Psychophysical evidence of nociceptor sensitization in vulvar vestibulitissyndrome

Vulvar vestibulitis syndrome (VVS) is a long lasting disorder of superficia l dyspareunia in young women. Quantitative sensory testing including mechan ical and temperature pain thresholds and warm/cold difference limen (WCL), was performed in the vestibular mucosa in 22 women (mean ace 25.0 years) wi th vestibulitis and 20 control subjects (mean age 25.6 years). The tests we re 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 sympt omatic 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 patien ts and 43.8 +/- 0.8 degreesC in controls, P < 0.0001. In addition, pain thr eshold to cold was 21.6 +/- 1.2 degreesC in patients whereas cooling down t o 6 degreesC was usually not painful in controls. WCL was 4.9 +/- 0.5 degre esC 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 nocicepto rs in their vestibular mucosa. (C) 2001 International Association for the S tudy of Pain. Published by Elsevier Science B.V. All rights reserved.