Effect of Parkinson's disease and two therapeutic interventions on muscle activity during walking: a systematic review

EFFECTS OF TREADMILL GAIT TRAINING ON BALANCE IN PARKINSON'S PATIENTS AFTER DEEP BRAIN STIMULATION

Objective

After deep brain stimulation (DBS), patients with Parkinson's disease (PD) typically still present significant gait and postural stability problems, and thus additional interventions are needed. In this way, our purpose was evaluate the comparative effectiveness of treadmill training, with and without body weight support, on balance outcomes among patients with PD after DBS.

Methods

Eleven patients with PD that were using bilateral subthalamic nucleus DBS were evaluated using Time Up and Go test (TUG); Berg Balance Scale (BBS) and Static Posturography. In phase 1, all subjects participated in 8-weeks of treadmill training in conjunction with conventional physiotherapy. After six weeks (wash-out), each patient then participated in a subsequent 8-weeks of treadmill training with partial body weight support.

Results

After the phase 1, there were improvements on the cognitive TUG performance (Before: 15.7 ± 1,8 sec; After: 13.7 ± 3.1 sec; p < 0.01) and an increase of anteroposterior and medio-lateral body oscillation with eyes closed. After the phase 2, there were improvements in conventional (Before: 12.3 ± 2.0 sec; After: 10.7 ± 1.7 sec; p < 0.01) and cognitive (Before: 14.6 ± 3.5 sec; After: 12.5 ± 1.6 sec; p < 0.05) TUG performances. There were no significant changes in the Berg Balance Scale following either training protocol.

Conclusion

Both trainings improved static and dynamic balance and had similar results; however, supported treadmill training seemed to be a potentially superior option, as patients tended to feel safer. Level of Evidence II, therapeutic studies - investigation of treatment outcomes.

Characterization of the vastus lateralis torque-length, and knee extensors torque-velocity and power-velocity relationships in people with Parkinson's disease

Introduction

Parkinson's disease (PD) is a prevalent neurodegenerative condition observed primarily in the elderly population that gives rise to motor and non-motor symptoms, one of which is muscle weakness. The aim of this study was to characterize the vastus lateralis torque-fascicle length (T-L) and the knee extensors torque-angular velocity (T-V) and power-angular velocity (P-V) relationships in PD patients and to investigate the influence of muscle geometry on muscle mechanics.

Methods

Participants (11 PD: patients, 9 CR: age matched healthy controls; 10 CY: young healthy controls) performed: (i) isometric contractions (e.g., MVC) to obtain the torque-angle and T-L relationships; (ii) isokinetic (e.g., iso-velocity) contractions to obtain the T-V and P-V relationships. During the experiments, the architecture of vastus lateralis (pennation angle, fascicle length, muscle thickness) was also determined by using an ultrasound apparatus.

Results

Significant differences were observed between PD patients and physically matched control groups (CR and CY) in terms of maximum isometric force (calculated as the apex of the T-L curve) and maximum mechanical power (apex of the P-V curve), but not in maximum shortening velocity. Among the mechanical variables investigated, mechanical power was able to identify differences between the less and the more affected side in PD patients, suggesting that this parameter could be useful for clinical evaluation in this population.

Conclusions

The observed results cannot be explained by differences in muscle geometry at rest (similar in the three cohorts), but rather by the muscle capacity to change in shape during contraction, that is impaired in PD patients.

Limb and joint kinetics during walking in individuals with Mild-Moderate Parkinson's disease

Given the known deficits in spatiotemporal aspects of gait for people with Parkinson's disease (PD), we sought to determine the underlying gait abnormalities in limb and joint kinetics, and examine how deficits in push-off and leg swing might contribute to the shortened step lengths for people with PD. Ten participants with PD and 11 age-matched control participants walked overground and on an instrumented treadmill. Participants with PD then walked on the treadmill with a posteriorly directed restraining force applied to 1) the pelvis to challenge push-off and 2) the ankles to challenge leg swing. Spatiotemporal, kinematic, and force data were collected and compared between groups and conditions. Despite group differences in spatiotemporal measures during overground walking, we did not observe these differences when the groups walked on a treadmill at comparable speeds. Nevertheless, the hip extension impulse appeared smaller in the PD group during their typical walking. When challenging limb propulsion, participants in the PD group maintained step lengths by increasing the propulsive impulse. Participants with PD were also able to maintain their typical step length against resistance intended to impede swing limb advancement, and even increased step lengths with cuing. The presence of reduced hip extension torque might be an early indicator of gait deterioration in this neurodegenerative disease. Our participants with PD were able to increase hip extension torque in response to needed demands. Additionally, participants with PD were able to increase limb propulsion and leg swing against resistance, suggesting a reserve in limb mechanics.

