COGNITIVE ASPECTS OF VESTIBULAR DISORDERS pt. 2
- From: "georgia" <jwissmille@xxxxxxx>
- Date: 29 Jul 2005 20:21:33 -0700
The whole frontal lobe of our brain is involved in all our planning,
decision making, handling two things at the same time, problem solving,
sticking to a task, mental stamina -- a lot of those things sound very
similar to the areas I was pinpointing for vestibular disorders.
We don't understand how the vestibular apparatus links in so intimately
with the frontal lobe in terms of the mental processes we see
impaired. That is an unknown. It will be a very difficult area to
study based on our present knowledge. It is potentially a fruitful
area to study over future years,
however. In any event, the key problems in vestibular recall are
the input and the output. I say this because the storage part, the
retention part, is actually not so badly affected.
We know this because we are able to measure the storage component.
You might call it the tape recorder. Memory retention involves the
temporal lobe and can be measured by using so-called recognition
tasks. In recognition tasks, the patient is simply asked, "have you
seen this word in the last half hour or not?" Patients are given
virtually everything but the answer. It's like a multiple-choice
With that level of assistance, people with vestibular disorders do
It is also frustratingly well because on standard psychological tests,
vestibular patient can look darn good. This adds to their feeling of
invalidation. Doing well on those recognition tasks can make the
patient and sometimes the examiner believe that the physical and
chemical malfunction is all psychosomatic or hysterical.
But if the examiner takes it a step further and asks how good is a
person at putting in the information and then without much help pulling
it out (much more like real life), that's when we see significant
I've coined a few terms to discuss the problems that arise when
kinds of tests are given to vestibular patients.
First of all, we find in the clinic that vestibular patients have a
reduced channel capacity.
We all have a certain capacity to take in new information at a certain
rate; we get used to being able to do and to do it at our own rate. We
know when we are tired we'll be a little more poor at it, or when
several things are coming at us at once it will be reduced, but we know
what it feels like, and we're pretty comfortable with our rate. It's
similar to a computer's capacity to process information at a certain
This capacity is considerably reduced in the majority of patients we
in the clinic with vestibular disorders.
Another area bears on the sequencing of information. The ability to
recall in what order we learned or heard or were exposed to information
is crucial to later recalling it in a meaningful or useful way.
For reasons we don't fully understand, most vestibular patients find it
very difficult to properly sequence information.
If they're presented with a task, like the one we use in our clinic to
measure sequencing, the "divided attention recall test," where we break
up the person's attention, we find our patients have real difficulty.
This task is much more like real life than mere recognition tasks. We
present a series of words to the person and, not only do they have to
pull back the word that they saw a couple of words ago (so they're
starting to have to reach back), but at the same time they're having to
sort every new word into a category. So there's two different things
going on at once, and they're also having to reach back and recall
How many of you with vestibular problems find it hard to track a
conversation, especially if there's more than one person you're
listening to converse? You find that it's real fuzzy trying to reach
back and see where it was just going, much less the big task of
what's going on right now.
I would imagine that the majority of you have had that experience.
Even extremely bright people who have vestibular problems have massive
problems with this. It's also extremely fatiguing.
Thus the sequencing problem that shows up in tasks like this is unique.
They can reach back, the people who have taken this test, and hold back
some of that information, but they often reach back too far or too
recently; it's as though the time tag, the ability to know just about
when that word happened, is very loose or gone. We don't understand it,
but it's exceedingly similar to a kind of problem seen in early
Alzheimer's disease. It seems to indicate a loss of a kind of time
setting or time tag.
Finally, the lack of internal conceptual validation, the "aha, I've got
it" experience, the sense of being valid about what you're thinking,
seeing the big picture, being sure you've accurately completed a
detailed task, being certain you remembered the correct name or fact,
having that satisfying feeling of "yep, that's the match," -- is
Even though the majority of people we test are darn smart in many ways,
they lack this sense of rightness. The vestibular patients we see
often do rather well on the standard kinds of psychological tests, but
we find they have a real problem knowing they are right, inside. They
may be right 90% of the time, but they don't have that internal
That's a difficult one to understand, but we know from studies done
years ago of people with brain injury that deep areas in the front part
of the brain from the deep thalamus out to the front part of the brain
are very important for locking into a kind of "gold standard," matching
your sense with what is somehow stored in the brain and knowing that
Again, it raises fascinating questions about is there some way when
you're very young that the vestibular system is wired into this whole
area. We have absolutely no way of knowing that at this time. We
do know the vestibular system links with your visual system, and visual
control is very much a frontal lobe function, but there is no real
knowledge of other networks going into
these memory centers.
