PEM discussion thread

My immediate PEM symptoms change every few weeks, but at the moment I get body chills, a sore throat and painful legs. If I have a headache the next day, I definitely overdid it, but I count the immediate and the delayed onset as PEM. I don't have symptoms when I'm not in PEM apart from occasionally feeling tired.

 

Thanks for this. This has helped me to understand my immediate PEM which was most intense naturally in my severer years. I would get an immediate headache, nausea, exhaustion came with it. I don't know whether OI has the exhaustion as well as PEM. I also got immediate aching of sinuses, flu like symptoms (maybe that one was immediate PEM). There were other so many other symptoms but I cannot remember them all right now.

So the immediate headache and nausea sounds like it mostly came from the OI. I remember I got different types of nausea throughout my overall ME, which might explain that I was experiencing not only OI nausea but PEM nausea at other times. I wonder if I even was getting a double up of different types of nausea on top of each other. What I mean by different types of nausea was that one type my stomach felt like it had gravel in it. Another type was straight feeling of nausea. There was 3rd type but I can't remember how I described it. I did record it, but need to find it.

 

What may be useful to remember is that doctors devise clinical terms for two quite different purposes. They may use the term as a diagnostic pointer or they may use it as an indicator of ill-health or disability. Unfortunately, most doctors who devise such terms forget that there are two different purposes and things get muddled.

As an example: the GALS screen for rapid assessment of joint problems was in set up by four doctors, ostensibly with the aim of being diagnostic screen for joints not being entirely normal in the context of a complaint in one joint or some other body part. But some of the doctors also wanted the screen to indicate how disabled the person was, for that joint. They ended up testing the shoulder by asking the person to put their hand up and behind their head. This is an indicator of a shoulder being significantly difficult to use. But a much more sensitive test of whether a shoulder is at all abnormal - maybe just a bit restricted from an old episode of inflammation - is to ask the person to put their hand down and round behind the back to touch the spine.

PEM seems to have been devised as a diagnostic term for recognising ME/CFS as opposed to fatigue from anaemia or heart failure or whatever. It is like nail pitting or lifting, which distinguishes psoriatic arthritis from rheumatoid. Nail lifting can be a real nuisance but for 80% of people is trivial in comparison to their arthritis and nail pitting causes no trouble.

So I think any fact sheet needs to separate two quite different issues. One is why doctors have this term PEM, which they use for diagnosis. The other is what it is like to suffer worsening from exertion or other things in ME/CFS.

 

The Institute of Medicine report in 2015 (now National Academy) does not emphasise delay they way the CMO report (UK, 2002) did. Here’s how they describe PEM:

They go into more detail about the onset of PEM on p.79:

And here’s what they say about duration/how prolonged PEM is, also p.79:

The word “delay” does not appear in the Summary or Key Facts documents, but I found one mention of “delay” in the Clinicians’ Guide (not prominent):

Edited to fix formatting in quotes.

 

I looked at Moore et al. 2023 again - this is the study from Hanson's group called "Recovery from Exercise in Persons with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)" available here https://www.mdpi.com/1648-9144/59/3/571.

It's relevant for this discussion because it focuses on symptoms of PEM rather than physiological correlates of PEM following a 2-day CPET in people with ME/CFS (well assessed by a physician, met CCC criteria and were not doing any regular exercise) and sedentary controls.

The issue of delayed onset only comes up in the limitations part of the discussion (I added the bolding):

So while they saw delayed onset of PEM, it was not the norm. The average pattern was this:


I'm actually not sure if the two CPETS were done on days 0 and 1 or days 1 and 2, but I think it was days 0 and 1. I may have missed this in the paper.

 

I wonder if the intensity or nature of the exertion might impact the delay. Exercise with a CPET is pretty extreme, and might on average produce a quicker response in terms of PEM compared to less intense exertion. Maybe there is some kind of dose response relationship here.

 

Really good question.

I experience both immediate and delayed PEM. I had a visit yesterday - I only manage a few a year - where I talked to someone I love very much and am very familiar with for 45 mins. While lying down in my own bed. A small bit of having to multitask - talk and listen through noise - at the end of the visit, but no exposure to perfume or levels of light or movement that can be difficult in other PEM-triggering events. During the visit, I started getting worse brainfog, headache, a very wired/revved up feeling, increased pain all over, increased sensitivity to noise. Those symptoms continued and intensified and those are still my symptoms now. Eventually, I will come down from the wired feeling, but the others will persist. When the symptoms abate (these daysusually within a week), I will think I'm OK, but then do something that I can usually tolerate and get fired straight into the PEM hellpit again.

