Levodopa Is a Double-Edged Sword for Balance and Gait in People With Parkinson's Disease

The effects of L-DOPA on gait abnormalities in a unilateral 6-OHDA rat model of Parkinson's disease

Parkinson's Disease (PD) is a neurodegenerative movement disorder characterized by dopamine (DA) cell loss in the substantia nigra pars compacta (SNc). As PD progresses, patients display disruptions in gait such as changes in posture, bradykinesia, and shortened stride. DA replacement via L-DOPA alleviates many PD symptoms, though its effects on gait are not well demonstrated. This study aimed to assess the relationship between DA lesion, gait, and deficit-induced reversal with L-DOPA. To do so, Sprague-Dawley rats (N = 25, 14 males, 11 females) received unilateral medial forebrain bundle (MFB) DA lesions with 6-hydroxydopamine (6-OHDA). An automated gait analysis system assessed spatiotemporal gait parameters pre- and post-lesion, and after various doses of L-DOPA (0, 3, or 6 mg/kg; s.c.). The forepaw adjusting steps (FAS) test was implemented to evaluate lesion efficacy while the abnormal involuntary movements (AIMs) scale monitored the emergence of L-DOPA-induced dyskinesia (LID). High performance liquid chromatography (HPLC) assessed changes in brain monoamines on account of lesion and treatment. Results revealed lesion-induced impairments in gait, inclusive of max-contact area and step-sequence alterations that were not reversible with L-DOPA. However, the emergence of AIMs were observed at higher doses. Post-mortem, 6-OHDA lesions induced a loss of striatal DA and norepinephrine (NE), while prefrontal cortex (PFC) displayed noticeable reduction in NE but not DA. Our findings indicate that hemiparkinsonian rats display measurable gait disturbances similar to PD patients that are not rescued by DA replacement. Furthermore, non-DA mechanisms such as attention-related NE in PFC may contribute to altered gait and may constitute a novel target for its treatment.

Kinect-based objective assessment of the acute levodopa challenge test in parkinsonism: a feasibility study

INTRODUCTION

The acute levodopa challenge test (ALCT) is an important and valuable examination but there are still some shortcomings with it. We aimed to objectively assess ALCT based on a depth camera and filter out the best indicators.

METHODS

Fifty-nine individuals with parkinsonism completed ALCT and the improvement rate (IR, which indicates the change in value before and after levodopa administration) of the Movement Disorder Society-Sponsored Revision of the Unified Parkinson's Disease Rating Scale part III (MDS-UPDRS III) was calculated. The kinematic features of the patients' movements in both the OFF and ON states were collected with an Azure Kinect depth camera.

RESULTS

The IR of MDS-UPDRS III was significantly correlated with the IRs of many kinematic features for arising from a chair, pronation-supination movements of the hand, finger tapping, toe tapping, leg agility, and gait (rs =  - 0.277 ~  - 0.672, P < 0.05). Moderate to high discriminative values were found in the selected features in identifying a clinically significant response to levodopa with sensitivity, specificity, and area under the curve (AUC) in the range of 50-100%, 47.22%-97.22%, and 0.673-0.915, respectively. The resulting classifier combining kinematic features of toe tapping showed an excellent performance with an AUC of 0.966 (95% CI = 0.922-1.000, P < 0.001). The optimal cut-off value was 21.24% with sensitivity and specificity of 94.44% and 87.18%, respectively.

CONCLUSION

This study demonstrated the feasibility of measuring the effect of levodopa and objectively assessing ALCT based on kinematic data derived from an Azure Kinect-based system.

The Effect of taVNS at 25 Hz and 100 Hz on Parkinson's Disease Gait-A Randomized Motion Sensor Study

BACKGROUND

Transcutaneous electrostimulation of the auricular branch of the vagal nerve (taVNS) has the propensity to reach diffuse neuromodulatory networks, which are dysfunctional in Parkinson's disease (PD). Previous studies support the use of taVNS as an add-on treatment for gait in PD.

OBJECTIVES

We assessed the effect of taVNS at 25 Hz (taVNS25), taVNS at 100 Hz (taVNS100), and sham earlobe stimulation (sVNS) on levodopa responsive (arm swing velocity, arm range of motion, stride length, gait speed) and non-responsive gait characteristics (arm range of motion asymmetry, anticipatory postural adjustment [APA] duration, APA first step duration, APA first step range of motion), and turns (first turn duration, double 360° turn duration, steps per turn) in advanced PD.

METHODS

In our double blind sham controlled within-subject randomized trial, we included 30 PD patients (modified Hoehn and Yahr stage, 2.5-4) to assess the effect of taVNS25, taVNS100, and sVNS on gait characteristics measured with inertial motion sensors during the instrumented stand and walk test and a double 360° turn. Separate generalized mixed models were built for each gait characteristic.

RESULTS

During taVNS100 compared to sVNS arm swing velocity (P = 0.030) and stride length increased (P = 0.027), and APA duration decreased (P = 0.050). During taVNS25 compared to sVNS stride length (P = 0.024) and gait speed (P = 0.021) increased and double 360° turn duration decreased (P = 0.039).

CONCLUSIONS

We have found that taVNS has a frequency specific propensity to improve stride length, arm swing velocity, and gait speed and double 360° turn duration in PD patients. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

The impact of anxiety on gait impairments in Parkinson's disease: insights from sensor-based gait analysis

BACKGROUND

Sensor-based gait analysis provides a robust quantitative tool for assessing gait impairments and their associated factors in Parkinson's disease (PD). Anxiety is observed to interfere with gait clinically, but this has been poorly investigated. Our purpose is to utilize gait analysis to uncover the effect of anxiety on gait in patients with PD.

METHODS

We enrolled 38 and 106 PD patients with and without anxiety, respectively. Gait parameters were quantitively examined and compared between two groups both in single-task (ST) and dual-task (DT) walking tests. Multiple linear regression was applied to evaluate whether anxiety independently contributed to gait impairments.

RESULTS

During ST, PD patients with anxiety presented significantly shorter stride length, lower gait velocity, longer stride time and stance time, longer stance phase, smaller toe-off (TO) and heel-strike (HS) angles than those without anxiety. While under DT status, the differences were diminished. Multiple linear regression analysis demonstrated that anxiety was an independent factor to a serials of gait parameters, particularly ST-TO (B = -2.599, (-4.82, -0.38)), ST-HS (B = -2.532, (-4.71, -0.35)), ST-TO-CV (B = 4.627, (1.71, 7.64)), ST-HS-CV(B = 4.597, (1.66, 7.53)), ST stance phase (B = 1.4, (0.22, 2.58)), and DT stance phase (B = 1.749, (0.56, 2.94)).

CONCLUSION

Our study discovered that anxiety has a significant impact on gait impairments in PD patients, especially exacerbating shuffling steps and prolonging stance phase. These findings highlight the importance of addressing anxiety in PD precision therapy to achieve better treatment outcomes.

Unveiling the Unpredictable in Parkinson's Disease: Sensor-Based Monitoring of Dyskinesias and Freezing of Gait in Daily Life

BACKGROUND

Dyskinesias and freezing of gait are episodic disorders in Parkinson's disease, characterized by a fluctuating and unpredictable nature. This cross-sectional study aims to objectively monitor Parkinsonian patients experiencing dyskinesias and/or freezing of gait during activities of daily living and assess possible changes in spatiotemporal gait parameters.

METHODS

Seventy-one patients with Parkinson's disease (40 with dyskinesias and 33 with freezing of gait) were continuously monitored at home for a minimum of 5 days using a single wearable sensor. Dedicated machine-learning algorithms were used to categorize patients based on the occurrence of dyskinesias and freezing of gait. Additionally, specific spatiotemporal gait parameters were compared among patients with and without dyskinesias and/or freezing of gait.

RESULTS

The wearable sensor algorithms accurately classified patients with and without dyskinesias as well as those with and without freezing of gait based on the recorded dyskinesias and freezing of gait episodes. Standard spatiotemporal gait parameters did not differ significantly between patients with and without dyskinesias or freezing of gait. Both the time spent with dyskinesias and the number of freezing of gait episodes positively correlated with the disease severity and medication dosage.

CONCLUSIONS

A single inertial wearable sensor shows promise in monitoring complex, episodic movement patterns, such as dyskinesias and freezing of gait, during daily activities. This approach may help implement targeted therapeutic and preventive strategies for Parkinson's disease.

3D Kinematics Quantifies Gait Response to Levodopa earlier and to a more Comprehensive Extent than the MDS-Unified Parkinson's Disease Rating Scale in Patients with Motor Complications

BACKGROUND

Quantitative 3D movement analysis using inertial measurement units (IMUs) allows for a more detailed characterization of motor patterns than clinical assessment alone. It is essential to discriminate between gait features that are responsive or unresponsive to current therapies to better understand the underlying pathophysiological basis and identify potential therapeutic strategies.

OBJECTIVES

This study aims to characterize the responsiveness and temporal evolution of different gait subcomponents in Parkinson's disease (PD) patients in their OFF and various ON states following levodopa administration, utilizing both wearable sensors and the gold-standard MDS-UPDRS motor part III.

