Objective: To investigate clinical features of postural instability and the relationship between severity of instability and falls during daily living in patients with Parkinson's disease (PD).
Methods and subjects: We recorded trunk movements of subjects maintaining a seated position for 2 minutes using both a force plate and a position sensor system. We compared 13 patients with falls (fallers), 7 without falls (non-fallers), and 8 age-matched normal controls.
Results: The tendency for the values of both lateral COP displacement and trunk displacement was to increase in 1) patients compared with controls, and 2) fallers compared to non-fallers. Among patients who showed a large value of lateral COP displacement, greater than the value of the mean plus one standard deviation of controls, 90% had lumbar scoliosis and 60% of these patients fell down more than 5 times during the one-year follow-up period.
Conclusion: We demonstrated that PD patients who had fallen frequently tended to have a 1) lumbar scoliosis, and 2) large value of lateral COP displacement. These results suggest that the measurement of both lateral COP displacement during sitting and spinal curvature would be useful in predicting the risk of falling in PD patients.