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How does dysautonomia cause leg weakness?

Discussion in 'Autonomic, Cardiovascular, and Respiratory' started by dan062, Nov 19, 2014.

  1. dan062

    dan062 Senior Member

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    I was having a look at the vagus nerve, and the ANS in general, last night.

    For those that don't know, it's the tenth cranial nerve which acts as a conduit between the brain (it terminates in the brain-stem) and the immune system (it ends in the colon, host to 80% of that).

    As it's the main plumbing between our neurological and immunological centers it's received a lot of attention in CFS research.

    Looking at the various plexi (branches off the vagus nerve) and what symptoms those would correspond to, I can see how researchers are thinking that it's pretty key to CFS/ME whatever its involvement in the disease (direct infection, as Van Elzakker is postulating, or merely carrying inflammation from the gut to the brain as others think, etc).

    It explains, for me, just about every symptom we commonly encounter bar one: leg weakness.

    Is there a connection between a part of the PNS (most obviously, the sciatic nerve, and its offshoots) and one of the branches of the ANS around about where it provides provides autonomic innervation to the bladder (I believe the nerve I'm thinking of is the pudendal nerve)? If so, perhaps vagal dysfunction would simply carry on through that and down the nervous system via a direct connection.

    Per the diagram below, the vagus nerve ends in the colon so it definitely doesn't directly provide innervation (and therefore cause symptoms) for any organs beyond that level in the body.

    Or perhaps it's a central problem: would inflammation in the brain-stem rebound in the basal ganglia, which it is strongly inter-connected with and is situated relatively close by?

    Diagram

    [Tagging @Jonathan Edwards again]
     
    Last edited: Nov 19, 2014
  2. Jonathan Edwards

    Jonathan Edwards "Gibberish"

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    Are you thinking that vagal nerve damage (i.e. loss of activity) would cause ME symptoms or that an intact vagus nerve could cause ME symptoms?

    The vagus cannot reroute to command the legs, no.
     
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  3. dan062

    dan062 Senior Member

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    OK, so vagal damage (causing loss of activity) has nothing to do with leg / muscle weakness? That's what I deduced by looking at the anatomy diagrams but I wanted to make sure, as I mentioned, that dysfunction in the vagal nerve couldn't simply carry over into the leg innervation through some sort of connection.

    I was trying to follow the logic of the vagal damage / infection theories to explain ME symptoms.

    (The theories I'm referring to are by Van Elzakker and point five in Galland, here.)

    If muscle weakness (particularly affecting the legs judging by the severe cases of ME in wheelchairs) cannot be explained by dysautonomia and lack of activity in the vagus nerve then it would seem like an only a partial explanation for the condition.

    Perhaps the answer has to do with point 5) in the second study (Galland) where he proproses that vagal inflammation, meditated in the gut, triggers changes in the HPA axis (I'm guessing that as muscle weakness is seen in the likes of Addison's that it can be a consequence of endocrine disruptions, too).
     
  4. Martial

    Martial Senior Member

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    Anything that effect's the nervous system or brain will present full body symptoms including muscular weakness.
     
  5. adreno

    adreno PR activist

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    Studies have found autoantibodies blocking norepinephrine and acetylcholine receptors in POTS. This could probably explain leg/muscle weakness.
     
    Last edited: Nov 19, 2014
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  6. Gingergrrl

    Gingergrrl Senior Member

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    @dan062 I am not sure if this is helpful but I have to use a wheelchair when we go out but I do not have any issues whatsoever with leg weakness. For me it is because when I walk more than a few feet, I get short of breath and chest pressure and an overall sense of fatigue that I just cannot go any farther.

    If anything I have weakness in my arms and the most difficult activities are those in which I have to raise my arms above my head such as getting a plate from a cabinet or using a hairdryer (which I can no longer do.) But my legs are totally normal with no issues.
     
  7. Revel

    Revel Senior Member

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    Ditto, @Gingergrrl.

    Sometimes I feel all over weakness, but mainly it's as though my body is made of two halves. My legs would work just fine if only my upper torso would comply (mostly my arms are about as useful as two strands of al dente spaghetti).

    Following a bad PEM episode, the weakness and muscle pain in my legs can disappear within days, but the rest of me can take weeks to catch up, and lately I return to a progressively lower level of functioning each time.
     
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  8. dan062

    dan062 Senior Member

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    Thanks, @adreno, that does indeed help.

    As I wrote above, if there's no possibility that there could be a direct neurological cause, the explanation must be something to do with an endocrinological / HPA disturbance. I think that fits the bill pretty tidily and I'll look into those studies.
     
  9. dan062

    dan062 Senior Member

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    I think one of the 'weirdest' things about ME, as practitioners must perceive it, is that the weakness is so variable and fluctuating.

