Pupils Used to Communicate with People with Locked-In Syndrome

Suffering from locked-in syndrome is a horrible way to live, not being able to move or even express oneself. Even basic communication is impossible due to extreme paralysis, but people in this state are nevertheless conscious. (French movie Le Scaphandre et le Papillon (The Diving Bell and the Butterfly) is an inspiring story that looks at one such patient.) So creating a communication link of any sort can allow for significant improvement in these peoples lives since, at the very least, they’d be able to express their needs, signal pain, and help scientists research the condition.

Now a simple new technique, which doesn’t require expensive technology, may offer that hope. It’s no longer news that hard math problems make people’s pupils to dilate. A team of international researchers decided to use this fact, offering participants in a study the option of answering questions with a ‘yes’ by trying to solve a hard multiplication, while a ‘no’ is expressed by simply ignoring the problem. A camera was used to detect changes in pupil size.

First trying this approach with healthy subjects, the team achieved nearly perfect results when comparing answers between the “pupil language” and spoken responses. Trying the same with actual locked-in people, and comparing responses to questions with known answers, the responses were slightly less than perfect, but nevertheless showed that this technique can be used to communicate with people stuck in such a state. Moreover, this approach requires neither high tech equipment nor any training for use in practice.

Pupil responses allow communication in locked-in syndrome patients