Monday, January 31, 2011


Its all about the hand.
or anyone interested in evidence-based stroke recovery treatment options, the lower extremity offers a much smaller palette than the upper extremity. Simply, there are a lot less evidence-based treatment options for the lower extremity.

One of the reasons this is true is because the ankle foot orthosis is an effective way of providing compensation for the deficits in gait after stroke. Another reason is that canes and walkers are also extraordinarily effective at compensating for gait deviations and deficits poststroke.

There are other reasons. For instance, there is the general consensus among therapists that what comes back first is the leg, and later on the arm and hand. This is a classic gotcha question for therapists teaching students. "What comes back first the upper or lower extremity?" The wise student will say
the politically correct answer; the lower extremity. But this is not necessarily true. We tend to focus very much on hand and all its intricate movements, especially finger extension. But in the lower extremity we don't typically look at the analog of finger extension: toe extension. Why does nobody care about toe extension? Simple: The toes are hidden by the shoes. Also, toe extension is not essential to a functional gait. Toe extension which helps raise the ankle is compensated for by the ankle foot orthosis.

Another reason for the near myopic focus on the upper extremity is that it's more interesting. The shoulder has more range of motion in more planes and pivots than it's analog the hip. But but more movement in the shoulder is small potatoes.

The main reason for the focus on the upper extremity is the hand. Even before brain imaging the hand fascinated researchers. This delicate instrument at the distal end of the limb drives clinical rehabilitation research related to stroke. There is a common belief that if you can get the hand "back in the game" and somehow get the hand
to grasp release every other aspect of the upper extremity will come back naturally. This is because the entire upper extremity is there at the behest of the hand. You could further argue, although a bit of a stretch, that the reason we walk is to get the hand where it needs to go so that the hand can do what it needs to do.

But there's another huge reason. The brain. The swath of real estate that hand takes up on the brain is huge. The point to point representation of the brain is called the homunculus. The hand takes up almost as much room as the entire face! The face! Where our mouth is! Whe
re our eyes are! Where are ears are! Our identity! When it comes to the brain the hand is, quite literally, huge.

Enter neuroscience, almost all of whom focus on the brain. Neuroscientists are fascinated with the hand for a few reasons. First of all, because of its delicacy, if you figure out the hand the rest of the body is easy. If you are interested in motor learning there's no better laboratory than the hand.

But there may be another reason that neuroscientists are fascinated with the hand. Imagine if you doing clinical research on stroke survivors. They all are different ages, have had their
stroke in different parts of their brain, they're all in different physical shape, they all have different diets, they all have different sequelae, etc. etc.

Now imagine you're doing research and you can have as many study participants as you want and they all have a stroke in exactly the same spot, be the same age, eat the same diet, wake up at the same time in the morning, always show up on time and that you can easily blind (not let them know which group there in) and are genetically related!

Where can you find such study participants? Rats! (And mice) But why rats and mice? Why are rats and mice so important to the equation of figuring out the science of motor learning in the hand? Here's why...

Freaky, huh?


oc1dean said...

Peter, Just watched Dale Corbett on titled
Neuroplasticity and Stroke Recovery: Past, Present and Future
He also demostrates how rat paws are similar to humans as far as grasping is concerned. I really liked his enrichment theory. We need baby mobiles hanging above each survivors bed. I would have needed tons of caffiene in order to stay awake and be enriched. Probably the same idea that music therapy is good during the acute stay.

Peter G Levine said...

Thanks Dean. There's this general prejudice that comes out sometimes among some of the folks who do rehabilitation research for stroke with human participants. The prejudice is described in one word: "Ratchoppers." Because they're working with animals and not people it's much more difficult to transfer what's going on in the laboratory to the bedside. Of course, both human and animal participants are needed to begin to solve this riddle. But mistakes have been made assuming that what is true in rats is also true in humans. And this is sometimes lost on bench scientists that work with animals. They figure, hey it works in my animals so let's just superimpose it on humans. I guess the best way to do it would be to test the idea animals, and then do the hard work of testing it on humans, and then introduce a clinically. But human trials are expensive and take a really really long time. You could have a therapist look at the rat studies, skip the human trials, and bring it right to the bedside. But how many therapists -- how many neurologists or physiatrist for that matter -- look at this stuff?

Linda said...

I used to breed pet rats and I am very aware of how much these animals are capable of and how trainable they can be. I actually had a baby rat have an accident and stop breathing briefly. The rats behavior was very different from his liter mates. One noteworthy behavior was that he seemed unaware of things like heights or edges and would walk right off a table.

I watched the video Dean commented on and found it very interesting.

My work experience is in microbiology, genetics and infectious diseases. I think I am very glad I stayed away from work involving animal model research.

Linda in Winnipeg

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