Mucosal versus muscle pain sensitivity in provoked vestibulodynia

Abstract

Background: An estimated 8.3%-16% of women experience vulvovaginal discomfort during their lifetime. Frequently these patients report provoked pain on contact or with attempted intercourse, commonly referred to as provoked vestibulodynia (PVD). Despite the burden of this condition, little is known about its potential etiologies including pelvic floor muscular dysfunction and mucosal components. This knowledge would be beneficial in developing targeted therapies including physical therapy.

Objective: To explore the relative contribution of mucosal versus muscle pain sensitivity on pain report from intercourse among women with PVD.

Design: In this proof of concept study, 54 women with PVD underwent a structured examination assessing mucosal and pelvic muscle sensitivity.

Methods: We examined three mucosal sites in the upper and lower vestibule. Patients were asked to rate their pain on cotton swab palpation of the mucosa using a 10-point visual analog scale. Muscle pain was assessed using transvaginal application of pressure on right and left puborectalis, and the perineal muscle complex. The Gracely pain scale (0-100) was used to assess the severity of pain with intercourse, with women rating the lowest, average, and highest pain levels; a 100 rating the highest level of pain.

Results: The lower vestibule's mucosa 5.81 (standard deviation =2.83) was significantly more sensitive than the upper vestibule 2.52 (standard deviation =2.6) (P<0.01) on exam. However, mucosal sensitivity was not associated with intercourse pain, while muscle sensitivity was moderately associated with both average and highest intensity of intercourse pain (r=-0.46, P=0.01 and r=-0.42, P=0.02), respectively.

Conclusion: This preliminary study suggests that mucosal measures alone may not sufficiently capture the spectrum of clinical pain report in women with PVD, which is consistent with the empirical success of physical therapy in this population.

Keywords: dyspareunia; pain sensitivity; pelvic floor muscle pain; pressure pain threshold; provoked vestibulodynia; vulvar pain; vulvodynia.

Figure 1

Anatomical locations of the mucosal sites tested with a cotton swab. Notes: Upper vestibule includes sites 2, 10, and 12. With 2 and 10 marking an imaginary line through the urethral meatus, and 12 is equidistant between. The lower vestibule sites include 5, 6, and 7 and are a mirror image of the upper vestibule. Reprinted from The Journal of Pain; 13(9); Zolnoun D, Bair E, Essick G, Gracely R, Goyal V, Maixner W; Reliability and reproducibility of novel methodology for assessment of pressure pain sensitivity in pelvis; pages 910–920; Copyright 2012, with permission from Elsevier.

Figure 2

Finger sensor (A) and algometer (B) for calibration. Notes: (A) Adapted from The Journal of Pain; 13(9); Zolnoun D, Bair E, Essick G, Gracely R, Goyal V, Maixner W; Reliability and reproducibility of novel methodology for assessment of pressure pain sensitivity in pelvis; pages 910–920; Copyright 2012, with permission from Elsevier.

Figure 3

Anatomical location of muscle sites tested. Notes: Reprinted from The Journal of Pain; 13(9); Zolnoun D, Bair E, Essick G, Gracely R, Goyal V, Maixner W; Reliability and reproducibility of novel methodology for assessment of pressure pain sensitivity in pelvis; pages 910–920; Copyright 2012, with permission from Elsevier.

Figure 4

Scatter plot of intercourse pain vs muscle pain detection. Notes: The black line represents spearman’s correlation between average pain report with intercourse and muscle pain detection threshold, while the red line represents the correlation between highest pain with intercourse and muscle pain detection threshold. Abbreviations: IRAL, average pain with intercourse; IRHL, highest pain with intercourse.