METHODS

Seventeen PD patients were assessed while wearing a full-body set of 15 IMUs in their OFF state and at 20-minute intervals following the administration of a supra-threshold levodopa dose. Gait was reconstructed using a biomechanical model of the human body to quantify how each feature was modulated. Comparisons with non-PD control subjects were conducted in parallel.

RESULTS

Significant motor changes were observed in both the upper and lower limbs according to the MDS-UPDRS III, 40 minutes after levodopa intake. IMU-assisted 3D kinematics detected significant motor alterations as early as 20 minutes after levodopa administration, particularly in upper limbs metrics. Although all "pace-domain" gait features showed significant improvement in the Best-ON state, most rhythmicity, asymmetry, and variability features did not.

CONCLUSION

IMUs are capable of detecting motor alterations earlier and in a more comprehensive manner than the MDS-UPDRS III. The upper limbs respond more rapidly to levodopa, possibly reflecting distinct thresholds to levodopa across striatal regions.

Visual feedback improves propulsive force generation during treadmill walking in people with Parkinson disease

Persons with Parkinson's disease experience gait alterations, such as reduced step length. Gait dysfunction is a significant research priority as the current treatments targeting gait impairment are limited. This study aimed to investigate the effects of visual biofeedback on propulsive force during treadmill walking in persons with Parkinson's. Sixteen ambulatory persons with Parkinson's participated in the study. They received real-time biofeedback of anterior ground reaction force during treadmill walking at a constant speed. Peak propulsive force values were measured and normalized to body weight. Spatiotemporal parameters were also assessed, including stride length and double support percent. Persons with Parkinson's significantly increased peak propulsive force during biofeedback compared to baseline (p <.0001, Cohen's dz = 1.69). Variability in peak anterior ground reaction force decreased across repeated trials (p <.0001, dz = 1.51). While spatiotemporal parameters did not show significant changes individually, stride length and double support percent improved marginally during biofeedback trials. Persons with Parkinson's can increase propulsive force with visual biofeedback, suggesting the presence of a propulsive reserve. Though stride length did not significantly change, clinically meaningful improvements were observed. Targeting push-off force through visual biofeedback may offer a potential rehabilitation technique to enhance gait performance in Persons with Parkinson's. Future studies could explore the long-term efficacy of this intervention and investigate additional strategies to improve gait in Parkinson's disease.

The Effect of Upright Stance and Vision on a Cognitive Task in Elderly Subjects and Patients with Parkinson's Disease

Standing compared to sitting enhances cognitive performance in healthy subjects. The effect of stance on cognitive performance has been addressed here in patients with Parkinson's disease (PwPD). We hypothesized that a simple cognitive task would be less enhanced in PwPD by standing with respect to sitting, because of a larger cognitive effort for maintenance of standing posture than in healthy subjects. We recruited 40 subjects (20 PwPD and 20 age-matched healthy subjects, HE). Each participant performed an arithmetic task (backward counting aloud by 7) in two postural states, sitting and standing, with eyes open (EO) and with eyes closed (EC). All trials lasted 60 s and were randomized across subjects and conditions. The number of correct subtractions per trial was an index of counting efficiency and the ratio of correct subtractions to total subtractions was an index of accuracy. All conditions collapsed, the efficiency of the cognitive task was significantly lower in PwPD than HE, whilst accuracy was affected to a lower extent. Efficiency significantly improved from sitting to standing in HE under both visual conditions whilst only with EO in PwPD. Accuracy was not affected by posture or vision in either group. We suggest that standing, compared to sitting, increases arousal, thus improving the cognitive performance in HE. Conversely, in PwPD this improvement was present only with vision, possibly due to their greater balance impairment with EC consuming an excess of attentional resources. These findings have implications for balance control and the risk of falling in PwPD in the absence of visual cues.

Gait-related beta-gamma phase amplitude coupling in the subthalamic nucleus of parkinsonian patients

Analysis of coupling between the phases and amplitudes of neural oscillations has gained increasing attention as an important mechanism for large-scale brain network dynamics. In Parkinson's disease (PD), preliminary evidence indicates abnormal beta-phase coupling to gamma-amplitude in different brain areas, including the subthalamic nucleus (STN). We analyzed bilateral STN local field potentials (LFPs) in eight subjects with PD chronically implanted with deep brain stimulation electrodes during upright quiet standing and unperturbed walking. Phase-amplitude coupling (PAC) was computed using the Kullback-Liebler method, based on the modulation index. Neurophysiological recordings were correlated with clinical and kinematic measurements and individual molecular brain imaging studies ([123I]FP-CIT and single-photon emission computed tomography). We showed a dopamine-related increase in subthalamic beta-gamma PAC from standing to walking. Patients with poor PAC modulation and low PAC during walking spent significantly more time in the stance and double support phase of the gait cycle. Our results provide new insights into the subthalamic contribution to human gait and suggest cross-frequency coupling as a gateway mechanism to convey patient-specific information of motor control for human locomotion.

Distinguishing features of Parkinson's disease fallers based on wireless insole plantar pressure monitoring

Postural instability is one of the most disabling motor signs of Parkinson's disease (PD) and often underlies an increased likelihood of falling and loss of independence. Current clinical assessments of PD-related postural instability are based on a retropulsion test, which introduces human error and only evaluates reactive balance. There is an unmet need for objective, multi-dimensional assessments of postural instability that directly reflect activities of daily living in which individuals may experience postural instability. In this study, we trained machine-learning models on insole plantar pressure data from 111 participants (44 with PD and 67 controls) as they performed simulated static and active postural tasks of activities that often occur during daily living. Models accurately classified PD from young controls (area under the curve (AUC) 0.99+/- 0.00), PD from age-matched controls (AUC 0.99+/- 0.01), and PD fallers from PD non-fallers (AUC 0.91+/- 0.08). Utilizing features from both static and active postural tasks significantly improved classification performances, and all tasks were useful for separating PD from controls; however, tasks with higher postural threats were preferred for separating PD fallers from PD non-fallers.

Generalization of In-Place Balance Perturbation Training in People With Parkinson Disease

BACKGROUND AND PURPOSE

Reactive balance training improves reactive postural control in people with Parkinson disease (PwPD). However, the extent to which reactive balance training generalizes to a novel, unpracticed reactive balance task is unknown. This study aimed to determine whether reactive training stepping through support surface translations can be generalized to an unpracticed, instrumented tether-release task.

METHODS

Twenty-five PwPD (70.52 years ± 7.15; Hoehn and Yahr range 1-3) completed a multiple baseline, open-label, uncontrolled pre-post intervention study. Stepping was trained through a 2-week (6-session) intervention with repeated support surface translations. Performance on an untrained tether-release task (generalization task) was measured at 2 baseline assessments (B1 and B2, 2 weeks apart), immediately after the intervention (P1), and 2 months after training (P2). The tether-release task outcomes were the anterior-posterior margin of stability (MOS), step length, and step latency during backward and forward steps.

RESULTS

After support surface translation practice, tether-release stepping performance improved in MOS, step length, and step latency for both backward and forward steps compared to baseline (P < 0.05). Improvements in MOS and step length during backward and forward steps in the tether-release task, respectively, were related to stepping changes in the practiced task. However, the improvements in the generalization task were not retained for 2 months.

DISCUSSION AND CONCLUSIONS

These findings support short-term generalization from trained balance tasks to novel, untrained tasks. These findings contribute to our understanding of the effects and generalization of reactive step training in PwPD.

Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content available at http://links.lww.com/JNPT/A465).

Towards a better understanding of anticipatory postural adjustments in people with Parkinson's disease

INTRODUCTION

Previous studies have shown that anticipatory postural adjustments (APAs) are altered in people with Parkinson's disease but its meaning for locomotion is less understood. This study aims to investigate the association between APAs and gait initiation, gait and freezing of gait and how a dynamic postural control challenging training may induce changes in these features.

METHODS

Gait initiation was quantified using wearable sensors and subsequent straight walking was assessed via marker-based motion capture. Additionally, turning and FOG-related outcomes were measured with wearable sensors. Assessments were conducted one week before (Pre), one week after (Post) and 4 weeks after (Follow-up) completion of a training intervention (split-belt treadmill training or regular treadmill training), under single task and dual task (DT) conditions. Statistical analysis included a linear mixed model for training effects and correlation analysis between APAs and the other outcomes for Pre and Post-Pre delta.

RESULTS

52 participants with Parkinson's disease (22 freezers) were assessed. We found that APA size in the medio-lateral direction during DT was positively associated with gait speed (p<0.001) and stride length (p<0.001) under DT conditions at Pre. The training effect was largest for first step range of motion and was similar for both training modes. For the associations between changes after the training (pooled sample) medio-lateral APA size showed a significant positive correlation with first step range of motion (p = 0.033) only in the DT condition and for the non-freezers only.

CONCLUSIONS

The findings of this work revealed new insights into how APAs were not associated with first step characteristics and freezing and only baseline APAs during DT were related with DT gait characteristics. Training-induced changes in the size of APAs were related to training benefits in the first step ROM only in non-freezers. Based on the presented results increasing APA size through interventions might not be the ideal target for overall improvement of locomotion.

