Destroyed non-dopaminergic pathways in the early stage of Parkinson's disease assessed by posturography

Background: The early stage of Parkinson's disease (PD) (Hoehn-Yahr (HY) I-II stages) is characterized by a negative pull test, which clinically excludes postural instability. Previous studies with dynamic posturography detected balance disturbances even at the onset of the disease but the age dependency or prediction of dyskinesia with dynamic posturography are not known. Objective/hypothesis: We hypothesized that the postural instability evoked by dynamic posturography was part of the early stage of PD. Furthermore, we studied how we can provoke dyskinesia. Methods: Postural instability with static and dynamic posturography (passing balls with different weights around the body) was studied in 45 patients with PD in their HY I, II stages. They were compared with 35 age-matched healthy controls. Eighteen patients with dyskinesia were involved in the study. Fourteen patients were followed for two years. Results: The pathway and velocity of the movement assessed by static and the dynamic posturography were significantly higher in the group > 65 years than that of age-matched healthy controls, while the group <= 65 years showed a significant increment only in the antero-posterior sway during dynamic posturography. The imbalance of patients with dyskinesia was significantly (p < 0.05) provoked by dynamic posturography compared to patients with PD without dyskinesia. The results were independent of age. Conclusion: Postural instability is part of the early symptoms of PD. Non-dopaminergic pathways may be involved in the early stage of PD.