A multiple domain postural control assessment in people with Parkinson's disease: traditional, non-linear, and rambling and trembling trajectories analysis

Post-mechanotherapy differences in postural control in patients with Achilles tendinopathy - A randomized controlled trial

BACKGROUND

Neuromuscular deficits affecting functional ability can occur in patients with Achilles tendinopathy during difficult balance activities. This study aimed to assess postural control in patients with Achilles tendinopathy after shockwave and sonotherapy, using advanced analytical methods, including rambling-trembling signal decomposition and sample entropy.

RESEARCH QUESTION

What are the differences in postural control between patients with Achilles tendinopathy after shockwave therapy, ultrasound therapy, and placebo ultrasound?

METHODS

Thirty-nine patients were included in the study, and randomly assigned to 3 groups, i.e., shockwave therapy, ultrasound therapy and placebo ultrasound. Postural sway was assessed during quiet standing with eyes open and closed, with two force platforms, one for the affected and the other for the non-affected limb, at baseline and at weeks 1 and 6 after treatment. Rambling-trembling trajectories and sample entropy were calculated for the antero-posterior and medio-lateral directions.

RESULTS

The parameters of trembling trajectory in both directions were significantly smaller for the affected compared to non-affected limb. The ultrasound group had significantly larger rambling-trembling trajectories in the antero-posterior and medio-lateral sway directions than the shockwave therapy group. Also, all patients had more difficulty controlling their postural sway while standing with eyes closed compared to eyes open. Sample entropy was not significantly affected by the therapy type, timepoint and limb condition.

SIGNIFICANCE

As opposed to sample entropy, rambling-trembling decomposition can complement or replace traditional linear measures of COP time series in functional assessment of the Achilles tendon.

Fall assessment in healthy older adults: Approach using rambling-trembling decomposition method

BACKGROUND

This study explored useful indices of potential fall risk in healthy older adults based on comprehensive clinical and simple quantitative posturographic measurements.

METHODS

A total of 64 community-dwelling older adults aged ≥65 years were classified into fallers and non-fallers based on previous fall history. After excluding two participants due to missing data, 16 and 46 participants were included in the faller and non-faller groups, respectively. We conducted major clinical measurements, including timed up and go test, 10-m walk test, functional reach test, one-leg stand test, isometric muscle strength tests, open-close stepping test, and sit-to-stand test. For quantitative posturographic measurements, participants performed standing tasks with their eyes open and closed. In the standing tasks, the time series of the center of pressure in the anteroposterior and mediolateral directions were measured and decomposed into rambling and trembling components to evaluate postural control in detail, separately. The mean velocity and root mean square of the center of pressure, rambling, and trembling were calculated and compared between fallers and non-fallers.

FINDINGS

A significant fall-related difference was found only in the mean velocity of the rambling in the anteroposterior direction; fallers displayed greater values than non-fallers, especially while standing with their eyes closed.

INTERPRETATION

The clinical measures failed to distinguish differences in fall risk, whereas the rambling component in the anteroposterior direction could detect substantial differences. The mean velocity of the rambling component could be useful as a sensitive screening biomarker for potential fall risks in healthy older adults.

Sensory reweighting of postural control requires distinct rambling and trembling sway adaptations

BACKGROUND

Implementation of the Sensory Organization Test (SOT) under the rambling-trembling (RM-TR) framework allows for an examination of both individual sensory contributions and compensatory mechanisms, a valuable insight in research and clinical settings. Such investigation could substantially improve our ability to assess and treat fall risk in older adults and people living with neurological disorders.

RESEARCH QUESTION

How are RM and TR components of sway influenced by SOT-induced challenges in healthy adults?

METHODS

Twenty-three healthy adults (27.4±8 years; 10 male) volunteered to participate in this cross-sectional study. Each participant completed a VR-based SOT program, which included six conditions with varied visual environments (normal, blacked-out, conflict) and support surfaces (stable, unstable foam), while a force plate captured forces at the plantar surface. Center of pressure (COP) was calculated and decomposed into RM-TR components. For each time series, range, root-mean-square (RMS) and sample entropy (SampEn) were extracted. Individual contributions of somatosensation, vision, and vestibular sense, as well as the preference ratio, were calculated. Repeated measures ANOVA were used to compare the effects of time series type (COP, RM, TR) and SOT condition. Paired t-tests were used to assess the difference in preference ratio between RM and TR components.

