Inability to point to test-verified evidence of their pain or its cause has been a harsh reality for patients with Fibromyalgia and other pain syndromes. Aside from FM specialists, the medical profession and the public in general often do not believe that “pain can be very severe – and sometimes untreatable – in a person who does not seem to be injured,” observes FM expert Richard Gracely, PhD. 1
But that is changing with the emergence of sophisticated technologies supporting genetic and brain imaging analyses.
“There are now multiple, converging lines of evidence confirming that the pain of Fibromyalgia is ‘real’ and that there are strong neurobiological underpinnings to this condition,” write Richard E. Harris, PhD, and Daniel J. Clauw, MD, in a new review of recent research findings. Like Dr. Gracely, both of these FM experts are active in research at the University of Michigan’s Chronic Pain and Fatigue Research Center in Ann Arbor.2
Published in the December 2006 issue of Current Pain and Headache Reports, their report is titled “How do we know that the pain of Fibromyalgia is ‘real’?”3 And their conclusion is, it’s time for the medical community to “move past” speculation that FM may be a psychological issue and concentrate on understanding the condition’s cause(s) and mechanisms.
Further, this “state of the science” summary, which cites more than 44 studies, indicates: “There has been parallel recognition that many pain syndromes classically thought to be ‘ideopathic’ [of unknown cause], including for example irritable bowel syndrome, temporomandibular syndrome, tension headache, and idiopathic low back pain, share overlapping symptom expression and underlying mechanisms with Fibromyalgia.”
Following are some report highlights.
Evidence for a Decreased Pain Threshold; Males Under-Diagnosed
Studies have demonstrated definitively that FM patients have tenderness or decreased pain thresholds throughout their body – not just at the so-called “tender points.”
Pain research indicates these are points where everyone is more tender, and therefore they are useful to assess overall pain sensitivity. But interestingly, there is also evidence that the number of men with Fibromyalgia is likely much greater than currently believed, owing to a problem with use for diagnosis of the American College of Rheumatology “tender point” test guidelines, which do not take into account sex-based differences in sensitivity.
A major pain study found that women in general “are 10 times more likely than men to have more than 11 tender points on examination – and thus the overwhelming majority of males with chronic widespread pain will not meet criteria for Fibromyalgia (even though they likely have the same condition),” Harris and Clauw observe.
Studies indicate “a very strong genetic predisposition” for Fibromyalgia and related pain conditions. Many genetic “polymorphisms” associated with increased risk of various pain syndromes have to do with sensory processing. (By definition, a polymorphism is a genetic variant that appears in at least 1 percent of a population.)
For example, a study that tracked a population of initially pain free young women over time found that those who later developed temporomandibular disorder (TMD) had lower central pain thresholds than the other women at baseline. Additionally, they exhibited certain genetic polymorphisms that predicted both their baseline pain sensitivity and their development of TMD.
Taken collectively, according to Harris and Clauw, the human studies cited in this article – and many animal studies – “suggest that pain sensitivity is at least partially genetically determined.” They also indicate that pain sensitivity is both:
n A “trait” that is relatively stable over time,
n And a “state,” meaning that external factors can influence it.
Brain Imaging Corroborates Heightened Sensitivity
Various imaging technologies have enabled researchers to scan pain-related activation in the brains of FM patients versus healthy subjects, and identify differences.
For example, one study using functional magnetic resonance imaging (fMRI) subjected FM patients’ and control subjects’ thumbs to relatively slight and then purposely painful pressure. They found that the first application of pressure did not register at all in the pain processing parts of the control subjects’ brains. But in the FM patients, it registered as dramatically as did the painful one in normal subjects.
Another study involving increasing application of heat produced similar results. The brain response was consistent with what the FM patients had reported verbally, one of the reports commented.
Still other imaging studies show that pain affects the “mood centers” of FM patients’ brains differently than those of controls. And a series of studies employing SPECT scanning – which involves infusion of radioactive tracers – identified differences in blood flow/supply in pain-related parts of FM patients’ brains versus those of healthy subjects.
Overall, Harris and Clauw propose: “There are now overwhelming data suggesting that Fibromyalgia and a number of overlapping pain syndromes are characterized in part by augmented central nervous system processing of pain…. Future studies that focus on central neurobiological and/or genetic influences in Fibromyalgia may bring insight into mechanisms of this problematic disease and ultimately result in improved treatments.”
1. “Fibromyalgia Pain is Real – Brain Scan Proves What Sufferers Have Always Known,” WebMD Medical News, June 12, 2002.
2. Daniel Clauw, MD, is a Professor of Medicine in the Division of Rheumatology at the University of Michigan, and directs the University’s Chronic Pain and Fatigue Research Center (CPFRC); Richard E. Harris, PhD, is a member of the 25-member CPFRC research team; and Richard Gracely, PhD, is Co-Director. Their focus is on clinical care of and research into overlapping conditions such as FM, CFS, Gulf War Illnesses, and multiple chemical sensitivity. To review the CPFRC’s current FM-related clinical trials, visit http://www.med.umich.edu/painresearch/study/index.htm
3. An abstract of the article “How do we know that the Pain of Fibromyalgia is ‘Real’?" with author e-mail contact information is archived at http://www.immunesupport.com/library/showarticle.cfm/id/7517. Full text of the article may be purchased from the publisher, at http://www.current-reports.com/article_frame.cfm?PubID=PA10-6-1-01&Type=Abstract
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