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Is fibromyalgia a discrete clinical entity? Is it a disease?

Discrete clinical entity (a term often used in the medical literature, usually without definition): "there is something specific and definable going on, involving a specific part of the anatomy, a particular pathological process, or a physiological function outside of healthy parameters. The term “disease” is best reserved for these specific entities." - Steven Novella

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If doctors/specialists today don't agree (as you know, since you've pointed out the controversy), what will qualify as an answer to this yes/no question? –  Geobits Jul 21 at 18:30
    
@Geobits Presentation of the best evidence, and a conclusion that is appropriately assertive or cautious or undecided. I also don't know that doctors and specialists today don't agree. I don't know that Wikipedia editors have chosen the most up-to-date information on the topic. I don't know that classification by those organizations is relevant. –  user5582 Jul 21 at 18:30
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@Articuno can you provide some examples of the claim being made? I am sure it's notable, but a one line question is hardly indexable by search engines, and also you could probably explain the terms "discrete clinical entity" in more common language for us mortals ;-) –  Sklivvz Jul 21 at 18:52
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A. Where is the claim exactly? B. Isn't this a question about definitions? which are out of scope. –  Ilya Melamed Jul 22 at 7:21
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@Articuno, if many people believe that, then you'll find an example with no problem. I didn't say that the question is about the definition of discrete medical entity, the question is about whether or not fibromyalgia falls under that definition, or some other definition, this is still off topic. –  Ilya Melamed Jul 22 at 8:51

3 Answers 3

No, it is not currently understood to be a discrete clinical entity; it is a clinical syndrome (2013):

Guidelines from three continents showed remarkable consistency regarding the clinical concept of FMS (fibromyalgia syndrome), acknowledging that FMS is neither a distinct rheumatic nor mental disorder, but rather a cluster of symptoms, not explained by another somatic disease. While FMS remains an integral part of rheumatology, it is not an exclusive rheumatic condition and spans a broad range of medical disciplines.


Source:

Mary-Ann Fitzcharles, Yoram Shir, Jacob N. Ablin, et al., “Classification and Clinical Diagnosis of Fibromyalgia Syndrome: Recommendations of Recent Evidence-Based Interdisciplinary Guidelines,” Evidence-Based Complementary and Alternative Medicine, vol. 2013, Article ID 528952, 9 pages, 2013. doi:10.1155/2013/528952

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This answer is based solely on consistency amongst guidelines... am I understanding that correctly? –  user5582 Jul 21 at 19:03
    
And if we take this source (Evidence-Based Complementary and Alternative Medicine) at face value, does that mean that fibromyalgia is not a discrete clinical entity or disease? –  user5582 Jul 21 at 19:30
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As I understand it, a syndrome is a set of symptoms without there necessarily being a single underlying aetiology. In that case its existence is more or less defined by the existence of commonly agreed guidelines for diagnosis and treatment. ME/CFS falls into this category, for example. It may (or my not) have different underlying causes, but does that mean it is not a "discrete clinical entity"? It depends on what you mean by clinical entity, in the case where the cause is unknown. –  Dikran Marsupial Jul 21 at 19:50
    
@DikranMarsupial Yes, that would mean CFS has not yet been shown to be a discrete clinical entity. Acceptance amongst physicians reflects that: informahealthcare.com/doi/abs/10.1300/… –  user5582 Jul 21 at 19:57
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@DikranMarsupial Agreed. This doesn't at all bear on the reality of the symptoms. –  user5582 Jul 21 at 20:09

I think this paper suggests "no", but I haven't had time to look further than the abstract yet.

Autoimmunity Reviews Volume 11, Issue 8, June 2012, Pages 585–588

Review Is fibromyalgia a discrete entity?

Jacob N. Ablina,
Dan Buskilab,
Boudewijn Van Houdenhovec,
Patrick Luytend,
Fabiola Atzenie,
Piercarlo Sarzi-Puttinie, , 

Abstract

Fibromyalgia (FM) is defined as chronic widespread pain (CWP) with allodynia or hyperalgesia to pressure pain, and is classified as one of the largest group of soft tissue pain syndromes. Its pathogenesis is not entirely understood, although it is currently believed to be the result of a central nervous system (CNS) malfunction that increases pain transmission and perception. There are no instrumental tests to confirm the diagnosis, but many of the differential diagnoses can be excluded by means of an extensive clinical examination and patient history. Although fibromyalgia is a recognisable clinical entity, it would seem appropriate to consider the entire range of tenderness and distress in clinic patients in order to tailor treatment on an individual basis.

http://www.sciencedirect.com/science/article/pii/S1568997211002382

quoting from the paper it says:

Take-home messages

• Fibromyalgia is defined as chronic widespread pain (CWP) with allodynia or hyperalgesia to pressure pain.

