The effects of gaze stabilization on gait parameters in individuals with Parkinson's disease

The purpose of this study was to examine the effects of gaze fixation on head stabilization and gait during straight over ground walking in individuals with Parkinson's disease (PD). Eight individuals with PD (Age: 62.3 ± 8.1 years) volunteered for the study. Full body kinematic data were collected at 120 Hz using a Vicon motion capture system. Two visual conditions were used to determine the effects of gaze fixation: FREE gaze and FIXED gaze. During FIXED gaze, participants were required to fixate on a still target 13 m ahead. During FREE gaze, participants were free to visually scan the environment. Five straight walking trials were performed in each experimental condition for a total of ten walking trials. Head segment stabilization strategies as well as gait parameters were compared between conditions. Step width, step length, stride time, cadence, double support time, centre of mass (CoM) velocity and CoM medial-lateral deviation were calculated for two strides of each over ground walking trial. Comparisons of mean values and variability were made using repeated measures ANOVAs. Results revealed that maintaining a FIXED gaze had no significant effect on head stabilization strategies or gait parameters with the exception of a significant increase in step width variability (p = 0.003). CoM velocity was not significantly different between FREE and FIXED gaze conditions (FREE: 1.17 ± 0.20 m/s; FIXED: 1.16 ± 0.19 m/s). CoM medial-lateral deviation was observed to be greater in FIXED (47.1 ± 36.9 cm) compared to FREE (26.9 ± 15.1 cm), though not significantly. These results suggest that gaze fixation to a target in front while walking increases step width variability and CoM M-L deviations indicative of reduced postural stability. This is an important consideration for use of visual cues to promote gait in PD.