"PNP slows down" - linearly-reduced whole body joint velocities and altered gait patterns in polyneuropathy.

Introduction: Gait disturbances are a common consequence of polyneuropathy (PNP) and a major factor in patients' reduced quality of life. Less is known about the underlying mechanisms of PNP-related altered motor behavior and its distribution across the body. We aimed to capture whole body movements in PNP during a clinically relevant mobility test, i.e., the Timed Up and Go (TUG). We hypothesize that joint velocity profiles across the entire body would enable a deeper understanding of PNP-related movement alterations. This may yield insights into motor control mechanisms responsible for altered gait in PNP. Methods: 20 PNP patients (61 ± 14 years) and a matched healthy control group (CG, 60 ± 15 years) performed TUG at (i) preferred and (ii) fast movement speed, and (iii) while counting backward (dual-task). We recorded TUG duration (s) and extracted gait-related parameters [step time (s), step length (cm), and width (cm)] during the walking sequences of TUG and calculated center of mass (COM) velocity [represents gait speed (cm/s)] and joint velocities (cm/s) (ankles, knees, hips, shoulders, elbows, wrists) with respect to body coordinates during walking; we then derived mean joint velocities and ratios between groups. Results: Across all TUG conditions, PNP patients moved significantly slower (TUG time, gait speed) with prolonged step time and shorter steps compared to CG. Velocity profiles depend significantly on group designation, TUG condition, and joint. Correlation analysis revealed that joint velocities and gait speed are closely interrelated in individual subjects, with a 0.87 mean velocity ratio between groups. Discussion: We confirmed a PNP-related slowed gait pattern. Interestingly, joint velocities in the rest of the body measured in body coordinates were in a linear relationship to each other and to COM velocity in space coordinates, despite PNP. Across the whole body, PNP patients reduce, on average, their joint velocities with a factor of 0.87 compared to CG and thus maintain movement patterns in terms of velocity distributions across joints similarly to healthy individuals. This down-scaling of mean absolute joint velocities may be the main source for the altered motor behavior of PNP patients during gait and is due to the poorer quality of their somatosensory information. Clinical Trial Registration: https://drks.de/search/de, identifier DRKS00016999.

Age-related changes in mobility assessments correlate with repetitive goal-directed arm-movement performance.

BACKGROUND: There is ample evidence that mobility abilities between healthy young and elderly people differ. However, we do not know whether these differences are based on different lower leg motor capacity or instead reveal a general motor condition that could be detected by monitoring upper-limb motor behavior. We therefore captured body movements during a standard mobility task, namely the Timed Up and Go test (TUG) with subjects following different instructions while performing a rapid, repetitive goal-directed arm-movement test (arm-movement test). We hypothesized that we would be able to predict gait-related parameters from arm motor behavior, even regardless of age. METHODS: Sixty healthy individuals were assigned to three groups (young: mean 26 ± 3 years, middle-aged 48 ± 9, old 68 ± 7). They performed the arm-movement and TUG test under three conditions: preferred (at preferred movement speed), dual-task (while counting backwards), and fast (at fast movement speed). We recorded the number of contacts within 20 s and the TUG duration. We also extracted TUG walking sequences to analyze spatiotemporal gait parameters and evaluated the correlation between arm-movement and TUG results. RESULTS: The TUG condition at preferred speed revealed differences in gait speed and step length only between young and old, while dual-task and fast execution increased performance differences significantly among all 3 groups. Our old group's gait speed decreased the most doing the dual-task, while the young group's gait speed increased the most during the fast condition. As in our TUG results, arm-movements were significant faster in young than in middle-aged and old. We observed significant correlations between arm movements and the fast TUG condition, and that the number of contacts closely predicts TUG timefast and gait speedfast. This prediction is more accurate when including age. CONCLUSION: We found that the age-related decline in mobility performance that TUG reveals strongly depends on the test instruction: the dual-task and fast condition clearly strengthened group contrasts. Interestingly, a fast TUG performance was predictable by the performance in a fast repetitive goal-directed arm-movements test, even beyond the age effect. We assume that arm movements and the fast TUG condition reflect similarly reduced motor function. TRIAL REGISTRATION: German Clinical Trials Register (DRKS) number: DRKS00016999, prospectively registered on March, 26, 2019.

Automated Assessment of Balance Rehabilitation Exercises With a Data-Driven Scoring Model: Algorithm Development and Validation Study.

