A method of communicating with brain damaged patients who appear to be in a permanent vegetative state has been discovered by scientists in the UK and Belgium and reported in the Lancet online today, 10 November.
Out of sixteen patients diagnosed in the vegetative state, three could repeatedly and reliably respond to two distinct commands, despite being behaviourally entirely unresponsive: “One of the patients had been in a vegetative state for almost two years and yet he was able to understand what we were trying to do and show he was aware, despite looking completely vegetative’ said the report author Professor Adrian Owen.
Instead of using functional magnetic resonance imaging (fMRI) which is expensive and not accessible for widespread use, scientists used comparatively cheap and portable EEG (electroencephalography) to track changes in brain waves to communicate with people in a vegetative state. The researchers instructed the patients in a vegetative state to imagine they were making a fist with their right hand or wiggling their toes, and then measured brain activity while electrodes were attached to their scalp. The researchers reported no significant relation between patients’ clinical histories (age, time since injury, cause, and behavioural score) and their ability to follow commands. When separated according to cause, two of the five traumatic and one of the 11 non-traumatic patients were able to successfully complete this task.
Despite rigorous clinical assessment, many patients in the vegetative state are being misdiagnosed. ‘Many patients, probably thousands, have had their food and fluids cut off and died, based on what we now know may well have been mistaken assumptions that they had lost all capacity for consciousness. The Lancet EEG study, together with earlier functional MRI studies, holds out the hope that we may develop ways to communicate with aware patients who have routinely been diagnosed as ‘vegetative,’ says the director of a US Center for Medical Ethics. This research is significant because the EEG method is cheap, portable, widely available and objective, so could allow the widespread use of this bedside technique for the re-diagnosis of patients who behaviourally appear to be entirely vegetative, but who might have residual cognitive function and conscious awareness. It can be taken into the community, to patients in nursing and care homes, and used in addition to current methods of assessing severely brain-injured patients, so that, theoretically, many more patients at the bedside could be assessed to detect covert awareness.
Interestingly, the EEG did not pick up the same signs of consciousness in three of the healthy and aware patients (the ‘controls’). Clearly the volunteers were aware and conscious, which shows that a negative result did not mean that vegetative patients were definitely unaware, but a positive result did mean they had awareness. So, as helpful as the study is, there is an important caveat: it does not follow that patients are definitely unconscious if EEGs do not detect these signs.
In the future, the researchers claim that these devices will help people communicate with the outside world, giving doctors important information about their state of mind and whether or not they are in pain. Many of the technological and scientific building blocks to enable this are already in place. Brain-computer interfaces have been developed and already used to move cursors and even spell out words so, as Prof Owen says: ‘Our next goal will be to integrate our system with brain-computer interfaces to create a true communication system for patients who have no other means for communicating their thoughts and wishes’.
Being trapped in a lifeless body, unable to communicate, is a terrifying ordeal, as one man explains, having been paralysed and blind for several days, although able to hear everything that was happening: “I felt trapped, afraid and terribly concerned. I didn’t know whether I would survive or not”. This Lancet study shows that communication with such patients is not so far into the future now, and holds out hope that routine classification of patients as ‘PVS’ may be increasingly challenged.