On July 16, the Solve ME/CFS Initiative hosted a webinar with Dr. Peter Rowe, director of the Chronic Fatigue Clinic at Johns Hopkins Children’s Center, called, “Inducing Post-Exertional Malaise in ME/CFS: A Look at the Research Evidence.” Dr. Rowe has followed up with his responses to questions that were unable to be answered during the webinar due to time limitations. Given the number of questions posed, Dr. Rowe’s responses will be featured in a series of blog posts, beginning with this one.
Q: Has there been a study distinguishing PEM in CFS, controls and other fatiguing illnesses?
The VanNess study (Journal of Women’s Health 2010; 19: 239-44) quantified the duration of the exacerbation of key symptoms following a cardio-pulmonary exercise test to exhaustion in ME/CFS patients and healthy controls. An important finding of that study was that only 4% of the CFS patients felt like they had returned to their pre-exercise baseline after 48 hours, compared with 100% of the healthy patients. In fact, 60% of the ME/CFS participants took at least five days to return to their baseline level of function.
As described in the Institute of Medicine report (pages 80-81), studies show that PEM occurs with moderate frequency and intensity in only 2% to 7% of healthy individuals (Jason L.A., et al. Fatigue: Biomedicine, Health and Behavior 2013). PEM has been reported in adults with depression, but differences in the measurement of PEM in the various studies limit the validity of comparisons to ME/CFS.
Okamoto and colleagues compared the prevalence of Fukuda CFS symptoms among individuals with postural tachycardia syndrome (POTS) to those who had POTS and met the Fukuda criteria for the definition of CFS (CFS + POTS). In general, those with POTS who did not meet criteria for CFS had a similar range of Fukuda criteria, but at a lower level of severity. In the non-CFS POTS group, 80% reported severe fatigue, and slightly more than 40% of the non-CFS POTS group met study criteria for PEM. In the non-CFS POTS group, 80% reported severe fatigue, while slightly more than 40% met study criteria for PEM. A PEM prevalence of 40% is much higher than would be expected among healthy individuals, although still lower than would be expected for those meeting criteria for CFS. Those with CFS + POTS had a 75% prevalence of PEM.
Some ME/CFS studies have included controls with multiple sclerosis (MS). The response of those with MS to exercise differs significantly from those with ME/CFS. After exercise, ME/CFS individuals have greater and longer-lasting flares in pain, mental fatigue and physical fatigue than multiple sclerosis patients and healthy controls (White A.T., et al. Psychosomatic Medicine 2012; 74: 46-54).
Q: You clearly stated many studies that show the relation of PEM and CFS. Are there hopeful insights in research for a treatment of these symptoms that will improve the quality of life of patients?
I do not think anyone has identified a specific treatment for PEM itself. The absence of a specific PEM treatment, however, should not be taken as an indication that PEM is untreatable. In clinical practice, usually if we can find a way to improve general ME/CFS symptoms and function in an important way, PEM tends to improve as well. PEM might still be present as an individual gets better, but as improvement occurs, it takes a greater amount of exertion to trigger the same level of PEM symptoms.
Part of the challenge is that there appear to be several stimuli that can trigger PEM (e.g., exercise, cognitive challenges, orthostatic stress, neuromuscular strain). Reducing the intensity of PEM symptoms might require different treatments depending on which factor is the most impressive trigger for each person.
For example, take individuals who experience increased symptoms after orthostatic stress (prolonged standing, waiting in line) and who have one of the common orthostatic intolerance syndromes in ME/CFS (e.g., postural tachycardia syndrome or neurally mediated hypotension). Treatment directed at the orthostatic intolerance has been associated with overall improvement, better tolerance of exercise, and less severe PEM (Bou-Holaigah I., et al. JAMA 1995; 274:96 1-7).
For those with increased ME/CFS symptoms and PEM following application of a neuromuscular strain—as we find frequently in adolescents and young adults with ME/CFS (Journal of Pediatrics 2014; 165: 360-6)—we find that manual physical therapy can help improve overall function. The manual therapy attempts to normalize tightness and restricted limb and spine range of motion, or to reduce what physical therapists term adverse neural tension or neural tension dysfunction. Once the areas of nerve and soft tissue dysfunction improve, patients often tolerate exercise with less PEM. I would point out that those observations are based on our clinical experience, but have not been tested in a randomized clinical trial.