Besides the behavioural scales, other prognostic approaches are being developed based on spectroscopy – which focuses on the metabolism of the neurons in the regions of the network of consciousness – and on diffusion tensor imaging, a technique that helps to detect axonal damage and disorders in the architectural organisation of the white matter’s nerve fibres.
Coupled with other more traditional examinations, these techniques, which are now validated, not only aim to establish whether or not a patient will regain consciousness in the first few weeks after falling into a coma, but whether he/she will suffer after-effects and which ones. These questions are currently at the heart of European and US multicentric studies with which the Coma Science Group is associated.
Establishing communication with patients with residual consciousness is one of your main objectives. Are we entering into the world of the brain-computer interface here?
In 2006, within the framework of a collaboration between the Coma Science Group and the University of Cambridge, we were able to detect residual consciousness in an English patient, who showed the clinical signs of a vegetative state, using fMRI. We asked her to actively perform two mental imagery tasks: to imagine playing tennis, on the one hand, and to imagine walking through her house, on the other hand. We showed that the mapping of her brain activations coincided every time with those previously recorded in healthy volunteers asked to perform the same imagery tasks.
In 2010, thanks to real-time fMRI, we managed to “interact” with a patient in Liège who was initially considered to be in a vegetative state, whereas he did in fact have residual consciousness. We asked him simple questions to which he had to reply yes or no. Since the real-time fMRI wasn’t sufficiently precise to characterise the patterns of the respective "yes" and "no" brain activations, we instructed the patient to imagine playing tennis if he wanted to answer yes to a question and to imagine walking through his house if he wanted to say no. It turned out that he answered correctly to the questions asked and that we consequently entered into communication with him.
As fMRI is both an unwieldy and expensive technique, the European DECODER project, in which the Coma Science Group is participating, aims to develop reliable, portable and cheap communication tools. The route currently undergoing the most investigation is that of cognitive evoked potentials, which is detected using electroencephalography.
