PEM discussion thread - post-exertional malaise

[Evergreen]

I think defining PEM only as a delayed crash is problematic. This is particularly important when PEM is rightly regarded as the core feature of ME/CFS and is often touted as a feature that contraindicates exercise therapies. If patients and clinicians are unsure early on whether they have ME/CFS or not, then they can endure years of unnecessary confusion, and do things that may be detrimental to their long-term health as @Utsikt described above.

This is my n=1: I’ve had plenty of instant PEM when I was gaslit into exercising 6-24 months post covid. I fully believed that I did not have PEM because it was not delayed. Nobody told me that I didn’t have PEM, they just told me that exercise would make things better.
In retrospect, it’s obvious that I had PEM, because it looked exactly like the often delayed PEM that I now experience when I’m unable to pace properly, 36 months post covid.

I think @richie put this well:

"ME needs PEM and PEM needs to be delayed" goes well beyond cohorting and may leave many patients int the netherworld of MUPS, thrown out of the ME boat into the hands of whom? If PEM is observably delayed in the majority of patients with ME diagnosis then it is reasonable to hypothesise that the delay is related to the overall ME biology but it may be that patients with similar biology simply present PEM in another way. That happens in many conditions.

Differences in the way individual's body works and the demands on them and how they manage their activity will all impact on how PEM manifests. E.g. I had crashes from onset, but when my ME/CFS improved to mild and I was able to work half-days, I did not get severe crashes like others describe, and like I had previously experienced. But I remember very clearly that even though there was variation in how I felt at the beginning of the day, every single day, I would start feeling awful every day at about 11/11.30am. I had to go to bed as soon as I got home from work. The exacerbation of symptoms started during the exertion, and continued for the rest of the day. Not calling that PEM doesn't make sense to me.

PEM during mild and moderate severity for me was mostly just feeling more crap following overexertion often for weeks or months. It didn't send me to bed like flu would. I wonder if it had, would I have deteriorated over time as I did? But again, if PEM is defined narrowly as completely incapacitating, then someone like me during that time could be considered as not having PEM.

PEM is a term created by clinicians listening to patients and discussing with other clinicians, and giving a name to a pattern of worsening way out of proportion to exertion their patients described. That pattern including a delay between the patient doing a bit more activity than usual, and getting much sicker a day or two later, and in many cases that lasted for days or weeks, and the amount of worsening would be way out of proportion to the exertion, which would have not caused any symptoms before the illness.

It is this observed pattern those doctors named PEM. And this pattern that more clinicians writing guidelines and definitions named PEM.

I'm not sure this is universally true.

This is from p.148 of the 2007 NICE guidelines - I thought it was a nice way of seeing how PEM was characterized in the 2000s:



The UK CMO 2002 report heavily emphasizes the delayed nature of PEM, but also acknowledges:

Younger patients do not always experience the delayed onset of symptoms after increased physical or cognitive activity, but they generally do have a prolonged recovery period after activity.

That alone suggests to me that the primary feature of PEM is not the delay, but the prolonged nature of it.

By contrast, the Canadian 2003 criteria, while being very clear that PEM is a core feature separate from fatigue, do not highlight delay nearly as much:

Post-Exertional Malaise and/or Fatigue: There is an inappropriate loss of physical and mental stamina, rapid muscular and cognitive fatigability, post exertional malaise and/or fatigue and/or pain and a tendency for other associated symptoms within the patient's cluster of symptoms to worsen. There is a pathologically slow recovery period-usually 24 hours or longer.

They go into more detail here:

