Supine-induced Increase in Blood Flow Velocity in the Anterior Humeral Circumflex Artery Associates with Nocturnal...

: Nocturnal pain is common in rotator cuff tears (RCTs). Among its patterns, a pain type relieved by sitting upright, referred to here as "sitting-relief pain," appears to behave differently from other nocturnal pain types. Peak systolic velocity in the anterior humeral circumflex artery (PSV-AHCA) has been suggested as a marker, but findings have varied across settings. Exploring this vascular response may help connect patients' subjective pain experiences with objective physiological data, potentially offering a bridge between symptoms and measurable signs. This study investigated the association between PSV-AHCA and nocturnal pain characteristics in patients with RCTs.

: A cross-sectional study was conducted with 78 patients with RCTs. Participants were classified into three groups based on nocturnal pain characteristics: Sitting-Relief-Pain, Other-Pain, and Pain-Free. PSV-AHCA was measured in both sitting and supine positions using Doppler ultrasound. After confirming the absence of major confounders, comparisons were made across groups and positions.

: The Sitting-Relief-Pain group showed an increase in PSV-AHCA from sitting to supine (22.7 to 26.7 cm/s; d=0.712; P=0.001), whereas the Other-Pain and Pain-Free groups showed no significant changes. In the supine position, PSV-AHCA was higher in the Sitting-Relief-Pain group than in the Other-Pain (P=0.008) and Pain-Free (P=0.004) groups.

: Sitting-relief pain may represent a specific pattern of nocturnal pain in RCTs, with a distinct vascular response to posture. Doppler ultrasound in physiotherapist-led assessment may assist in identifying this pattern and distinguishing it from other types of nocturnal pain.