Neural Correlates of Painful Genital Touch in Women with Vulvar Vestibulitis Syndrome

Vulvar vestibulitis syndrome (VVS) is a common cause of dyspareunia in pre-menopausal women. Recent evidence points to the importance of the sensory component in VVS, particularly the heightened processing of tactile and pain sensation in the vulvar vestibule. The goal of the present study was to examine the neural basis of heightened sensitivity to touch (i.e. allodynia) in women with VVS. Using functional magnetic resonance imaging, we compared regions of neural activity in 14 women with VVS and 14 age- and contraceptive-matched control women in response to the application of mild and moderate pressure to the posterior portion of the vulvar vestibule. Intensity and unpleasantness ratings were recorded after each scan; these ratings were significantly higher for women with VVS than controls. All women with VVS described moderate pressure as painful and unpleasant, and 6 of the 14 women with VVS described mild pressure as painful and unpleasant. In contrast, none of the stimuli was painful for control women. Correspondingly, women with VVS showed more significant activations during pressure levels that they found to be either painful or non-painful than did controls during comparable pressure levels. During pressure described as painful by women with VVS, they had significantly higher activation levels in the insular and frontal cortical regions than did control women. These results suggest that women with VVS exhibit an augmentation of genital sensory processing, which is similar to that observed for a variety of syndromes causing hypersensitivity, including fibromyalgia, idiopathic back pain, irritable bowel syndrome, and neuropathic pain.