Exploring Potential Predictors of Treadmill Training Effects in People With Parkinson Disease

OBJECTIVE

To explore the potential predictors of people with Parkinson disease (PD) who would benefit the most from treadmill training.

DESIGN

A cohort study.

SETTING

Medical university rehabilitation settings.

PARTICIPANTS

Seventy participants diagnosed of idiopathic PD.

INTERVENTIONS

Twelve sessions of treadmill training.

MAIN OUTCOME MEASURES

Hierarchical logistic regression models were used to explore significant predictors of the treadmill training effect with respect to 3 health domains: Unified Parkinson's Disease Rating Scales part III (UPDRS III); gait speed; Parkinson's Disease Questionnaire-39 (PDQ-39). A receiver operating characteristic (ROC) curve analysis was conducted to identify proper cut-off points for clinical use.

RESULTS

Male sex (adjusted odds ratio [OR]: 3.73, P=.036) significantly predicted the improvement of UPDRS III. Individuals with a slower baseline gait speed (cut-off: 0.92 m/s, adjusted OR: 14.06, P<.001) and higher baseline balance confidence measured by the Activity-specific Balance Confidence scale (cut-off: 84.5 points, adjusted OR: 4.66, P=.022) have greater potential to achieve clinically relevant improvements in gait speed. A poorer baseline PDQ-39 score (cut-off: 23.1, adjusted OR: 7.47, P<.001) predicted a greater quality of life improvement after treadmill training.

CONCLUSIONS

These findings provide a guideline for clinicians to easily identify suitable candidates for treadmill training. Generalization to more advanced patients with PD warrants further investigation.

Gait impairment-related axonal degeneration in Parkinson's disease by neurite orientation dispersion and density imaging

Microstructural alterations in the brain networks of Parkinson's disease (PD) patients are correlated with gait impairments. Evaluate microstructural alterations in the white matter (WM) fiber bundle tracts using neurite orientation dispersion and density imaging (NODDI) technique in PD versus healthy controls (HC). In this study, 24 PD patients and 29 HC were recruited. NODDI and high-resolution 3D structural images were acquired for each participant. The NODDI indicators, including the intracellular neurite density index (NDI), orientation dispersion index (ODI), and isotropic volume fraction (ISO), were compared between the two groups. Diffusion-weighted (DW) images were preprocessed using MRtrix 3.0 software and the orientation distribution function to trace the main nerve fiber tracts in PD patients. Quantitative gait and clinical assessment scales were used to compare the medication "ON" and "OFF" states of PD patients. The NDI, ODI, and ISO values of the WM fiber bundles were significantly higher in PD patients compared to HC. Fiber bundles, including the anterior thalamic radiation, corticospinal tract, superior longitudinal fasciculus, forceps major, cingulum, and inferior longitudinal fasciculus, were found to be significantly affected in PD. The NDI changes of PD patients were well correlated with stride lengths in the "ON" state; ODI changes were correlated with the stride time in the "ON" and "OFF" states and ISO changes were correlated with the stride time and cadence in the "ON" state. In conclusion, combination of NODDI technique and gait parameters can help detect gait impairment in PD patients early and accurately.

Mesencephalic Locomotor Region and Presynaptic Inhibition during Anticipatory Postural Adjustments in People with Parkinson's Disease

Individuals with Parkinson's disease (PD) and freezing of gait (FOG) have a loss of presynaptic inhibition (PSI) during anticipatory postural adjustments (APAs) for step initiation. The mesencephalic locomotor region (MLR) has connections to the reticulospinal tract that mediates inhibitory interneurons responsible for modulating PSI and APAs. Here, we hypothesized that MLR activity during step initiation would explain the loss of PSI during APAs for step initiation in FOG (freezers). Freezers (n = 34) were assessed in the ON-medication state. We assessed the beta of blood oxygenation level-dependent signal change of areas known to initiate and pace gait (e.g., MLR) during a functional magnetic resonance imaging protocol of an APA task. In addition, we assessed the PSI of the soleus muscle during APA for step initiation, and clinical (e.g., disease duration) and behavioral (e.g., FOG severity and APA amplitude for step initiation) variables. A linear multiple regression model showed that MLR activity (R2 = 0.32, p = 0.0006) and APA amplitude (R2 = 0.13, p = 0.0097) explained together 45% of the loss of PSI during step initiation in freezers. Decreased MLR activity during a simulated APA task is related to a higher loss of PSI during APA for step initiation. Deficits in central and spinal inhibitions during APA may be related to FOG pathophysiology.

A Novel Home-Based Telerehabilitation Program Targeting Fall Prevention in Parkinson Disease: A Preliminary Trial

Background and Objectives

Falls in a person with Parkinson disease (PwP) are frequent, consequential, and only partially prevented by current therapeutic options. Notably, most falls in PwPs occur in the home or its immediate surroundings; however, our current strategies for fall prevention are clinic-centered. The primary objective of this nonrandomized pilot trial was to investigate the feasibility and preliminary efficacy of the novel implementation of home-based PD telerehabilitation (tele-physical/occupational therapy) focusing on fall risk reduction and home-safety modification.

Methods

Persons with mild-to-moderate PD who were identified as being at risk of falls by their movement disorders neurologist were recruited from a tertiary movement disorders clinic. After an initial in-person evaluation by the study physical and occupational therapists, 15 patients with PD (Hoehn and Yahr Stage 2 (n = 8) and Stage 3 (n = 7)) participated in 4 biweekly PT/OT televisits with care partner supervision over the course of 10 weeks. The Goal Attainment Scale (GAS) was implemented to assess progress toward individualized PT/OT goals established at baseline. Outcomes were assessed at the end of the intervention at 10 weeks and at a six-month follow-up.

Results

Participants completed all 120 protocol-defined televisits without dropouts and adverse events. At 10 weeks, mean composite PT and OT-GAS scores showed significant improvement from baseline (PT: p < 0.001, OT: p < 0.008), which continued at 6 months (PT: p < 0.0005, OT: p < 0.0005). Home-modification recommendations made through novel virtual home-safety tours were cumulatively met by participants at 87% at 10 weeks and 91% at 6 months.

Discussion

Home-based telerehabilitation is a promising new strategy toward fall prevention in PD. The GAS has the potential to serve as an effective and patient-driven primary outcome variable for rehabilitation interventions for heterogeneous PwPs to assess progress toward personalized goals.

Trial Registration Information

ClinicalTrial.gov identifier: NCT04600011.

Early-onset and late-onset Parkinson's disease exhibit a different profile of gait and posture features based on the Kinect

INTRODUCTION

Gait and posture abnormalities are the common disabling motor symptoms in Parkinson's disease (PD). This study aims to investigate the differential characteristics of gait and posture in early-onset PD (EOPD) and late-onset PD (LOPD) using the Kinect depth camera.

METHODS

Eighty-eight participants, including two subgroups of 22 PD patients and two subgroups of 22 healthy controls (HC) matched for age, sex, and height, were enrolled. Gait and posture features were quantitatively assessed using a Kinect-based system. A two-way analysis of variance was used to compare the difference between different subgroups.

RESULTS

EOPD had a significantly higher Gait score than LOPD (p = 0.031). Specifically, decreased swing phase (p = 0.034) was observed in the EOPD group. Although the Posture score was similar between the two groups, LOPD was characterized by an increased forward flexion angle of the trunk at the thorax (p = 0.042) and a decreased forward flexion angle of the head relative to the trunk (p = 0.009). Additionally, age-independent features were observed in both PD subgroups, and post hoc tests revealed that EOPD generally performed worse gait features. In comparison, LOPD was characterized by worse performance in posture features.

CONCLUSIONS

EOPD and LOPD exhibit different profiles of gait and posture features. The phenotype-specific characteristics likely reflect the distinct neurodegenerative processes between them.

Exercise and gait/movement analyses in treatment and diagnosis of Parkinson's Disease

Cardinal motor symptoms in Parkinson's disease (PD) include bradykinesia, rest tremor and/or rigidity. This symptomatology can additionally encompass abnormal gait, balance and postural patterns at advanced stages of the disease. Besides pharmacological and surgical therapies, physical exercise represents an important strategy for the management of these advanced impairments. Traditionally, diagnosis and classification of such abnormalities have relied on partially subjective evaluations performed by neurologists during short and temporally scattered hospital appointments. Emerging sports medical methods, including wearable sensor-based movement assessment and computational-statistical analysis, are paving the way for more objective and systematic diagnoses in everyday life conditions. These approaches hold promise to facilitate customizing clinical trials to specific PD groups, as well as personalizing neuromodulation therapies and exercise prescriptions for each individual, remotely and regularly, according to disease progression or specific motor symptoms. We aim to summarize exercise benefits for PD with a specific emphasis on gait and balance deficits, and to provide an overview of recent advances in movement analysis approaches, notably from the sports science community, with value for diagnosis and prognosis. Although such techniques are becoming increasingly available, their standardization and optimization for clinical purposes is critically missing, especially in their translation to complex neurodegenerative disorders such as PD. We highlight the importance of integrating state-of-the-art gait and movement analysis approaches, in combination with other motor, electrophysiological or neural biomarkers, to improve the understanding of the diversity of PD phenotypes, their response to therapies and the dynamics of their disease progression.