• The pathogenesis of FM is not entirely understood.

• FM is a disease with multi-symptoms, considered a stress-related disorder overlapping other ‘functional somatic’ syndromes.

• FM treatment requires an individualised, multimodal and multidisciplinary approach.

I can't see where it explicitly gives an answer, but the take home message clearly implies a "no" (especially the third point) as far as I can see.

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I agree with your interpretation of this one paper. Would be good to get a sense of where this stands amongst the entire body of research. It's pretty recent, so that's good as a starting point. –  user5582 Jul 21 at 20:12
    
I looked up the papers that have cited this one (only 12) on Google Scholar, but they don't seem to shed any more light. This one might be of some interest indirectly sciencedirect.com/science/article/pii/S1297319X08000353 but I really must go home! ;o) –  Dikran Marsupial Jul 21 at 20:16

One would be mistaken by thinking the name of a condition determines whether the biology has been fully established or not. For instance, Guillain–Barré syndrome, is still known as this, even though the biology is well known.

Fibromyalgia is a clearly recognised clinical syndrome for which the pathophysiology is gradually unravelling. Patients start out with normal pain perception, and move to a state of hightened pain perception along with a host of other changes. This may or may not respond to the usual treatment of aerobic exercise and cognitive based therapies, with so far, little good evidence for response to pharmacological agents ( though Naltrexone looks promising ).

Although the pathogenesis of fibromyalgia is not completely understood, research shows biochemical, metabolic, and immunoregulatory abnormalities. These substantiate the proposal that fibromyalgia can no longer be considered a subjective pain condition. [1]

There are a number of biological changes that can be detected:

The important biologic elements here include proinflammatory cytokines, the HPA axis, other neuroendocrine axes, and the autonomic nervous system. Growth hormone abnormalities are also thought to contribute to symptoms in fibromyalgia. [1]

There appears to be a genetic basis for fibromyalgia:

High-throughput genotyping is rapidly identifying a series of single-nucleotide polymorphism (SNP) haplotypes that influence neurotransmitter levels and receptor levels in the brain and thus contribute to the various abnormalities in pain processing.[30] Such SNP haplotypes constitute vulnerability elements in the development of fibromyalgia and other central sensitivity syndromes. [1]

A recent study using Resting-state functional-connectivity MRI is also interesting showing network disruption in CNS processing [2]

The study included 18 patients with fibromyalgia and 18 healthy individuals matched for age. They evaluated resting (intrinsic) connectivity in 3 brain networks: (1) the default mode network (DMN), which is most active at rest and is deactivated during performance of externally focused tasks; (2) the executive attention network (EAN), involved with cognitive processing of memory and attention; and (3) the medial visual network, which served as a control and is involved in processing visual information.

Fibromyalgia patients had greater connectivity within the DMN and right EAN and greater connectivity between the DMN and the insular cortex, a region of the brain that processes evoked pain. In addition, they found a direct link to ratings of self-reported spontaneous pain at the time of the scan and the extent of both right EAN and DMN connectivity to the insula.

According to the researchers, the findings "strongly implicate the insular cortex as being a key node in the elevated intrinsic connectivity in patients with fibromyalgia."

"The results of this study provide direct evidence of disrupted intrinsic connectivity within multiple brain networks in patients with fibromyalgia," Dr. Napadow and colleagues conclude. Their approach "represents a novel step forward in finding the neural correlates of spontaneous clinical pain," they add.

I think the difference between a disease and syndrome is often semantic, and doesn't contribute to management or understanding.


References:

[1] http://emedicine.medscape.com/article/329838-overview

[2] http://www.medscape.com/viewarticle/726425

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I think the difference is that until a thing has been determined to be a discrete clinical entity, research is spent trying to distinguish the various causes and pathways that are implicated so that if they are discovered to be different enough, they will be treated as separate diseases. Is that thinking incorrect? –  user5582 Jul 22 at 8:04
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Medical research never stops since we can never know enough about everything. Fibromyalgia is a distinct recognisable clinical entity for which the neuroendocrine basis is currently being unravelled. Whether you want to treat as separate diseases ( eg. CFS has similar underpinnings as do chemical sensitivity syndromes ) or a single disease with different manifestations depends on whether your're a lumper or a splitter. –  HappySpoon Jul 22 at 8:10
    
I did not suggest that research stops. I suggested that the nature of research might change. Regardless, this is just side discussion on the usefulness of the distinction. –  user5582 Jul 22 at 8:13

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