Pain in women: Neural processing of genital pain in women with vulvar vestibulitis syndrome: A functional magnetic resonance imaging study

Abstract

Vulvar vestibulitis syndrome (VVS) is a common cause of painful intercourse, affecting up to 12% of pre-menopausal women in the general population. Traditionally viewed as a sexual problem, recent evidence points to the importance of the sensory component in women with VVS, specifically, their heightened processing of vulvar tactile and pain sensation. The objective of the present study was to compare regions of neural activity, via fMRI, in affected and non-affected women during mild and strong vestibular pressure application. Fourteen women with VVS and 14 matched control participants (mean age 25.7 years) underwent psychophysical testing, consisting of the application of various pressures to the posterior portion of the vulvar vestibule with a vulvalgesiometer while pain intensity and unpleasantness ratings were recorded. Pressure values from this session were used during the fMRI scans. One anatomical and 4-6 functional scans (BOLD protocol, block design) were recorded. The mild stimulation condition was not painful for either group, while the strong stimulation condition was painful for women with VVS but not for non-affected women. For both conditions, women with VVS rated intensity and unpleasantness significantly higher than the control group. These differences were reflected in the associated neural activation patterns; both groups showed neural responses in similar regions, including primary and secondary somatosensory cortices and the insular cortex, during both conditions relative to the no-stimulation baseline; however, women with VVS had higher levels of activity in these regions as compared with control women. Combined with previous findings that women with VVS have a heightened perception of genital touch and pain, these results suggest that pain experienced by women with VVS results from augmented processing of genital stimulation and support the re-interpretation of VVS as a pain syndrome rather than a sexual disorder.