Orthostatic stress testing in myalgic encephalomyelitis/chronic fatigue syndrome patients with or without concomitant fibromyalgia: effects on pressure pain thresholds and temporal summation. — CFSMEATLAS
Orthostatic stress testing in myalgic encephalomyelitis/chronic fatigue syndrome patients with or without concomitant fibromyalgia: effects on pressure pain thresholds and temporal summation.
van Campen, C Linda M C, Rowe, Peter C, Verheugt, Freek W A et al. · Clinical and experimental rheumatology · 2021 · DOI
Quick Summary
This study tested how standing up quickly (which can trigger ME/CFS symptoms) affects pain sensitivity in ME/CFS patients. Researchers measured how much pressure patients could tolerate on their finger and shoulder before and after a tilt test. They found that ME/CFS patients became more pain-sensitive after the tilt test, meaning their bodies responded to pain more strongly than healthy people, and this effect was even more pronounced in those who also had fibromyalgia.
Why It Matters
This research provides objective evidence that physical stressors like orthostatic changes directly worsen pain perception in ME/CFS, supporting patient experiences of increased pain during symptom flares. Understanding these pain mechanisms may eventually help develop targeted treatments to reduce post-exertional symptom worsening, a hallmark of ME/CFS.
Observed Findings
ME/CFS patients with fibromyalgia showed significantly lower pressure pain thresholds both before and after tilt testing (finger: 2.0→1.5 kg/cm²; shoulder: 1.2→1.0 kg/cm²) compared to ME/CFS patients without fibromyalgia (finger: 5.0→3.3 kg/cm²; shoulder: 2.2→1.9 kg/cm²).
ME/CFS patients without fibromyalgia still showed significant decreases in pressure pain thresholds post-tilt compared to healthy controls.
Healthy controls showed no significant changes in pressure pain thresholds before and after tilt testing.
Windup (temporal summation) was significantly elevated in ME/CFS patients before tilt testing compared to healthy controls but did not change after tilting in either group.
Inferred Conclusions
Orthostatic stress negatively influences pain perception physiology in ME/CFS patients, similar to effects seen with exercise.
Concomitant fibromyalgia diagnosis further exacerbates pain perception abnormalities in ME/CFS patients.
Baseline pain sensitivity abnormalities (elevated windup) characterize ME/CFS but appear not to be acutely worsened by orthostatic stress in the immediate post-test period.
Remaining Questions
What are the specific neurobiological mechanisms by which orthostatic stress decreases pressure pain thresholds in ME/CFS?
Do these acute changes in pain perception persist beyond the immediate post-test period, or do they resolve over hours or days?
What This Study Does Not Prove
This study demonstrates correlation between orthostatic stress and decreased pain thresholds but does not establish the specific biological mechanisms causing this change. It also cannot prove that orthostatic stress is the primary driver of pain in ME/CFS, only that it acutely influences pain perception during testing. The findings may not generalize to other types of physical or cognitive stressors.
How do other common stressors (cognitive tasks, viral infection, sleep deprivation) compare to orthostatic stress in their effects on pain physiology in ME/CFS?
Can interventions that improve orthostatic tolerance (such as vasoactive medications or physical counterpressure maneuvers) prevent the post-tilt decrease in pressure pain thresholds?