Reductions in Cerebral Blood Flow Can Be Provoked by Sitting in Severe Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Patients.
Campen, C Linda Mc van, Rowe, Peter C, Visser, Frans C · Healthcare (Basel, Switzerland) · 2020 · DOI
Quick Summary
This study tested whether a simple sitting test could detect blood flow problems in the brains of severely ill ME/CFS patients. Researchers found that 90% of severe ME/CFS patients had significant drops in brain blood flow when sitting upright—dropping by about 24.5%—while healthy people's brain blood flow barely changed. This sitting test was easier to tolerate than standard tilt tests and could be useful for diagnosing blood flow problems in the most severely affected patients.
Why It Matters
This finding is clinically important because it provides a gentler, better-tolerated diagnostic test for orthostatic intolerance in severely ill ME/CFS patients who cannot complete standard tilt tests. The results validate that blood flow problems are a measurable, objective feature of ME/CFS and support the need for further investigation into vascular and neurological mechanisms underlying the disease.
Observed Findings
Seated cerebral blood flow was significantly lower in ME/CFS patients (474 mL/min) compared to healthy controls (627 mL/min).
ME/CFS patients showed a mean 24.5% reduction in cerebral blood flow when moving from supine to sitting, versus only 0.4% reduction in healthy controls.
Patients without orthostatic intolerance symptoms (10 patients) showed minimal CBF reduction (-2.7%), similar to healthy controls.
Patients with a prior POTS diagnosis had significantly greater CBF reductions (28.8%) than those without POTS (22.3%).
No significant differences in CBF parameters were found between patients with and without fibromyalgia.
Inferred Conclusions
A sitting test is sufficient to provoke clinically significant cerebral blood flow reductions in severe ME/CFS patients and may be an adequate diagnostic tool for orthostatic intolerance in this severely affected population.
The magnitude of CBF reductions during sitting in severe ME/CFS patients is similar to CBF reductions observed during head-up tilt in less severely affected patients, suggesting a spectrum of severity.
Orthostatic intolerance symptoms strongly correlate with abnormal CBF reduction during positional changes, and this test may help identify patients with this physiological dysfunction.
Remaining Questions
What is the underlying mechanism causing abnormal cerebral blood flow regulation in ME/CFS—is it vascular, neurological, autonomic, or multifactorial?
What This Study Does Not Prove
This study does not prove that reduced brain blood flow causes ME/CFS symptoms, only that the two occur together. It cannot establish whether blood flow abnormalities are a primary cause, a consequence of other physiological changes, or part of a broader dysautonomic process. The cross-sectional design prevents any conclusions about whether blood flow changes develop over time or vary with disease course.
How do cerebral blood flow reductions relate to specific ME/CFS symptoms and functional impairment, and do they predict treatment response?
Does the severity or pattern of CBF reduction change over time, and can it be used to monitor disease progression or recovery?
Are there interventions that can improve or normalize cerebral blood flow in ME/CFS patients, and would such improvements correlate with symptom improvement?