Shoulder Dysfunction in Parkinson's Disease: Implications of Motor Subtypes, Disease Severity, and Spinopelvic Alignment.

Purpose: To investigate shoulder function and muscle alterations in patients with Parkinson's disease (PD) and to determine their association with spinopelvic parameters and clinical status.

Methods: This prospective cohort study included 62 PD patients (divided into PIGD [n=30] and non-PIGD [n=32] groups) and 35 controls. The American Shoulder and Elbow Surgeons score (ASES), range of motion (ROM), and shoulder muscle stiffness were assessed for each group. Data on clinical demographics, PD disease severity, and shoulder parameters were extracted and analyzed.

Results: The PIGD group had significantly lower ASES total and sub-scores (all p < 0.05) compared to the controls. Both PIGD and non-PIGD groups demonstrated reduced abduction and forward flexion (all p < 0.05) compared to controls. The PIGD group also had decreased external rotation compared to the non-PIGD group and controls (all p < 0.05). Infraspinatus muscle stiffness was higher in the PIGD group than in controls (p = 0.012). Correlation analysis revealed that shoulder condition was significantly associated with PD disease severity and PIGD score, while muscle stiffness was linked to spinopelvic alignment and PIGD score. Various clinical factors, including PD disease severity, PIGD score, tremor score, and spinopelvic alignment, significantly correlated with shoulder ROM.

Conclusion: PD patients experienced shoulder dysfunction in various ways, including decreased ASES scores, limited ROM, and increased shoulder muscle stiffness. Our study highlighted the impact of PD motor subtype, disease severity, and spinopelvic alignment on the development of shoulder dysfunction, offering deeper insights into the pathophysiological basis of shoulder disorders in PD.