Brain study hints at how fibromyalgia works

By Kathryn Doyle

NEW YORK (Reuters Health) - Brain scans show that people with fibromyalgia reacted differently from those without the pain disorder to non-painful sights and sounds in a small new study.

Researchers say the results suggest what might be going wrong in the nervous system and possible new approaches to alleviating patients' pain.

"If we understand the mechanism, we may come up with new and potentially better forms of treatment," said lead author Marina López-Solà of the department of Psychology and Neuroscience at the University of Colorado, Boulder.

The new results suggest not only that fibromyalgia is related to greater processing of pain-related signals, but also potentially to a misprocessing of other types of non-painful sensory signals that may be important to address during treatment, Lopez-Sola told Reuters Health by email.

She and her team used functional magnetic resonance imaging to assess brain responses among 35 women with fibromyalgia and 25 similar women without the disorder.

The researchers found that fibromyalgia patients were hypersensitive to non-painful stimulation compared to people without the disorder, they reported September 15 online in Arthritis and Rheumatism.

Researchers showed the subjects some colors, played some tones and asked subjects to perform very simple motor tasks at the same time.

Areas of the brain's cortex primarily responsible for processing visual, auditory and motor signals were significantly activated in the healthy comparison group, but not in the fibromyalgia group.

However, other brain regions that are not relevant for primary processing of sensory information, like the insula, which is involved with perception and motor control, and anterior lingual gyrus, which handles visual processing, were activated in fibromyalgia sufferers but not in healthy controls.

What seems to be happening is that the brains of fibromyalgia patients are under-processing certain forms of sensory information at the first stages of processing, but are also amplifying the signal at a later level of sensory integration of multiple sensory inputs, Lopez-Sola said.

"When you are in pain, it is probable that you are more concentrated on your own pain than on the tasks you have to pay attention to," said Dr. Pedro Montoya of the Research Institute on Health Sciences at the Universitat Illes Balears in Palma de Mallorca, Spain, who was not part of the new study.

Brain regions such as the insula are involved in the processing of bodily information and pain, he said.

"For me, these findings provide further support for the idea that psychological strategies aimed at changing the focus of attention from the body to external cues could be useful for these patients," Montoya said.

There were only a small number of people involved in the study, and the researchers did not account for other mental health conditions the participants may have had, both factors that limit the results, said Dr. Winfried Hauser, associate professor of Psychosomatic Medicine at Technische Universitat Munchen in Germany.

People with fibromyalgia often also have conditions like depression, so some people believe the pain disorder has a mental basis, said Michael E. Geisser, professor in the department of physical medicine and rehabilitation at the University of Michigan in Ann Arbor.

But evidence for an neuro-anatomical basis for fibromyalgia is growing, said Geisser, who was not part of the new study.

"There is increasing evidence that fibromyalgia is not just a pain condition," he told Reuters Health by email. "More recent research done on persons with fibromyalgia, such as the research by Lopez-Sola and colleagues, suggests that persons with fibromyalgia suffer from a central processing deficit of multiple types of sensory stimuli, not just pain."

"It's as if the volume control for sensation in persons with fibromyalgia is turned up, or louder, for many types of sensation compared to persons without the disorder," he said.

That might help explain why many people with fibromyalgia also often suffer from fatigue, cognitive problems or mood disturbance, Geisser said.

Further research to improve understanding of where there are problems in the brain for people with the disorder could lead to the development of new treatments, Geisser said.

For example, it would be interesting to see if a treatment targeted at dampening response in an area of the brain that "overreacted" in this study - like the insula - helped to treat fibromyalgia symptoms, he said.

SOURCE: http://bit.ly/1mbOikg

Arthritis Rheum 2014.

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