What are the practical ramifications of all these deficits that I've
The three areas of dysfunction I just listed -- the decreased channel
capacity, the diminished sequencing ability, and that lack of the aha
experience inside -- those three areas cause incredible difficulties
with simple daily life functions.
Let's start with personal life, your home, your shopping, your social
interactions, your family responsibilities. The above difficulties
I've spoken of wreak havoc with your ability to function in any normal
personal setting, from planning a menu to organizing your day's do
to tracking your children's conversation.
There's an astonishing contrast between the ease which most of our
patients remember encountering in social situations prior to their
illness compared to the difficulty they feel now when they try to deal
with more than one person at a time. Situations which seemed hum-drum
when they were well now appear impossible.
Occupationally, any time-locked task that has to be done by a certain
time obviously is going to be affected. We don't even have to go into
the detail I've gone into to say that the fatigue that is felt causes
great problems with those kind of tasks. But any task that requires
tracking more than one train of thought at a time, like that of a
receptionist answering phone calls and plugging them into the right
message boxes and so forth would be dramatically impaired.
Finally psychiatric complications such as depression and anxiety are
almost too obvious to mention. After this kind of alteration of your
most basic habits of thought, it's hard to conceive of not experiencing
anxiety, depression, and disappointment with yourself.
Even if you have a supportive family structure that understands the
cognitive problems, you end up inside not getting that sense of
satisfying "I'm doing what I should be doing."
That links with that certainty inside that I spoke about. Even when
you're fatigued and vestibular and you know you put in a good day and
have done the best you can, that internal lock that says "I know I did
this, I can retrieve what I did today, I can look at the big picture,
and I had a good day" is not there for most vestibular patients. That
alone, even within a loving supportive family and with no financial
problems, would create anxiety and depression.
PHYSICAL AND PSYCHOLOGICAL RELATIONSHIPS
Why do these kind of memory and functioning patterns exist among
There are three very obvious factors that many psychologists will
raise. Those of you who have seen psychologists may recognize these
diagnoses. First, pain is bound to cause problems with concentration
and depression. Second, anybody with as much fatigue as the
vestibular patient experiences will have a lot of trouble. Finally,
the depression ensuing from that and everything else affects people's
attention span and concentration and memory.
So, those of you who have gone through psychological tests often end up
with a psychologist telling you that you have a few problems with
attention but you're above average IQ, and there's nothing much to
about; in fact, on their tests you look pretty darn good. The things
that they do see, the mild attention and concentration problems, are
probably due to the pain, the fatigue, and the depression.
Well, the hypotheses that we have are somewhat different than that.
We don't know that ours are correct, but they do not include the
above. The reason that we don't explain the difficulty vestibular
patients have as due to pain, fatigue and depression is that if you
people with pain, with fatigue and depression, they either don't have
this pattern of difficulty or it's far milder.
If we test people with a lot of pain or depression or fatigue, they
do badly on a variety of attention and concentration tests. On those
tests, however, vestibular patients may do pretty well. If, instead,
we test using the tasks where we divide up the patient's attention
between sorting words by category and pulling back recent words, we
that even when they're feeling stable and are not in much pain, on this
one test vestibular patients perform badly.
Obviously common sense leads us to explore this further. We can only
conclude that this kind of malfunction seems highly specific to most
vestibular patients. Shortly we will have enough control patients to
publish these findings.
Our hypothesis is that the reason you have this problem as a vestibular
patient is that your brain stem is affected. The brain stem is a
stalk connected to the spinal cord. There are nuclei located in the
brain stem that attach to your balance system; they are also highly
important for keeping your cortex, your thinking areas, alert and
aroused and attentive.
Could it be that since you're constantly fighting the mismatch from
visual input and your disordered balance system that a very basic
mechanism -- a mechanism that was developed as you learned to sit and
crawl and that influenced how you later manipulated objects and then
walked and spoke and thought, a mechanism that's taken for granted and
built into very fundamental habits -- could it be that something that
fundamental is being distorted? That the vestibular and visual
disturbance interferes with nuclei functioning within the brain stem
thus interferes with your sequencing of information and impairs and
reduces your channeling capacity?
It's an intriguing hypothesis, exceedingly difficult to test.
Nevertheless it makes some sense, as anyone with a vestibular disorder
can speak to. Basic problems with reading, watching letters
transpose, problems with movement and the orienting to the environment
-- these are manipulations of the environment that were learned at a
very fundamental developmental stage.
Question: Can some of these problems be described as dyslexia?
Answer: Yes, these symptoms can be misunderstood as dyslexia,
although dyslexia has some other components to it.
Question: Is this damage permanent? Will the brain cells die from
not being used?
Answer: We have no way of finding out the physical damage. The
MRI's (Magnetic Resonance Imaging scans) often look perfect. It's
likely that your vestibular system is sending inaccurate information to
other brain areas that don't know how to handle it and/or information
that gets distorted at very elementary levels of functioning. Those
basic functioning areas seem to need accurate information from the
vestibular system to think.
