Look at someone’s face and you might get an idea of what they’re thinking — if they’re sad, in pain, or feeling unwell. But when a patient is unable to move any part of their body purposefully — as in the case with those in a coma, a minimally conscious, or vegetative state — things become more difficult. Which is why Dr. Adrien Owen’s pioneering research into monitoring brainwave patterns in these types of patients is so important. He and his team at the Brain and Mind Institute at the University of Western Ontario have found a way for some patients to communicate without having to talk, lift a finger or even bat an eyelid.
Brain World: Can you explain the difference between various immobile states?
Adrian Owen: Right now there are three basic categories: vegetative, coma, and minimally conscious. People often confuse vegetative state with being in a coma, but it’s quite different. Patients in a vegetative state may open their eyes, have sleep and wakeful cycles. They may “wake up” and look around the room, leading to onlookers believing they can see as you or I see. But their eyes don’t fixate on anything, they look around in a non-purposeful manner. They don’t respond to people to moving objects, to music. These people are detached from the outside world but are nonetheless animate.
Coma is often the first stage after severe brain injury. In a coma, a person looks as though they are asleep — their eyes are closed, they move very little. And minimally conscious is a term that defines a kind of halfway state — a person may be able to respond to some extent, but it’s not clear. For example, they may be able to move their hand, but not enough to be able to communicate. This is the gray area between being severely disabled and in a vegetative state. And it’s here in this gray area that we’re working.
BW: So what abilities define these various states?
AO: The categories we have — vegetative, minimally conscious, and coma — are really a matter of convenience. They allow us to put a label on a person’s physical state, but in reality there are patients who are borderline or others who fluctuate between one state and another. We’re working towards a complete spectrum, where the patient’s abilities are described as they are, rather than us trying to make a label fit. So, for example, instead of a category, we’d say, “This patient can process visual information but not auditory; they can hear speech but they can’t understand,” and so on. That way, anyone treating that patient knows what the patient can and can’t do rather than simply knowing they are “minimally conscious,” which, realistically, is rather meaningless when treating an individual patient.
BW: So which kind of patients are you working with?
AO: Some patients, such as Jean-Dominique Bauby, who many people know of — he is the author of “The Diving Bell and the Butterfly” — for example, are able to move only one part of their body. Bauby was able to blink only one eyelid but as a result could communicate relatively effectively. This is called “locked-in syndrome” — the patient is completely conscious but unable to move effectively.
To test a patient like this, a doctor may ask him or her to squeeze his right hand, for example. If the patient consistently fails to respond, they may be classed as vegetative. Our patients are “locked-in patients plus”. They’re totally locked in. They don’t have the locked-in syndrome — they can’t move their eyes or some other body part to communicate. Our patients can’t move any body part purposefully.
BW: So how do your patients communicate without moving?
AO: We put an EEG system on these patients and ask them the standard question — squeeze your right hand, say — but rather than looking at their hand, we view the EEG. If we can see a spike in the premotor cortex — the part of the brain that would usually show activity when a person squeezes their hand — we know the patient can understand the question and is generating a response, even if it’s not physical. The response simply isn’t getting down from the brain to the body, so the hand doesn’t move. We’ve now perfected this technique using MRI scans. While functional MRI measures the magnetic fields produced by brain activity and EEG measures the electrical activity caused by these same changes, both are just different ways of measuring how a person’s brain is responding under different conditions.