This study aimed to establish normative reference values for quantitative sensory discrimination testing at the proximal medial thigh and related patient-reported outcome measures to support clinical assessment of somatosensory changes in individuals with chronic pelvic pain including vulvodynia. It was hypothesized that the tactile acuity measures two-point discrimination (TPD), point localization accuracy (PLA), point localization duration (PLD), graphesthesia accuracy (GA), and graphesthesia duration (GD) would differ significantly based on age and body mass index (BMI).

This cross-sectional study evaluated tactile acuity in 51 pre-menopausal females aged 18–50 years at the proximal medial thigh. Quantitative sensory discrimination testing included TPD, PLA, PLD, GA, and GD. Participants also completed demographic questionnaires and validated outcome measures including the Short-Form McGill Pain Questionnaire (SF-MPQ), Pain Catastrophizing Scale (PCS), Pain Self-Efficacy Questionnaire (PSEQ), Central Sensitization Inventory (CSI), Female Sexual Function Index (FSFI), and Pelvic Floor Distress Inventory (PFDI-20).
Participants were categorized by age (18–30 years vs. 31–50 years) and BMI (≤24.99 vs. ≥25.00). Sample size was determined using prior normative data and G*Power analysis targeting large effect size of .7 and 80% power (α = 0.05). Statistical analyses were performed using SPSS, with significance set at p < 0.05. Correlation and multiple regression analyses examined relationships between sensory discrimination tests, outcome measures, and demographic variables.

Mean TPD was 39.92 mm. PLA averaged 43%, with mean PLD of 53.88 seconds. GA averaged 44%, with mean GD of 58.35 seconds.
TPD was significantly correlated with PLA (r = 0.284, p = 0.04) and age (r = 0.477, p < 0.001). PLA correlated with PLD (r = 0.462, p < 0.001) and was associated with BMI, parity, and sexual orientation. Multiple regression analysis demonstrated that PLD (β = -0.342, p = 0.002) and sexual orientation (β = 0.583, p = 0.004) significantly predicted PLA (R² = 0.311, p < 0.001). PLD was independently predicted by BMI (β = -0.347, p = 0.027). GA and GD were also significantly associated with BMI.
Age-based comparisons revealed significant differences between younger (n = 25) and older (n = 26) groups for TPD (p < 0.001) and GD (p = 0.017), as well as BMI, parity, employment status, and FSFI scores. No other outcome measures differed significantly by age.
BMI based comparisons demonstrated significant differences between normal-weight (n = 14) and overweight (n = 37) groups for PLA (p = 0.021), GA (p = 0.039), GD (p = 0.040), and CSI (p = 0.024). No additional measures showed significant differences.

Significant differences in quantitative sensory discrimination were observed based on age and BMI. Younger participants demonstrated greater tactile acuity (lower TPD and GD), while individuals with normal BMI demonstrated higher accuracy on discrimination tasks. These findings suggest that somatosensory processing at the proximal medial thigh is influenced by individual characteristics, including age and body composition.

This study is the first to examine multiple discrimination modalities at the proximal medial thigh and compare outcomes by age and BMI. Quantitative sensory discrimination testing is a feasible, low-cost, and clinically applicable method for assessing somatosensory function. The normative values established in this study provide clinicians with reference points to identify potential sensory processing alterations. These findings support further investigation in larger and clinical populations, including individuals with chronic pelvic pain such as vulvodynia.

Continence 19S (2026) 102545
DOI: 10.1016/j.cont.2026.102545