Abstract
BACKGROUND: Parkinson's disease (PD) is characterized by motor symptoms altering gait domains such as slow walking speed, reduced step and stride length, and increased double support time. Gait disturbances occur in the early, mild to moderate, and advanced stages of the disease in both backward walking (BW) and forward walking (FW), but are more pronounced in BW. At this point, however, no information is available about BW performance and disease stages specified using the Hoehn and Yahr (H&Y) scale. The objectives of this study were to examine the link between clinical scores and gait parameters in PD, and to assess gait parameters in both FW and BW among PD patients in early disease stages (H&Y: 1-2) and advanced disease stages (H&Y: 3-4), as well as among PD patients with mild and moderate disease severity as per the Movement Disorder Society-Unified Parkinson's Disease Rating Scale Part III (MDS-UPDRS III). METHODS: Spatiotemporal gait parameters were analyzed during FW and BW over a 5-meter walkway at a comfortable speed using 3D motion capture. Correlations and regressions between clinical scores and gait parameters were examined. Wilcoxon Mann-Whitney rank sum tests were used to compare PD patients in early and advanced disease stages and assess differences in gait parameters for both FW and BW conditions. RESULTS: The study included a total of 25 PD patients (aged 65 ± 9 years), among whom 10 were in the H&Y stages 1-2 and 15 in stages 3-4. All participants were evaluated with the MDS-UPDRS III, with 17 having a total score ≤ 32 (mild impairment and disability) and 8 having a total score > 32 (moderate impairment and disability). During BW, PD patients with H&Y stages 1-2 had significantly (p < 0.05) longer step lengths, stride lengths, and a higher walk ratio compared to those with H&Y stage 3-4. Regardless of the walking condition, no difference was found between PD patients with a MDS-UPDRS III total score ≤ 32 and patients with a MDS-UPDRS III total score > 32. DISCUSSION: The study demonstrates that individuals with PD in H&Y stages 3-4 exhibit compromised FW and BW abilities in comparison to those in stages 1-2. Notably, the disparities are more prominent in the realm of backward walking. These findings substantiate the existence of distinct gait patterns between the early and advanced stages of the disease, with the variations being particularly accentuated in the context of backward walking. CONCLUSIONS: Taken together, our results suggest that backward walking may hold greater clinical utility in assessing and managing PD patients. TRIAL REGISTRATION: The research procedure was approved by the ethical committee of the Medical Faculty of Kiel University (D438/18). The study is registered in the German Clinical Trials Register on 20,200,904 (DRKS00022998).