Though I completely agree that PEM is needed for a ME diagnoses and I believe it should be there for a diagnoses, im the one who just voted no. I'll explain why I say this and I have three situations in which you may not notice PEM.
situation 1 (start of this illness, before its a full time set in illness)
Firstly the first year or 6mths or so of my ME, I was like woolie just described. I didnt seem to have PEM at all. I was only getting ME flares with what could of been atribuated to late nights.
eg I'd crash and get sick if I'd stayed up late for several nights working on an assignment. So was I getting sick cause I had less sleep then normal? (Ive read hat that can really knock ones immune system around) was I getting sick due to stress of assignments? or did I get sick cause I worked hard studying? It wasnt obvious PEM though I was getting very sick.
Also for that first 6mths to a year, I had completely well times in between these bouts of what doctors were diagnosing as "an unknown virus" (they just diagnosed me over and over "you must of caught another virus". Till I pointed out that no one catches viruses that much over and over and over again. (it was the complete wellness in between the bouts which hid it was ME/CFS)
. Note physical exercise I was completely fine with till I'd had this illness for about a year (it was only assignments or study for exams which made me ill and put me in bed for up to a week, rest of time I was fine).
situation 2 (very severe ME cases, constant ongoing severe symptoms)
When I was completely bedridden with severe ME and extremely sick. I was very very sick all the time and couldnt do much at all. I was so constantly extremely sick. All I did most of the time for about a 9 month period was slept and only was awake about 20 mins a day to eat and drink so no noticable PEM,
I'd just wake up once a day and struggle to stay awake, it was so hard just to keep my eyes open and then eat a little and fall straight back asleep again. I went up to 3 days at a time without waking up at all in a comatose state, that couldnt be related to anything causing it as my whole state was constantly so bad.
situation 3 (POTS with ME)
POTS stopping one from being able to go into PEM. For PEM you often have to be doing a certain level of activity to trigger it. The amount of triggering activity is dependant on how bad your ME is. Now say you have developed severe POTS due to your ME and now cant do the amount of activity which usually causes your PEM (that's the situation I found myself in, could no longer do the on feet activities which caused me PEM).
Ive heard also one of the ME specialists talk about this about those with bad POTS with the ME not being able to go into PEM, so I know Im not the only one who has had times where I dont get PEM as I just cant do enough on my feet to get PEM
I do get symptoms if I push myself in a wheelchair eg sore arms and dizziness but those can go away quickly when I stop the exercise so I dont call those PEM. I cant push myself for long enough in the wheelchair to cause me actual delayed PEM as I get symptoms which stop me being able to do so fast eg arm pain by the time Ive pushed myself across a room or dizziness with the effort.
With my brain problems worst now though I get PEM from too much brain stuff even if I cant be on my feet enough at times to cause PEM.
So yeah, I definately do have ME and have sometimes got PEM but in some situations I do not with my ME and have gone through lengthy time periods without PEM so I know one can have this disease without obvious PEM
We NEED PEM though in our diagnostic criteria or otherwise too many will be wrongly diagnosed which can be dangerous if they have serious other issues.