Stability Changes in Fall-Prone Individuals With Parkinson Disease Following Reactive Step Training

BACKGROUND AND PURPOSE

Poor reactive steps may lead to falls in people with Parkinson disease (PwPD). However, whether reactive steps can be improved in PwPD at risk for falls or whether step training reduces falls remains unclear. This study aimed to determine whether 2 weeks of reactive step training result in (1) immediate and retained improvements in stepping and (2) fewer prospective falls in PwPD at fall risk.

METHODS

Twenty-five PwPD (70.52 years ± 7.15; Hoehn & Yahr range 1-3) at risk for falls completed a multiple baseline, open-label, uncontrolled pre-/postintervention study. Stepping performance was assessed at 2 baseline assessments (B1 and B2) followed by a 2-week, 6-session training protocol. Stepping was assessed immediately (P1) and 2 months after training (P2). Primary outcomes were anterior-posterior margin of stability (MOS), step length, and step latency during backward stepping. Fall frequency was measured for 2 months before and after training.

RESULTS

MOS during backward steps was significantly larger (better) after training ( P < 0.001, d = 0.83), and improvements were retained for 2 months ( P = 0.04, d = 0.66). Step length was not statistically significant different after training ( P = 0.13, d = 0.46) or at follow-up ( P = 0.08, d = 0.62), although effect sizes were medium and large, respectively. Step latency improved after initial exposure ( P = 0.01, d = 0.60) but not following training ( P = 0.43, d = 0.35). Twelve participants experienced fewer falls after training than before (10 = no change, 5 = increase; P = 0.12). Greater improvements in MOS were related to fewer falls ( P = 0.04).

DISCUSSION AND CONCLUSIONS

Two weeks of reactive step training resulted in immediate and retained improvements in some reactive stepping outcomes in PwPD at risk for falls and may reduce fall risk. Reactive step training may be a viable approach to reduce falls in PwPD.

Transcutaneous auricular vagus nerve stimulation improves gait and cortical activity in Parkinson's disease: A pilot randomized study

OBJECTIVE

In this randomized, double-blind, sham-controlled trial, we explored the effect of 20 Hz transcutaneous auricular vagus nerve stimulation (taVNS) on gait impairments in Parkinson's disease (PD) patients and investigated the underlying neural mechanism.

METHODS

In total, 22 PD patients and 14 healthy controls were enrolled. PD patients were randomized (1:1) to receive active or sham taVNS (same position as active taVNS group but without releasing current) twice a day for 1 week. Meanwhile, all subjects were measured activation in the bilateral frontal and sensorimotor cortex during usual walking by functional near-infrared spectroscopy.

RESULTS

PD patients showed instable gait with insufficient range of motion during usual walking. Active taVNS improved gait characteristics including step length, stride velocity, stride length, and step length variability compared with sham taVNS after completion of the 7-day therapy. No difference was found in the Unified Parkinson's Disease Rating Scale III, Timed Up and Go, Tinetti Balance, and Gait scores. Moreover, PD patients had higher relative change of oxyhemoglobin in the left dorsolateral prefrontal cortex, pre-motor area, supplementary motor area, primary motor cortex, and primary somatosensory cortex than HCs group during usual walking. Hemodynamic responses in the left primary somatosensory cortex were significantly decreased after taVNS therapy.

CONCLUSION

taVNS can relieve gait impairments and remodel sensorimotor integration in PD patients.

Carpets with visual cues can improve gait in Parkinson's disease patients: may be independent of executive function

BACKGROUND

Gait impairment is common in Parkinson's disease (PD) patients, which greatly reduces their quality of life. Executive dysfunction is associated with gait impairment. Compensatory strategies, including visual cues, have been shown to be effective in improving PD gait. In this study, we aimed to understand whether carpets with visual cues could improve PD gait, and how the improvement varies across patients with different executive function state.

METHODS

We designed carpets with chessboard and stripe cues. A total of 65 Chinese PD patients were recruited. Movement Disorder Society Unified Parkinson's Disease Rating Scale, L-dopa equivalent daily dosage, Hoehn & Yahr stage, Frontal Assessment Battery, Mini Mental State Examination Scale, Hamilton Anxiety Scale, and Hamilton Depression Scale were evaluated. Gait parameters including stride length, gait speed and fall risk were recorded by a wearable electronic device.

RESULTS

The stride length and gait speed were significantly improved and the fall risk was significantly mitigated when PD patients walked on carpets with chessboard and stripe patterns. Further analysis showed the amelioration of gait parameters was independent of executive dysfunction.

CONCLUSIONS

Our study demonstrates that carpets with visual cues can improve the gait of PD patients even in those with mild executive dysfunction.

Overview on wearable sensors for the management of Parkinson's disease

Parkinson's disease (PD) is affecting about 1.2 million patients in Europe with a prevalence that is expected to have an exponential increment, in the next decades. This epidemiological evolution will be challenged by the low number of neurologists able to deliver expert care for PD. As PD is better recognized, there is an increasing demand from patients for rigorous control of their symptoms and for therapeutic education. In addition, the highly variable nature of symtoms between patients and the fluctuations within the same patient requires innovative tools to help doctors and patients monitor the disease in their usual living environment and adapt treatment in a more relevant way. Nowadays, there are various body-worn sensors (BWS) proposed to monitor parkinsonian clinical features, such as motor fluctuations, dyskinesia, tremor, bradykinesia, freezing of gait (FoG) or gait disturbances. BWS have been used as add-on tool for patients' management or research purpose. Here, we propose a practical anthology, summarizing the characteristics of the most used BWS for PD patients in Europe, focusing on their role as tools to improve treatment management. Consideration regarding the use of technology to monitor non-motor features is also included. BWS obviously offer new opportunities for improving management strategy in PD but their precise scope of use in daily routine care should be clarified.

Arm swing asymmetry in people with Parkinson's disease and its relationship with gait: A systematic review and meta-analysis

BACKGROUND

Individuals with Parkinson's disease present arm swing alterations that can adversely affect their locomotion.

OBJECTIVE

To identify differences in arm swing asymmetry (ASA) between individuals with Parkinson's disease (PD) and healthy individuals and to investigate the relationship between ASA, temporal-spatial gait parameters, and disease progression.

METHODS

A literature search was conducted in PubMed, Scopus, ProQuest, Web of Science, and EBSCOhost up to February 2023. Cross-sectional studies evaluating parameters of arm swing (AS) and ASA were included. Methodological quality was assessed using the Critical Appraisal Checklist, and the quality of the evidence was measured with a modified Grading of Recommendations Assessment, Development, and Evaluation.

RESULTS

Fourteen studies were included in the systematic review (1130 participants). Irrespective of the medication phase (ON or OFF) and the type of walk test employed, the meta-analysis showed moderate-quality evidence that individuals with PD have increased ASA amplitude (SMD = 0.84; 95% CI: 0.69, 0.99; I²= 0%).Very low-quality evidence suggests higher ASA velocity (SMD=0.64; 95% CI: 0.24, 1.05; I²=59%) and lower AS amplitude on both the most affected (ES = -1.99, 95% CI: -3.04, -0.94, I2: 91%) and the least affected sides (ES = -0.75, 95% CI: -1.05, -0.44; I²=66%). Meta-regression indicated that ASA is inversely related to disease duration (Z: -2.4892, P< 0.05) and motor symptoms progression (Z: -2.1336, P< 0.05).

CONCLUSIONS

Regardless of the medication phase and the type of walk test employed, individuals with PD exhibited greater ASA and decreased AS amplitude than healthy individuals. ASA decreases as the disease progresses and symptoms worsen.

Classifying Tremor Dominant and Postural Instability and Gait Difficulty Subtypes of Parkinson's Disease from Full-Body Kinematics

Characterizing motor subtypes of Parkinson's disease (PD) is an important aspect of clinical care that is useful for prognosis and medical management. Although all PD cases involve the loss of dopaminergic neurons in the brain, individual cases may present with different combinations of motor signs, which may indicate differences in underlying pathology and potential response to treatment. However, the conventional method for distinguishing PD motor subtypes involves resource-intensive physical examination by a movement disorders specialist. Moreover, the standardized rating scales for PD rely on subjective observation, which requires specialized training and unavoidable inter-rater variability. In this work, we propose a system that uses machine learning models to automatically and objectively identify some PD motor subtypes, specifically Tremor-Dominant (TD) and Postural Instability and Gait Difficulty (PIGD), from 3D kinematic data recorded during walking tasks for patients with PD (MDS-UPDRS-III Score, 34.7 ± 10.5, average disease duration 7.5 ± 4.5 years). This study demonstrates a machine learning model utilizing kinematic data that identifies PD motor subtypes with a 79.6% F1 score (N = 55 patients with parkinsonism). This significantly outperformed a comparison model using classification based on gait features (19.8% F1 score). Variants of our model trained to individual patients achieved a 95.4% F1 score. This analysis revealed that both temporal, spectral, and statistical features from lower body movements are helpful in distinguishing motor subtypes. Automatically assessing PD motor subtypes simply from walking may reduce the time and resources required from specialists, thereby improving patient care for PD treatments. Furthermore, this system can provide objective assessments to track the changes in PD motor subtypes over time to implement and modify appropriate treatment plans for individual patients as needed.

