Vestibular tactile and pain thresholds in women with vulvar vestibulitis syndrome

TLDR

Vulvar vestibulitis syndrome is a common cause of dyspareunia in pre‑menopausal women, yet the sensory function of the vulvar vestibule is poorly understood. The study aimed to compare punctate tactile and pain thresholds in the genital region of women with VVS to matched pain‑free controls. Researchers measured tactile and pain thresholds using modified von Frey filaments applied to the vestibule and surrounding areas. Women with VVS exhibited significantly lower tactile and pain thresholds at the vestibule and labium minus, lower thresholds on the deltoid indicating systemic hypersensitivity, higher distress ratings for equivalent pain, and greater catastrophizing about intercourse pain, suggesting a vestibular‑specific pathology compounded by generalized hypersensitivity.

Abstract

Vulvar vestibulitis syndrome (VVS) is a common cause of dyspareunia in pre-menopausal women. Little is known about sensory function in the vulvar vestibule, despite Kinsey's assertion that it is important for sexual sensation. We examined punctate tactile and pain thresholds to modified von Frey filaments in the genital region of women with VVS and age- and contraceptive-matched pain-free controls. Women with VVS had lower tactile and pain thresholds around the vulvar vestibule and on the labium minus than controls, and these results were reliable over time. Women with VVS also had lower tactile, punctate pain, and pressure-pain tolerance over the deltoid muscle on the upper arm, suggesting that generalized systemic hypersensitivity may contribute to VVS in some women. In testing tactile thresholds, 20% of trials were blank, and there was no group difference in the false positive rate, indicating that response bias cannot account for the lower thresholds. Women with VVS reported significantly more catastrophizing thoughts related to intercourse pain, but there was no difference between groups in catastrophizing for unrelated pains. Pain intensity ratings for stimuli above the pain threshold increased in a parallel fashion with log stimulus intensity in both groups, but the ratings of distress were substantially greater in the VVS group than in controls at equivalent levels of pain intensity. The data imply that VVS may reflect a specific pathological process in the vestibular region, superimposed on systemic hypersensitivity to tactile and pain stimuli.