Dissecting the nature of post-exertional malaise, Hartle et al, 2021

A few weeks ago I filled out my disability tax credit form explaining ME and PEM, and how this affects my ability to perform my daily activities. I uploaded it and sent it to my GP for approval. She called and told me that she had difficulty understanding. So there you go, she read it, she listened and still doesn't understand. I kindly asked to to just sign and date it because it was a renewal and that the revenue agency have my records. It's a hit and miss scenario.

 

"My name is Megan Hartle and I’m currently a third-year pharmacy student, on track to graduate with a PharmD in 2023 from Drake University in Des Moines, Iowa. I first got involved with the Bateman Horne Center after my brother was diagnosed with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) in 2018. I reached out to the BHC hoping to get professionally involved in the ME/CFS community. I was very excited to learn more about ME/CFS, but I did not anticipate the impact this internship would have on me, or that I would become published in a year! [Here is a link to the paper, “Dissecting the Nature of Post-Exertional Malaise.”]"

https://batemanhornecenter.org/unexpected-impact/

 

There is no mention of delayed PEM.

I'm interested to know what medications the >10 years pwME took to recover from PEM?

My PEM has been consistent throughout 30 years, it has always been delayed, but has worsened from exercising ie OI

 

seems like some confusion over what pem is .as far as i am aware it is not the rapid fatiguability that occurs when doing something to me i think of pem as the very disabling increase in symptoms the following day that can last for days or weeks and may lead to a permanent reduction in my ability to take care of myself .

 

I agree with this distinction. PEM as described by @alktipping is a diagnostic feature of ME and of some at least with Long Covid. More rapid fatiguability occurs in many conditions and is significantly different to what people with ME understand by PEM.

Having said that it is worrying that a number of researchers while claiming to recognise the significance of PEM fail to understand this distinction.

 

I would say an increase in rapid fatiguability is a symptom of PEM, not PEM itself.

An increase in fatiguability has also been a symptom of a my ME becoming more severe even when not obviously in PEM (which doesn't necessarily mean I'm not in PEM though).

I'm still trying to work out the relationship between PEM and the severity of ME, like the chicken and the egg.....

 

You may be right @Invisible Woman, but I wonder if increased fatiguability is a symptom of the ME, and a contributory factor to triggering PEM, though distinguishing the two will complex as once PEM is triggered fatiguability is increased even more along with the other ME symptoms.

My reason for regarding increased fatiguability as distinct to PEM, is because you can have increased fatiguability in many other conditions where you don’t see PEM. The equating of the two in ME by some researchers and/or clinicians represents an ongoing failure to understand that ME is not just fatigue.

However, there may be logical and experimental problems in distinguishing the two if increased ‘increased fatiguability’ is always a consequence of PEM.

[added - is ‘increased fatiguability’ the best description of this phenomenon or might it rather be considered ‘reduced spare capacity’ or alternatively a ‘lowered activity or energy ceiling’?]

 

The fact that someone with ME can do something and feel fine and think it has been within their tolerance then collapse three days later is so unusual that concentrating on why it happens is the most important aspect of PEM.

The most clear cut, unique symptoms of a disease give the the greatest chance of finding useful information that can then be used for everyone.

In genetic diseases the faulty genes are discovered by looking at the most ill but the test can then be used to find less sick people.

 

Whereas historically with ME it has been studied by looking at the least ill.

 

It's so hard to pin it down.....

For me, the increase in fatiguability has a compound, perhaps exponential, characteristic that none of the descriptions quite describe.

It's not just the energy available or capacity is reduced by a certain %, nor is it that fatiguability increases by a certain factor (twice as fast say).

It's once you hit that invisible threshold then every single thing done beyond costs exponentially more.

It's like you're driving a car and realise you're running out of fuel but the nearest petrol station is uphill and it's closing soon so you have to accelerate....what happens to me kind of equates to how that scenario would affect my fuel consumption. I am sure there's a much better way to out it though!

