Parts of the brain of patients in this particular state actually are reacting to external stimuli.

Parts of the brain of patients in this particular state actually are reacting to external stimuli. Does that mean we have to change our definition of a person in a vegetative state?

I think we have underestimated a proportion of patients in a vegetative state. Not all patients react in the scanners, but so far we have used the term 'permanent vegetative state', for example. And I think these results will help coin a new understanding that there's no such thing as the 'permanent' vegetative state. There's always room for improvement and so we are going to the term 'vegetative state' or 'unresponsive wakefulness syndrome'.

'Unresponsive wakefulness syndrome.' So someone who's in an unresponsive state then - is this a common occurence after they come out of a coma?

There are different options when you awake from coma. You can either go into a vegetative state or a minimally responsive state or you can improve quickly to normal consciousness. But it is quite often. It is estimated that in Germany there are 5 to 20 thousand people suffering from a vegetative state.

When you say 'quickly', what do you mean by quickly? What's the normal length of time for someone to recover from this kind of state?

For example, if you had a head injury, and you were in a coma for one or two weeks, you could proceed to normal levels of consciousness within one or two weeks. But it can also be much longer, in terms of many years, before you make gradual steps toward improvement.

So this really does raise a lot of ethical questions as well. What do you do with a patient who is in this particular state on a long-term basis?

It is very difficult. We have to be aware that these patients might have - or surely have needs, and they are responsive, so we shouldn't deprive them of rehabilitation efforts, and that is one important issue there. And also you have to be aware that they can react and the whole surroundings, the whole environment has to adapt to that.

Now you yourself are carrying out a study on 60 different patients, if I'm correct. What is your study hoping to achieve?

Yes, that's correct. We're including patients as we speak, so we hope to increase that number to several hundreds. Our main goal is to build a new data base for better understanding of what the actual outcome of these patients is, what their potential for recovery is, if you only look long enough.

Do these new developments mean that hopefully there'll be new therapies coming out as well?

What these study results do is they raise interest in the whole topic of consciousness. So hopefully this will be used to gather more interest in further treatment developments, as well, yes.

You've obviously had a lot of experience in this area. Can you tell us about an impressive story that you've seen in the recovery of a patient - or is that common?

Well, it's not very common that you see miraculous events, but when you talk to people who are long enough in the field they always can report about patients who had a very good outcome. We had a young man who was 16 years old and suffered cardiac arrest and he was believed to never be able to recover again. But within nine months he was able to leave the hospital on foot and this is surely a story that gives hope, also for relatives.

(Interview: Anne O'Donnell)