The malaise that follows exertion is difficult to describe but is often reported to be similar to the generalized pain, discomfort and fatigue associated with the acute phase of influenza. Delayed malaise and fatigue may be associated with signs of immune activation: sore throat, lymph glandular tenderness and/or swelling, general malaise, increased pain or
cognitive fog. Fatigue immediately following activity may also be associated with these signs of immune activation. Patients who develop ME/CFS often lose the natural antidepressant effect of exercise, feeling worse after exercise rather than better. Patients may have a drop in body temperature with exercise. Thus fatigue is correlated with other symptoms,
often in a sequence that is unique to each patient. After relatively normal physical or intellectual exertion, a patient may take an inordinate amount of time to regain her/his pre-exertion level of function and competence. For example, a patient who has bought a few groceries may be too exhausted to unpack them until the next day. The reactive fatigue of post-exertional malaise or lack of endurance usually lasts 24 hours or more and is often associated with impairment of cognitive functions. There is often delayed reactivity following exertion, with the onset the next day, or even later. However, duration of symptoms also varies with the context. For example, patients who have already modified their activities to better coincide with the activity level they can handle without becoming overly fatigued will be expected to have a shorter recovery period than those who do not pace themselves adequately.

The International Consensus Primer, endorsed by many clinicians, does not emphasize delay either:

PENE: a pathological, low threshold of fatigability
• post-exertional exhaustion & symptom flare
- immediate or delayed, & not relieved by rest
• prolonged recovery period

Post- Exertional Neuroimmune Exhaustion (PENE pen-e)
Normal fatigue is proportional to the intensity and duration of activity, followed by a quick restoration of energy. PENE is characterized by a pathological low threshold of physical and mental fatigability, exhaustion, pain, and an abnormal exacerbation of symptoms in response to exertion. It is followed by a prolonged recovery period.

The 2021 NICE guidelines use the words "often" and "typically" to qualify delay in PEM, but do not qualify the disproportionate or prolonged nature of it at all:

Post-exertional malaise after activity in which the worsening of symptoms:
－is often delayed in onset by hours or days
－is disproportionate to the activity
－has a prolonged recovery time that may last hours, days, weeks or longer.

In my view, that's because the disproportionate and prolonged parts are the absolutely essential ones.

 

[Trish]

I would see it a bit more nuanced, but fair enough.

Yes, sorry, I'm not having a nuance sort of day.

 

[Utsikt]

@Evergreen thank you for putting so much relevant info together like that.

The 2021 NICE guidelines use the words "often" and "typically" to qualify delay in PEM, but do not qualify the disproportionate or prolonged nature of it at all:
In my view, that's because the disproportionate and prolonged parts are the absolutely essential ones.

I agree with this interpretation.

 

[Trish]

I do get that PEM is not just the delayed crash that puts people to bed in darkness and silence for weeks.

A question on how you interpret prolonged.

Someone who gets home from a half day at work, and has to lie down for an hour or two before getting dinner, and can do the same day after day. Is that prolonged enough to call it PEM?

If they go dancing one weekend night, need a lie in the next morning, but can get upand go out to lunch and go back to work on Monday as usual. Is that PEM?

 

[Trish]

What I'm trying to understand is if someone who needs the lie down after work, but can also increase their activity without crashing, are the getting PEM?

 

[Utsikt]

What I'm trying to understand is if someone who needs the lie down after work, but can also increase their activity without crashing, are the getting PEM?

Those people are at a much higher level of functioning, and it might be that PEM behaves differently at that point.

We’ve seen some studies that find differences between mild/moderate and severe (or worse). It might be that whatever PEM is, it behaves differently in bodies with an inherently different physiology.

I think that this might be a viable description of PEM:

The duration and intensity of the increase of symptoms is disproportionate to the exertion, and can not be explained by DOMS, deconditioning, etc.​

After all, some very few people with what looked like ME/CFS with PEM have improved from e.g. LP or GET. Most don’t improve or get worse, so it should not be recommended at all, but I don’t think we can claim that they didn’t have PEM just because they could tolerate increased activity.

 

[Trish]

When my ME was mild I had the experience described by others too of getting home from work and needing to lie down for an hour or two, and being able to go back to work day after day. But I also crashed every couple of months or so when I exceeded what I regard as my PEM limit and needed a week or more off work. For me the daily hour or two was not the same. There wasn't the extra symptoms that I got with PEM crashes, it was just my usual pain, exhaustion and OI that made me need to lie down. So did I have 2 different version of PEM, or was the milder daily version something else?

Others with mild to moderate describe having PEM lasting hours rather than days sometimes, and that includes the extra symptoms and being crashed out in bed. And the rest of the time they have the usual daily increase in exhaustion, brain fog or whatever.

