Gait complexity and frequency content analyses of patients with Parkinson´s disease

The gait kinematics for Parkinson´s disease (PD) are usually examined in the time domain and limited to selected points on motion-time graphs. Wavelet analysis allows the examination of the whole waveform and demonstrates a high potential to assess the effects of PD treatment. The purpose of this study was to investigate whether differences existed in gait complexity and the frequency content of foot trajectories during walking between patients with PD and healthy individuals by using wavelet analyses. Fifteen persons with idiopathic PD and eleven healthy age- and height- matched healthy adults (HAs) were recruited. The foot trajectories of each subject during walking were detected by using a three-camera Optotrak Certus motion capture system. The scale wavelet energy raitos and wavelet entropy were computed after seven-scale wavelet decomposition, and the results of the two groups were compared using Wilcoxon rank-sum test with Bonferroni correction for multiple testing. The results showed that, the PD subjects walked with a higher degree of complexity for the foot motion in anteroposterior direction and a lower degree of complexity for the foot motion in vertical direction. Both groups had comparable gait frequency, but the differences in the energy distributed over some frequency bands were significant between the PD and control groups. In addition to previously described gait kinematics in time domain, the parameters of scale wavelet energy ratios and wavelet entropy could be used to provide additional insight into gait changes.