According to Jennie, “ME/CFS patients experience more than fatigue after exertion; we suffer from an exacerbation of all symptoms (including immune symptoms), and 'fatigue' is a completely inadequate word to describe the prostration and collapse.” She
writes:
Fourth, post-exertional malaise might occur in GWI. Appendix B of the report presents a combined summary of symptoms reported by veterans in the studies discussed in Chapter 3. Fatigue was reported by a median of more than 30% by Gulf War veterans. The fatigue category includes reports of “fatigue lasting 24h after exertion . . . problems with fatigue lasting more than 24 hours after having made a physical effort” (p. 116). Depending on how one defines and measures post-exertional malaise, these results could be interpreted to fit that term. ME/CFS patients experience more than fatigue after exertion; we suffer from an exacerbation of all symptoms (including immune symptoms), and “fatigue” is a completely inadequate word to describe the prostration and collapse. But will the IOM panel realize that? I think many researchers, even those working in the field, may perceive that PEM is a fatigue experience. If PEM is equated to fatigue lasting more than 24 hours after exertion – which is reported by Gulf War veterans – the argument that post-exertional malaise is unique to ME/CFS falls apart.
However, the descriptions of post-exertional prostration or collapse vary. The CCC describes the
tendency for other associated symptoms within the patient's cluster of symptoms to worsen during
Post-Exertional Malaise and/or Fatigue:
2. 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.
But symptom exacerbation, primarily in the neuroimmune regions, defines
Post-Exertional Neuroimmune Exhaustion (PENE) according to the ICC:
A. Postexertional neuroimmune exhaustion (PENE pen’-e): Compulsory
This cardinal feature is a pathological inability to produce sufficient energy on demand with prominent symptoms primarily in the neuroimmune regions. Characteristics are as follows:
1. Marked, rapid physical and/or cognitive fatigability in response to exertion, which may be minimal such as activities of daily living or simple mental tasks, can be debilitating and cause a relapse.
2. Postexertional symptom exacerbation: e.g. acute flu-like symptoms, pain and worsening of other symptoms.
3. Postexertional exhaustion may occur immediately after activity or be delayed by hours or days.
4. Recovery period is prolonged, usually taking 24 h or longer. A relapse can last days, weeks or longer.
5. Low threshold of physical and mental fatigability (lack of stamina) results in a substantial reduction in pre-illness activity level.
Such differences matter: “If PEM is equated to fatigue lasting more than 24 hours after exertion – which is reported by Gulf War veterans – the argument that post-exertional malaise is unique to ME/CFS falls apart.”