Can we fix it? That is a very complex question but obviously among
the most important questions to ask. Our clinic, which has been doing
some of these studies, is very dedicated to trying to improve these
memory problems. We're up against the fatigue problem, which we can
One of our goals is to try to teach people tricks or handy ways of
remembering things that would help anybody walking around the streets,
shorthand ways of remembering things using pictures and so forth.
We've discovered if the picture is highly dramatic and a
picture, patients become highly vestibular, and it interferes with the
memory. So we have to train people to remove a lot of motion from
their images. These tricks are one aspect of our work. Using them,
we have seen some improvement, but not without effort and time and
learning to make these strategies become automatic.
Increasing patients' stamina, allowing them to take in larger amounts
information is an area which we're highly interested in pushing. A
couple of our patients have been able to move into that phase, and we
see that slowly, again not without a lot of effort, the capacity to
increase the amount is there. I have a guess that part of the reason
that improvement is that one is learning new habits -- is training him-
or herself to think again. As a vestibular patient, you must learn to
move around in a slightly different-sized intellectual room. As you
learn, just as in physical vestibular therapy,
compensating becomes automatic. You become comfortable with that
little basic mental operation and this one, and you don't have to be
thinking consciously about every step.
These new automatic habits allow you to take in more.
Our goal is to train these habits so people can actually improve on
their performance and feel the difference at home. Again it's
confounded by the fluctuating symptoms of the vestibular condition, by
depression, by stress, by all kinds of other things that enter into
memory and finally by the fatigue that is constantly there because of
the mismatch of your vision and your balance system.
Nevertheless, those who have reached that stage do feel a sense of
gratification, and that drives us on. Our own sense here in the
clinic is that given enough time, people will develop these new
habits. We hope that we're developing a mental operation therapy
similar to the physical vestibular therapy. Because it's so much more
subtle and abstract, we suspect it will be very slow going. We feel
that the rewards are there, and we continue to be dedicated to
To go on, then, after completing the initial study that I mentioned on
the divided attention/recall test, we plan to do two studies in which
look at the channel capacity, the limit on taking on new information
before suddenly the slate is wiped clean and none of it comes back.
We are asking what is the sequencing problem when it comes to memory.
How can we get around it? How can we understand it? Can we
actually find some interesting little patterns that might help
compensate for its dysfunction?
Finally, later on, we hope to study this very intriguing difficulty
that sense of closure, of certainty, inside. I suspect it's a
multi-faceted experience that requires five or six different things to
Within all this, of course, we have to include studies of people with
pain, but no vestibular problems, depression but no vestibular
fatigue and no vestibular problems, head injury and no vestibular
problems. That allows us to control for some of those confounding
variables that people now use to explain the problem.
Question: Do other people have problems with getting the first part
of a word and then losing the second part, or getting the first part of
a sentence and losing the second part?
Answer: These are indeed very common difficulties among vestibular
Question: What effects might medicine have?
Answer: Many of the medications for vestibular problems are
sedatives, even the anti-histamines and pain medications have a
effect. These will have an effect on memory and concentration.
Vestibular patients who need medication to control their symptoms are
often caught between a rock and hard place -- the vestibular symptoms
cause them cognitive difficulties, but if they medicate to control the
symptoms, the medication causes cognitive problems.
Question: I have a problem with getting the general idea of articles
when I'm reading. Is this common?.
Answer: Definitely. In our clinic, we work on sequence and memory
aids, in order to break the material down into simpler steps --
an article, say, into key points. If there are more than five or six,
then you will have trouble. Even simple articles can seem very
complex. You can break reading materials down into key points, but
it's hard work. You need to pick things that are worth it to you.
Otherwise you'll get too fatigued and discouraged.
Question: Why do we mis-read, even
when we know we are misreading?
Answer: It's called a substitute syndrome. Vestibular patients
experience the syndrome often; it's very frustrating. I don't know
why it's so rampant in vestibular patients. Probably it's linked to
underlying injury to the vestibular system that goes beyond the
vertigo, etc. When we tested a patient who was no longer having
vertigo and whose scores were rather impressive in other areas, this
"mis-reading" syndrome still existed. We don't know why. We ask, is
the perilymph fistula creating a direct problem different from the
vertigo? We need a larger sample and controls to really
Question: Do you have any help for family members?
Answer: A vestibular dysfunction affects the whole family because it
affects the patient's total life. Family members need help and
understanding almost as much as the patient him- or herself. In the
clinic, we include family members' perspectives because they can
sometimes give clues to behavior that patients aren't aware of. We
also do counseling with family members.
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