November 6, 2013
Fibromyalgia Linked to Altered Brain Signals For Pain
Rebekah Eliason for redOrbit.com – Your Universe Online
A new study has found hyperalgesia may be a responsible contributor for increased pain sensitivity in fibromyalgia patients. Hyperalgesia is a condition that causes a disruption in the brain signals for reward and punishment. These findings suggest a link between this altered brain process and widespread pain that is resistant to opiod therapy, the use of morphine and its derivatives, in people with fibromyalgia.
The chronic condition of fibromyalgia is a musculoskeletal syndrome. It is characterized by widespread joint and muscle pain but symptoms often include fatigue, sleep disturbances and cognitive difficulty. Previously, researchers estimated that 3.4 percent of women and 0.5 percent of men suffer from this disorder. Occurrence of fibromyalgia is known to increase with age and affects more than 7 percent of women who are between the ages of 60 and 79.
Lead author of the study Dr. Marco Loggia from Massachusetts General Hospital and Harvard Medical School in Boston said, “In patients with fibromyalgia there is an alteration in the central nervous system pain processing and a poor response to topical pain treatments, trigger point injections and opioids. Our study examines the disruption of brain function involved in the individual experience of pain anticipation and pain relief.”
Participants in this study consisted of 31 patients with fibromyalgia and 14 healthy people. Two tests, functional magnetic resonance imaging (fMRI) and cuff pressure pain stimuli on the leg, were performed on all participants. While undergoing the MRI, patients were given visual clues to inform them of impending pain onset (pain anticipation) and pain offset (relief anticipation).
Researchers found the fibromyalgia patients exhibited less robust responses during pain anticipation and relief in brain regions involved in sensory, affective, cognitive and pain regulating processes. For healthy control patients, in a central region of the brain responsible for the processing of reward and punishment, the ventral tegmental area (VTA), a group of neurons showed activation during the pain anticipation and stimulation as well as deactivation during anticipated relief. These same responses were significantly diminished in fibromyalgia patients.
“Our findings suggest that fibromyalgia patients exhibit altered brain responses to punishing and rewarding events, such as expectancy of pain and relief of pain," Dr. Loggia explained. "These observations may contribute to explain the heightened sensitivity to pain, as well as the lack of effectiveness of pain medications such as opioids, observed in these patients. Future studies should further investigate the neurochemical basis underlying these dysfunctions.”
This study was published in Arthritis & Rheumatism, a journal of the American College of Rheumatology.