It’s all in the news these days. A man who has been in a coma (or is it “coma-like”, “almost coma” or what?) since a car accident in 1984 has now regained consciousness, and cognitive abilibties such as his speech. It’s already been written so much about this topic, but little is actually addressing the science. Often, the sensationalism is only covered. You can get them all by this simple google.
So why start writing about this here at BrainEthics? The story should have been covered by now? I think there are several reasons to address this story in a bit more detail, one of them being that the science, ethics and philosophical consequences are not – or very superfluously – noted. Another good reason is that the article describing this case has come out, and it’s available for free (PDF). Before we get to it, let me briefly let you know what I’d like to mention here:
- the diagnosis – coma, vegetative state and related mental states are still very hard to tell apart, even to specialists
- the development – much has happened to our knowledge about these states, but this knowledge has neither reached the general public, science writers nor always professionals dealing with these patients
- the future – in addition to developments in traditional diagnosis, neuroimaging is already having a significant impact on our understanding on the relations and distinctions between these different states
- the ethics – should we reach a scientifically valid model about states of consciousness the next step is to determine who is conscious and who is not – but still we are likely to ask “are our judgements correct?
If you are involved in a car accident and lose consciousness, the time from when you lose consciousness until you wake up is characterized by different stages where the brain’s level of functioning changes; from improved primitive reflexes to cognitive and mental restoration. A soon as you reach a state where you become aware of your surroundings, even the feeblest sensation, you have reach a state that is called post-traumatic amnesia (PTA). The person is conscious and appears responsive and they may even be able to talk to family members and medical staff, however after a short time, the person will forget all recollection of conversations and actions. The person will be disorientated and may not know the date, where they are, or why they are there.
The important discussion here is that we are discussing whether a person is conscious, or if he has any chance of becoming conscious again. A person in a coma is not conscious – he cannot be awakened, fails to respond normally to pain or light, does not have sleep-wake cycles, and does not take voluntary action. Coma is separate from vegetative state, in which the patient still has no cognitive neurological function or awareness of the environment. However, he has noncognitive function and a preserved sleep-wake cycle. Even more perplexing, the patient may exhibit spontaneous movements and he may open his eyes in response to external stimuli, and even track moving objects (or people) with his eyes. So why is this person not conscious? We know this from the fact that 1) he does not respond to verbal commands; 2) he shows no voluntary movements, only reflexes; 2) reports from people in this stage that have awakened show that they have had no experience. This, of course, is coupled to a variety of theory-bound measures of preserved vs. non-operative reflexes, and more recently neuroimaging.
What makes the diagnosis of coma and vegetative state so hard is that there are cases where patients show almost exactly the same symptoms as these conditions, only that they are aware. Patients in a minimally conscious state are indeed conscious, they may drift in and out of awareness, but they show signs of voluntary movement and communication. Terry Wallis is thought to be in this state, not coma, nor vegetative state. Another condition is locked-in syndrome, in which the patient is aware and awake, but cannot move or communicate due to complete paralysis of all voluntary muscles in the body.
The frequency of misdiagnosis of these patients has not been reviewed in full, but the fear is that it happens more often that we would like to. The misdiagnosis goes both ways: sometimes a patient is thought to be conscious while actually being in a persistent vegetative state. Other times – and this is the most problematic error – a patient that has some level of awareness (e.g. locked-in) is diagnosed with a coma or vegetative state.
How can we be so wrong about these patients? One reason is that we have just began to explore this field at the level of detail that we do today, incorporating better diagnostic tools and multi-modal assessment tools such as EEG, SPECT and MRI. A willingness to study consciousness, that mongrel concept that we still really don’t know what means, is another reason for the recent developments in this field. In all, our ability to distinguish between conscious and unconscious states has gone from a dichotomic distinction to a range of possibilities that are sometimes hard to distinguish.
This development is often the reason to the sensational awakenings that we can hear from time to time. News about a person regaining consciousness after 20 years from a coma (!) should be taken with a grain of salt. 20 years ago the diagnosis and distinctions to other (conscious) conditions was notas developed as today. So we should maybe think of this rather as a sensational awakening of the science surrounding these patients, not the patients themselves. That’s a bit harsh, but it is true that the conceptual and diagnostic improvements in this fueld has come through the past few years only.
What can we expect to happen in this field? First of all we can expect that neuroimaging tools will be used more. Today we can record EEG to exclude ideas about brain death; we use MRI images to see where in the brain we find lesions. But studies showing differences in the brain’s activity between these different patients have been emerging – see this article (PDF). The problem with these studies are that they are group studies. As I have argued previously, going from group study mean differences to the ability to identify individual differences – and diagnosing people on this ground – is not a straightforward thing. So tools needs to be developed that makes it possible to look at an individual scan to determine whether a person is conscious or not. As Steven Laureys from the University of Liège says:
Chronically unconscious or minimally conscious patients represent unique problems for diagnosis, prognosis, treatment, and everyday management. They are vulnerable to being denied potentially life-saving therapy….. This case shows that old dogmas need to be oppugned.
It should be noted that efforts are already being made for developing a “consciousness meter“. This stems from the finding of mid-operational awakenings; people undergoing surgery that are put into anaesthesia nevertheless wake up during surgery yet without the ability to notify others about their presence, often suffering pain as their sensations are restored. In other words; an induced locked-in syndrome. However, interesting as it has been it’s been hard to find any updates on the effectiveness of this apparatus. But we should probably think along these lines. Saying that, the consciousness meter suggested is based on EEG, and any measurement of a traumatised brain is bound to show different signals. That needs to be kept in mind.
What, then, about treatment? This is bound to follow the trace of our enhanced knowledge of these conditions. But what is interestig with the case of Terry Wallis is that he showed signes of rewiring of fibres in the brain. While these findings are in no way conclusive, they suggest that new intervention tools can be developed that focus on the regeneration of fibres in the brain. Not only general restitution, but maybe more focal, to the regions in which we have seen Wallis’ brain change (see changes in cerebellum, as indicated by white arrow below).
Diffusion tensor images of a brain at the first scan (left) and 18 months later (right). Color shows direction of white matter fibers, e.g., green for anterior-posterior fiber tracts. Large red area in second scan (arrow) shows what scientists think is growth of new neural processes in a part of the brain that controls movement. (Credit: Weill Cornell Citigroup Biomedical Imaging Center/Henning U. Voss.)
The growing knowledge about brain function and diagnosis of these cases should make us ask whether we are using the most up to date knowledge about these stages and states. Even more troublesome, spreading the knowledge to the entire world is a problematic affair, and even within the developed world. One thing is having an operational diagnostic system; an entirely different thing is seeing it implemented throughout the world. While the diagnosis of brain death is more or less universal across regions, cultures and religions, spreading the news about differential mental state diagnosis is only now beginning to spread. Hopefully, the use of evidence based medicine will provide the tools for such a knowledge dispersal.
Understanding that there is a tight relationship between the brain and the mind has a deep impact on our self-knowledge. Knowing how the brain works and breaks is a tale about yourself. It’s a direct relationship, not only a superficial association of flesh and mind. A loss of brain function is a loss of mental life (or part of it). All in all, the scientific study of unconscious states such as coma and persistent vegetative states are one part of the story that ties the brain and mind together tightly to a coherent picture of our minds as natural, biological phenomena.
Read Full Post »