A patient in this state might show involuntary movements, but has no self-awareness or about the environment. Repeated tests over the years showed no improvement in the man’s condition, until the vagus nerve was stimulated.
To trigger his vagus nerve, researchers from the French National Centre for Scientific Research in Bron, implanted a device in his chest to see if he could respond to some signals from the outside world.
The vagus nerve connects several brain areas including the thalamus and the locus coeruleus, which is responsible for the release of brain chemicals that are involved in arousal and alertness.
Stimulating the vagus nerveThe team wrapped very thin electrodes around the vagus nerve and monitored his situation for a month before the nerve was stimulated. He was then treated continuously over six months, with each treatment involving 30 seconds of stimulation followed by five minutes of rest.
The starting electrical current was 0.25 milliamperes, increasing by 0.25mA per week until 1.5mA was reached.
As soon as stimulation began, the man started to open his eyes more often. To test if the patient had any reaction, doctors proceeded to put an object in front of the patient’s eyes to see if he could follow it.
The result was positive and doctors carried on testing his reactions. He responded positively when he was asked to turn his head and also reacted by widening his eyes when the doctor came close to his face. He also attempted to follow an instruction to smile.
The team led by Angela Sirigu,, observed the changes through the brain imaging and electrical recordings of brain activity (EEG). The brain recordings provided additional evidence that a significant change happened.
Plasticity is possible in vegetative statesAccording to Sirigu, the vagus nerve stimulation makes it “possible to improve patients’ presence in the world.” This result, proved wrong the belief that patients who have been unconscious for more than a year, cannot be slightly conscious again.
Dr Nicholas Schiff, a neurologist at Weill Cornell Medicine and New York Presbyterian agrees, commenting that “a shift in observable behaviours from none – a vegetative state – to some limited ones – a minimally conscious state – can occur.”
He adds that there is “strongly accumulating evidence that it is possible in many cases to increase brain activity (long) after severe injury”, but he said that unfortunately “there is essentially no infrastructure to have clinical follow-up” or even “larger investigative studies.”
Steven Laureys of the University of Liege in Belgium, is happy to see what this study has found.
He said, “Clinicians for way too long have considered patients of unresponsive wakefulness as just waiting to die. And that is not true. There is some capacity for plasticity, and this is one other study showing that there can be changes.”
However, experts say that more time is needed to carry out multiple studies, to prove that the thalamus really is the door to consciousness. This can help bring back patients, who are in vegetative states or a minimally conscious position.
Laureys agreed by saying, “We need to be careful. It’s not that we can now implant any patient and give them back consciousness. The challenge is to understand why this works. It will not work in all patients.” MIMS
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