Objective impairment of tandem gait in Parkinson's disease patients increases with disease severity

Introduction: Tandem gait abnormalities have been reported to increase with advancing age, play a role in fall-prediction in Parkinson's disease, and distinguish it from atypical parkinsonism. Tandem gait has been scored based on the number of side steps off a straight line in these studies. Objective measurement of spatiotemporal tandem gait parameters in Parkinson's disease has not been previously reported. Methods: Subjects (74 Parkinson's disease and 28 controls) were enrolled after IRB approval. Those with more than 1 fall/day or a Montreal Cognitive Assessment score < 10 were excluded. Subjects tandem walked ("heel to toe") on a 20 foot pressure-sensor mat. Data was collected and analyzed using PKMAS software (Protokinetics). Results: Compared to controls, on tandem gait, Parkinson's subjects had increased step width, stride width and path width, with a slower stride velocity and an increased time spent in all phases of the gait cycle. Parkinson's subjects also applied greater pressure with each step and had greater step-to-step variability in tandem gait measures. While Hoehn & Yahr stage 1 subjects were not significantly different from controls, stage 2 and 2.5 + groups were different. Parkinson's subjects with freezing of gait also walked with a wider base compared to those without gait freezing. Tandem gait spatiotemporal parameters were not correlated with fall frequency. Conclusions: Tandem gait is impaired in Parkinson's disease in a stage-dependent manner, with wider base and increased step-to-step variability, which could suggest involvement of cerebellar and mediolateral balance pathways.