Hulens, Mieke, Bruyninckx, Frans, Dankaerts, Wim et al. · Pain medicine (Malden, Mass.) · 2021 · DOI
Researchers found that small fluid-filled sacs called perineural cysts (Tarlov cysts) near nerve roots in the spine were present in 39% of patients diagnosed with fibromyalgia or ME/CFS—three times more common than in the general population. These cysts may irritate nerves and could potentially explain why some patients with these conditions experience widespread pain and fatigue. This finding suggests that fibromyalgia, ME/CFS, and symptomatic Tarlov cysts might share a similar underlying cause related to spinal fluid pressure.
This study offers a potential anatomical and physiological explanation for ME/CFS symptoms that goes beyond the central sensitization hypothesis, suggesting a treatable structural component may contribute to pain and fatigue in some patients. If validated, identifying Tarlov cysts could enable targeted clinical interventions and help differentiate ME/CFS patient subgroups with different underlying mechanisms.
This study does not prove that Tarlov cysts cause ME/CFS or fibromyalgia, only that they co-occur more frequently than in the general population. The cross-sectional design cannot establish causation, and the study does not demonstrate that treating the cysts resolves ME/CFS symptoms. Additionally, the lack of a matched control group limits the strength of prevalence comparisons.
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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Primary citation
Hulens, Mieke, Bruyninckx, Frans, Dankaerts, Wim, Rasschaert, Ricky, De Mulder, Peter, Stalmans, Ingeborg, et al. (2021). High Prevalence of Perineural Cysts in Patients with Fibromyalgia and Chronic Fatigue Syndrome.. Pain medicine (Malden, Mass.). https://doi.org/10.1093/pm/pnaa410
BibTeX
@article{mecfsatlas-hulens-2021-high-prevalence,
author = {Hulens, Mieke and Bruyninckx, Frans and Dankaerts, Wim and Rasschaert, Ricky and De Mulder, Peter and Stalmans, Ingeborg and Vansant, Greet and Bervoets, Chris},
title = {High Prevalence of Perineural Cysts in Patients with Fibromyalgia and Chronic Fatigue Syndrome.},
journal = {Pain medicine (Malden, Mass.)},
year = {2021},
doi = {10.1093/pm/pnaa410},
note = {PubMed: 33260218},
url = {https://www.mecfsatlas.com/evidence/hulens-2021-high-prevalence},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-28. https://www.mecfsatlas.com/evidence/hulens-2021-high-prevalence
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