 

I can't remember what's been written here previously but has there been any discussion about PEM being Orthostatic Intolerance?

 

Though OI interacts both with ‘fatiguability’ and PEM, I think the fact that we can see PEM triggered by cognitive activity would suggest that there is no simple equivalence between OI and PEM, as for some people at least it is possible to trigger PEM without being up right.

 

I have developed bad OI in the past few years and it is independent of PEM. Though one can influence the other of course.

 

My guess is that in some cases immediate 'PEM' might actually be OI or fatiguability, which are usually more immediate and feel distinctly different (drained, weak, lightheaded, etc) versus the delayed PEM (flu-like, poisoned, grotty). But it's hard to say, and I think some people get the flu-like, poisoned and grotty feeling pretty quickly.

Sensory stuff also starts quite quickly, compared to immune stuff (some severe patients have told me a 'crash' is different to PEM, because it is largely neurocognitive and sensory--they may be using more distinction with that term than others are, however). That might be something else again or it might just be part of PEM--e.g., if some signalling process is going wrong, the first signs of that might be sensory and neurocognitive, and then progress to more peripheral effects with time.

This is entirely unscientific, of course, without proper observation and long-term monitoring of patients to record these changes.

 

It might also be a sign of already being in significant PEM, which seems to reflect my experience. Activity when not in PEM often makes me feel great, though of course it doesn't last long.

I can only get any sense of where I am by starting to do something. If I can't push through my body's initial resistance fairly quickly (I hesitate to call it a warm-up when it's something as minimal as making breakfast, but in effect that's what it is!), I know I need to stop before I fall over.

If I can warm up okay, I can be confident that I'm not in deep PEM. I might still be in enough of a deficit to make myself really unwell, though, and it's impossible to know at the time what the outcome is going to be. This is the real conundrum, because I spend most of my time in this "batteries not fully charged, but not down to 10% either" state. I've never got anywhere near working out a way to establish whether I'm at 80% or 30%.*


*By this I mean 80% or 30% for an ME patient, not for a healthy person.

 

At times when my ME has been relatively mild, I find I can get quite high in situations where I find myself able to engage in unexpectedly increased activity levels. I have learned now to be cautious when in that state. However once in the Falklands I ended running up and down ‘mountains’ with very rocky steep slopes in a decidedly euphoric state, and was lucky I did not fall and break a leg or worse. [This is not normal behaviour for me as I used to do a lot of fell walking, and would never normally head off leaving my companions behind in such circumstances.] Obviously the next day I experienced PEM, though surprisingly not particularly high levels of lactic acid in the specific muscle groups involved.

I have heard others report similar experiences. I, with no evidence whatsoever, attribute it to endorphins being released at lower activity levels than normal because of previous inactivity.

This seems to contradict a deconditioning model of ME, though I have no idea if it could happen now when I have had continuous very low activity levels for some eight years.

[added - now PEM is triggered at such a low activity level, and my orthostatic intolerance so restricts how long I can remain upright, that I suspect I could not achieve the necessary activity levels to achieve this ‘endorphin’ high. I have only experienced this rarely and only when in periods of apparent spontaneous recovery.]

 

Yeah, I have felt that 'I feel great' thing in the short term. I think it's the endorphins. Then they wear off...

 

The immediate pathogenesis of PEM is immune related in my case (allergies or viral) and not from going over my limits. They both cause orthostatic impairment but at different levels.

Maybe immediate and delayed PEM are related in some way.

 

The marked contrast in how I feel when those endorphins (or possibly adrenaline? Or both?) kicks in makes it even harder to resist keeping going.

It feels so amazing to feel well, good even. It took a lot of self discipline to stop even when it started to dawn on me that there would be a hefty price tag.

I think it's one of the dangers to the newly ill who experience this & makes them more likely to buy in to pacing up or GET, especially as it can take such a long time to figure out the PEM pattern.