For decades, scientists have looked for ways to reach patients in persistent vegetative states in the hopes of “waking them up.”
A new study has found that there may be one sign of hope in the form of an implant that stimulates a key nerve in the body.
Researchers from the Institut des Sciences Cognitives Marc Jeannerod in France wanted to see if an implant that affected the vagus nerve could help a person in a persistent vegetative state.
The team worked with the family of a 35-year-old man who had been in a persistent vegetative state after being in a car accident 15 years prior.
The team was able to implant a device, often used for patients with epilepsy, that stimulates the vagus nerve.
This is the longest cranial nerve, extending from the cranium to the abdomen. It affects a host of systems in the body from the digestive system to the respiratory system.
The team implanted the device and then monitored the patient’s brain activity, eyes, and other functions that would indicate consciousness.
Dr. Angela Sirigu, director of the Institut des Sciences Cognitives Marc Jeannerod, and other researchers published their findings last month in Current Biology.
“Brain plasticity and brain repair are still possible even when hope seems to have vanished,” Sirigu said in a statement.
By using EEG and PET scans the team found that after the device was implanted the patient’s brain activity increased dramatically and he appeared to respond to simple commands and even react in surprise.
While this was only in one patient, the team hopes to replicate their findings in a larger study.
Although the patient did show signs of being more aware, he died months later from a lung infection.
The authors said his death was not related to the study.
“The patient’s death was not linked to our protocol,” Sirigu told the Guardian. “We respected the family decision to not communicate about the event. What was important for us was to keep the event in the privacy of this wonderful family.”
Why target the vagus nerve
Dr. Richard Temes, director at the Center for Neurocritical Care at North Shore University Hospital in New York, said these vagus nerve implants have been used for years in epileptic patients.
He added that a key part of the vagus nerve is its relationship to the thalamus area of the brain.
“The thalamus is very important for instance for arousal sleep,” Temes told Healthline, explaining its ties to circadian rhythms. “What that is, is the levels of consciousness. Thalamus is sort of the engine behind that.”
Temes said this work was important for helping shed light on what happens to a brain as it achieves consciousness.
“This is trying to take a dive deep into that and looking at the brain itself and the electrical activity of the brain,” Temes said.
What this means for other patients
Dr. Aaron Lord, director of neurocritical care at NYU Langone Health, said the development of certain devices like brain implants for people with Parkinson’s disease has helped renew interest in the field of waking patients in vegetative states.
“There’s been some brewing interest in the last 15 or 20 years,” Lord told Healthline. “Are there things we can do for these patients to improve their level of conscious?”
Lord pointed out that there are different levels of “unconsciousness” and that people can move between levels or plateau at a certain level, including being comatose, in a vegetative state, and in a minimally conscious state.
Some people who arrive at a hospital in a coma can recover quickly, while others may need years of rehab. Some will remain in a persistent or permanent vegetative state for the rest of their lives.
Patients who have been declared “brain dead” exhibit no response to stimuli and have no chance of recovery.
Lord cautions that this study’s findings do not mean patients can miraculously “wake up” with the right device.
“This is not a dramatic awakening from a vegetative state that we see in the movies, but I think it does provide some hope for patients and families,” Lord said.
Additionally, he said it will take a lot more research before this kind of therapy could be considered standard practice.
“It’s a nice proof of principal study,” he said. But “every patient is going to be different.”
However, Lord said this study may help families looking for even small signs of hope or awareness in a loved one.
“Going from no response to maybe being able to recognize a loved one … or some sense that they’re interacting with the world could be meaningful,” he said.