Axial rigidity is related to the risk of falls in patients with Parkinson's disease

BACKGROUND: Rigidity is a cardinal symptom of Parkinson's disease (PD) and is often clinically assessed by passively flexing and extending a patient's limb. Objective measurements had been employed to examine rigidity in PD subjects, including wrist, elbow or knee. OBJECTIVE: This study aimed to investigate the relationship between an objective measurement of trunk rigidity and risk of falls in patients with mild to moderate PD. METHODS: An isokinetic dynamometer Biodex System 3 was employed to assess trunk rigidity in 36 patients with mild to moderate PD at a University Department in a cross-sectional study. Risk of falls was measured by the Get Up & Go test (GU&G). Disease severity (Hoehn and Yahr staging score and the Unified Parkinson's Disease Rating Scale III), disease duration and functional status (Schwab & England activities of daily living scale) were also evaluated. RESULTS: Significant correlations between trunk extensors rigidity at 45 degrees/s and 60 degrees/s and risk of falls were obtained. A correlation between trunk extensors tone at 30 degrees/s and the GU&G test almost reached significant almost reached statistical significance (r = 0.306; p = 0,066). Significant correlations between trunk flexors-extensors tone and clinical status, disease duration and functional status at 30 degrees/s, 45 degrees/s and 60 degrees/s were also obtained. CONCLUSION: The results from this study suggest that the axial rigidity is related to the risk of falls in patients with mild to moderate PD. Further studies are needed with quantitative devices for axial rigidity assessment to determine the relationship between trunk rigidity in PD patients with higher disease severity and risk of falls.