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

<b>Background</b>: 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. <b>Objective</b>: To compare pressure pain threshold (PPT) and SEL-derived tissue deformation between women with FM and healthy controls across standardized FM tender-point sites. <b>Methods</b>: 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 <i>t</i>-test or the Mann-Whitney U test according to distribution. <b>Results</b>: Women with FM exhibited lower PPT across all assessed sites (<i>p</i> < 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. <b>Conclusions</b>: 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.