    I've hard a really hard time explaining to a couple of people, without sounding crazy, that sometimes my legs feel like they are going to give out at any moment (and climbing the stairs I look like an old man), and other times they feel relatively normal.

    The only other neuro conditions I've found with weakness that is supposed to fluctuate to this extent are myasthenia gravis and Lambert Eaton syndrome (LES). Both have endocrine explanations (myasthenia is treated with acetylcholine inhibitors), so thinking about it from this perspective, @adreno's explanation certainly adds up.

    @Gingergrrl Thanks for that. Just another of the countless mysteries of this condition why some of us have different extremities affected.
     
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  10. adreno

    adreno PR activist

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    Last edited: Nov 20, 2014
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  11. adreno

    adreno PR activist

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  12. adreno

    adreno PR activist

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  13. dan062

    dan062 Senior Member

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    Thanks, @adreno, this is fascinating. Unfortunately (for us) yet another biomarker only testable in research settings at present, but I think the theory is particularly cogent.

    Strangely enough, I find any explanation that takes the mystery out of CFS/ME to be oddly comforting. I've always wondered why the research seems to have been fixed on hypothesizing the persistence of exotic and unusual infections (e.g. XMRV in the past and the vagal nerve infection idea being proposed at present).

    It's always seemed to me that in the sanitized age of allergy and autoimmunity we live in that CFS/ME simply being another neuro autoimmune disease on the list-- just not recognized as such, yet -- is more plausible. Particularly as they all seem to be tipped off by an infection given the right genetic predisposition / microbiome disturbance.

    Raw deal as usual for us, of course (being untreated and all that), but at least it makes the whole thing less perplexing.
     
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  14. Jonathan Edwards

    Jonathan Edwards "Gibberish"

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    Ah - I may have confused you dan062. I am not an expert autonomic neuroanatomist but I am fairly sure that the vagus itself has effects limited largely to the internal visceral organs. But the autonomic system includes sympathetic fibres that go everywhere, including vessels in muscle and skin. Disturbed sympathetic drive - maybe relating to the studies adreno mentioned could easily produce generalised weakness. And in fact the vagus could contribute by failing to control heart rate. The only reservation to this is that in other situations where blood supply is marginal, like heart failure, weakness tends to come in the form of general exhaustion with shortness of breath rather than specific leg weakness. And sympathetic peripheral neuropathy does not look quite like ME.

    So, getting back to the original issue of the vagus, I am finding it hard to blame the vagus itself for all these things, but I would be very open to the idea that a lot of symptoms are mediated by autonomic changes driven by hypothalamus.
     
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  15. Valentijn

    Valentijn Senior Member

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    Even more interesting: exertion makes LES symptoms worse. It also can include pain, orthostatic hypotension, ataxia, difficulty climbing stairs or standing up, and several of the other symptoms which some ME patients get.

    The only thing really missing is the swollen lymph nodes, which would only be a problem in LES if it's secondary to a cancer involving the lymph nodes.
     
  16. Valentijn

    Valentijn Senior Member

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    My leg muscles can definitely get worn out after walking for a while ... one upper leg muscle stopped working completely after an extended death-march through a hospital. I literally could not stand up, or even lift that leg a bit :p I also tend to stagger a bit after more moderate amounts of walking. Then it feels like some muscles aren't working properly or aren't cooperating with the other muscles, and my movements get jerky as a result.

    But if my OI is bad, I can't walk long enough for muscles to get worn out anyhow.
     
  17. Valentijn

    Valentijn Senior Member

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    Can the vagus nerve also impact the systolic and/or diastolic blood pressure? My heart rate can get high, but it's almost always in response to low pulse pressure, "low" oxygen saturation (sometimes it freaks out if I hit 97% :meh:), or heat. Hence my rise in heart rate generally seems to be a healthy attempt to compensate for some other dysfunction.
     
  18. Sidereal

    Sidereal Senior Member

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    Actually fluctuating symptoms like intermittent weakness and paralysis are characteristic of channelopathies. Not a huge amount is known about these disorders, it is a relatively new but to my mind very exciting area of research. Peter Behan co-authored a hypothesis paper many years ago about how symptoms of CFS could relate to a channelopathy. It can be found online somewhere.

    In routine clinical practice when patients (especially if they are female) present with weird paroxysmal problems like this neurologists will tend to diagnose non-epileptic (i.e. psychogenic) seizures or conversion disorder (formerly known as hysteria) or other historical trash pseudodiagnoses of this sort.
     
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  19. dan062

    dan062 Senior Member

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    Thanks. Very interesting. I guess we have at least two possible explanations so. Would you mind elaborating on the point in bold, above?
     
  20. dan062

    dan062 Senior Member

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    Hadn't encountered that term before but guessed what it meant. MG is listed as one (LES isn't on Wikipedia but pretty sure it should be). This is an interesting line of thought.
     

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