Does One Measure Fit All? The Role of Experimentally Induced Pain Tests in the Assessment of Women with Provoked Vestibular Pain.

Abstract

Purpose: A diagnostic algorithm was recently suggested to address the underlying mechanisms of provoked-vestibulodynia (PVD). It delineates four subgroups (Hormonal-associated, Augmented-anterior, Hymenal-associated and Hypertonicity-associated), each manifesting a distinctive vulvar pain-hypersensitivity regarding location (circumferential vs posterior-only vestibulodynia) and pain characteristics. We aimed to explore the significance of various experimentally induced vulvar pain measures in the manifestation of pain hypersensitivity in each subgroup.

Methods: Women with PVD (n = 113) and 43 controls reported pain intensity provoked during vaginal penetration and tampon insertion. Vestibular tenderness (anterior and posterior) was assessed by Q-tip test, and pressure stimulation delivered to the puborectalis assessed muscle tenderness. Pain thresholds were measured using a vulvar-algesiometer. These measures were compared between patients and controls and among the PVD subgroups. Correlations between the clinical and experimentally induced-pain measures were assessed. Finally, to address whether the association between experimentally induced-pain measures and dyspareunia severity is mediated by hypertonicity, the conditional indirect effect was analyzed in each subgroup.

Results: Compared to controls, augmented vulvar pain-hypersensitivity and hypertonicity were observed among patients (p < 0.001). ANOVA revealed no subgroup differences in dyspareunia severity. Nevertheless, some experimentally induced-pain measures were differently correlated with dyspareunia intensity in each subgroup, allowing discrimination of subgroups according to the unique findings of vulvar pain-hypersensitivity. The degree of pelvic floor muscle-hypertonicity mediated the association between vulvar pain-hypersensitivity and dyspareunia severity, emphasizing the key role of hypertonicity in distinguishing between subgroups.

Conclusion: The findings offer more evidence of variations among PVD subtypes, demonstrating that insertional dyspareunia may originate from dissimilar alterations in the mucosal and muscular tissues. The results also emphasize the significance of utilizing a wide battery of tests to capture different experimentally induced-pain measures, revealing the unique patterns of vulvar pain-hypersensitivity in each subgroup.