It's such a complicated picture, with each of us having a different story.

In the end I think the main thing is to include everyone who gets disproportionate worsening after activity at a level they easily coped with before they were ill, and that worsening isn't just the aching and tiredness that healthy people get after exercise, it's feeling much more ill and having to stop for hours or longer.

 

[Utsikt]

In the end I think the main thing is to include everyone who gets disproportionate worsening after activity at a level they easily coped with before they were ill, and that worsening isn't just the aching and tiredness that healthy people get after exercise, it's feeling much more ill and having to stop for hours or longer.

Yeah, I think this is what PEM is. And then we could possibly give reports of how different people experience it. But very briefly, like ‘often delayed’, ‘from stimuli’, etc

 

[Evergreen]

A question on how you interpret prolonged.

Someone who gets home from a half day at work, and has to lie down for an hour or two before getting dinner, and can do the same day after day. Is that prolonged enough to call it PEM?

From that info alone, I don't think you could definitively say, that is or isn't PEM. But you could say, that's not normal. If I read about someone with anaemia or back pain or post-surgery having to do that, I would think nothing of it - they're fatigued. For what it's worth, for most of the time I was able to work half-days, I was only able to heat up meals in the microwave, and would not have been able to do anything like look after kids had I had any.

If you had more info, e.g. that this is a person who has improved from moderate ME/CFS following an infection to this level, and who used to be bedbound for a week after medical appointments, but has been managing to work half-days for 3 years now without having to reduce activities outside work and without unbearable symptoms...then I would say, yes, that's PEM, in a nice mild form, but still completely life-changing.

If they go dancing one weekend night, need a lie in the next morning, but can get upand go out to lunch and go back to work on Monday as usual. Is that PEM?

I would say needing a lie-in after a night of dancing is normal.

What I'm trying to understand is if someone who needs the lie down after work, but can also increase their activity without crashing, are the getting PEM?

Yeah, I think you could argue they are if you had the "more info" I talked about above, but it's mild and improving ME/CFS, the stuff of dreams for people with more severe ME/CFS, but the stuff of nightmares for healthy people.

 

[Peter T]

Those people are at a much higher level of functioning, and it might be that PEM behaves differently at that point.

For me, even when I was mild, PEM would be delayed, involve the full flue like symptoms and send me to bed for two weeks or more.

We lack good descriptive data with concrete measures of activity as well as the subjective experiences to identify what patterns there are and what percentage of people have what experiences.

I personally do not regard having to lie down for a couple of hours after work then feeling fine as PEM, I see it as the chronic fatigue or even exhaustion and rapid fatiguability that is part and parcel of every day ME/CFS, I only see it as PEM when it behaves qualitatively different to normal fatigue/tiredness.

A lot of the time we can not unambiguously say what is PEM and what is not PEM, and will not be able to until we get to the point where we can describe the different physiological process happening. However if some one does not experience the delay, the symptoms unrelated to the exertion, never experiences ongoing deterioration and delayed recovery regardless of rest, this may be part of the ongoing horrors of ME/CFS, but I would hesitate to currently label it as PEM.

 

[Mij]

If they go dancing one weekend night, need a lie in the next morning, but can get upand go out to lunch and go back to work on Monday as usual. Is that PEM?

I don't know how to answer this but I experienced this for 11 years after onset during the time period. I didn't have symptoms of delayed PEM. As long as I got adequate rest for 2-3 days in between activities I was ok and back to my 'normal'. I was able to control my activities because I didn't work or have other obligations.

PEM is a cumulative effect so I most likely would have 'crashed' if I continued to go over my limit. So yes, I would say it was early signs of PEM.

To add, I also experienced flu-like symptoms like Peter describes during that time. But I no longer have flu-like symptoms during PEM for the last 22 years.

 

[Utsikt]

To add, I also experienced flu-like symptoms like Peter describes during that time. But I no longer have flu-like symptoms during PEM for the last 22 years.

This is why it’s so difficult to learn to judge your threshold, because the symptoms and warning signs can change.

 

[Mij]

I was only able to figure it out when my symptoms stabilized through trial and error. It took YEARS to figure out though.

