Quantitative sensory testing in vulvodynia patients and increased peripheral pressure pain sensitivity

Abstract

Objective: To assess both regional (vulvar) and overall (generalized) pain sensitivity in women with vulvodynia to determine whether both are increased, suggestive of altered central pain processing.

Methods: Seventeen patients (aged 18-60 years) with vulvodynia and 23 age-matched control subjects were included in this cross-sectional study. Pressure pain thresholds in the vulvar area were evaluated in 23 defined locations using a newly developed vulvodolorimeter. Peripheral pressure pain sensitivity was assessed by applying 1) continuously ascending pressures to 3 bilateral locations (thumb, deltoid, and shin), and 2) discrete pressure stimuli to the thumb using both an ascending and random sequence of varying pressures.

Results: Pain thresholds at all vulvar locations were lower in the women with vulvodynia than in pain-free control subjects. Similarly, peripheral pain thresholds were lower at the thumb in women with vulvodynia when obtained by discrete ascending or random staircase paradigms, as well as at the thumb, deltoid, and shin when tested by dolorimeter (P <.05). Findings were similar in both those with generalized vulvar dysesthesia and those with localized vestibulodynia. The quantitative results obtained with the vulvodolorimeter and with the more subjective cotton-tipped swab testing routinely used in diagnosis were strongly correlated.

Conclusion: Women with vulvodynia displayed significantly increased pressure pain sensitivity in both the vulvar region and in peripheral body regions, suggesting a "central" component to the mechanisms mediating this disorder. Both the novel vulvodolorimeter and the thumb pressure stimulator may assist in future experimental tests of this and related hypotheses.