The evolution of axial postural abnormality in Parkinson's disease: a 3-year longitudinal observational study

Axial postural abnormality (APA) contains various forms and the progression patterns and clinical predictors for each APA remain unknown. We aimed to investigate the evolution of APA and elucidate its relationships to clinical picture in Parkinson's disease (PD).

151 PD patients underwent anterior neck flexion (ANF), anterior trunk flexion (ATF) at thoracic and lumbar fulcrum, and lateral trunk flexion (LTF) assessments for 3 years. APA was assessed using a linear mixed-effects model. The cumulative incidence of APA progression was displayed using Kaplan-Meier curves with log-rank test to compare differences. Univariate and multivariate Cox proportional hazards analyses were performed to investigate risk factors for different types of APA progression.

ANF and ATF (thoracic fulcrum) began to increase significantly at 1-year follow-up. Lumbar fulcrum (ATF) and LTF began increasing at the 2-year and 3-year follow-ups, respectively. The overall cumulative progression risks for four APAs were different, with ANF having a significantly higher risk than thoracic fulcrum (ATF) and lumbar fulcrum (ATF), followed by LTF. We identified predictors for ANF progression were disease duration and bradykinesia symptoms. Exercise status and bradykinesia symptoms were associated with progression of ATF (thoracic fulcrum), and Hoehn-Yahr stage was associated with progression of ATF (lumbar fulcrum). LTF progression was associated with levodopa equivalent daily dose and MDS-UPDRS III posture subitem.

The APA of PD patients follow a "top to down, sagittal to coronal plane" pattern. An increased APA is associated with motor symptoms. Regular physical activity can slow the deterioration of APA in PD.