BACKGROUND: Balance rehabilitation programs represent the most common treatments for balance disorders. Nonetheless, lack of resources and lack of highly expert physiotherapists are barriers for patients to undergo individualized rehabilitation sessions. Therefore, balance rehabilitation programs are often transferred to the home environment, with a considerable risk of the patient misperforming the exercises or failing to follow the program at all. Holobalance is a persuasive coaching system with the capacity to offer full-scale rehabilitation services at home. Holobalance involves several modules, from rehabilitation program management to augmented reality coach presentation. OBJECTIVE: The aim of this study was to design, implement, test, and evaluate a scoring model for the accurate assessment of balance rehabilitation exercises, based on data-driven techniques. METHODS: The data-driven scoring module is based on an extensive data set (approximately 1300 rehabilitation exercise sessions) collected during the Holobalance pilot study. It can be used as a training and testing data set for training machine learning (ML) models, which can infer the scoring components of all physical rehabilitation exercises. In that direction, for creating the data set, 2 independent experts monitored (in the clinic) 19 patients performing 1313 balance rehabilitation exercises and scored their performance based on a predefined scoring rubric. On the collected data, preprocessing, data cleansing, and normalization techniques were applied before deploying feature selection techniques. Finally, a wide set of ML algorithms, like random forests and neural networks, were used to identify the most suitable model for each scoring component. RESULTS: The results of the trained model improved the performance of the scoring module in terms of more accurate assessment of a performed exercise, when compared with a rule-based scoring model deployed at an early phase of the system (k-statistic value of 15.9% for sitting exercises, 20.8% for standing exercises, and 26.8% for walking exercises). Finally, the resulting performance of the model resembled the threshold of the interobserver variability, enabling trustworthy usage of the scoring module in the closed-loop chain of the Holobalance coaching system. CONCLUSIONS: The proposed set of ML models can effectively score the balance rehabilitation exercises of the Holobalance system. The models had similar accuracy in terms of Cohen kappa analysis, with interobserver variability, enabling the scoring module to infer the score of an exercise based on the collected signals from sensing devices. More specifically, for sitting exercises, the scoring model had high classification accuracy, ranging from 0.86 to 0.90. Similarly, for standing exercises, the classification accuracy ranged from 0.85 to 0.92, while for walking exercises, it ranged from 0.81 to 0.90. TRIAL REGISTRATION: ClinicalTrials.gov NCT04053829; https://clinicaltrials.gov/ct2/show/NCT04053829.

Unravelling delayed therapy escape after thalamic deep brain stimulation for essential tremor? - Additional clinical and neuroimaging evidence.

BACKGROUND: Delayed therapy escape after thalamic deep brain stimulation (DBS) for essential tremor is a serious yet frequent condition. It is often difficult to detect this process at onset due to its gradual evolution. OBJECTIVE: Here we aim to identify clinical and neuroimaging hallmarks of delayed therapy escape. METHODS: We retrospectively studied operationalized and quantitative analyses of tremor and gait, as well as [18F]fluorodeoxyglucose (FDG) PET of 12 patients affected by therapy escape. All examinations were carried out with activated DBS (ON) and 72 h after deactivation (OFF72h); gait and tremor were also analyzed directly after deactivation (OFF0h). Changes of normalized glucose metabolism between stimulation conditions were assessed using within-subject analysis of variance and statistical parametric mapping. Additionally, a comparison to the [18F]FDG PET of an age-matched control group was performed. Exploratory correlation analyses were conducted with operationalized and parametric clinical data. RESULTS: Of the immediately accessible parametric tremor data (i.e. ON or OFF0h) only the rebound (i.e. OFF0h) frequency of postural tremor showed possible correlations with signs of ataxia at ON. Regional glucose metabolism was significantly increased bilaterally in the thalamus and dentate nucleus in ON compared to OFF72h. No differences in regional glucose metabolism were found in patients in ON and OFF72h compared with the healthy controls. CONCLUSIONS: Rebound frequency of postural tremor seems to be a good diagnostic marker for delayed therapy escape. Regional glucose metabolism suggests that this phenomenon may be associated with increased metabolic activity in the thalamus and dentate nucleus possibly due to antidromic stimulation effects. We see reasons to interpret the delayed therapy escape phenomenon as being related to long term and chronic DBS.

Exploring the Acceptability and Feasibility of Providing a Balance Tele-Rehabilitation Programme to Older Adults at Risk for Falls: An Initial Assessment.

Falls are a major health concern. The HOLOBALANCE tele-rehabilitation system was developed to deliver an evidence based, multi-sensory balance rehabilitation programme, to the elderly at risk of falls. The system delivers a series of balance physiotherapy exercises and cognitive and auditory training tasks prescribed by an expert balance physiotherapist following an initial balance assessment. The HOLOBALANCE system uses augmented reality (AR) to deliver exercises and games, and records task performance via a combination of body worn sensors and a depth camera. The HOLOBALANCE tele-rehabilitation system provides feedback to the supervising clinical team regarding task performance, participant usage and user feedback. Herewith we present the findings from the first 25 study participants regarding the feasibility and acceptability of the proposed system. The results of the clinical study indicate that the system is acceptable by the end users and also feasible for using in hospital and home environments.

Gait Analysis of Patients After Allogeneic Hematopoietic Cell Transplantation Reveals Impairments of Functional Performance.

Background: After allogeneic hematopoietic cell transplantation (alloHCT), patients often report functional impairments like reduced gait speed and muscle weakness. These impairments can increase the risk of adverse health events similar to elderly populations. However, they have not been quantified in patients after alloHCT (PATs). Methods: We compared fear of falling (Falls Efficacy Scale-International) and temporal gait parameters recorded on a 10-m walkway at preferred and maximum gait speed and under dual-task walking of 16 PATs (aged 31-73 years) with 15 age-matched control participants (CONs) and 17 seniors (SENs, aged >73 years). Results: Groups' gait parameters especially differed during the maximum speed condition: PATs walked slower and required more steps/10 m than CONs. PATs exhibited greater stride, stance, and swing times than CONs. PATs' swing time was even longer than SENs'. The PATs' ability to accelerate their gait speed from preferred to fast was smaller compared with CONs'. PATs reported a greater fear of falling than CONs and SENs. Conclusion: Gait analysis of alloHCT patients has revealed impairments of functional performance. Patients presented a diminished ability to accelerate gait and extending steps possibly related to a notable strength deficit that impairs power-generation abilities from lower extremities. Furthermore, patients reported a greater fear of falling than control participants and even seniors. Slowing locomotion could be a risk-preventive safety strategy. Since functional disadvantages may put alloHCT patients at a higher risk of frailty, reinforcing appropriate physical exercises already during and after alloHCT could prevent adverse health events and reduce the risk of premature functional aging.