Brain-Computer Interface Enables Coma Patients to Communicate

The 13 patients involved, and a control group of healthy volunteers, were required to answer 10 to 12 questions using the four commands, ‘yes', ‘no', ‘stop', and ‘go'. The patients answered the question mentally while a speech computer repeated the four possible answers a number of times. Based on their electroencephalographs (EEGs), the researchers were able to ascertain whether the patient concentrated on an answer and if so, which one.

The results of the study showed that three of the ten coma patients could correctly answer more than half of the questions; moreover, all ten managed an average of 25% - 33% correct answers. According to the researchers, an important advantage of this method is that they were not dependent on motor responses, which are not even possible for many patients, and which are often just unconscious reflexes. BCI systems, however, are based on the fact that even the idea of a certain behavior triggers measurable changes in brain activity, which can be converted into signals; the system has already demonstrated very effective communication with patients with locked-in syndrome. The results of the study were presented at the annual meeting of the European Neurological Society (ENS), held during June 2010 in Berlin (Germany).

"A great deal of experience is required to give a definitive diagnosis of the state of consciousness of a coma patient, particularly since difficult ethical questions are linked to the classification,” said study presenter Gustave Moonen, M.D., Ph.D. "Innovative technologies such as the brain-computer-interface may now allow better diagnosis in coma patients of whether consciousness is still existent and how pronounced it is, and for the first time also enable communication with those affected. New studies show that around 40% of patients diagnosed as in a persistent vegetative state, on closer examination, in fact, exhibit signs of consciousness.”

Locked-in syndrome is a condition in which a patient is aware and awake but cannot move or communicate due to complete paralysis of nearly all voluntary muscles in the body, except for the eyes. Total locked-in syndrome is a version of locked-in syndrome where the eyes are paralyzed as well. It is the result of a brain stem lesion in which the ventral (anterior) part of the pons is damaged. In French, the common term is maladie de l'emmuré vivant, literally translated as "walled-in alive disease.”

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