Understanding Fibromyalgia; How Experts are Diagnosing and Treating Their Patients - Episode 3

The Pathophysiology of FM

Published on: 
, , ,

Experts discuss the pathophysiology of fibromyalgia (FM) and how it relates to other chronic pain diseases.


Wendy Wright, DNP, ANP-BC, FNP-BC, FAANP, FAAN, FNAP: Like to segue if we can. Over to what is the actual pathophysiology. Can you speak about what- A, what are the risk factors or the triggers? What are- what is the pathophysiology of this condition? You said we now know, let's throw it out there and let's talk about it.

Daniel Clauw, MD: Well, being a female does increase one's risk of this condition. But one of the reasons that I and a lot of people like the new criteria that don't require a tender point count is that the new criteria are not nearly as biased towards identifying females as the old criteria. Women have a lot more tenderness and a lot more tender points. And the 1990 criteria fibromyalgia was 92% women. The 2010, 2016 criteria, it's more like a 2 to 1 ratio rather than a 9 to 1 ratio. You identify a lot more men, and that is important for providers to think of the diagnosis of fibromyalgia in men, because it used to be the case that people would just not even think of that label in a male patient.

Benjamin Natelson, MD: I should just jump in and say, what's happened over the years as the case definition for fibromyalgia has changed is that it has become more and more overlapping with another medically unexplained condition, chronic fatigue syndrome, which is the illness I started studying many years ago. And I don't see that as a benefit. I see a testable hypothesis, is chronic fatigue syndrome and fibromyalgia the same along in the similar illness spectrum, or are they different? And I've spent the last decade doing experiments to try to see whether they are the same or different.

Briefly, we've found many studies that are different between CFS. And I've had to do a mixed group of CFS and FM patients rather than FM alone, just because of the way my center was set up. But most recently, we've done a proteome study on spinal fluid in which we look to see whether CFS alone was different from CFS plus FM. And in that study, they overlap. For me, we still use the original 1990 case definition, which indeed does skew it toward women. We're not finding 9 to 1 in our center. We're finding maybe 3 to 1, but I continue to use that because it's quite separate from chronic fatigue syndrome, whereas the new case definition the old case definition explained, had a prevalence of what was it? 4% Dan. But with the new expanded case definition, it's more. For me, it remains a research question. And I like to use the 1990 case definition because it's very easy to apply, and it lets me separate those patients in some way from those with chronic fatigue syndrome alone. And there really are different treatments for the ones with FM and the ones who do not have FM.

Wendy Wright, DNP, ANP-BC, FNP-BC, FAANP, FAAN, FNAP: So, we heard that.

Daniel Clauw, MD: I did want to say, I don't agree with that. I think people should be using the new criteria. The old criteria are old because the reason we developed new ones is they weren't good. The prevailing view is that all of these are chronic overlapping pain conditions, really share pathophysiology and chronic fatigue is in there. But this would include irritable bowel, headache, vulvodynia, interstitial cystitis. Those are now all acknowledged or thought to be sort of the same. And again, there are a subset of people in whom the fatigue is a lot more prominent, and the pain is a lot less prominent and in whom the label, the CFS, is the appropriate label. We do tons of work, I get funded work in this, and the overwhelming sense is that these are a lot more similar than they are different. Of course, there's a little bit of difference between the people who have pain and the ones that don't. Pain pathways will become involved, but at the core, they really look very similar.

Benjamin Natelson, MD: That's where Dan and I disagree.

Daniel Clauw, MD: There's probably other areas, but that's the first one we'll identify tonight well.

Benjamin Natelson, MD: It's an area for research to understand. Some people say they're an effective spectrum of disease. And I mean, people make these statements and they're not data driven. I do agree with Dan, that we do need data, but for my position, it's still a research question. And I continue to use the 1990 case definition and the 1994 case definition for chronic fatigue syndrome. And then I can look at them, see if they overlap or they can be separated, and how are they the same or different?

Transcript edited for clarity.