Predicting Ambulatory Capacity in Parkinson's Disease to Analyze Progression, Biomarkers, and Trial Design

BACKGROUND

In Parkinson's disease (PD), gait and balance is impaired, relatively resistant to available treatment and associated with falls and disability. Predictive models of ambulatory progression could enhance understanding of gait/balance disturbances and aid in trial design.

OBJECTIVES

To predict trajectories of ambulatory abilities from baseline clinical data in early PD, relate trajectories to clinical milestones, compare biomarkers, and evaluate trajectories for enrichment of clinical trials.

METHODS

Data from two multicenter, longitudinal, observational studies were used for model training (Tracking Parkinson's, n = 1598) and external testing (Parkinson's Progression Markers Initiative, n = 407). Models were trained and validated to predict individuals as having a "Progressive" or "Stable" trajectory based on changes of ambulatory capacity scores from the Movement Disorders Society Unified Parkinson's Disease Rating Scale parts II and III. Survival analyses compared time-to-clinical milestones and trial outcomes between predicted trajectories.

RESULTS

On external evaluation, a support vector machine model predicted Progressive trajectories using baseline clinical data with an accuracy, weighted-F1 (proportionally weighted harmonic mean of precision and sensitivity), and sensitivity/specificity of 0.735, 0.799, and 0.688/0.739, respectively. Over 4 years, the predicted Progressive trajectory was more likely to experience impaired balance, loss of independence, impaired function and cognition. Baseline dopamine transporter imaging and select biomarkers of neurodegeneration were significantly different between predicted trajectory groups. For an 18-month, randomized (1:1) clinical trial, sample size savings up to 30% were possible when enrollment was enriched for the Progressive trajectory versus no enrichment.

CONCLUSIONS

It is possible to predict ambulatory abilities from clinical data that are associated with meaningful outcomes in people with early PD. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Prevention of Falls in Parkinson's Disease: Guidelines and Gaps

Background

People living with Parkinson's disease (PD) have a high risk for falls.

Objective

To examine gaps in falls prevention targeting people with PD as part of the Task Force on Global Guidelines for Falls in Older Adults.

Methods

A Delphi consensus process was used to identify specific recommendations for falls in PD. The current narrative review was conducted as educational background with a view to identifying gaps in fall prevention.

Results

A recent Cochrane review recommended exercises and structured physical activities for PD; however, the types of exercises and activities to recommend and PD subgroups likely to benefit require further consideration. Freezing of gait, reduced gait speed, and a prior history of falls are risk factors for falls in PD and should be incorporated in assessments to identify fall risk and target interventions. Multimodal and multi-domain fall prevention interventions may be beneficial. With advanced or complex PD, balance and strength training should be administered under supervision. Medications, particularly cholinesterase inhibitors, show promise for falls prevention. Identifying how to engage people with PD, their families, and health professionals in falls education and implementation remains a challenge. Barriers to the prevention of falls occur at individual, environmental, policy, and health system levels.

Conclusion

Effective mitigation of fall risk requires specific targeting and strategies to reduce this debilitating and common problem in PD. While exercise is recommended, the types and modalities of exercise and how to combine them as interventions for different PD subgroups (cognitive impairment, freezing, advanced disease) need further study.

Differential spatiotemporal gait effects with frequency and dopaminergic modulation in STN-DBS

Objective

The spatiotemporal gait changes in advanced Parkinson's disease (PD) remain a treatment challenge and have variable responses to L-dopa and subthalamic deep brain stimulation (STN-DBS). The purpose of this study was to determine whether low-frequency STN-DBS (LFS; 60 Hz) elicits a differential response to high-frequency STN-DBS (HFS; 180 Hz) in spatiotemporal gait kinematics.

Methods

Advanced PD subjects with chronic STN-DBS were evaluated in both the OFF and ON medication states with LFS and HFS stimulation. Randomization of electrode contact pairs and frequency conditions was conducted. Instrumented Stand and Walk assessments were carried out for every stimulation/medication condition. LM-ANOVA was employed for analysis.

Results

Twenty-two PD subjects participated in the study, with a mean age (SD) of 63.9 years. Significant interactions between frequency (both LFS and HFS) and electrode contact pairs (particularly ventrally located contacts) were observed for both spatial (foot elevation, toe-off angle, stride length) and temporal (foot speed, stance, single limb support (SLS) and foot swing) gait parameters. A synergistic effect was also demonstrated with L-dopa and both HFS and LFS for right SLS, left stance, left foot swing, right toe-off angle, and left arm range of motion. HFS produced significant improvement in trunk and lumbar range of motion compared to LFS.

Conclusion

The study provides evidence of synergism of L-dopa and STN-DBS on lower limb spatial and temporal measures in advanced PD. HFS and LFS STN-DBS produced equivalent effects among all other tested lower limb gait features. HFS produced significant trunk and lumbar kinematic improvements.

Translating digital healthcare to enhance clinical management: a protocol for an observational study using a digital health technology system to monitor medication adherence and its effect on mobility in people with Parkinson's

INTRODUCTION

In people with Parkinson's (PwP) impaired mobility is associated with an increased falls risk. To improve mobility, dopaminergic medication is typically prescribed, but complex medication regimens result in suboptimal adherence. Exploring medication adherence and its impact on mobility in PwP will provide essential insights to optimise medication regimens and improve mobility. However, this is typically assessed in controlled environments, during one-off clinical assessments. Digital health technology (DHT) presents a means to overcome this, by continuously and remotely monitoring mobility and medication adherence. This study aims to use a novel DHT system (DHTS) (comprising of a smartphone, smartwatch and inertial measurement unit (IMU)) to assess self-reported medication adherence, and its impact on digital mobility outcomes (DMOs) in PwP.

METHODS AND ANALYSIS

This single-centre, UK-based study, will recruit 55 participants with Parkinson's. Participants will complete a range of clinical, and physical assessments. Participants will interact with a DHTS over 7 days, to assess self-reported medication adherence, and monitor mobility and contextual factors in the real world. Participants will complete a motor complications diary (ON-OFF-Dyskinesia) throughout the monitoring period and, at the end, a questionnaire and series of open-text questions to evaluate DHTS usability. Feasibility of the DHTS and the motor complications diary will be assessed. Validated algorithms will quantify DMOs from IMU walking activity. Time series modelling and deep learning techniques will model and predict DMO response to medication and effects of contextual factors. This study will provide essential insights into medication adherence and its effect on real-world mobility in PwP, providing insights to optimise medication regimens.

ETHICS AND DISSEMINATION

Ethical approval was granted by London-142 Westminster Research Ethics Committee (REC: 21/PR/0469), protocol V.2.4. Results will be published in peer-reviewed journals. All participants will provide written, informed consent.

TRIAL REGISTRATION NUMBER

ISRCTN13156149.

Using the Instrumented Sway System (ISway) to Identify and Compare Balance Domain Deficits in People With Multiple Sclerosis

OBJECTIVE

To develop a multiple sclerosis (MS)-specific model of balance and examine differences between (1) MS and neurotypical controls and (2) people with MS (PwMS) with (MS-F) and without a fall history (MS-NF).

DESIGN AND SETTING

A cross-sectional study was conducted at the Gait and Balance Laboratory at the University of Kansas Medical Center. Balance was measured from the instrumented sway system (ISway) assessment.

PARTICIPANTS

In total, 118 people with relapsing-remitting MS (MS-F=39; MS-NF=79) and 46 age-matched neurotypical controls.

INTERVENTION

Not applicable.

OUTCOME MEASURES

A total of 22 sway measures obtained from the ISway were entered into an exploratory factor analysis to identify underlying balance domains. The model-derived balance domains were compared between (1) PwMS and age-matched, neurotypical controls and (2) MS-F and MS-NF.

RESULTS

Three distinct balance domains were identified: (1) sway amplitude and velocity, (2) sway frequency and jerk mediolateral, and (3) sway frequency and jerk anteroposterior, explaining 81.66% of balance variance. PwMS exhibited worse performance (ie, greater amplitude and velocity of sway) in the sway velocity and amplitude domain compared to age-matched neurotypical controls (P=.003). MS-F also exhibited worse performance in the sway velocity and amplitude domain compared to MS-NF (P=.046). The anteroposterior and mediolateral sway frequency and jerk domains were not different between PwMS and neurotypical controls nor between MS-F and MS-NF.

CONCLUSIONS

This study identified a 3-factor, MS-specific balance model, demonstrating that PwMS, particularly those with a fall history, exhibit disproportionate impairments in sway amplitude and velocity. Identifying postural stability outcomes and domains that are altered in PwMS and clinically relevant (eg, related to falls) would help isolate potential treatment targets.

Comparative efficacy of 24 exercise types on postural instability in adults with Parkinson's disease: a systematic review and network meta-analysis

OBJECTIVE

To compare, rank and evaluate the 24 exercise types that improve postural instability in patients with Parkinson's disease (PD).

