Millions of women suffer from vulvodynia, a disorder involving chronic pain in the vulvar region. Scientists have debated whether the biological processes underlying “localized” pain disorders (the pain is felt in one part of the body), like vulvodynia, are similar to mechanisms for “generalized” pain disorders (pain is felt throughout the body), like fibromyalgia.
Researchers funded by the Gynecologic Health and Disease Branch used functional magnetic resonance imaging (fMRI) to assess the brain’s reaction to pressure on the thumb. They compared the brain images for three groups of women: patients diagnosed with vulvodynia; patients diagnosed with fibromyalgia; and healthy women with no chronic pain conditions.
Scientists found that women with vulvodynia (the localized pain disorder) had brain responses that were very similar responses to those of women with fibromyalgia (the generalized pain disorder). Healthy women with no pain disorder showed a different pattern of brain response. Moreover, women with “provoked” vulvodynia—who experience pain upon touch—showed a different pattern of brain activation compared with women who experienced the pain even when not touched (“unprovoked” vulvodynia).
The results of the study indicate that the same brain mechanisms may be at work in localized and generalized pain disorders. The differences in fMRI findings for women with provoked and unprovoked vulvar pain may also help distinguish between subtypes of vulvodynia (PMID: 23578957).