Researchers have developed a non-invasive brain-computer interface that detects the responses of completely locked-in patients by measuring changes in blood oxygen levels in the brain. A trial study showed that patients with completely locked-in syndrome were able to respond “yes” or “no” to spoken questions, by thinking the answers.
Patients suffering from complete paralysis, but with preserved awareness, cognition, and eye movements and blinking are classified as having locked-in syndrome. If eye movements are also lost, the condition is referred to as completely locked-in syndrome.
Counter to expectations, the participants in the study reported being “happy”, despite their extreme condition. The research was conducted by a multinational team, led by Professor Niels Birbaumer, at the Wyss Center for Bio and Neuroengineering in Geneva, Switzerland.
The results overturn previous theories that postulate that people with completely locked-in syndrome lack the goal-directed thinking necessary to use a brain-computer interface and are, therefore, incapable of communication.
Responses 70 Percent Correct
Extensive investigations were carried out in four patients with ALS (amyotrophic lateral sclerosis, also known as Lou Gehrig’s disease) — a progressive motor neuron disease that leads to complete destruction of the part of the nervous system responsible for movement.
The researchers asked personal questions with known answers and open questions that needed “yes” or “no” answers including: “Your husband’s name is Joachim?” and “Are you happy?”. They found the questions elicited correct responses in seventy percent of the trials.
Professor Birbaumer said:
“The striking results overturn my own theory that people with completely locked-in syndrome are not capable of communication. 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.”
The question “Are you happy?” resulted in a consistent “yes” response from the four people, repeated over weeks of questioning.
Professor Birbaumer added:
“We were initially surprised at the positive responses when we questioned the four completely locked-in patients about their quality of life. 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.
What we observed was that as long as they received satisfactory care at home, they found their quality of life acceptable. 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”.
In one case, a family requested that the researchers asked one of the participants whether he would agree for his daughter to marry her boyfriend ‘Mario’. The answer was “no”, nine times out of ten.
The brain-computer interface in the study used near-infrared spectroscopy combined with electroencephalography (EEG) to measure blood oxygenation and electrical activity in the brain. While other brain-computer interfaces have previously enabled some paralyzed patients to communicate, near-infrared spectroscopy is, so far, the only successful approach to restore communication to patients suffering from completely locked-in syndrome.
The work was funded by Deutsche Forschungsgemeinschaft; Stiftung Volkswagenwerk; German Ministry of Education and Research; the Federal Ministry of Education and Research; Eva and Horst Köhler-Stiftung; National Natural Science Foundation of China; and EU grant LUMINOUS.
Reference:
- Chaudhary U, Xia B, Silvoni S, Cohen LG, Birbaumer N (2017). Brain-Computer Interface- Based Communication in the Completely Locked-In State. PLoS Biol 15(1): e1002593. dx.plos.org/10.1371/journal.pbio.1002593
Last Updated on November 22, 2023