A completely locked-in patient is able to type out words and short sentences to his family, including what he would like to eat, after being implanted with a device that enables him to control a keyboard with his mind.
The findings, published in Nature Communications, overturn previous assumptions about the communicative abilities of people who have lost all voluntary muscle control, as well as giving a unique insight into what it is like to be in a C.
People with locked-in syndrome can see, hear, and smell, but can't move or speak due to complete paralysis of their voluntary muscles.
Some people can communicate by blinking or moving their eyes, but those with completely locked-in syndrome can't.
The University of TFC;bingen in Germany enabled three patients with CLIS to answer questions by detecting telltale patterns in their brain activity.
The parents of the current patient, who was diagnosed with the disease in 2015, wrote to the medical team, saying that he was losing the ability to communicate with his eye movements, because of the advance.
The problem with fNIRS is that it is slow and only gives the correct answer 70% of the time, meaning questions have to be repeated to get a reliable answer.
With a classification accuracy of 70%, it is almost impossible to enable free spelling for a locked down patient.
They suggested implanting two microelectrode arrays into the part of the man's brain involved in planning and controlling voluntary movements. He was able to consent to the procedure because he still had control of his eye movements.
The man learned how to change the sound wave's frequencies through a computer program. He used the same strategy to control the spelling program, which allowed him to select letters one at a time to form words and phrases at an average rate of about one character per minute.
If you have a choice of no communication and a communication of one character per minute, the choice is obvious.
The 36-year-old from Germany has requested goulash soup and beer, despite being fed through a tube that doesn't allow him to speak, and asked if his four-year-old son would like to watch a Disney movie. On one day, he told his family that his biggest wish was a new bed and that he would come with them for barbecue.
The man's quality of life is given some insight by such sentences. He said that even if it is not positive, it is not negative. It was an emotional moment.
The research answers a question that has been asked for a long time, whether people with CLIS also lose the ability of their brain to generate commands for communication. Ours is the first study to achieve communication by someone who has no remaining voluntary movement and who now uses the BCI as their sole means of communication.
To enable words to be spelled out faster, and to create a dictionary of common words or sentences for patients to choose between, further studies are needed to demonstrate the safety and efficacy of the approach.
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