A new brain-computer interface may help people communicate that are living in a complete locked-in state (CLIS), a term used to describe those suffering from complete paralysis, with no ability for eye movement or blinking.

Researchers, led by professor Niels Birbaumer at the Wyss Center for Bio and Neuroengineering in Geneva, Switzerland, have developed the computer interface, which is designed to use near-infrared spectroscopy combined with electroencephalography to measure blood oxygenation and electrical activity in the brain.

The technology has already had positive results for those suffering from CLIS.

The researchers carried out investigations in four patients with advanced amyotrophic lateral sclerosis (ALS)—two of them in permanent CLIS and two entering the CLIS without reliable means of communication—by asking them personal questions with known answers and open questions that needed a yes or no answer.

Three patients completed more than 46 sessions spread over several weeks, and one patient completed 20 sessions. The sessions resulted in an above-chance-level correct response rate over 70 percent. 

These results are, potentially, the first step towards the end of completely locked-in states, at least for patients with ALS, said researchers.

“The striking results overturn my own theory that people with completely locked-in syndrome are not capable of communication,” Birbaumer said in a statement. “We found that all four patients we tested were able to answer the personal questions we asked them, using their thoughts alone.”

“If we can replicate this study in more patients, I believe we could restore useful communication in completely locked-in states for people with motor neuron diseases,” he added.

Quality-of-life was also measured. The question “Are you happy?” resulted in a consistent “yes” response from the four people, repeated over weeks of questioning.

“We were initially surprised at the positive responses when we questioned the four completely locked-in patients about their quality of life,” Birbaumer said. “All four had accepted artificial ventilation in order to sustain their life, when breathing became impossible; thus, in a sense, they had already chosen to live.”

Previous theories have postulated that people with this disorder lack the goal-directed thinking necessary to use a brain-computer interface and are incapable of communication.

 “What we observed was that as long as they received satisfactory care at home, they found their quality of life acceptable,” he added. “It is for this reason, if we could make this technique widely clinically available, it could have a huge impact on the day-to-day life of people with completely locked-in syndrome.”

Professor John Donoghue, director of the Wyss Center, said this development will lead to further advancements for patients with CLIS.

“Restoring communication for completely locked-in patients is a crucial first step in the challenge to regain movement,” Donoghue said in a statement. “The Wyss Center plans to build on the results of this study to develop clinically useful technology that will be available to people with paralysis resulting from ALS, stroke or spinal cord injury.”

Other brain-computer interfaces have previously enabled some paralyzed patients to communicate, but near-infrared spectroscopy has so far been the only successful approach to restore communication to patients suffering from completely locked-in syndrome.

The study was published in PLOS Biology.