Locked-in syndrome leaves people completely paralysed, but with full awareness, brain function and sometimes eye movement. And until now, communication was thought to be impossible.
But a recent study saw researchers set up four patients with a brain-computer interface, allowing a computer to measure their brainwaves. They then asked the patients a series of simple, fact-based, "yes" or "no" questions - and the computer was able to detect the correct response seven times out of ten. One of those questions was "Are you happy?"
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.
In the trial, a non-invasive brain-computer interface detected patients' responses to the "yes" or "no" questions by measuring changes in blood oxygen levels in the brain. The researchers asked personal questions with known answers and open questions like "Your husband's name is Joachim?" and "Are you happy?". They found the questions elicited correct responses in seventy percent of the trials.
The question "Are you happy?" resulted in a consistent "yes" response, repeated over weeks of questioning.
"The striking results overturn my own theory that people with completely locked-in syndrome are not capable of communication," Professor Birbaumer said. "We found that all four patients we tested were able to answer the personal questions we asked them, using their thoughts alone."
Professor Birbaumer said is the study can be replicated in more patients, he believes we could restore useful communication in completely locked-in states for people with motor neuron diseases.
"We were initially surprised at the positive responses when we questioned the four completely locked-in patients about their quality of life," Professor Birbaumer added. "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. The answer was "no", nine times out of ten.
Professor John Donoghue, Director of the Wyss Center, said restoring communication for completely locked-in patients is a crucial first step in the challenge to regain movement.
"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," Professor John Donoghue said. "The technology used in the study also has broader applications that we believe could be further developed to treat and monitor people with a wide range of neuro-disorders."
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 paralysed patients to communicate, near-infrared spectroscopy is, so far, the only successful approach to restore communication to patients suffering from completely locked-in syndrome.