Force Control Issues in Upper and Lower Limbs in Parkinson's Disease and Freezing of Gait

Parkinson's Disease (PD) has been found to cause force control deficits in upper and lower limbs. About 50% of patients with advanced PD develop a debilitating symptom called freezing of gait (FOG), which has been linked to force control problems in the lower limbs, and some may only have a limited response to the gold standard pharmaceutical therapy, levodopa, resulting in partially levodopa-responsive FOG (PLR-FOG). There has been limited research on investigating upper-limb force control in people with PD with PLR-FOG, and without FOG. In this pilot study, force control was explored using an upper-and-lower-limb haptics-enabled robot in a reaching task while people with PD with and without PLR-FOG were on their levodopa medication. A healthy control group was used for reference, and each cohort completed the task at three different levels of assistance provided by the robot. Similar significant proportional force control deficits were found in the upper and lower limbs in patients with PLR-FOG versus those without FOG. Some aspects of force control were found to be retained, including an ability to increase or decrease force in response to changes in resistance while completing a reaching task. Overall, these results suggest there are force control deficits in both the upper and lower limbs in people with PLR-FOG.

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.

Neuromuscular assessment of force development, postural, and gait performance under cognitive-motor dual-tasking in healthy older adults and people with early Parkinson's disease: Study protocol for a cross-sectional Mobile Brain/Body Imaging (MoBI) study

Background

Neuromuscular dysfunction is common in older adults and more pronounced in neurodegenerative diseases. In Parkinson's disease (PD), a complex set of factors often prevents the effective performance of activities of daily living that require intact and simultaneous performance of the motor and cognitive tasks.

Methods

The cross-sectional study includes a multifactorial mixed-measure design. Between-subject factor grouping the sample will be Parkinson's Disease (early PD vs. healthy). The within-subject factors will be the task complexity (single- vs. dual-task) in each motor activity, i.e., overground walking, semi-tandem stance, and isometric knee extension, and a walking condition (wide vs. narrow lane) will be implemented for the overground walking activity only. To study dual-task (DT) effects, in each motor activity participants will be given a secondary cognitive task, i.e., a visual discrimination task for the overground walking, an attention task for the semi-tandem, and mental arithmetic for the isometric extension. Analyses of DT effects and underlying neuronal correlates will focus on both gait and cognitive performance where applicable. Based on an a priori sample size calculation, a total N = 42 older adults (55-75 years) will be recruited. Disease-specific changes such as laterality in motor unit behavior and cortical control of movement will be studied with high-density surface electromyography and electroencephalography during static and dynamic motor activities, together with whole-body kinematics.

Discussion

This study will be one of the first to holistically address early PD neurophysiological and neuromuscular patterns in an ecologically valid environment under cognitive-motor DT conditions of different complexities. The outcomes of the study aim to identify the biomarker for early PD either at the electrophysiological, muscular or kinematic level or in the communication between these systems.

Clinical Trial Registration

ClinicalTrials.Gov, NCT05477654. This study was approved by the Medical Ethical Committee (106/2021).

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.

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.

Automatic extraction of upper-limb kinematic activity using deep learning-based markerless tracking during deep brain stimulation implantation for Parkinson's disease: A proof of concept study

Optimal placement of deep brain stimulation (DBS) therapy for treating movement disorders routinely relies on intraoperative motor testing for target determination. However, in current practice, motor testing relies on subjective interpretation and correlation of motor and neural information. Recent advances in computer vision could improve assessment accuracy. We describe our application of deep learning-based computer vision to conduct markerless tracking for measuring motor behaviors of patients undergoing DBS surgery for the treatment of Parkinson's disease. Video recordings were acquired during intraoperative kinematic testing (N = 5 patients), as part of standard of care for accurate implantation of the DBS electrode. Kinematic data were extracted from videos post-hoc using the Python-based computer vision suite DeepLabCut. Both manual and automated (80.00% accuracy) approaches were used to extract kinematic episodes from threshold derived kinematic fluctuations. Active motor epochs were compressed by modeling upper limb deflections with a parabolic fit. A semi-supervised classification model, support vector machine (SVM), trained on the parameters defined by the parabolic fit reliably predicted movement type. Across all cases, tracking was well calibrated (i.e., reprojection pixel errors 0.016-0.041; accuracies >95%). SVM predicted classification demonstrated high accuracy (85.70%) including for two common upper limb movements, arm chain pulls (92.30%) and hand clenches (76.20%), with accuracy validated using a leave-one-out process for each patient. These results demonstrate successful capture and categorization of motor behaviors critical for assessing the optimal brain target for DBS surgery. Conventional motor testing procedures have proven informative and contributory to targeting but have largely remained subjective and inaccessible to non-Western and rural DBS centers with limited resources. This approach could automate the process and improve accuracy for neuro-motor mapping, to improve surgical targeting, optimize DBS therapy, provide accessible avenues for neuro-motor mapping and DBS implantation, and advance our understanding of the function of different brain areas.

