Neuropsychologists in France have restored a minimal level of consciousness in a man with profound brain injuries who has been in a vegetative state for more than a decade. Their findings, published Monday in Current Biology , unlock a potential path for bringing consciousness back to thousands of patients previously thought beyond help.

Doctors generally accept that the damage from a traumatic brain injury is irreparable after a person spends 12 months in a vegetative state. New research has just turned this idea on its head.

“We choose a patient who was in a vegetative state [for] 15 years, showing no sign of change since his car accident,” neuroscientist and study co-author Dr. Angela Sirigu said in an email. Little else is publicly known about the 35-year-old man, as the researchers have chosen not to share his identity and his family has declined to speak on his behalf.

Brain activity returned to the patient due to the researchers’ use of a technique called vagus nerve stimulation (VNS), which they had hoped could rehabilitate his consciousness.

The vagus nerve connects “most of the key organs — heart and lungs included — to the brain stem,” Samuel K. Moore wrote in IEEE Spectrum. “It’s like a back door built into the human physiology, allowing you to hack the body’s systems.” Since the 1990s, stimulating the vagus nerve with an electrical current from a pacemaker-like device has been explored, with mixed results, as a treatment for neurological issues such as epilepsy, migraines and depression.

Sirigu and her colleagues tried VNS on the vegetative patient for six months.

After the first month of the procedure, an electroencephalogram (EEG) brain scan “revealed a significant increase in theta band (4–7 Hz) power,” which is the brain wave associated with daydreaming and ideation. The brain activity does not represent full consciousness; more like the trance you fall into when you are driving on a particularly straight stretch of highway, but it is a marked improvement from an unresponsive vegetative state.

Yet visitors noticed the change in the patient. “After VNS, the patient could respond to simple orders that were impossible before,” Sirigu said, “to follow an object with his gaze, to turn the head [to] the other side of the bed on verbal request.” The patient even managed to stay awake and show more attentiveness when read to by his mother.

The researchers plan to pursue the VNS approach in other patients whose traumatic brain injuries were thought beyond remedy, and the team is hopeful. “Changes even in severe clinical patients are possible when the right intervention is appropriate and powerful,” Sirigu said. “After this case report we should consider testing larger populations of patients.”

A version of this story appeared on Miles O’Brien Productions.