Fifteen years ago, a 20-year-old man was involved in a horrific car accident that left him in a vegetative state. He had no awareness of himself or his surroundings and after years of being unresponsive, it was thought he would never wake up. Now, thanks to an experimental technique, the 35-year-old has surprised doctors and loved ones by showing signs of regaining consciousness.
It is generally thought anyone who spends more than 12 months with problems affecting their consciousness will not be able to regain it. Anyone who is in a vegetative state for more than a few weeks is said to be in a persistent vegetative state (PVS) and a paper in 2011 found people perceive those in PVS to have “less mental capacity than the dead”.
The patient, whose name has been withheld to preserve his privacy, suffered from severe traumatic brain injury (TBI) following the accident in 2002. On admission to hospital, he showed signs of brain swelling, internal bleeding, and his skull was fractured. Following a series of tests, he was diagnosed as being in a vegetative state (VS) four weeks after the initial accident.
In an attempt to restore his consciousness, scientists implanted an experimental stimulator on his man’s chest. Just one month later he showed signs of movement, attention and increased brain activity.
Having already shown positive results in the treatment of epilepsy and depression, the stimulator was placed on the vagus nerve, which connects the brain to the stomach. This involved implanting a Cyberonics vagus nerve stimulator device (VNS) with a pulse generator in the upper left side of the patient’s chest. A double-coil electrode was wrapped around the vagus nerve at the neck level. The device was switched on one month after implantation as a current was passed through it. During the first month and a half, the current amplitude was increased every week.
In an attempt to restore consciousness, scientists implanted an experimental stimulator known as a VNS on the patient’s chest. Just one month later he showed signs of movement, attention and increased brain activity
After a month of receiving the treatment, the patient began to follow simple instructions he would never have been able to do before. For example, he could follow an object with his eyes and turn his head when asked. His mother said he was more able to stay awake when his therapist read to him.
The researchers also monitored his brain activity, which revealed major changes. In particular, the experts looked for an EEG signal which is used to determine whether someone is vegetative or minimally conscious. The signal increased in areas of the brain related to movement, awareness, and sensation. The brain also increased in connectivity, and metabolic activity grew.
The signal increased in areas of the brain related to movement, awareness, and sensation and the patient’s brain also increased in connectivity, and metabolic activity grew
“It is possible to improve a patient’s presence in the world,” said Angela Sirigu of Institut des Sciences Cognitives Marc Jeannerod in Lyon, France.
What this shows is that “brain plasticity and brain repair are still possible even when hope seems to have vanished,” Sirigu added.
While the story is inspirational, it is important to bear in mind the statistical significance; many more patients need to be treated with vagus nerve stimulation before it can be described as a breakthrough. To this end, the researchers are planning a large collaborative study to understand the potential of VNS for patients in a vegetative or minimally conscious state.
Sirigu says the findings will also advance understanding of “this fascinating capacity of our mind to produce conscious experience.”
The results are published today in the journal Current Biology.
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