Cognitive, Psychophysical, and Neural Correlates of Vulvar Pain in Primary and Secondary Provoked Vestibulodynia: a Pilot Study

Introduction: Provoked vestibulodynia (PVD) is a common condition characterized by localized, provoked pain that can be present since first vaginal penetration attempt (primary) or can develop after a period of pain-free penetration (secondary). Research has demonstrated psychosocial and psychophysical differences between women with these subtypes of PVD, but the question of whether neural responses to pain also differ remains to be investigated.

Aim: This study aims to examine whether cognitive, psychophysical, and neural responses to vulvar pressure pain differ between women with PVD1 and PVD2.

Methods: Women with PVD1 and PVD2 were compared for group differences using multiple modalities, including questionnaires, psychophysical testing, and neuroimaging. Pain ratings were held constant across groups, rather than amount of pressure applied.

Main Outcome Measures: Demographics, sexual functioning, four questionnaires examining anxiety and catastrophizing, quantitative sensory testing at the vulvar vestibule using a vulvalgesiometer, and functional and structural magnetic resonance imaging (MRI).

Results: Findings suggest that women with PVD1 are more anxious and that they catastrophize more about their vulvar and nonvulvar pain than women with PVD2. Overall, MRI results demonstrated structural and functional similarities to other chronic pain findings for both groups of women. Gray matter (GM) density also differed between groups: women with PVD1 showed significant decreases in GM throughout areas associated with pain processing. Functionally, between-groups differences were found during painful vulvar stimulation despite lower pressures applied to the vulva for women with PVD1 because of their heightened sensitivity; the determination of the level of vulvar pressure to elicit pain was based on subjective ratings.

Conclusions: Findings are limited by sample size and liberal alpha values; however, future research is certainly warranted based on the preliminary findings of this study suggesting both similarities and differences between PVD1 and PVD2. Overall, women with PVD1 seem to fare worse on several pain-related and psychosocial variables compared with women with PVD2.