 

[JemPD]

Hi sorry when i clicked on this thread it took me to page 6 meaning i must have read pages 1-5 at some point but have no recollection of doing so & no strength to go over it again, so please forgive me if i repeat anyone, even myself lol! Also after reading a bit i couldnt continue past beginning of page 7, so apologies if the converstation has moved on, but i started writing this & didnt want to waste the effort once written. Pls forgive me if it irrelevant now!

In my personal opinion (I might not be correct at all), we should say that it is reported that it can often be delayed.

So something like this (changes in red):

Patients with PEM report that it can (list is not exhaustive yet):

• Often be delayed by up to multiple days
• Have a gradual or instant onset
• Last for up to days, weeks and months
• Also be triggered by stimuli or sensory overload
• Not be alleviated by rest

well to me, the use of the word 'can', precludes it being 'always' on its own (ie without the addition of a qualifier such as 'often')... Otherwise it would say patients report that it 'is'.

So in your example I think saying that patients report that it is

often delayed etc etc

or

that we say that it can be

delayed etc etc



I also question whether specifying that patients 'report' it neccessary.... We have no biomedical evidence, so pateint reports are all we have. Seems redundant to me.

I get the need to make it clear that it's not always delayed without absolute certainty, thats certainly important. But either we say that patients report that PEM can be delayed, or we say that it's often delayed. And I think the latter is better because it seems more common - at least from every patient report i read.

And most importantly I dont think most healthy people have problems understanding feeling rotten immediately after doing something. So while we need to make sure we dont use language that means someone like yourself @Utsikt rules out their immediate uptick in symptoms being PEM, I dont think it would be accurate or helpful to make it seem as though it's just as likely to be immediate as delayed.

-------------------------------------

One thing i will mention, that i did learn over my more mild/moderate yrs back 10yrs or so ago, is that the PEM that at the time i thought was immediate (after some exertion or other), actually wasnt.

It was actually delayed PEM from the effects of culmulative but small (so not noticed individually) over-exertions, that had happened during the previous few days. And then i'd go & do the final small over-exrt, & would crash either immediately after, or even during that exertion.
(I didnt know then that the cumulative effect of multiple small seemingly innocuous things still came out of the overall 'weekly exertion budget')

When this happened my mother & I would puzzle over how 3 wks previously I'd done that same exertion & not crashed because of it, without realising that it was actually the culmination of the smaller less noticable things that I was having a delayed reaction to, rather than the one that seemed implicated in the seemingly 'immediate' onset crash.

I mean obviously i cant guarantee that was/is the case but it certainly became what seemed like a recognisable pattern which only started to appear/make sense once i read someone somewhere talking about the cumulative effect of things over a wk or a month etc.


I'm not suggesting that as an explanation for anyone elses experience of immediate PEM
Am only mentioning it just as an addition to add to the general discussion, while its in my mind. In case it useful to anyone

Edit:I hope that al makes sense. It took me all day to write it sory if not pls ignore

 

[Kitty]

One thing i will mention, that i did learn over my more mild/moderate yrs back 10yrs or so ago, is that the PEM that at the time i thought was immediate (after some exertion or other), actually wasnt.

It was actually delayed PEM from the effects of culmulative but small (so not noticed individually) over-exertions, that had happened during the previous few days. And then i'd go & do the final small over-exrt, & would crash either immediately after, or even during that exertion.

Yup, important points. I went on much the same journey!

It took a long time to work it out. What forced me to really think about it was when I crashed badly after going to the petrol station to top the car up, and collected milk and cat food while I was there. I was still relatively mild, so going face down for a week after a 25-minute excursion to a location half a mile away—which I drove, not walked—was ridiculous.

It had almost nothing to do with it, of course. I was still working back then and my friend had broken her leg, so I'd been giving her lifts and helping her with stuff too.

 

[Utsikt]

I’ll add some brief comments to explain my wording and current opinion (which might be wrong or inaccurate). Bolding is mine.

I also question whether specifying that patients 'report' it neccessary.... We have no biomedical evidence, so pateint reports are all we have. Seems redundant to me.

