Psychophysical evidence of nociceptor sensitization in vulvar vestibulitis syndrome

Vulvar vestibulitis syndrome (VVS) is a long lasting disorder of superficial dyspareunia in young women. Quantitative sensory testing including mechanical and temperature pain thresholds and warm/cold difference limen (WCL), was performed in the vestibular mucosa in 22 women (mean ace 25.0 years) with vestibulitis and 20 control subjects (mean age 25.6 years). The tests were carried out on days 7-11 of the menstrual cycle. Patients had allodynia to mechanical testing with von Frey filaments, 14.3 +/- 3.1 mN in the symptomatic posterior area as compared with 158 +/- 33.5 mN in healthy subjects, P < 0.0001. The pain threshold to heat was 38.6 +/- 0.6 degreesC in patients and 43.8 +/- 0.8 degreesC in controls, P < 0.0001. In addition, pain threshold to cold was 21.6 +/- 1.2 degreesC in patients whereas cooling down to 6 degreesC was usually not painful in controls. WCL was 4.9 +/- 0.5 degreesC in patients and 9.6 +/- 1.5 degreesC in healthy subjects, P < 0.01. The results are compatible with the hypothesis that patients with VVS have an increased innervation and/or sensitization of thermoreceptors and nociceptors in their vestibular mucosa. (C) 2001 International Association for the Study of Pain. Published by Elsevier Science B.V. All rights reserved.