Sunday, June 9, 2013

Fibromyalgia - a changing concept

During the 1980ies rheumatologists saw more patients being referred to them with chronic joint pain, morning stiffness, and sleep disorders. The rheumatologists saw other symptoms as well, but these three were the reasons, why general practitioners or orthopedists referred these patients - they thought it could be an auto inflammatory rheumatic disease. But the patients didn't test for inflammation. As we now know body pain can be present without tissue damage, but back then this idea was just emerging.

The early definitions of the fibromyalgia syndrome differentiated joint pain and tender points, and therefore looked at fibromyalgia from a peripheral perspective. The 1990 ACR criteria looked like this:
• Pain in both sides of body, above and below the waist and in the C,D or L spine for at least 3 months
• Pain from pressure applied with approx 4 kg/cm2 in 11/18 specified points
• No other cause of the pain (Wolfe F, Smythe HA, Yunus MB et al, Arthritis Rheum 1990; 33:160-172). To sum it up, these criteria only included pain and localized tenderness.
This set of criteria was classificatory and not diagnostically, as patients with the diagnosis fibromyalgia were classified in fulfilling these criteria or not. The 1990 ACR criteria were established for scientific reasons, to include a more homogenous group of patients in studies. But the ACR criteria were soon used as a diagnostic tool - and I must admit that I did so, too, during the 1990ies. L. Crofford answered a question at one ACR annual meeting, quoted from memory: "If the ACR criteria are met, you can assume that it is fibromyalgia." It might be so in most of the patients, but still there's room for discussion - according to the knowledge we have today.
The 1990 ACR fibromyalgia criteria enabled scientist to start studying the disease. In this process the importance of symptoms other than pain became evident. These symptoms like fatigue, depressive mood (fibro blues), cognitive changes (fibro fog) or somatic symptoms like tension-type headaches are forming the disease as well as pain. Neuroendocrinal, neurophysiological, and neuroimaging studies contributed to understanding of fibromyalgia as a dysregulation of pain processing.
Multiple symptoms and different levels of symptom expression in the individual patient contribute to the problem of lots of physicians to accept fibromyalgia as a disease. Here is a list of possible symptoms:
• pain / widespread pain
• allodynia
• stiffness / morning stiffness
• fatigue
• cognitive changes
• mood disorder (depressive symptoms)
• anxiety
• sleep disturbance / no restorative sleep
• restless legs syndrome
• psychological stress
• swelling (sometimes subjective, but often not, but not suggestive of rheumatoid arthritis)
• numbness
• and so on.
Fibromyalgia isn't a primary psychogenic condition, but depression might develop in the course of the disease as in any chronic condition. Here we come close to the hen and egg problems, but nevertheless this problem leads us to the question: what causes fibromyalgia?
There might be genetic factors as fibromyalgia aggregates in families. Genes that control serotonin, dopamine, or other catecholamine metabolism might be included, but so far genetics can't explain the disease.
Psychological and stress-related factors are contributing to the development of fibromyalgia. Depression and anxiety are present in 30% to 80% of patients, so depression isn't a necessary factor in the individual patient - some physicians have the wrong idea, if there's no depression it can't be fibromyalgia.
The current debate is on neurological versus somatoform disorder. I'd rather see a connection between both concepts, but for the time being it is undecided. There's lots of evidence that central (pain) sensitization is at the core of fibromyalgia. Constant pain shapes central pain processing structurally and functionally (spinal hyperexcitability, changes in thalamic and cortical pain matrix, and impaired function of normal descending inhibitory mechanisms - Fitzcharles and Yunus).

Fibromyalgia is an entity with characteristic features and a neurobiological basis. Though you might read yourself through a plethora of despair on the net, when it comes to therapy of fibromyalgia, a favorable outcome is possible. Fibromyalgia patients, who do well, have set up realistic goals, are physically active, and hardly use medications. Treatment strategies that use a multimodal approach (behavioral therapy plus exercise plus more) are effective though greater studies still have to be completed as to ascertain, who is benefiting the most.

Related links:
Mary-Ann Fitzcharles and Muhammad B. Yunus: The Clinical Concept of Fibromyalgia as a Changing Paradigm in the Past 20 Years.  
Fibromyalgia and a New Paradigm?  

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