So I think that's different from your experience, where you described that you feel crappy, but no more than you were before.

I definitely call what I'm currently experiencing PEM in all its weird and wonderful glory. And I shouldn't be posting but that's wiredness for you.

 

I agree, if something is quickly eased by rest within a few minutes then that is not PEM. It doesn't meet the prolonged criterion.

For me, though, if my legs start feeling sore and stiff after walking too much, they're going to be sore and stiff for the next week or so. If I'm upright to the point of really triggering OI, then I'm going to have PEM. But if I just briefly get black in front of my eyes as soon as I stand up, I'll often be fine (though it happens more when not fine, so it may just be a more subtle less-fine). OI in people without ME/CFS causes fatigue, i.e. people do not just bounce back from dizziness without any consequences. But what Physios for ME and physiologists like Workwell point out is that they can't train us, and that that stands out as something they only see in ME/CFS and long COVID. So ultimately, I expect studies will show differences between us and people with other conditions in what looks similar on paper.

 

But (assuming this is exertion induced) isn't it not PEM because it got better quickly, not because it came on quick?

 

I'd say it's more positional than exertional, and it's not PEM because there's no delay.

PEM isn't necessarily long lasting—sometimes the worst of it can be over inside a day—but it's always delayed.

Do you think it's useful to stick to this separation? I've assumed the delay's important because it could help with diagnosis (people with most pain and fatigue conditions are likely to get rapid onset worsening), and it might be a clue in research. But I don't actually know.

ETA: cross-posted with Trish

 

We could define "prolonged" means "not relieved by rest". I don't know if immediate PEM is same as rapid fatiguability since I don't have an experience with immediate PEM. But the rapid fatigue is usually relieved by rest in my case, even if that doesn't necessarily prevent PEM the next day.

I wouldn't know where to put my half-day PEM though. It is delayed, disproportionate to the exertion and not relieved by the rest. That's probably why I've been calling it a PEM. But it certainly is nothing compared to other patients who are dispatched to the bed for days or weeks after similar exertion.

 

Definitely isn’t for me. It changes something deeper. It’s like getting an allergic reaction or getting food poisoning when the PEM is immediate. (By that I mean showing up within an hour of overrexertion).

 

Thank you. I'll keep in mind that immediate PEM != rapid fatiguability from now on.

 

It seems fairly clear to me that different people have different concepts of PEM here. Not surprisingly, perhaps.

The OI in question was OI induced by exertion so we were talking exertional.
I don't see any value in insisting on delay if only because activities may be spread out over long enough for the problem to start while still exerting.

I agree that the fact that PEM is often delayed may be telling us something crucial about mechanism and it may also be a good diagnostic discriminator. But I think readers are going to get confused if they are told that PEM is only what we call delayed worsening.

From the mechanistic point of view, my current thought about how all this works would allow for worsening with and without delay to both be features of a more complicated picture. Some PEM may require cell migration and activation in tissue such as muscle, which may fit well with building up over 24-48 hours. But the same signalling mechanism could be activated straight away on other tissues such as lymph node where the right cells are already in place and just need to make some RNA or even just phosphorylate some proteins, which could take a few minutes.

 

Moore et al. 2023 did something interesting on that score - they told subjects to rest, and it seemed to work, in that they had less PEM before they did the first CPET than they did when initially assessed:

But of course even in that semi-rested state prior to CPET, their symptom/PEM scores were still high compared to controls (eyeballing it from the figure in my post above, about 4.5 for pwME compared to about 0.3 for controls on a scale of 0 to 10).

Here's what Moore et al. say about it in the discussion (my bolding):

 

I can see the potential confusion, of course. I spent years in PEM before I even realised it was delayed, and pre-internet—when patients very rarely got to talk to one another—that was probably common.

One of the things I'm trying to get clear in my head (and not succeeding) is whether we need more than one term, or if that would just make things worse.

Personally, I found Trish's descriptions of rapid fatiguability and PEM as different concepts really helpful, but of course I saw it through the eyes of an experienced ME/CFS patient. It might have been a lot less helpful before I'd understood PEM as a consequence of previous exertion—which is delayed, but can both catch up with itself and compound.