Fibromyalgia Pain Isn ¹t All In Patients¹ Heads, New Brain Study Finds

[Guest guest]

Source:   University Of Michigan Health System

(http://www.med.umich.edu/1toolbar/whatsnew.htm)

Date:   Posted 6/7/2002

Fibromyalgia Pain Isn¹t All In Patients¹ Heads, New Brain Study Finds

ANN ARBOR, MI ­ A new brain-scan study confirms scientifically what

fibromyalgia patients have been telling a skeptical medical community for

years: They¹re really in pain.

In fact, the study finds, people with fibromyalgia say they feel severe

pain, and have measurable pain signals in their brains, from a gentle finger

squeeze that barely feels unpleasant to people without the disease. The

squeeze¹s force must be doubled to cause healthy people to feel the same

level of pain ‹ and their pain signals show up in different brain areas.

The results, published in the current issue of Arthritis & Rheumatism, the

journal of the American College of Rheumatology, may offer the proof of

fibromyalgia¹s physical roots that many doubtful physicians have sought. It

may also open doors for further research on the still-unknown causes of the

disease, which affects more than 2 percent of Americans, mainly women.

Lead authors Gracely, Ph.D., and Clauw, M.D., did the study

at town University Medical Center and the National Institutes of

Health, but are now continuing the work at the University of Michigan Health

System. In an editorial in the same issue, Clauw and U-M rheumatologist

Crofford, M.D., stress the importance of fibromyalgia research and

care.

To correlate subjective pain sensation with objective views of brain

signals, the researchers used a super-fast form of MRI brain imaging, called

functional MRI or fMRI, on 16 fibromyalgia patients and 16 people without

the disease. As a result, they say, the study offers the first objective

method for corroborating what fibromyalgia patients report they feel, and

what¹s going on in their brains at the precise moment they feel it. And, it

gives researchers a road map of the areas of the brain that are most ‹ and

least ‹ active when patients feel pain.

" The fMRI technology gave us a unique opportunity to look at the

neurobiology underlying tenderness, which is a hallmark of fibromyalgia, "

says Clauw. " These results, combined with other work done by our group and

others, have convinced us that some pathologic process is making these

patients more sensitive. For some reason, still unknown, there¹s a

neurobiological amplification of their pain signals. "

Further results from the study were presented last year at the ACR annual

meeting. The project will continue later this year at UMHS, joining other

fMRI fibromyalgia research now under way.

For decades, patients and physicians have built a case that fibromyalgia is

a specific, diagnosable chronic disease, characterized by tenderness and

stiffness all over the body as well as fatigue, headaches, gastrointestinal

problems and depression. Many patients with the disease find it interferes

with their work, family and personal life. Statistics show that far more

women than men are affected, and that it occurs mostly during the

childbearing years.

The ACR released classification criteria for fibromyalgia in 1990, to help

doctors diagnose it and rule out other chronic pain conditions. Clauw and

Crofford¹s editorial looks at the current state of research, and calls for

rheumatologists to take the lead in fibromyalgia care and science.

But many skeptics have debated the very existence of fibromyalgia as a

clearly distinct disorder, saying it seemed to be rooted more in

psychological and social factors than in physical, biological causes. Their

argument has been bolstered by the failure of research to find a clear

cause, an effective treatment, or a non-subjective way of assessing

patients.

While the debate has raged, neuroscientists have begun to use brain scan

technology to identify the areas of the normal human brain that become most

active during pain. A few studies have even assessed the blood flow in those

areas in fibromyalgia patients during baseline brain scans. The new study is

the first to use both high-speed scanning and a painful stimulus.

In the study, fibromyalgia patients and healthy control subjects had their

brains scanned for more than 10 minutes while a small, piston-controlled

device applied precisely calibrated, rapidly pulsing pressure to the base of

their left thumbnail. The pressures were varied over time, using painful and

non-painful levels that had been set for each patient prior to the scan.

The study¹s design gave two opportunities to compare patients and controls:

the pressure levels at which the pain rating given by patients and control

subjects was the same, and the rating that the two different types of

participants gave when the same level of pressure was applied.

The researchers found that it only took a mild pressure to produce

self-reported feelings of pain in the fibromyalgia patients, while the

control subjects tolerated the same pressure with little pain.

" In the patients, that same mild pressure also produced measurable brain

responses in areas that process the sensation of pain, " says Clauw. " But the

same kind of brain responses weren¹t seen in control subjects until the

pressure on their thumb was more than doubled. "

Though brain activity increased in many of the same areas in both patients

and control subjects, there were striking differences too. Patients feeling

pain from mild pressure had increased activity in 12 areas of their brains,

while the control subjects feeling the same pressure had activation in only

two areas. When the pressure on the control subjects¹ thumbs was increased,

so did their pain rating and the number of brain areas activated. But only

eight of the areas were the same as those in patients¹ brains.

In all, the fibromyalgia patients¹ brains had both some areas that were

activated in them but not in controls, and some areas that stayed " quiet " in

them but became active in the brains of controls feeling the same level of

pain. This response suggests that patients have enhanced response to pain in

some brain regions, and a diminished response in others, Clauw says.

The study was supported in part by the National Fibromyalgia Research

Association, the U.S. Army and the NIH. In addition to Clauw and Gracely,

the research team included Petzke, M.D.; and M. Wolf, BA. For

more information on fibromyalgia research and treatment at UMHS, visit

http://www.med.umich.edu/intmed/rheumatology/fmweb.