Date: Mon, 25 Oct 1999 18:45:32 -0400
From: "Eddie Bollenbach"
One of the reasons PPS is so difficult to get a handle on is that the physician cannot detect increases in weakness by manual muscle testing. Actually, I'm starting to think that whether you call it PPS (Post-Polio Syndrome) or PPMA (Post-Polio Progressive Muscular Atrophy) noticeable weakness (measurable weakness) or loss of contractile power by affected muscles is not the problem.
In a normal individual there are (broadly) two types of muscle fibers that are components of voluntary muscle: Type I and Type II fibers. They are also called "slow twitch (Type I)" and "fast twitch (Type II").
When you stain a muscle biopsy and look at it under the microscope the slow twitch Type I appear lighter in color while the faster Type II generally are darker. Again, in normals there is a random and approximately equal distribution of slow twitch and fast twitch fibers within the muscle. When you contract a muscle to do work the fast twitch contract first and have a high capacity for extracting energy from sugar anaerobically. That means even though you can't deliver oxygen rapidly to the muscle the fast twitch can do its thing, quickly, way before circulation can deliver oxygen. The result of this is a build up of lactic acid. When you initially contract a muscle to do work it is the type II's that contract.
Most of the type I's remain uncontracted until the muscle's Type II fibers begin to fatigue (it doesn't take them long to poop out). They can't last long without oxygen working anaerobically. When the Type II fibers contract they use oxygen and can continue to contract for a long time. The muscles in the body that maintain posture, for example, have a lot of slow twitch and remain contracted throughout the day.
The ratio of Type I and Type II muscles can change. If one engages in body building you will gain more fast twitch. If one engages in distance exercise of long duration you get more slow twitch. Slow twitch is the white meat on a turkey (for reference).
Anyway, If you had polio you probably have more slow twitch than fast twitch. For some reason now we are losing some of the slow twitch fibers we built up during recovery from acute polio. The result is an extreme fatiguability of muscles that used to work just fine. So we are having an inability to sustain muscle contraction. But instantaneous strength frequently remains intact.
Post Polio Syndrome does not progress in the sense that the muscle goes to zero contraction power. A lot of the weakness we develop, in my opinion, results from our inability to tolerate exercise because of the loss of endurance due to denervation of muscle fibers, and the change in their ratio (does that make sense?)
No one can predict how fatigued particular muscles are going to get. However, the thing you must know, because we have seen this over and over again for almost twenty years, is that the fatigue and weakness do not "generalize" to other muscles throughout the body.
I'll say that again another way. You should not expect _all_ of your muscles to become involved. PPS is asymmetrical and affects only some muscles. If the muscles are important postural muscles this is more of a problem than if the muscles are below the hip. The problems you have are not due to generalization of weakness but rather due to _where_ the weakness happened to develop.
You _will_ not lose strength until all you have is your head. This will not happen, first of all, and secondly no one except maybe the amazing Kreskin could predict something like this for anybody unless they have something like ALS (Amyotrophic Lateral Sclerosis aka "Lou Gehrig Disease") . It just isn't the case for polio. In ALS upper motor neurons in the brain go and then everything downstream from there. In PPS some lower motor neurons seem to be losing mostly endurance. ALS is malignant. PPS or PPMA (as they called it at NIH) is not.
Date: Tue, 26 Oct 1999 19:53:53 -0400
From: "Eddie Bollenbach" <edward.bollenbach AT snet.net>
>>Is it possible for one's immune system to be too strong? This must mean something different than too healthy. Right? I am getting very lost here.<<
I don't think "strong" and "weak" are the correct terms.
The immune system is extremely complicated with the function of many of the aspects of immunity depending on the function of other parts of the system. You could suddenly develop an immune response to one of your own tissues. This may happen because viral parts are embedded in the tissue and your immune system tries to get at em, or certain molecules, like proteins, may pick up smaller molecules and your body starts to recognize the combination as foreign (non-self) and attacks it immunologically.
In autopsies of recovered polio patients in the 50's David Bodian showed that the spinal cords of those supposedly recovered from polio had immune activity and inflammation.
Some recent autopsies of individuals with PPS showed similar activity. It may not be autoimmune but due to virus fragments or it may be autoimmune. And, the whole process may not be the "cause" of PPS. We just don't know exactly yet.
Contact Professor Edward P. Bollenbach
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