METHODS

We searched the data in PubMed, MEDLINE, Embase, PsycINFO, Cochrane library, and Web of Science from their inception date to January 23, 2023. Randomized controlled trials (RCTs) that aimed at determining the effectiveness of physical activity interventions on postural instability in adults with PD. This review focused on different balance outcome categories: (a) balance test batteries (BBS); (b) static steady-state balance (sSSB); (c) dynamic steady-state balance (dSSB); (d) proactive balance (PB); (e) reactive balance (RB).

RESULTS

Among 10,474 records, 199 studies (patients = 9523) were eligible for qualitative synthesis. The random-effects NMA model revealed that the following exercise training modalities had the highest p score of being best when compared with control group: body-weight support treadmill training (BWS_TT) for BBS (p score = 0.97; pooled standardised mean difference (95% CI): 1.56 (0.72 to 2.39)) and dSSB (1.00; 1.53 (1.07 to 2.00)), aquatic exercise (AQE) for sSSB (0.85; 0.94 (0.33 to 1.54)), Pilates for PB (0.95; 1.42 (0.59 to 2.26)). Balance and gait training with the external cue or attention (BGT_ECA) and robotic assisted gait balance (RA_GT) had similar superior effects in improving RB. The confidence in evidence was often low according to Confidence in Network Meta-Analysis.

CONCLUSIONS

There is low quality evidence that BWS_TT, AQE, Pilates, BGT_ECA and RA_GT are possibly the most effective treatments, pending outcome of interest, for adults with PD.

Transcranial direct current stimulation suggests not improving postural control during adapted tandem position in people with Parkinson's disease: A pilot study

BACKGROUND

Balance impairments in people with Parkinson's disease (PD) demonstrated mainly in challenging postural tasks, such as increased body oscillation may be attributed to the deficits in the brain structures functionality involved in postural control (e.g., motor cortex, midbrain, and brainstem). Although promising results, the effect of transcranial direct current stimulation (tDCS) on postural control in people with PD is unclear, especially in objective measures such as the center of pressure (CoP) parameters. Thus, we analyzed the effects of a single session of tDCS on the CoP parameters during the adapted tandem position in people with PD.

METHODS

Nineteen people with PD participated in this crossover, randomized, and double-blind study. Anodal tDCS was applied over the primary motor cortex in two conditions of stimulation (2 mA/active and sham) on two different days for 20 min immediately before the postural control evaluation. Participants remained standing in an adapted tandem position for the postural control assessment for 30 s (three trials). CoP parameters were acquired by a force plate.

RESULTS

No significant differences were demonstrated between stimulation conditions (p-value range = 0.15-0.89).

CONCLUSIONS

Our results suggested that a single session of tDCS with 2 mA does not improve the postural control of people with PD during adapted tandem.

Challenges and advances in the use of wearable sensors for lower extremity biomechanics

The use of wearable sensors for the collection of lower extremity biomechanical data is increasing in popularity, in part due to the ease of collecting data and the ability to capture movement outside of traditional biomechanics laboratories. Consequently, an increasing number of researchers are facing the challenges that come with utilizing the data captured by wearable sensors. These challenges include identifying/calculating meaningful measures from unfamiliar data types (measures of acceleration and angular velocity instead of positions and joint angles), defining sensor-to-segment alignments for calculating traditional biomechanics metrics, using reduced sensor sets and machine learning to predict unmeasured signals, making decisions about when and how to make algorithms freely available, and developing or replicating methods to perform basic processing tasks such as recognizing activities of interest or identifying gait events. In this perspective article, we present our own approaches to common challenges in lower extremity biomechanics research using wearable sensors and share our perspectives on approaching several of these challenges. We present these perspectives with examples that come mostly from gait research, but many of the concepts also apply to other contexts where researchers may use wearable sensors. Our goal is to introduce common challenges to new users of wearable sensors, and to promote dialogue amongst experienced users towards best practices.

Functional connectome predicting individual gait function and its relationship with molecular architecture in Parkinson's disease

Gait impairment is a common symptom of Parkinson's disease (PD), but its neural signature remains unclear due to the interindividual variability of gait performance. Identifying a robust gait-brain correlation at the individual level would provide insight into a generalizable neural basis of gait impairment. In this context, this study aimed to detect connectome that can predict individual gait function of PD, and follow-up analyses assess the molecular architecture underlying the connectome by relating it to the neurotransmitter-receptor/transporter density maps. Resting-state functional magnetic resonance imaging was used to detect the functional connectome, and gait function was assessed via a 10 m-walking test. The functional connectome was first detected within drug-naive patients (N = 48) by using connectome-based predictive modeling following cross-validation and then successfully validated within drug-managed patients (N = 30). The results showed that the motor, subcortical, and visual networks played an important role in predicting gait function. The connectome generated from patients failed to predict the gait function of 33 normal controls (NCs) and had distinct connection patterns compared to NCs. The negative connections (connection negatively correlated with 10 m-walking-time) pattern of the PD connectome was associated with the density of the D2 receptor and VAChT transporter. These findings suggested that gait-associated functional alteration induced by PD pathology differed from that induced by aging degeneration. The brain dysfunction related to gait impairment was more commonly found in regions expressing more dopaminergic and cholinergic neurotransmitters, which may aid in developing targeted treatments.

Effect of Pro-kin visual feedback balance training on balance function of individuals with early Parkinson's disease: a randomized controlled pilot trial

Background

Parkinson's disease (PD) is the second most common neurodegenerative disease. Patients often present with balance dysfunction. Several studies have applied visual feedback training to stroke patients and demonstrated significant improvement. However, the application of visual feedback balance training in PD patients has not been reported.

Objective

To observe the effects of visual feedback balance training combined with conventional rehabilitation training on the balance function of patients with early PD.

Methods

Fifty patients with early PD were randomly divided into control group and observation group. The control group received conventional rehabilitation training, including body position transfer, weight shifting, movement in all directions and gait training. The observation group were added with visual feedback balance training on the basis of the training above. All patients were trained 5 times per week for 4 weeks. Berg Balance Scale (BBS), Time Up-and-Go test (TUG) and Pro-Kin balance training instrument were used to evaluate the balance function of patients before and after treatment, and the balance function were compared between the two groups.

Results

The BBS and TUG scores of the observation group and the control group were improved significantly (P<0.01), and the BBS and TUG scores of the observation group were improved more obviously than control group (P<0.01). The length and area of eye open and closed condition in the observation group and the control group were significantly reduced compared with those before training (P<0.01), and the degree of reduction in the observation group was more obvious (P<0.01). The length and area of the observation group and the control group before and after training when eye open were smaller than those when eye closed (P<0.01).

Conclusion

The conventional rehabilitation therapy can improve the balance function of PD patients, but the combination of visual feedback balance training and conventional rehabilitation therapy can improve the balance function more significantly.

Gait and balance in apolipoprotein Ɛ4 allele carriers in older adults and Parkinson's disease

Background

Gait and balance impairments are among the most troublesome and heterogeneous in Parkinson's disease (PD). This heterogeneity may, in part, reflect genetic variation. The apolipoprotein E (APOE) gene has three major allelic variants (ε2, ε3 and ε4). Previous work has demonstrated that older adult (OA) APOE ε4 carriers demonstrate gait deficits. This study compared gait and balance measures between APOE ε4 carriers and non-carriers in both OA and PD.

Methods

334 people with PD (81 APOE ε4 carriers and 253 non-carriers) and 144 OA (41 carriers and 103 non-carriers) were recruited. Gait and balance were assessed using body-worn inertial sensors. Two-way analyses of covariance (ANCOVA) compared gait and balance characteristics between APOE ε4 carriers and non-carriers in people with PD and OA, controlling for age, gender, and testing site.

Results

Gait and balance were worse in people with PD compared to OA. However, there were no differences between APOE ε4 carriers and non-carriers in either the OA or PD group. In addition, there were no significant group (OA/PD) by APOE ε4 status (carrier/non-carrier) interaction effects for any measures of gait or balance.

Conclusions

Although we found expected impairments in gait and balance in PD compared to OA, gait and balance characteristics did not differ between APOE ε4 carriers and non-carriers in either group. While APOE status did not impact gait and balance in this cross-sectional study, future work is needed to determine whether progression of gait and balance deficits is faster in PD APOE Ɛ4 carriers.

