How does dysautonomia cause leg weakness?

[dan062]

Can the vagus nerve also impact the systolic and/or diastolic blood pressure?

Definitely the ANS and I'm pretty sure the vagus specifically (there's more to the autonomic system than just the vagus nerve, although it's the main conduit). Control of blood pressure, heart rate, and blood temperature are its key functions.

 

[lansbergen]

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.

The sympaticus can be involved. I am pretty sure mIne were bad at both sides and it lasted years. Ofcourse I have only the clinical improvement picture to go on.

 

[lansbergen]

Peter Behan co-authored a hypothesis paper many years ago about how symptoms of CFS could relate to a channelopathy.

I remember that.

 

[Jonathan Edwards]

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% ), or heat. Hence my rise in heart rate generally seems to be a healthy attempt to compensate for some other dysfunction.

That was the impression I had got - that OI in ME was a failure of increase in venous tone leading to low central venous pressure on standing and compensatory tahcycardia. I suspect the vagus can have some effect on venous tone centrally but I have always thought of that as sympathetic. So I would expect it to be the sympathetic system that is underperforming. Moreover, if there is a tachycardia response that would seem to indicate that vagal tone is changing appropriately, even if decreasing from a steady level, on standing. So this is why I find it hard to see all this as due a 'lazy vagus'.

But autonomic pathways have got more complicated recently. Maybe somebody else knows?

 

[Jonathan Edwards]

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

Peripheral neuropathy with sympathetic involvement often produces quite florid pink or purplish oedema - presumably due to stasis in venules not getting sympathetic tone. (There may be absence of sweating.) But this may be complicated by absence of sensation blocking input to 'fidget' reflexes that are needed to pump blood back to the heart. A pure sympathetic neuropathy might be different - I do not have experience with these.

 

[dan062]

Peripheral neuropathy with sympathetic involvement often produces quite florid pink or purplish oedema - presumably due to stasis in venules not getting sympathetic tone. (There may be absence of sweating.) But this may be complicated by absence of sensation blocking input to 'fidget' reflexes that are needed to pump blood back to the heart. A pure sympathetic neuropathy might be different - I do not have experience with these.

Thank you again.

I'm beginning to think that biting the bullet and enrolling in med school might be the quickest way of figuring all this craziness out!

 

[CFS_Kristin]

@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.

Where do you feel the weakness in your arms? Is it overall? Under the armpits?

I have been dealing with weak arms ever since I got sick with CFS/POTS. I get a pulsating feeling and it used to be under my arm pits and now it's an overall weakness in my arms.

 

[PNR2008]

I've always have had leg weakness and pain but I have arachnoiditis due to back injury, surgery, oil-based dye in mylogram (take your pick).