Once only possible in an MRI scanner, vibrating pads and electrode caps could soon help locked-in people communicate on a day-to-day basis
YOU wake up in hospital unable to move, to speak, to twitch so much as an eyelid. You hear doctors telling your relatives you are in a vegetative state – unaware of everything around you – and you have no way of letting anyone know this is not the case. Years go by, until one day, you're connected to a machine that allows you to communicate through your brain waves. It only allows yes or no answers, but it makes all the difference – now you can tell your carers if you are thirsty, if you'd like to sit up, even which TV programmes you want to watch.
In recent years, breakthroughs in mind-reading technology have brought this story close to reality for a handful of people who may have a severe type of locked-in syndrome, previously diagnosed as being in a vegetative state. So far, most work has required a lab and a giant fMRI scanner. Now two teams are developing devices that are portable enough to be taken out to homes, to help people communicate on a day-to-day basis. The technology might also be able to identify people who have been misdiagnosed.
People with "classic" locked-in syndrome are fully conscious but completely paralysed apart from eye movements. Adrian Owen of Western University in London, Canada, fears that there is another form of the condition where the paralysis is total. He thinks that a proportion of people diagnosed as being in a vegetative state – in which people are thought to have no mental awareness at all – are actually aware but unable to let anyone know. "The possibility is that we are missing people with some sort of complete locked-in syndrome," he says.
Owen's group and others are on a mission to give a voice to as many such people as possible. He is also asking ethicists how to respond if such people, once they can communicate, express a wish to die (see "What if they want to die?").
People most often enter a vegetative state after emerging from a coma. Instead of fully awakening, they enter a twilight zone between the two states. Their eyes may sometimes open, but their gaze wanders randomly and they do not respond to attempts to communicate, a key measure of consciousness. There is no official tally, but Derick Wade, a neurological rehabilitation consultant at Oxford University Hospitals has estimated that there are about 6000 people in the UK in a persistent vegetative state.
Owen's group has previously shown that a proportion of these people can in fact understand and follow instructions. The group made headlines in 2010 when they demonstrated this using an fMRI scanner, which shows brain activity. They asked people to imagine they were playing tennis or walking around their home. Not only did the scans show that about one in five of those tested could think about the different activities on cue, but three people so far have been able to use the different patterns of brain activity that these thoughts produced to answer simple yes or no questions.
One man tested, for instance, who had been classed as in a vegetative state for 12 years after a car crash, correctly answered questions about his name and those of his carer and a relative. He went on to signal that he was not in pain – and that he liked watching ice hockey on TV. "They were important questions for his family," says Owen. "It's about quality of life."
Brain scanning is a laborious process, though, so it is no good for helping people communicate frequently or easily. The size and cost of fMRIs mean that most care homes do not have them. To make the technology more accessible, Owen's team has been developing a version of the technique that uses an electrode cap to record the brain's electrical signals, or EEG. Because an EEG can only read surface brain activity, they had to find different mental tasks. Their first approach was to ask people to think about squeezing a hand or wiggling their toes.
The team showed in 2011 that three out of 16 people classed as being in a vegetative state could generate discernibly different patterns of brain activity in response to these commands. But Owen thinks this could still miss some people with awareness, as even people without brain injuries find the task difficult: one quarter of healthy volunteers he tested couldn't do it. "It's quite hard to imagine squeezing your hands," he says.
Now he has a new version, which involves placing vibrating devices on someone's arms, and asking them to pay attention to one vibrator or the other as they are asked questions, Owen told the Barts Neuroscience Symposium in London last week.
Focusing on sensory information like vibration seems to be easier to read on an EEG than imagined movements, he says. "Tactile stimulation works very well." Still, it's early days and Owen's work is unpublished as yet. "We have had some successes," is all he will say for now.
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