Movement smoothness during a functional mobility task in subjects with Parkinson's disease and freezing of gait - an analysis using inertial measurement units.

BACKGROUND: Impairments of functional mobility may affect locomotion and quality of life in subjects with Parkinson's disease (PD). Movement smoothness measurements, such as the spectral arc length (SPARC), are novel approaches to quantify movement quality. Previous studies analyzed SPARC in simple walking conditions. However, SPARC outcomes during functional mobility tasks in subjects with PD and freezing of gait (FOG) were never investigated. This study aimed to analyze SPARC during the Timed Up and Go (TUG) test in individuals with PD and FOG. METHODS: Thirty-one participants with PD and FOG and six healthy controls were included. SPARC during TUG test was calculated for linear and angular accelerations using an inertial measurement unit system. SPARC data were correlated with clinical parameters: motor section of the Unified Parkinson's Disease Rating Scale, Hoehn & Yahr scale, Freezing of Gait Questionnaire, and TUG test. RESULTS: We reported lower SPARC values (reduced smoothness) during the entire TUG test, turn and stand to sit in subjects with PD and FOG, compared to healthy controls. Unlike healthy controls, individuals with PD and FOG displayed a broad spectral range that encompassed several dominant frequencies. SPARC metrics also correlated with all the above-mentioned clinical parameters. CONCLUSION: SPARC values provide valid and relevant clinical data about movement quality (e.g., smoothness) of subjects with PD and FOG during a functional mobility test.

Dual-task walking reduces lower limb range of motion in individuals with Parkinson's disease and freezing of gait: But does it happen during what events through the gait cycle?

BACKGROUND: It is unclear how dual-task gait influences the lower limb range of motion (RoM) in people with Parkinson's disease (PD) and freezing of gait (FOG). The lower limb kinematics during dual-task gait might differ from regular gait, but during what events in the gait cycle? METHODS: This is an observational within-subjects study. Thirty-two individuals with PD and FOG underwent a gait analysis. Single and dual-task gait was assessed by a 3D motion analysis system and the RoM data of the lower limb were extracted from hips, knees and ankles in the sagittal plane. Dual-task assignment was performed using word-color interference test. To compare both gait conditions, we used two different analyses: (1) common discrete analysis to provide lower limb RoM and (2) Statistical Parametric Mapping analysis (SPM) to provide lower limb joint kinematics. A correlation between lower limb RoM and spatiotemporal gait parameters was also performed for each gait condition. RESULTS: Common discrete analysis evidenced reductions in RoM of hips, knees and ankles during the dual task gait when compared to single gait. SPM analysis showed reductions in flexion-extension of hip, knees and ankles joints when dual task was compared to single task gait. These reductions were observed in specific gait events as toe off (for knees and ankles) and heel strike (for all joints). The reduction in lower limb RoM was positively correlated with the reduction in step length and gait speed. CONCLUSIONS: Lower limb joints kinematics were reduced during toe off and heel strike in dual task gait when compared to single gait. These findings might help physiotherapists to understand the influence of dual and single walking in lower limb RoM throughout the gait cycle in people with PD and FOG.

Sensitivity mapping of the human foot: thresholds at 30 skin locations.

BACKGROUND: Mechanoreceptors in the skin provide sensory input for the central nervous system about foot placement and loading. This information is used by the brain to actively control or regain balance and is important to establish memory traces for subsequent movement. A sensitivity map of the human foot could help to understand the mechanisms of the foot as a sensory organ for movement adjustment and balance control. MATERIALS AND METHODS: Touch and vibration perception threshold values from 30 plantar and dorsal foot locations were determined in more than 40 women and men between 20 and 35 years. Semmes Weinstein monofilaments and a vibrotactile neurothesiometer were used for skin sensitivity threshold detection. RESULTS: Large sensitivity differences were present between the 30 different foot sites. Gender effects were not present for touch but women had better sensitivities for vibration (p < 0.01), especially on the dorsal aspect of the foot. Age, in our cohort of 20- to 35-year-olds, did not have an influence on vibration or touch sensitivity. The heel had the highest detection thresholds for touch but was very sensitive for vibration stimuli. Compared to the dorsum, the plantar foot was substantially more sensitive, especially for vibration detection. CONCLUSION: The results suggest that primarily the fast adapting plantar mechanoreceptors are important in assisting balance control during human locomotion. CLINICAL RELEVANCE: The sensitivity map of the foot will help in understanding the function of the foot as a sensory organ and could be useful in creating footwear for better balance control and for the design of comfortable shoes.