A BBC documentary screening this evening on the ‘Inside Out’ program reports on what it describes as a breakthrough for patients in a vegetative state. It is based upon research by a group of neuroscientists in Cambridge, who have used sophisticated brain scans (functional magnetic resonance imaging (fMRI)) to look for signs of consciousness in patients who have previously been thought to be completely unaware of their surroundings.
The term “vegetative state” refers to patients who have suffered severe
brain damage for example from lack of oxygen, or severe head injury,
and have been in a coma. Such patients may wake from their coma, and be
able to breathe for themselves (without an artificial respirator) but
they show no signs of responding to external stimuli. They do not
appear to hear voices, or to recognise the faces of those around them.
They do not communicate. They have reflex responses, but do not appear
to feel pain. The lights are on, but as far as we can tell, noone is
home.
The Cambridge researchers have used fMRI to try to understand what is
happening in the brains of patients in a vegetative state. They have
reported that in some of these patients at least, their brains light up
in response to hearing voices. In two patients they saw patterns on the
brain scans that they believe indicate that those patients were able to
obey instructions. The researchers claim that their findings indicate
that “a patient that looked vegetative clinically was in fact entirely
aware”.
However there are good reasons to be cautious in interpreting these
results. Firstly, despite the claims of the scientists, it is not yet
clear that they have demonstrated awareness in patients in a vegetative
state. A wide range of brain responses can occur automatically and
unconsciously, as evidenced by studies of patients who are asleep or
under anaesthetic. These responses could be a type of brain reflex.
Secondly, only a minority of patients that have been studied so far
have shown the types of brain patterns that the scientists think
reflect awareness. It may be only occasional or rare patients in a
vegetative state who have this sort of response. Thirdly, it is not
clear that these findings provide hope for patients or their families.
Although the two patients who showed this brain response subsequently
had some clinical improvement, the extent of their improvement was very
small. They reached a state of severe disability known as a “minimal
conscious state”. (And one of them has subsequently relapsed.) Finally,
and perhaps most importantly, these patients may be in a far worse
state if they are actually aware. If a patient in a vegetative state is
completely unaware (as we have previously believed to be uniformly the
case), we can at least be sure that they are not suffering. But if
brain scans reveal that some of these patients are intermittently
aware, they may well be in pain, frightened, confused and depressed.
But they would have no way of telling us, or doing anything about it.
It remains to be seen whether the BBC documentary provides a balanced
perspective on this research. However there is a real risk that it will
provide false hope to the loved ones of patients with devastating brain
injury.
Links
New hope for ‘vegetative patients BBC 25/4/08
Detecting awareness in the vegetative state Science 2006
Functional Neuroimaging in the vegetative state Nature Reviews Neurosciences 2008
The light’s on, but is anybody home? Richard Burton Salon.com 2007
For those who are interested (and who are in the UK in the next 6 days), you can watch the Inside Out program by going to http://www.bbc.co.uk/iplayer/page/item/b00b24nv.shtml?q=inside+out&start=1&scope=iplayersearch&go=Find+Programmes&version_pid=b00b24jb
My concerns about the program’s reporting of Adrian Owen’s research were borne out.
They present the case-story of a patient who suffered a brain-stem stroke, and who was diagnosed as being locked-in shortly afterwards on the basis of preserved eye-movements.
The program implies that the Cambridge group’s research may be used to identify hundreds or thousands of patients in a vegetative state who have been misdiagnosed. However the case discussed in the program was not identified by fMRI scanning, but on the basis of observable behaviour. It is not clear that she was ever diagnosed as being in a vegetative state.
The researchers speculate that some patients who have been diagnosed as being in a vegetative state are actually fully locked-in. If they are able to use fMRI to communicate with such patients, that will put paid to remaining doubts about the significance of their findings. It will also allow the wishes of such patients to be known (but only for the brief periods when they are in an MRI scanner).
In the meantime, the hyperbole about “new hope” is likely to lead to multiple requests for functional neuroimaging for patients who have sustained severe brain injury, without any evidence that such scanning will provide them with benefit.
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