It’s hard to know what to do with
people when they are in a vegetative state. By vegetative, I don’t mean that
they are spending all day sitting on the couch and eating Oreos. A clinically
vegetative state is diagnosed if a patient does not respond to any sort of
external stimuli, whether visual, auditory, tactile, or noxious. This can occur
after severe brain injury, if a patient wakes up from the fully comatose state
but is not actually conscious, a state known as “wakefulness without
awareness.”
Okay. So we have a person sitting
over here, and they are not responding to anything we do to try to evoke a
reaction from them. What do we next?
Ethically,
this is a very complex question. Some people eventually regain their awareness,
and recover from this state. Others stay that way forever, in which case it
would hardly seem worthwhile to keep them alive. But the question is, how can
you know?
People
who are able to react on some levels, perhaps following a command, but not able
to fully interact, are described as being in a “minimally conscious state.”
This is the key state in clinical assessment. If someone is fully vegetative,
they no longer possess the facilities to be able to respond to any stimuli, to
be aware. However, if they are minimally conscious, they have the capacity to
respond.
It
seems like it should be simple to distinguish between these to states. Poke
them with a stick; if they respond, they are conscious. Obviously, there’s more
to it than that. It’s difficult to tell if a response is voluntary, even on a
subconscious level, or is merely a reflex – a kneejerk reaction. In the past,
medical officials have had to rely completely on motor responses, as in a
physical action. It’s very possible that a physical response is not actually a
sign of awareness, and is merely a reflex, and on the other hand it is very
possible that the patient has some bare minimum awareness, but is not able to
physically move. Basically, it seems like it is impossible to know – we need
some way to actually communicate with these unconscious patients, and, of
course, they are not conscious for us to do so.
With
technology continually developing, though, we may not need to. A study a few
years ago monitored brain activity of a series of presumed vegetative patients
as they were asked to imagine two situations – playing tennis (a motor imagery
task) and walking around their house (a spatial imagery task). Theoretically,
imagining these two different tasks would activate different parts of the
brain, visible in an MRI scan. A small number of the patients did seem to be
actually able to imagine these tasks when told, i.e. their brain activity
changed when they were told to do a certain thing. This implied that they had
some level of awareness – they were at the above-mentioned minimally conscious
state, rather than being vegetative.
Okay.
So we’ve figured out whether this person is actually conscious at all. Why do
we care? What can we do with that?
It
turns out that this simple information is enough to actually communicate with
the unconscious patients. For the next part of the study, the patients who
seemed to be able to respond were asked a series of yes and no questions. They
were told to answer, substituting the tennis or house imagery for “yes” and
“no.” They were able to correctly answer several questions about their personal
lives, which had been previously confirmed. This method of communication was
considered, with further development, able to allow patients in this state to
express their thoughts and opinions and generally improve their quality of
life.
An
example of the application of this occurred quite recently. A Canadian patient,
Scott Routley had been vegetative and incommunicative since getting into a car
crash twelve years ago. Undergoing interrogation in this method, Routley was
able to communicate to the doctors that he was not in any pain. It seems like
such a simple thing, but the ability to communicate with minimally conscious
patients could open many doors in improving their quality of life.
Original report of the study
here: http://www.nejm.org/doi/full/10.1056/NEJMoa0905370
- Megan Berry