Longitudinal Clinical and Ultrasonographic Characterization of Hemiplegic Shoulder Pain After Stroke: Early Pathophysiological Mechanisms, Temporal Trajectories, and Predictive Factors

Hemiplegic shoulder pain (HSP) is a common and disabling complication after stroke, significantly affecting rehabilitation outcomes and quality of life. Its pathophysiology is complex and multifactorial, involving the interaction between neurological impairment, altered biomechanics, and structural musculoskeletal changes. However, early mechanisms and temporal evolution remain insufficiently understood. This thesis aimed to investigate HSP through a longitudinal clinical and ultrasonographic approach, starting from the acute phase of stroke. The objectives were to characterize early shoulder alterations, describe the temporal trajectory of pain, and identify clinical and ultrasound predictors across different recovery stages. A prospective longitudinal design was adopted, integrating two studies with follow-up from ≤72 hours after stroke onset up to 12 months. Clinical assessment included pain scales (NRS/VAS), range of motion, strength (MRC), spasticity (MAS), and functional measures (DASH). Ultrasound evaluation assessed rotator cuff tendons, long head of the biceps, subacromial–subdeltoid bursa, joint effusion, capsular structures, and glenohumeral subluxation. Associations between clinical findings, imaging abnormalities, and pain were analyzed using longitudinal models. HSP was detectable in the acute phase and was primarily associated with glenohumeral subluxation and capsular changes. Over time, the relationship between pain and structural findings evolved, supporting a dynamic and multifactorial model. Early clinical and ultrasound features showed predictive value for subsequent pain development. HSP is a time-dependent condition emerging from the interaction between central and peripheral mechanisms. Longitudinal clinical–ultrasound assessment enables early identification of at-risk patients and supports a shift toward mechanism-based, phase-specific rehabilitation strategies.