I believe ‘report’ is essential to include exactly because we don’t have definitive studies. We can’t risk giving off the impression that the descriptions of PEM are based on ironclad evidence.

And most importantly I dont think most healthy people have problems understanding feeling rotten immediately after doing something. So while we need to make sure we dont use language that means someone like yourself @Utsikt rules out their immediate uptick in symptoms being PEM, I dont think it would be accurate or helpful to make it seem as though it's just as likely to be immediate as delayed.

That was the intention behind ‘often’. I take often to mean at least 50 % of the time. I don’t think we have good data here, and I don’t think we’ll strengthen the factsheet if we try to give a more exact estimate.

I mean obviously i cant guarantee that was/is the case but it certainly became what seemed like a recognisable pattern which only started to appear/make sense once i read someone somewhere talking about the cumulative effect of things over a wk or a month etc.

The key is that we simply don’t know if PEM is instant or delayed or accumulative. As you say, it can certainly seem one way or another, but it could just as well be correlation and not causation. Which is another reason for including ‘report’ for accuracy. And it’s why I think we should cover all three options.

 

[JemPD]

I’ll add some brief comments to explain my wording and current opinion (which might be wrong or inaccurate). Bolding is mine.

I believe ‘report’ is essential to include exactly because we don’t have definitive studies. We can’t risk giving off the impression that the descriptions of PEM are based on ironclad evidence.

That was the intention behind ‘often’. I take often to mean at least 50 % of the time. I don’t think we have good data here, and I don’t think we’ll strengthen the factsheet if we try to give a more exact estimate.

The key is that we simply don’t know if PEM is instant or delayed or accumulative. As you say, it can certainly seem one way or another, but it could just as well be correlation and not causation. Which is another reason for including ‘report’ for accuracy. And it’s why I think we should cover all three options.

Oh.
Yes, all very good points.

So good, that i now consider my post, that took me all day, redundant. LOL

 

[Kitty]

The key is that we simply don’t know if PEM is instant or delayed or accumulative.

Yes and no. It partly depends what form it takes, and what individuals mean by "PEM".

I've never developed the symptoms of what I call PEM until after I've slept. I wake up with the swollen neck glands and all the rest of the 'flu-like symptoms, they never appear shortly after I've done something challenging.

If I've gone a long way over my threshold I often don't sleep at all, which means those symptoms won't start until the following day (so a 48-hour delay). The most logical inference you could draw by looking at my symptom pattern is that it's caused by sleep. It probably isn't—it's more likely to be the time course that matters—but it looks like that.

If it hasn't developed in this way and it doesn't begin with visible symptoms of acute illness, it's not what I'd describe as PEM.

Maybe it'd be useful to drill down into what others mean by it? We've probably got half a dozen different definitions.

[Minor edit]

 

[Eleanor]

One thing i will mention, that i did learn over my more mild/moderate yrs back 10yrs or so ago, is that the PEM that at the time i thought was immediate (after some exertion or other), actually wasnt.

It was actually delayed PEM from the effects of culmulative but small (so not noticed individually) over-exertions, that had happened during the previous few days. And then i'd go & do the final small over-exrt, & would crash either immediately after, or even during that exertion.
(I didnt know then that the cumulative effect of multiple small seemingly innocuous things still came out of the overall 'weekly exertion budget')

When this happened my mother & I would puzzle over how 3 wks previously I'd done that same exertion & not crashed because of it, without realising that it was actually the culmination of the smaller less noticable things that I was having a delayed reaction to, rather than the one that seemed implicated in the seemingly 'immediate' onset crash.

Important point, and it's something the 'fatigue clinics' don't get at all when they tell people to do 'activity planners' - you can't just allocate a certain amount of effort to a particular activity, because it will take more out of you when you've been overstretched in other ways.

 

[Utsikt]

Oh.
Yes, all very good points.

So good, that i now consider my post, that took me all day, redundant. LOL

It’s certainly not redundant! It’s very valuable to get to check the logic - and I have no guarantee of being right just because it makes sense to me. If someone else asks ‘what about this’, we can both say that it has already been addressed. That process is what gives the end results its value.