After lying in a vegetative state for 15 years, a 35-year-old male patient in France appears to have regained minimal consciousness following months of vagus nerve stimulation, researchers report today in Current Biology.

The patient, who suffered severe brain damage in a car crash, had shown no signs of awareness or improvement before. He made no apparent purposeful movements and didn’t respond to doctors or family at his bedside. But after researchers surgically implanted a device that stimulates the vagus nerve, quiet areas of his brain began to perk up—as did he.

His eyes turned toward people talking and could follow a moving mirror. He turned his head to follow a speaker moving around his bed. He slowly shook his head when asked. When researchers suddenly drew very close to his face, his eyes widened as if he was surprised or scared. When caregivers played his favorite music, he smiled and shed a tear.

The reignited activity bumped his clinical status from vegetative to minimally conscious—an improvement, but still a severely disabled condition. Nevertheless, it gives the researchers optimism that this type of nerve stimulation could help treat other patients with severe brain damage and impaired consciousness. The fact that he was in a vegetative state for so long beforehand makes the results even more convincing, they argue. (The likelihood of regaining consciousness after a single year in an unresponsive state is rather dismal.)

“Our study demonstrates the therapeutic potential of vagus nerve stimulation to modulate large-scale human brain activity and alleviate disorders of consciousness,” the researchers, led by neurologist Angela Sirigu of Institut des Sciences Cognitives Marc Jeannerod in Lyon, France, conclude.

Other researchers were far more cautious in their interpretation of the study, though. For one thing, it only involves one patient. And while the patient did improve, it wasn’t a large improvement and is “of questionable significance to the patient,” according to Dr. Elizabeth Coulthard, an expert in dementia neurology at the University of Bristol.

In a statement, Coulthard continued:

While it is suggested that perhaps this opens an avenue for future research, one cannot infer any clinical benefit on the basis of this one patient. Even the small change demonstrated here may not be transferable to other people in a persistent vegetative state.

Energized research

Using vagus nerve stimulation to spark brain activity isn’t a new idea. The nerve is thought to play an important part in awareness. It extends from the brain, skims the heart, and ends in the colon. The central conduit carries a variety of bodily and visceral signals. When stimulated, it boosts metabolism in the forebrain and is thought to play a key role in alertness, arousal, and fight-or-flight responses.

Vagus nerve stimulation therapy is already used to prevent epileptic seizures by sending regular, mild pulses to the brain. And some early studies have provided hints that electrical jolts to the brain—including through the vagus nerve—could help people with traumatic brain injury. In particular, vagus nerve stimulation has been shown to improve recovery in rats with brain injuries.

The new study is one of several clinical efforts to test the method in humans.

For their test, the French researchers turned to an implantable, programmable device approved for use in patients with epilepsy. The gadget, installed in the left side of the chest, provides gentle pulses through a double-coil electrode that’s wrapped around the vagus nerve at neck level. In the six months after the surgery, the researchers gradually ramped up pulse intensity to a maximum of 1.5 mA.

Scans and tests done before and after the implantation showed improvement in brain activity. The researchers saw an increase in theta waves, which is an increase linked to transitioning from a vegetative to minimally conscious state. Positron Emission Tomography (PET) scans indicated that brain metabolism was boosted, too.

Analyzing electroencephalogram (EEG) data, the researchers found that connectivity and information sharing increased across the brain. Last, they noted increased activity in the parieto-temporal-occipital border, which is “a region labelled as a hot-zone for conscious awareness,” the researchers report.

Dr. Uzma Samadani, a neurologist and expert in traumatic brain injury [TBI] research at the University of Minnesota, expressed delight at the study and its findings. “I am emphatically in favor of this line of research,” she told Ars.

With colleagues, Samadani is conducting a trial of her own to test vagus nerve stimulation in patients with brain injuries.

"I believe that we do not have full understanding of the mechanisms of impaired consciousness associated with trauma but that vagus nerve stimulation appears to show promise in this isolated case report," she said. "Despite the fact that this is only one case, I am encouraged that this will provide evidence to funding boards that this is an area that needs to be considered. Our own work is currently being conducted using non-invasive VNS [vagus nerve stimulation] in moderate TBI patients, and we look forward to sharing our results in the future."

Current Biology, 2017. DOI: 10.1016/j.cub.2017.07.060 (About DOIs).