Smit, A A, Bolweg, N M, Lenders, J W et al. · Nederlands tijdschrift voor geneeskunde · 1998
Some ME/CFS patients experience dizziness or fainting when standing up, and researchers wondered if this was due to problems controlling blood pressure. This review looked at four studies that tested this by having patients lie flat and then tilt them upright to see how their bodies responded. While some patients did show heart rate increases or fainting, many of these patients already had these symptoms before testing, making it unclear whether the problem is truly a core feature of ME/CFS or something else.
This review is important because it provides a critical appraisal of early evidence for a popular theory about ME/CFS—that blood pressure regulation problems are a core feature. By identifying methodological limitations and highlighting unanswered questions, it demonstrates the need for more rigorous research designs that can distinguish primary autonomic pathology from secondary effects of reduced activity.
This review does not establish that cardiovascular dysregulation is absent in ME/CFS, nor does it prove that orthostatic symptoms in CFS patients are caused by inactivity rather than autonomic dysfunction. The authors emphasize that the evidence base at that time was insufficient to determine whether abnormal tilt responses represent a disease mechanism or an association in a subset of patients with pre-existing symptoms.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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