Abstract
BackgroundImpairments in biomechanics and neural control can disrupt the timing and muscle pattern activation necessary for smooth gait. Gait is one of the most affected motor characteristics in Parkinson’s disease (PD), but its smoothness has not been well-studied. This work applies the recently proposed spectral arc length measure (SPARC) to study, for the first time, gait in patients with PD. We hypothesized that the gait of patients with PD would be less smooth than that of healthy controls, as reflected in the SPARC measures.MethodsThe gait of 101 PD patients and 39 healthy controls was assessed using an inertial sensor. Smoothness of gait was estimated with SPARC (respectively from acceleration and angular velocity signals, SPARC-Acc and SPARC-Gyro) and harmonic ratios. Correlations between SPARC, traditional gait measures and the motor part of the Unified Parkinson’s Disease Rating Scale (UPDRS) were evaluated. Measurements and analysis were conducted with and without anti-PD medication.ResultsSPARC measures were lower (less smooth) in PD than in controls (SPARC-Acc: PD: − 6.11 ± 0.74; CO: -5.17 ± 0.79; p < 0.001). When comparing PD to controls, SPARC-Acc differed more than other measures of gait (i.e., largest effect size, which was > 1). SPARC measures were correlated with UPDRS motor score (r = − 0.65), while they were independent of other measures of gait smoothness. PD gait in the on state was smoother than in the off state (p < 0.001).ConclusionsSPARC calculated from trunk acceleration and angular velocity signals provide valid measures of walking smoothness in PD. SPARC is sensitive to Parkinson’s disease and PD medications and can be used of as another, complementary measure of the motor control of walking in PD.
Highlights
Impairments in biomechanics and neural control can disrupt the timing and muscle pattern activation necessary for smooth gait
We hypothesized that gait would be less smooth in patients with Parkinson’s disease (PD), compared to healthy controls, and, further, that the gait of PD fallers would be less smooth than the PD non-fallers. To better understand this new measure of smoothness in PD, we examined the effects of anti-parkinsonian medications and explored the correlation and differences between spectral arc length measure (SPARC), harmonic ratios, gait speed, stride time variability, and clinical measures
Patients with PD were included if they were diagnosed with PD by a movement disorders specialist, if they were between 40 and 85 years of age, and if they were not demented based on the Mini Mental State Examination (MMSE) [29]
Summary
Impairments in biomechanics and neural control can disrupt the timing and muscle pattern activation necessary for smooth gait. This work applies the recently proposed spectral arc length measure (SPARC) to study, for the first time, gait in patients with PD. We hypothesized that the gait of patients with PD would be less smooth than that of healthy controls, as reflected in the SPARC measures. Among patients with PD, the gait pattern is characterized by reduced speed, short stride length, shuffling steps, and, occasionally, typically in more advanced patients, freezing of gait episodes [2]. These changes in gait lead to disability, restricted function and reduced health-related quality of life. Measuring walking smoothness aims to quantify intermittency during gait; intermittent movements tend to have many accelerating and decelerating phases
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