RESULTS AND SIGNIFICANCE

TR sway behavior was impacted significantly by the sensory challenges induced by the SOT procedure, while RM was largely unaffected. Such findings are characteristic of healthy individuals, capable of competently re-weighting sensory input, but still facing challenge-based adaptations. Additionally, the mediolateral SampEn preference ratio was higher in TR compared to RM, indicating potential differences in compensation strategies between supraspinal and spinal/peripheral control mechanisms. These findings serve as a foundation for future RM-TR analyses using SOT procedures, aiding in our ability to implement targeted diagnostic and treatment methods, ultimately reducing the incidence of falls in aging and individuals with neurological conditions.

A non-expensive bidimensional kinematic balance assessment can detect early postural instability in people with Parkinson's disease

Background

Postural instability is a debilitating cardinal symptom of Parkinson’s disease (PD). Its onset marks a pivotal milestone in PD when balance impairment results in disability in many activities of daily living. Early detection of postural instability by non-expensive tools that can be widely used in clinical practice is a key factor in the prevention of falls in widespread population and their negative consequences.

Objective

This study aimed to investigate the effectiveness of a two-dimensional balance assessment to identify the decline in postural control associated with PD progression.

Methods

This study recruited 55 people with PD, of which 37 were men. Eleven participants were in stage I, twenty-three in stage II, and twenty-one in stage III. According to the Hoehn and Yahr (H&Y) rating scale, three clinical balance tests (Timed Up and Go test, Balance Evaluation Systems Test, and Push and Release test) were carried out in addition to a static stance test recorded by a two-dimensional movement analysis software. Based on kinematic variables generated by the software, a Postural Instability Index (PII) was created, allowing a comparison between its results and those obtained by clinical tests.

Results

There were differences between sociodemographic variables directly related to PD evolution. Although all tests were correlated with H&Y stages, only the PII was able to differentiate the first three stages of disease evolution (H&Y I and II: p = 0.03; H&Y I and III: p = 0.00001; H&Y II and III: p = 0.02). Other clinical tests were able to differentiate only people in the moderate PD stage (H&Y III).

Conclusion

Based on the PII index, it was possible to differentiate the postural control decline among the first three stages of PD evolution. This study offers a promising possibility of a low-cost, early identification of subtle changes in postural control in people with PD in clinical practice.

Multiscale Entropy Algorithms to Analyze Complexity and Variability of Trunk Accelerations Time Series in Subjects with Parkinson's Disease

The aim of this study was to assess the ability of multiscale sample entropy (MSE), refined composite multiscale entropy (RCMSE), and complexity index (CI) to characterize gait complexity through trunk acceleration patterns in subjects with Parkinson's disease (swPD) and healthy subjects, regardless of age or gait speed. The trunk acceleration patterns of 51 swPD and 50 healthy subjects (HS) were acquired using a lumbar-mounted magneto-inertial measurement unit during their walking. MSE, RCMSE, and CI were calculated on 2000 data points, using scale factors (τ) 1-6. Differences between swPD and HS were calculated at each τ, and the area under the receiver operating characteristics, optimal cutoff points, post-test probabilities, and diagnostic odds ratios were calculated. MSE, RCMSE, and CIs showed to differentiate swPD from HS. MSE in the anteroposterior direction at τ4 and τ5, and MSE in the ML direction at τ4 showed to characterize the gait disorders of swPD with the best trade-off between positive and negative posttest probabilities and correlated with the motor disability, pelvic kinematics, and stance phase. Using a time series of 2000 data points, a scale factor of 4 or 5 in the MSE procedure can yield the best trade-off in terms of post-test probabilities when compared to other scale factors for detecting gait variability and complexity in swPD.