News from the Meeting: Day 2

By | March 24, 2011

Bill Mc Carberg, Chief of Kaiser San Diego’s Chronic Pain Program presented an interesting and thoughtful review of recent advances in the group of disorders we call fibromyalgia. He presented not only fascinating new tidbits of new basic science data, but also some of the proposed revisions to the diagnostic criteria for the syndrome as well as some personal insights gained from a lifetime caring for many of these patients.

He validated some of my own personal suspicions by referring to fibromyalgia as a spectrum of related disorders. I think that this fit well with the shared impressions of many in the audience. Fibromyalgia highly variable disorder which not only waxes and wanes, but seems to have a highly variable presentation not only with respect to different individuals but also with respect to the same individual over time.

While taxonomy is not my favorite medical discipline, I thought that as he reported, the newly proposed diagnostic criteria for fibromyalgia are a major advance. The diagnosis of fibromyalgia will now rest almost exclusively on the history, with the physical exam and laboratory investigations used merely to exclude other conditions. The reason that this is so exciting is that there are no characteristic physical or laboratory findings in fibromyalgia. Even the “classical” 18 tender points were a misnomer, because on any given day a fibromyalgia was just as likely to be tender somewhere else or perhaps everywhere else. Likewise routine rheumatologic blood tests are now discouraged in the work up of fibromyalgia patients because they will very often have minor, variable and evanescent abnormalities in their rheumatoid factors and antinuclear antibodies, which in the past have prompted expensive and unproductive workups to rule out lupus, Sjogren’s syndrome and the like. This testing is now recommended only if something in the history or physical findings suggest a particular rheumatologic condition and not part of an obligatory fishing trip.

The new research data was just as interesting. Functional MRI’s done of both normal volunteers and patients with fibromyalgia clearly showed identical patterns when both normal volunteers and fibromyalgia patients were exposed to painful stimuli. The key difference was that the fibromyalgia patients showed stimulus response curves which were consistently shifted to the left, demonstrating the hyperpathia, which we all have come to expect with this syndrome.

Chemical data was equally intriguing. Repeated studies have shown that endorphin levels in the cerebrospinal fluid of patients with fibromyalgia were consistently normal or elevated and the endorphin binding sites in the brain and spinal cord are occupied to a greater degree than in normal subjects. This clearly shows that fibromyalgia is a disorder of neural control and explains something that we have long know, namely that opioids are in general ineffective in this condition. Since the receptors are already fully occupied there is no reason that adding exogenous opioid agonists would produce a therapeutic result.

Finally data on cortisol metabolism helped explain some of the conflicting data on the value of exercise in these patients. Doctors and patients have long known that moderate exercise is helpful in maintaining function in this disorder, but that during exacerbations of the disease even mild exertion causes a worsening of the muscle pains. In normal patients exercise is accompanied by an increase in cortisol production, but in fibromyalgia cortisol levels either remain constant or decrease with exercise.

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