What question did this study set out to answer?

To examine widespread somatosensory changes in unilateral frozen shoulder using different sensory thresholds.

January 18, 2026European Journal of Pain0 citationsOpen Access

Frozen Shoulder Is More Than Local Pain: Widespread Sensory Hyperalgesia or Hypoesthesia?

SYShiya YuSichuan University LGLi GouSichuan University JHJin HuangUniversity of Electronic Science and Technology of China

Key Points

To examine widespread somatosensory changes in unilateral frozen shoulder using different sensory thresholds.
37 unilateral frozen shoulder participants and 35 healthy controls were tested.
Pressure pain threshold, current perception threshold, and electrical pain threshold were measured.
Tests were conducted across multiple regions: lateral deltoid, medial forearm, cervical spine, and lumbar spine.
Bilateral assessments were made in frozen shoulder participants, and data analyzed using linear mixed models.
Frozen shoulder participants showed significantly reduced pressure pain thresholds across all tested sites.
Current perception and electrical pain thresholds were increased in affected shoulder and cervical spine regions.
Electrical thresholds were higher in the cervical spine than lumbar in frozen shoulder participants, opposite for healthy controls.
Electrical pain thresholds correlated with pressure pain thresholds and were negatively associated with pain intensity.

Abstract

ABSTRACT Background Frozen shoulder (FS) has long been considered a localised musculoskeletal disorder, yet FS often involves widespread pain, suggesting central sensory dysregulation. While pressure pain threshold (PPT) assesses mechanical sensitivity, electrical measures such as current perception threshold (CPT) and electrical pain threshold (EPT) may capture various sensory alterations but are rarely applied in FS. Objective To map somatosensory alterations in unilateral FS by comparing PPT, CPT, and EPT across multiple regions with matched healthy controls (HC). Methods 37 unilateral FS participants and 35 matched HCs underwent PPT, CPT, and EPT measurements at lateral deltoid (LD), medial forearm (MF), cervical spine (CS), and lumbar spine (LS). Bilateral LD and MF were tested in FS participants. Between‐group and regional differences were analysed using linear mixed models, and correlations with pain intensity were examined. Results FS participants exhibited significantly reduced PPT across all sites ( d = 1.27–4.55) and increased CPT and EPT at affected LD and CS regions ( d = 2.89–4.92). Electrical thresholds were higher over CS than LS in the FS group, whereas the opposite pattern appeared in the HC group. EPT correlated with PPT ( ρ = 0.54), and both were negatively associated with pain intensity ( ρ = −0.72 and −0.69, p < 0.001). Conclusions FS demonstrates mechanical hyperalgesia and electrical hypoesthesia, indicating central neuroplastic changes beyond the affected shoulder. Significance Statement This study integrates electrical and mechanical sensory testing, revealing multimodal evidence of central sensitization in FS and offering novel quantitative markers to guide individualised pain assessment and rehabilitation. Trail Registration ClinicalTrials.gov identifier: ChiCTR2400086393

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