Toward objective monitoring of Parkinson's disease motor symptoms using a wearable device: wearability and performance evaluation of PDMonitor®

Parkinson's disease (PD) is characterized by a variety of motor and non-motor symptoms. As disease progresses, fluctuations in the response to levodopa treatment may develop, along with emergence of freezing of gait (FoG) and levodopa induced dyskinesia (LiD). The optimal management of the motor symptoms and their complications, depends, principally, on the consistent detection of their course, leading to improved treatment decisions. During the last few years, wearable devices have started to be used in the clinical practice for monitoring patients' PD-related motor symptoms, during their daily activities. This work describes the results of 2 multi-site clinical studies (PDNST001 and PDNST002) designed to validate the performance and the wearability of a new wearable monitoring device, the PDMonitor^®, in the detection of PD-related motor symptoms. For the studies, 65 patients with Parkinson's disease and 28 healthy individuals (controls) were recruited. Specifically, during the Phase I of the first study, participants used the monitoring device for 2-6 h in a clinic while neurologists assessed the exhibited parkinsonian symptoms every half hour using the Unified Parkinson's Disease Rating Scale (UPDRS) Part III, as well as the Abnormal Involuntary Movement Scale (AIMS) for dyskinesia severity assessment. The goal of Phase I was data gathering. On the other hand, during the Phase II of the first study, as well as during the second study (PDNST002), day-to-day variability was evaluated, with patients in the former and with control subjects in the latter. In both cases, the device was used for a number of days, with the subjects being unsupervised and free to perform any kind of daily activities. The monitoring device produced estimations of the severity of the majority of PD-related motor symptoms and their fluctuations. Statistical analysis demonstrated that the accuracy in the detection of symptoms and the correlation between their severity and the expert evaluations were high. As a result, the studies confirmed the effectiveness of the system as a continuous telemonitoring solution, easy to be used to facilitate decision-making for the treatment of patients with Parkinson's disease.

5-HT1A agonists for levodopa-induced dyskinesia in Parkinson's disease

Levodopa is the most effective agent for treating the symptoms of Parkinson's disease (PD). However, levodopa-induced dyskinesia remains a significant complication that manifests after few years of treatment, for which therapeutic options remain limited. Several agonists of the serotonin type 1A (5-HT_1A) receptor with varying levels of efficacy and interaction at other sites, have been tested in the clinic. Clinical trials testing 5-HT_1A agonists have yielded inconsistent results in alleviating dyskinesia, especially that the antidyskinetic benefit observed was often accompanied by an adverse effect on motor function. In this article, we summarize and analyze the various clinical trials performed with 5-HT_1A agonists in PD patients with dyskinesia and offer perspectives on the future of this class of agents in PD.

Effectiveness of Center of Pressure Trajectory as Anticipatory Postural Adjustment Measurement in Parkinson's Disease With Freezing of Gait History

BACKGROUND

Evidence showed that patients with Parkinson's disease (PD) who have a history of freezing of gait (FOG) have hypometric anticipatory postural adjustment (APA) during gait initiation (GI) compared to PD without FOG.

OBJECTIVES

This study aimed to test the feasibility of center of pressure (COP) displacement during GI as the measure of APA in PD with and without a history of FOG.

METHODS

Patients with PD underwent COP trajectory measurements, including duration, length, velocity, and acceleration in different phases of APA (APA1, APA2a, APA2, and LOC), as well as evaluation of New Freezing of Gait Questionnaire (NFOG-Q), Tinetti balance and gait score, and Postural Instability and Gait Difficulty (PIGD) score in the on and off medication states.

RESULTS

The duration (seconds) of APA2a, APA2b, and LOC were highest while velocity in mediolateral direction (X) (m/s), including APA1, APA2a, APA2b, and LOC showed lowest in PD with FOG. Velocity in the mediolateral direction in different phases of APA increased in patients with FOG after dopaminergic therapy. APA2a (seconds) and APA2b (X) (m/s) were significantly associated with NFOG-Q part II, APA2b (X) (m/s) was significantly associated with NFOG-Q part III, and APA2a (seconds) was significantly associated with Tinetti balance and gait and PIGD score.

CONCLUSIONS

PD with FOG history showed a favorable response of APAs to dopaminergic replacement. The APA parameters by COP trajectory, especially lateral COP shift toward the stance foot (APA2b (X) (m/s) and APA2a (seconds)) are surrogate markers to assess PD with FOG history.

Effect of freezing of gait and dopaminergic medication in the biomechanics of lower limbs in the gait of patients with Parkinson's disease compared to neurologically healthy

INTRODUCTION

This study aims to evaluate the effects of medication, and the freezing of gait (FoG) on the kinematic and kinetic parameters of gait in people with Parkinson's disease (pwPD) compared to neurologically healthy.

METHODS

Twenty-two people with a clinical diagnosis of idiopathic PD in ON and OFF medication (11 FoG), and 18 healthy participants (control) were selected from two open data sets. All participants walked on the floor on a 10-meter-long walkway. The joint kinematic and ground reaction forces (GRF) variables of gait and the clinical characteristics were compared: (1) PD with FoG (pwFoG) and PD without FoG (pwoFoG) in the ON condition and control; (2) PD with FoG and PD without FoG in the OFF condition and control; (3) Group (PD with FoG and PD without FoG) and Medication.

RESULTS

(1) FoG mainly affects distal joints, such as the ankle and knee; (2) PD ON showed changes in the range of motion of both distal and proximal joints, which may explain the increase in step length and gait speed expected with the use of L-Dopa; and (3) the medication showed improvements in the kinematic and kinetic parameters of the gait of people with pwFoG and pwoFoG equally; (4) pwPD showed a smaller second peak of the vertical component of the GRF than the control.

CONCLUSION

The presence of FoG mainly affects distal joints, such as the ankle and knee. PD presents a lower application of GRF during the impulse period than healthy people, causing lower gait performances.

Speech and gait abnormalities in motor subtypes of de-novo Parkinson's disease

AIM

To investigate the presence and relationship of temporal speech and gait parameters in patients with postural instability/gait disorder (PIGD) and tremor-dominant (TD) motor subtypes of Parkinson's disease (PD).

METHODS

Speech samples and instrumented walkway system assessments were acquired from a total of 60 de-novo PD patients (40 in TD and 20 in PIGD subtype) and 40 matched healthy controls. Objective acoustic vocal assessment of seven distinct speech timing dimensions was related to instrumental gait measures including velocity, cadence, and stride length.

RESULTS

Compared to controls, PIGD subtype showed greater consonant timing abnormalities by prolonged voice onset time (VOT) while also shorter stride length during both normal walking and dual task, while decreased velocity and cadence only during dual task. Speaking rate was faster in PIGD than TD subtype. In PIGD subtype, prolonged VOT correlated with slower gait velocity (r = -0.56, p = 0.01) and shorter stride length (r = -0.59, p = 0.008) during normal walking, whereas relationships were also found between decreased cadence in dual task and irregular alternating motion rates (r = -0.48, p = 0.04) and prolonged pauses (r = -0.50, p = 0.03). No correlation between speech and gait was detected in TD subtype.

CONCLUSION

Our findings suggest that speech and gait rhythm disorder share similar underlying pathomechanisms specific for PIGD subtype.

Are movement-based mindful exercises (QIGONG, TAI CHI, AND YOGA) beneficial for stroke and Parkinson's disease? A scoping review

OBJECTIVE

To synthesize evidence from systematic reviews on the effects of qigong, tai chi, and yoga in people with neurological diseases.

METHODS

A systematic search was conducted in PubMed, PsycINFO, Embase, CINAHL and Cochrane Library until September 2022. Methodological quality was assessed using the AMSTAR 2 tool. A qualitative synthesis of included reviews and meta-analyses was performed. Citation matrices and the corrected covered area were used to explore the overlap of randomized controlled trials among reviews.

RESULTS

Nineteen systematic reviews (containing 74 trials and 80 meta-analyses) in people with Parkinson's disease (PD) or stroke were included. The critical domains of the AMSTAR 2 were not satisfied in more than half of the reviews, and only 4 evaluated the certainty of the evidence. The overlap was very high (21.7%) and high (11%) for tai chi studies in PD and stroke, respectively. In people with PD, qigong, yoga, and tai chi can improve balance, with tai chi being beneficial to increase functional mobility. For stroke patients, tai chi was better than controls to enhance motor function and independence, but not for health-related quality of life and quality of sleep. Findings on balance, walking ability and depression were inconclusive in stroke population.

CONCLUSIONS

Qigong, tai chi, and yoga appear to be effective to improve balance performance in people with PD. Tai chi practice enhances motor function and independency in stroke patients.

Dopamine replacement therapy normalizes reactive step length to postural perturbations in Parkinson's disease

BACKGROUND

Postural instability is one of the most disabling motor symptoms of Parkinson's disease (PD) given its association with falls and loss of independence. Previous studies have assessed biomechanical measures of reactive stepping in response to perturbations, showing that individuals with PD exhibit inadequate postural responses to regain balance.

RESEARCH QUESTION

Does dopamine replacement therapy normalize step length in response to balance perturbations?

METHODS

In this study, we estimated reactive step length, to a postural perturbation, retrospectively from a dataset of frontal plane video using 2D motion tracking and direct linear transform methods. We compared two perturbation methods: support surface translation and shoulder pull (the clinical standard) in 14 individuals with PD and 13 without PD (on and off medication), with and without partial body weight support (BWS). The primary outcome was the length of the first step taken to regain balance after the perturbation analyzed with mixed effects ANOVA, with post hoc analysis of anteroposterior (AP) and mediolateral (ML) components.

RESULTS

PD OFF medication exhibited shorter reactive step length compared to PD ON and compared to control groups for the surface translation perturbations, but no significant difference was observed for the shoulder pull perturbations.

SIGNIFICANCE

Dopamine replacement therapy affects step length in response to perturbation more robustly for surface translations than for a pull by the shoulders.

