The etiologic relation between disequilibrium and orthostatic intolerance in patients with myalgic encephalomyelitis (chronic fatigue syndrome). — CFSMEATLAS
The etiologic relation between disequilibrium and orthostatic intolerance in patients with myalgic encephalomyelitis (chronic fatigue syndrome).
Miwa, Kunihisa, Inoue, Yukichi · Journal of cardiology · 2018 · DOI
Quick Summary
This study looked at 44 ME/CFS patients to understand why they struggle to stay upright (orthostatic intolerance). Researchers found that balance problems—difficulty staying steady when standing with eyes closed—were common and seemed to make orthostatic intolerance worse. Patients with balance problems were more likely to have trouble completing a 10-minute standing test than those with only heart rate changes, suggesting balance issues may be just as important as blood pressure and heart rate problems in ME/CFS.
Why It Matters
This study identifies balance/disequilibrium as an underrecognized but clinically important factor in ME/CFS-related orthostatic intolerance, potentially explaining why some patients struggle more than others despite similar blood pressure or heart rate patterns. Understanding multiple contributing mechanisms to orthostatic intolerance could lead to more targeted, personalized treatment approaches and better patient stratification in future research and clinical practice.
Observed Findings
Disequilibrium (balance problems on tandem stance with eyes closed) was detected in 13 of 40 patients (32.5%) with orthostatic intolerance
100% of patients with disequilibrium reported standing intolerance symptoms vs. 87% without disequilibrium
46% of patients with disequilibrium failed to complete the 10-minute standing test compared to 3% without disequilibrium (p<0.01)
0% of patients with hemodynamic dysfunction alone (including those with postural tachycardia) failed the standing test, vs. 50% of those with disequilibrium alone
92% of patients with disequilibrium reported sitting intolerance symptoms vs. 58% without disequilibrium
Inferred Conclusions
Disequilibrium is a clinically significant contributor to orthostatic intolerance in ME/CFS patients, independent of hemodynamic dysfunction
Postural stability problems may be more predictive of OI-related disability than heart rate or blood pressure changes alone
Diequilibrium should be assessed and recognized as an important etiologic factor in ME/CFS orthostatic intolerance
Postural orthostatic tachycardia without disequilibrium appears less likely to cause functional test failure than previously appreciated
Remaining Questions
What This Study Does Not Prove
This study does not prove that disequilibrium causes orthostatic intolerance—it only shows they frequently occur together. The cross-sectional design cannot establish temporal relationships or determine whether balance problems are primary drivers of OI or secondary consequences of other ME/CFS pathology. The small sample and high female predominance limit generalizability to diverse ME/CFS populations.
Tags
Symptom:Orthostatic IntoleranceFatigue
Biomarker:Blood Biomarker
Method Flag:Weak Case DefinitionNo ControlsSmall Sample
What underlying neurological or vestibular mechanisms cause disequilibrium in ME/CFS patients?
Does disequilibrium precede orthostatic intolerance in disease course, or do they develop simultaneously?
Are there specific interventions (vestibular therapy, balance training, etc.) that could address disequilibrium and improve orthostatic tolerance in ME/CFS?
How do disequilibrium and hemodynamic dysfunction interact, and can they be present independently or do they share common etiologic pathways?