fuzzy pain

["Steven M. Belknap" <sbelknap@UIC.EDU>]

la stivn cusku di'e
>>I asked this woman to rate the severity of her pain as we adjusted her
>>pain medication.  Initially we used a drug-delivery system which
>>provided a continuous, high concentration of narcotic.  Surprisingly,
>>this was not very effective.  We had to push the dose to the point of
>>toxicity.  Then we noticed something interesting.  Her 1 to 10 ratings
>>of pain were markedly more episodic than is usually the case, spiking up
>>into the 7 to 9 range, so we changed to a subcutaneous patient
>>controlled analgesia system, in which she could squirt herself with
>>narcotic when her pain was severe and forego the narcotic when it wasn't
>>that bad.  But she also had baseline pain around 3. So we gave a very
>>low dose constant infusion of narcotic also This worked very well.  The
>>total daily dose of narcotic with this dosing regimen was 1/3 of the
>>total daily dose of narcotic she was originally getting, she had better
>>pain control, and less nausea and other adverse effects.

la lojbab cusku di'e
>What made this work was a large number of data points from the one
>observer under varying conditions, that allowed you to assign diagnostic
>meaning to her scale, probably correlated by your medical observations
>when she had spikes.

Well, yes. But pain is considered subjective. Pain is ordinarily not
thought of as being quantifiable on an interval scale. Certainly, most
people would agree that pain can be quantified on an *ordinal* scale. (This
ankle sprain doesn't hurt as much as my prior ankle fracture. My point was
that moving to a more sophisticated scale can sometimes be useful.

>I live in constant low level pain of several
>varieties that I mostly associate with stress.

Sorry to hear that. I would think that this would make stressful situations
doubly unpleasant. I retract my suggestion that you quadruple the size of
the dictionary to include a scale specific definition for every gismu.

>But I could never rank
>them on a 1 to 10 scale, because I have no idea what a 10 would be.  I
>could rank them relative to each other on an open-ended scale, but that
>would tell you relatively little without some correlation with responses
>to medicine and other medical factors.  If I were to arbitrarily tell
>you off the cuff that I am feeling pain at a 3 on a 1-10 scale, even >I<
>wouldn't know what I meant by that.

Agreed. Some patients become very upset when I ask them to rate their pain,
saying that pain can not be described in that way, so I accept that for
them at that time this is true. I stop asking them to rate their pain, and
take another approach. Other patients find this appoach useful. I entirely
agree that a speaker will not be properly understood by a listener if the
two have not (at least implicitly) agreed on a definition for their scale
they are using. I usually try something like this:

"Tell me about the pain."
...
"I know you are having pain. I know the medication isn't working as well as
we would like. Perhaps if we work together, we can improve the situation."
...
"Sometimes I find it helpful if a patient will rate how bad the pain is, so
I can adjust the dose of the pain medication to exactly the right dose.
Would you be willing to try that approach?"
...
"If being free of pain is a zero, and the worst, most horrible pain is a
ten, how would you rate your pain now?"
...

I generally do not *explicitly* specify what kind of scale I mean, but from
their answers, people seem to assume I mean a 10 interval scale, or a ratio
scale with granularity 11 (0,1,2,3,4,5,6,7,8,9,10). People will then
describe their pain as dropping from a 7 to a 3, or 50% better, or other
terms which imply some scale choice or other. One thing I've come to
appreciate as a physician is how differently people use language to
describe their internal experience. Yet, meaningful, useful conversation
can occur about this experience. Dismissing all this stuff as "subjective"
would be a disservice to many of my patients, and would leave many of them
in more pain than necessary.

>
>>>Discrete logics do model human thinking quite well
>>
>>Do you have some evidence to support this assertion?  It is at variance
>>with my own observations and with the scientific literature.
>
>I think that people BELIEVE they have to categorize and cubbyhole in
>order to be "objective".  Not being categorical has earned the label
>"slippery slope" for good reason.
>

Insisting on a nominal or categorical scale has earned the label "pedantic"
for good reason!

Many people are falsely taught that Aristotlean two-valued logic is the
"only" correct logic. Perhaps it would be better to label this approach as
Zoroastrianism, as Zoroaster's beliefs, as described in the Zend-Avesta,
seem to have influenced many later belief systems, and Aristotle did a lot
of other things besides introducing the law of the excluded middle. I
believe this misinformed insistence on two-valued logics does much harm.
Such dichotomy is an essential component of many religions, political
movements, and other belief systems. Nearly everybody is worshipping
Ormazd, though hardly anybody knows who Ormazd is!  Interestingly, false
dichotomies are a very common type of cognitive distortion exhibited by
people with depression.

>There is considerable evidence that strict categorization is innate (and
>fuzziness is learned).

What evidence do you know that strict categorization is innate? I know of
no convincing evidence to this effect.

>Young kids call any animal with 4 legs "doggy" -
>not "sort of a doggy".

This does not support your assertion that strict categorization is innate.
Kids probably tune their fuzzy neural net to output "doggy." for various
manifestations of doggishness. This is independent of the internal
algorithm they use to classify something as "doggy." By analogy, my fuzzy
logic rice cooker uses a fuzzy algorithm to adjust the temperature, but the
heat output of the algorithm is always a *precise* value. Fuzzy sets are
not wishy-washy, muddle-headed, slippery slope sets. This is a common
misunderstanding of what fuzzy logic and fuzzy sets are.

> It is only as we approach adulthood, and learn
>that not everyone agrees with us on everything we believe, that we start
>to hedge our categorizations.

My niece once identified a horse as a "naked zebra". (She'd seen zebras at
the zoo, had previously only seen horses in books.) Borderline cases are
part of a child's daily experience. It is one way they learn. I believe
that children are constantly confronted with counterexamples, and
disagreement about their assignment of names. Names (or categories, if you
prefer) are inherently fuzzy. Think of gryphons and their kin. Fuzzy
categories are old. I think that the logic boxes in our heads are fuzzy
logic boxes, and that the tuning begins at birth. We can output two-valued
logic, if that's what is required, but again, the output of a logic does
not specify the algorithm used to calculate that output. Granted that litle
is known about the basis of consciousness, but if brains have discrete
states, why do they seem so analog in function?

>
>I suspect that Peter argues against you at least partially on such a
>basis.  Questions of strength of feeling in opinion polls tend to be
>even more susceptable to manipulation by careful wording than do
>categorical yes/no opinion polls.

I think much of the argument results from believing that one's preferred
mode of thinking is the only valid mode of thinking. Just cause Frodo the
Hobbit can't wield a greatsword doesn't mean greatswords are not useful
weapons. (I am a great admirer of Frodo, however. He has other skills.)

>>the problem is that the numbers aren't being
>>used as numbers (in other words, a 3 restaurant isn't really 2 times
>>worse than a 6 restaurant), they're just being used as symbols for words
>>like "awful", "good", "bad", "wonderful" etc.  So why pretend that the
>>evaluation is somehow mathematical, when it is only subjective?
>
>This seems a key point.  In your pain example, and in the restaurant
>review examples, the numbers given are not necessarily linearly
>proportional.
>

We agree. This was early in the discussion of Guttman scales. It was a key
point, but not a source of confusion at the moment. See Bob Chassel's posts
on Guttman scales, which discuss this point in detail. I believe the
subjective/objective dichotomy is a false dichotomy. But I fear I'm
repeating myself.

cohomihe la stivn


Steven M. Belknap, M.D.
Assistant Professor of Clinical Pharmacology and Medicine
University of Illinois College of Medicine at Peoria

email: sbelknap@uic.edu
Voice: 309/671-3403
Fax:   309/671-8413