improvements couldn't be explained by chance, they deliberately chose a hard case: a 35-year-old man who had been in a vegetative state for more than a decade with no sign of improvement. Furthermore, a minimally conscious state still constitutes severe disability and the authors of the paper had to use special clinical tests and neuroimaging measures to prove that there has indeed been a change in the patient's state'.
A vegetative state is not a coma.
Vagus nerve implants are usually used to treat epilepsy and depression. His mother, who gave permission for the surgery to implant the nerve stimulating device, reported an improved ability to stay awake when listening to his therapist reading a book.
The patient in France was involved in a vehicle accident in 2001 that saw him spend over a decade without consciousness, a state which Steven Laureys of the University of Liege, Belgium, says many experts incorrectly believe is just a stage of "waiting to die".
The 35-year-old was left apparently unaware of the world around him following a auto accident in 2001, but is now responding to questions a month after having a stimulator placed on a nerve which connects the heart, lungs and digestive tract to the brain.
Angela Sirigu, who led the research at the Institute of Cognitive Sciences - Marc Jeannerod in Lyon, France, said the technique could trigger a radical change in neurological treatments worldwide.
After stimulation, the researchers also observed responses to "threat" that had been absent. PET results corroborated the EEG findings by showing extensive increases in metabolic activity in both cortical and subcortical regions of the brain, as early as three months after implantation of the stimulator.
Sirigu noted that "after VNS, the patient could respond to simple orders that were impossible before". Published this Monday in the u.s. journal Current Biology, this advert is for a 35 year old man, victim of a road accident fifteen years ago.
In the end, Sirigu said that her team was not, in fact, surprised by the encouraging results, based on evidence of the impact of VNS in prior animal research.