High Prevalence of Perineural Cysts in Patients with Fibromyalgia and Chronic Fatigue Syndrome, Hulens et al, 2020

John Mac

John Mac

Senior Member (Voting Rights)
Abstract
Objective
Pain in fibromyalgia (FM) and chronic fatigue syndrome (CFS) is assumed to originate from central sensitization. Perineural cysts or Tarlov cysts (TCs) are nerve root dilations resulting from pathologically increased cerebrospinal fluid pressure.
These cysts initially affect sensory neurons and axons in dorsal root ganglia and produce sensory symptoms (pain and paresthesia).
Symptomatic TC (STC) patients often complain about widespread pain and fatigue. Consequently, STC patients may initially be diagnosed with FM, CFS, or both.
The objective of this study was to document the prevalence of TCs in patients diagnosed with FM or CFS.

Design
A retrospective study.

Setting
An outpatient clinic for musculoskeletal disorders.

Subjects
Patients diagnosed with FM according to the 1990 American College of Rheumatology criteria or with CFS according to the 1994 Centers for Disease Control criteria were selected.

Methods
Review of lumbar and sacral magnetic resonance imaging scans including TCs ≥5 mm in size.

Results
In total, 197 patients with FM, CFS, or both underwent magnetic resonance imaging. Ninety-one percent were women.
The mean age was 48.1 (±11.9) years.
TCs were observed in 39% of patients, with a mean size of 11.8 (±5.2) mm.
In males, the prevalence was 12%, vs. 42% in females.

Conclusions
In patients diagnosed with FM or CFS, the prevalence of TCs was three times higher than that in the general population.
This observation supports the hypothesis that STCs, FM, and CFS may share the same pathophysiological mechanism, i.e., moderately increased cerebrospinal fluid pressure, causing irritation of neurons and axons in dorsal root ganglia.
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https://academic.oup.com/painmedicine/advance-article-abstract/doi/10.1093/pm/pnaa410/6015822
 
FMMM1 said:
I'm just wondering if we could get views from @Jonathan Edwards @Snow Leopard --- on this publication.
Thanks in advance.
Click to expand...

I don't think adds up:

This observation supports the hypothesis that STCs, FM, and CFS may share the same pathophysiological mechanism, i.e., moderately increased cerebrospinal fluid pressure, causing irritation of neurons and axons in dorsal root ganglia.

No it doesn't. The cysts occur mostly in the sacral roots as I understand it. So cysts do not explain 95% of the features of FM or CFS - in arms, head, gut, etc.. If they do not explain 95% they probably do not explain 100%. I doubt that the cysts have much to do with increased pressure anyway. They are probably a local stretch phenomenon - a bit like crowsfeet round the eyes or housemaid's knee.

This looks like another advert for quack interventions I am afraid.
 
Jonathan Edwards said:
I don't think adds up:

This observation supports the hypothesis that STCs, FM, and CFS may share the same pathophysiological mechanism, i.e., moderately increased cerebrospinal fluid pressure, causing irritation of neurons and axons in dorsal root ganglia.

No it doesn't. The cysts occur mostly in the sacral roots as I understand it. So cysts do not explain 95% of the features of FM or CFS - in arms, head, gut, etc.. If they do not explain 95% they probably do not explain 100%. I doubt that the cysts have much to do with increased pressure anyway. They are probably a local stretch phenomenon - a bit like crowsfeet round the eyes or housemaid's knee.

This looks like another advert for quack interventions I am afraid.
Click to expand...

Thanks @Jonathan Edwards seemed (to me) to be an interesting hypothesis since my wife has syringomyelia (voids in the spinal column caused by excess pressure) and one of our children has severe (i.e. disabling) fatigue.
Probably any theory which is attractive/resonates should be treated with caution - How to Make the World Add Up (Tim Harford) - Beware of your emotions [https://www.bbc.co.uk/programmes/m000q3d5]
 
FMMM1 said:
I'm just wondering if we could get views from@Snow Leopard --- on this publication.
Thanks in advance.
Click to expand...

I don't know what to make of this, the fact that they were only found in 39% of patients suggests this isn't the cause we're looking for. But it could be an epiphenomena.

The typical cause is injury or age, but any increased incidence may reflect impaired healing in the patient group.

https://en.wikipedia.org/wiki/Tarlov_cyst
The Mayo clinic claims hat Tarlov cysts are unusual and hence cannot be a major cause of lower back pain. But this argument seems circular, since it is not often looked for in back pain paitients.

I guess it is possible that people suffering from these cysts may be misdiagnosed, particularly with Fibromyalgia (since the predominant symptom is pain) but I think any misdiagnosis of ME or CFS would be the result of well, misapplying the criteria... CFS is not a pain condition, so...
Keeping that in mind, the patients were recruited from a Leuven outpatient clinic and hence there are significant participation biases. Mean age of the patients was 48 years old, and 91% were women.

The authors speculate about the association:
The high prevalence of TCs in FM and CFS suggests a link between STCs and FM and/or CFS. Possible pathophysiological mechanisms are central sensitization, moderately or intermittently increased cerebrospinal pressure, the particular characteristics of the blood–nerve barrier in the dorsal root ganglia, and axonal mechanical sensitivity.
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These mechanisms remain hypothetical. (though notably, they state "central sensitization still lacks scientific confirmation", I wonder if they had to add the suggestion of central sensitisation to please reviewers)
I do find the axonal mechanical sensitivity discussion intriguing in itself. However the authors seem to insist that the primary problem is likely due to increased cerebrospinal fluid pressure.

I did not know that this is another cause of foot-drop (a symptom that I have experienced as part of AFM.)
This was the cited study that noted the treatment of 213 patients with Symptomatic Tarlov Cysts:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4752851/
 
I'm revisiting this I think the proposed pathogenic mechanisms "Possible pathophysiological mechanisms are central sensitization, moderately or intermittently increased cerebrospinal pressure, the particular characteristics of the blood–nerve barrier in the dorsal root ganglia, and axonal mechanical sensitivity." are incorrect but the overall finding is still intriguing.

Well central sensitization would be an effect rather than a cause.

I wonder if this is just a side phenomena of another process...
 
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