Differences in Pressure Pain Threshold and Strain Elastography Between Women with and Without Fibromyalgia: A Cross-Sectional Study

Abstract

Background: Fibromyalgia (FM) is a chronic pain condition primarily linked to central sensitization, although peripheral tissue-related factors have also been suggested. Ultrasound strain elastography (SEL) provides a semi-quantitative, operator-dependent estimate of tissue deformation under standardized compression, yet evidence comparing SEL findings and pressure pain sensitivity between FM and healthy controls at standardized tender-point sites remains limited. Objective: To compare pressure pain threshold (PPT) and SEL-derived tissue deformation between women with FM and healthy controls across standardized FM tender-point sites. Methods: In this cross-sectional study, 84 women (42 with FM; 42 healthy controls) were recruited from a private rehabilitation center in Málaga (Spain). PPT and SEL were assessed bilaterally at 13 standardized tender-point sites. Between-group differences were examined using Student’s t-test or the Mann–Whitney U test according to distribution. Results: Women with FM exhibited lower PPT across all assessed sites (p < 0.01) and lower SEL-derived deformation scores at most sites, whereas no between-group SEL differences were observed at the dominant and non-dominant forearm, non-dominant lower cervical region, dominant paraspinal region, and bilateral lateral pectoral region. Conclusions: Compared with controls, women with FM showed reduced pressure pain thresholds and site-dependent differences in SEL-derived tissue deformation at standardized tender-point sites. Given the cross-sectional and exploratory design, SEL findings should be interpreted cautiously and considered non-diagnostic; heterogeneity across anatomical sites should be considered in future confirmatory and longitudinal studies.