Thursday, November 8, 2007

Structure vs. Function - Part I

I guess every field has it's own "vs." debate. They usually last for years without ever coming to a real conclusion.

One would think that by now most people would've noticed that it's not a question of "vs." but of interconnectedness - nature and nurture - not nature vs. nurture.

If you have a gene that makes you more susceptible to developing a certain illness there have to be factors in your environment that activate those genes - otherwise you don't get sick (in that specific way).

The old "vs." debate in Physiotherapy and similar fields is one between structure and function.

There are some who see treating tissues as their main approach - others like me have abandoned those models of thinking (long ago) ;-) and see themselves as "functional therapists" - or neuromodulators - as for example Diane Jacobs does (her excellent blog is here).

Why is there a debate at all?

Well - medicine is still influenced by what scientists/pioneers started when they cut up the first human bodies centuries ago - gross anatomy.

Even today - with all the new techniques that were developed since - medical students start by dissecting bodies and learning about the human animal that way.

What's more - starting with Mixter and Barr in the 30's - every decade more and more and finer and finer structures have been found and are presented as the "pain causing structure". First it was the ruptured disc - now we are down to the vessels that supply the disc and their pressure being elevated causing constricted flow and a sharp rise in pressure. With structural thinking there is just no end in sight - next they are going to focus on molecules being bent out of shape.

And if you haven't realized it by now: those people are dead! Yet medical professionals treat humans that are alive!

You can study the mechanics of flight in this picture - but not flight itself:

The Web Of Life

Do you see the problem now?

We - as examiners can see muscles and tendons and bones - all clearly discernible - but the Neurosciences haven't found a representation of a single muscle inside the brain yet - they just don't exist from the brains point of view. The brain "thinks" in movements, goals and actions to perform - and uses what's available at the time.

Have you ever seen a runner without legs? With special prosthetics - which are in some ways much better than legs they run just like you and me - yet they have only half (?) of the muscles we think a human being needs to be able to run.

Look at people who had polio - the muscles that weren't affected take over the function of those muscles that are paralyzed.

How does this affect treatment?

Let's look at the example of phantom limb pain: the missing limb hurts, it might be an involuntary clenching or burning pain or whatnot. So the "structural" oriented practitioners started looking for clues in what was left of the extremity. Some of the pain was attributed to the site of the amputation - resulting in another shortening operation, nodules of scar tissue being removed from the stump, the cutting of nerves from the spinal cord to the limb and so on and so forth.

Again the rule of thirds came into play: some got better, some stayed the same, some got worse.

In come the "functionalists" - led by V.S. Ramachandran - building on the work of others of course.

They realized that the cortical map of the amputated limb was still present in the brain - most accessible to study in the somatosensory cortex in the brain. And so called higher centers in the brain act on the information that is contained in those maps - not on what's outside in the real world.

Since pain is produced in the brain Ramachandran speculated that the cause of the pain could lie in the fact that the representation and the visual feedback from the limb didn't match (see Harris Hypothesis for more).

So he gave those amputees visual feedback of an intact limb with a mirror - and the pain vanished quickly.

Those findings have been replicated over and over again - Walter Reed is running a big trial with Iraqi War Veterans to see if mirror treatment is a viable treatment. Traumatic amputations are often much more difficult than "planned" ones.

The sucess rate of this kind of treatment is - at least in small trials well over 90%.

This doesn't mean that the "structuralists" are wrong - but just that they should try to "expand their thinking".

The techniques they use are still useful and are applied by me as well - but the reason why you do something and how you do it is different - helping you in cases when a patient fails to improve.

One kind of therapy that finally started to get around to acknowledging this is the McKenzie method. It originated as a purely mechanical way of treating back pain - but has since then evolved into a method that is able to treat the whole body. The term "derangement" now encompasses all things in a joint that can be "out of whack" - and only cares about if the patient gets better with repeated movement in the preferred direction.
Even large scale trials show that this kind of treatment is very effective. People aren't put into groups based on structural findings - their functional status is all that counts.

I've had discussions with the top people in Germany and the US about openly admitting that they "are only changing neural firing patterns" - not doing anything mechanical with a specific structure - and at least behind closed doors the Germans agreed - the US guru is still not talking to me. ;-)

And this despite the fact that they see how fast people can improve with this method.

Structural thinking is just so easy to grasp and not as "nebulous" as functional thinking - at least to some.

5 comments:

ORJ said...

"Since pain is produced in the brain Ramachandran speculated that the cause of the pain could lie in the fact that the representation and the visual feedback from the limb didn't match."

The two places most people have pain is 1. lower back and 2. neck and shoulders. Which are the only places on the body that you cannot visually inspect yourself.

Matthias Weinberger said...

Yes - that's why I think that the grooming behavior of chimpanzees and other primates is so important - it provides them with tactile feedback.

Not being able to visually inspect an area of our bodies makes it more prone to develop chronic pain in my opinion.

ORJ said...

"Not being able to visually inspect an area of our bodies makes it more prone to develop chronic pain in my opinion."

I suspect so too. Wonder if treatment could be done using video... Check this out: http://news.bbc.co.uk/2/hi/health/6960612.stm

OAndreas said...

Imagine having a totally realistic avatar of yourself that even shows your exact posture. And now imagine the possibility to virtually step out of your body and look at it from some distance. Now let a Physiotherapist join you in this virtual reality of yourself and let him show you what to do...

Wouldn't that be the best way of visual feedback possible?

Matthias Weinberger said...

Herta Flor has done a study where they put 8 electrodes on a patients back with different frequencies. The patients had to learn to distinguish which electrode was active and at what frequency. This led to rapid re-modeling of their deformed cortical map of the low back and to lasting pain relief.

Lorimer Moseley has suggested drawing a chessboard on the patients back and have him learn in which space you touch his back.

According to Bach-Y-Rita visual and tactile input are equal for the brain - as long as there's feedback the brain is able to correct any deficiency.

Video would be cool though. ;-)
And the fastest and easiest way to do it.

@Andreas: doesn't have to be perfect to work. Our brains even incorporate foreign objects (tools) into their body schema.
It would however be very helpful where people can't move any longer: stroke, MS, ALS, paraplegia, ...