Effects of Oral Levodopa on Balance in People with Idiopathic Parkinson's Disease

BACKGROUND

Balance impairment is a frequent cause of morbidity and mortality in people with Parkinson's disease (PD). As opposed to the effects of appendicular motor symptoms, the effects of Levodopa on balance impairment in idiopathic PD are less clear.

OBJECTIVE

To review the literature on the effects of oral Levodopa on clinical balance test performance, posturography, step initiation, and responses to perturbation in people with idiopathic PD (PwPD).

METHODS

A systematic search of three scientific databases (Pubmed, Embase, and Web of Science) was conducted in accordance with PRISMA guidelines. For the pilot meta-analysis, standardized mean differences with 95% confidence intervals were calculated using an inverse variance random effects model. Data not suitable for implementation in the meta-analysis (missing means or standard deviations, and non-independent outcomes) were analyzed narratively.

RESULTS

A total of 2772 unique studies were retrieved, of which 18 met the eligibility criteria and were analyzed, including data of 710 idiopathic PwPD. Levodopa had a significant positive effect on the Berg Balance Scale, the Push and Release test, and jerk and frequency parameters during posturography. In contrast, some significant negative effects on velocity-based sway parameters were found during posturography and step initiation. However, Levodopa had no significant effect on most step initiation- and all perturbation parameters.

CONCLUSION

The effects of Levodopa on balance in PwPD vary depending on the outcome parameters and patient inclusion criteria. A systematic approach with well-defined outcome parameters, and prespecified, sensitive and reliable tests is needed in future studies to unravel the effects of oral Levodopa on balance.

Gait Event Prediction Using Surface Electromyography in Parkinsonian Patients

Gait disturbances are common manifestations of Parkinson's disease (PD), with unmet therapeutic needs. Inertial measurement units (IMUs) are capable of monitoring gait, but they lack neurophysiological information that may be crucial for studying gait disturbances in these patients. Here, we present a machine learning approach to approximate IMU angular velocity profiles and subsequently gait events using electromyographic (EMG) channels during overground walking in patients with PD. We recorded six parkinsonian patients while they walked for at least three minutes. Patient-agnostic regression models were trained on temporally embedded EMG time series of different combinations of up to five leg muscles bilaterally (i.e., tibialis anterior, soleus, gastrocnemius medialis, gastrocnemius lateralis, and vastus lateralis). Gait events could be detected with high temporal precision (median displacement of <50 ms), low numbers of missed events (<2%), and next to no false-positive event detections (<0.1%). Swing and stance phases could thus be determined with high fidelity (median F1-score of ~0.9). Interestingly, the best performance was obtained using as few as two EMG probes placed on the left and right vastus lateralis. Our results demonstrate the practical utility of the proposed EMG-based system for gait event prediction, which allows the simultaneous acquisition of an electromyographic signal to be performed. This gait analysis approach has the potential to make additional measurement devices such as IMUs and force plates less essential, thereby reducing financial and preparation overheads and discomfort factors in gait studies.

Deep Brain Stimulation and Levodopa Affect Gait Variability in Parkinson Disease Differently

BACKGROUND

Both dopaminergic medication and subthalamic nucleus (STN) deep brain stimulation (DBS) can improve the amplitude and speed of gait in Parkinson disease (PD), but relatively little is known about their comparative effects on gait variability. Gait irregularity has been linked to the degeneration of cholinergic neurons in the pedunculopontine nucleus (PPN).

OBJECTIVES

The STN and PPN have reciprocal connections, and we hypothesized that STN DBS might improve gait variability by modulating PPN function. Dopaminergic medication should not do this, and we therefore sought to compare the effects of medication and STN DBS on gait variability.

MATERIALS AND METHODS

We studied 11 patients with STN DBS systems on and off with no alteration to their medication, and 15 patients with PD without DBS systems on and off medication. Participants walked for two minutes in each state, wearing six inertial measurement units. Variability has previously often been expressed in terms of SD or coefficient of variation over a testing session, but these measures conflate long-term variability (eg, gradual slowing, which is not necessarily pathological) with short-term variability (true irregularity). We used Poincaré analysis to separate the short- and long-term variability.

RESULTS

DBS decreased short-term variability in lower limb gait parameters, whereas medication did not have this effect. In contrast, STN DBS had no effect on arm swing and trunk motion variability, whereas medication increased them, without obvious dyskinesia.

CONCLUSIONS

Our results suggest that STN DBS acts through a nondopaminergic mechanism to reduce gait variability. We believe that the most likely explanation is the retrograde activation of cholinergic PPN projection neurons.

Effect and Relationship of Gait on Subcortical Local Field Potentials in Parkinson's Disease: A Systematic Review

OBJECTIVES

Developments in deep brain stimulation (DBS) technology have enabled the ability to detect local field potentials (LFPs) in Parkinson disease (PD). Gait dysfunction is one of the most prevalent deficits seen in PD. However, no consensus has been reached on the effect of gait on LFPs and the relationship between LFPs and clinical measures of gait. The objective of this systematic review was to synthesize existing research regarding the relationship between gait dysfunction and LFPs in PD.

METHODS

A systematic search of the literature yielded a total of ten articles, including 132 patients with PD, which met the criteria for inclusion.

RESULTS

Beta frequency band measures showed low-to-strong correlation to clinical gait measures (r = -0.50 to 0.82). Two studies found decreased beta power during gait; one found increased beta frequency peaks during gait; and one found higher beta power during dual-task gait than during single-task gait. One of the three studies comparing patients with and without freezing found significantly increased beta burst duration and power during gait in freezers compared with nonfreezers. All studies showed moderate-to-high methodologic quality.

CONCLUSIONS

This review highlights the need to consider the effect of gait on LFP recordings, particularly when used to guide DBS programming. Although sample sizes were small, it appears LFPs are associated to and modulated by gait in patients with PD. This evidence suggests that LFPs have the potential to be used as a biomarker of gait dysfunction in PD.

Additive Effect of Dopaminergic Medication on Gait Under Single and Dual-Tasking Is Greater Than of Deep Brain Stimulation in Advanced Parkinson Disease With Long-Duration Deep Brain Stimulation

INTRODUCTION

Patients with advanced Parkinson disease (PD) often experience problems with mobility, including walking under single- (ST) and dual-tasking (DT) conditions. The effects of deep brain stimulation in the subthalamic nucleus (DBS) versus dopaminergic medication (Med) on these conditions are not well investigated.

MATERIALS AND METHODS

We used two ST and two DT-gait paradigms to evaluate the effect of DBS and dopaminergic medication on gait parameters in 14 PD patients (mean age 66 ± 8 years) under DBS_OFF/Med_ON, DBS_ON/Med_OFF, and DBS_ON/Med_ON conditions. They performed standardized 20-meter walks with convenient and fast speed. To test DT capabilities, they performed a checking-boxes and a subtraction task during fast-paced walking. Quantitative gait analysis was performed using a tri-axial accelerometer (Dynaport, McRoberts, The Netherlands). Dual-task costs (DTC) of gait parameters and secondary task performance were compared intraindividually between DBS_OFF/Med_ON vs DBS_ON/Med_ON, and DBS_ON/Med_OFF vs DBS_ON/Med_ON to estimate responsiveness.

RESULTS

Dopaminergic medication increased gait speed and cadence at convenient speed. It increased cadence and decreased number of steps at fast speed, and improved DTC of cadence during the checking boxes and DTC of cadence and number of steps during the subtraction tasks. DBS only improved DTC of cadence during the checking boxes and DTC of gait speed during the subtraction task.

CONCLUSION

Dopaminergic medication showed larger additional effects on temporal gait parameters under ST and DT conditions in advanced PD than DBS. These results, after confirmation in independent studies, should be considered in the medical management of advanced PD patients with gait and DT deficits.

Effect of Levodopa and Environmental Setting on Gait and Turning Digital Markers Related to Falls in People with Parkinson's Disease

Background

It is unknown whether medication status (off and on levodopa) or laboratory versus home settings plays a role in discriminating fallers and non-fallers in people with Parkinson's disease (PD).

Objectives

To investigate which specific digital gait and turning measures, obtained with body-worn sensors, best discriminated fallers from non-fallers with PD in the clinic and during daily life.

Methods

We recruited 34 subjects with PD (17 fallers and 17 non-fallers based on the past 6 month's falls). Subjects wore three inertial sensors attached to both feet and the lumbar region in the laboratory for a 3-minute walking task (both off and on levodopa) and during daily life activities for a week. We derived 24 digital (18 gait and 6 turn) measures from the 3-minute walk and from daily life.

Results

In clinic, none of the gait and turning measures collected during on levodopa state were significantly different between fallers and non-fallers. In contrast, digital measures collected in the off levodopa state were significantly different between groups, (average turn velocity, average number of steps to complete a turn, and variability of gait speed, P < 0.03). During daily life, the variability of average turn velocity (P = 0.023) was significantly different in fallers than non-fallers. Last, the average number of steps to complete a turn was significantly correlated with the patient-reported outcomes.

Conclusions

Digital measures of turning, but not gait, were different in fallers compared to non-fallers with PD, in the laboratory when off medication and during a daily life.