Force Platform-Based Intervention Program for Individuals Suffering with Neurodegenerative Diseases like Parkinson

The term "neurodegenerative disease" refers to a set of illnesses that primarily affect brain's neurons. Substantia nigra (a midbrain dopaminergic nucleus) with lack of hormone called dopamine causes Parkinson's disease (PD), a neurological disorder. PD leads to tremor, stiffness, impaired posture and balance, and loss of automatic movements. Patient with Parkinson's often develops a parkinsonian gait that includes a tendency to lean forward, small quick steps as if hurrying forward, and reduced swinging of the arms. They also may have trouble initiating or continuing movement. Gait analysis is often used to diagnose neurodegenerative illnesses and determine their stage. In this study, we attempt to investigate postural balance, and of gait signals for Parkinson's patients, also, we incorporate interim rehabilitation technique. We included 25 PD patients who had 2.5 to 3 IV score of Hoehn and Yahr scale. A ten-minute walk test has been performed to observe primary and secondary results of dual task interference on gait velocities, and gait time motion vector for right and left legs was observed. Two experimental ground conditions include three conditions of trunk alignment, that is, erect on a regular basis (RE), trunk dorsiflexion 30° (TF1), and trunk dorsiflexion 50° (TF2) were analysed. We identified the walking speed of PD patients was decreased, and trunk dorsiflexion variables influence the gait pattern of Parkinson's disease patients, where higher 95% CI for TF1 condition was reported. The regular erect trunk showed swing time reduction (0.7%) in PD, so the higher unified PD rating scale (UPDRS) values have significant difference in swing phase time in Parkinson's patients. The average Hoehn and Yahr scale (H&Y scale) was 4.3 ± 2.5 reported in the study participants. In a 10-week follow-up evaluation, the stance duration was shown to be substantial, as was the slower speed gait in the baseline condition. Excessive flexion was discovered in our investigation at the lower limb joints, particularly the knee and ankle. Patients with Parkinson's disease had similar maximum dorsiflexion and minimum plantarflexion values in stance. The trunk fraction conditions were found significant in patients after rehabilitation training. The best response to rehabilitation treatment was seen when the trunk was rotated. When steps and posture distribution analysis performed, we found that the trunk flexure 1 (p < 0.05), and trunk flexure 2 (p < 0.01) were shown significant values. When GRF threshold characteristics are employed, mean accuracy improves by 52%. Regardless of gait posture, the step regular trunk flexure had significantly higher posture than the corresponding level steps, with a considerable rise in the 50 in trunk dorsiflexion 2 gait relative to the step "L." This study shows that there was some significant improvement observed in the gait parameters among patients with PD's which shows positive impact of the intervention. Furthermore, rehabilitation programmes can aid and improve poor gait features in patients with Parkinson's disease, especially those who are in the early stages of the condition. This gait and balance research provides a rationale for intervention treatments, and their use in clinical practise enhances evidence of therapeutic efficacy. However, prolonged follow-up is needed to determine whether the advantages will remain all across disease's course, and future studies may recommend a specific rehabilitation technique based on gait analysis results.

Enriched Rehabilitation Improves Gait Disorder and Cognitive Function in Parkinson's Disease: A Randomized Clinical Trial

Background: Studies on non-pharmacological strategies for improving gait performance and cognition in Parkinson's disease (PD) are of great significance. We aimed to investigate the effect of and mechanism underlying enriched rehabilitation as a potentially effective strategy for improving gait performance and cognition in early-stage PD. Methods: Forty participants with early-stage PD were randomly assigned to receive 12 weeks (2 h/day, 6 days/week) of enriched rehabilitation (ER; n = 20; mean age, 66.14 ± 4.15 years; 45% men) or conventional rehabilitation (CR; n = 20; mean age 65.32 ± 4.23 years; 50% men). In addition, 20 age-matched healthy volunteers were enrolled as a control (HC) group. We assessed the general motor function using the Unified PD Rating Scale-Part III (UPDRS-III) and gait performance during single-task (ST) and dual-task (DT) conditions pre- and post-intervention. Cognitive function assessments included the Montreal Cognitive Assessment (MoCA), the Symbol Digit Modalities Test (SDMT), and the Trail Making Test (TMT), which were conducted pre- and post-intervention. We also investigated alteration in positive resting-state functional connectivity (RSFC) of the left dorsolateral prefrontal cortex (DLPFC) in participants with PD, mediated by ER, using functional magnetic resonance imaging (fMRI). Results: Compared with the HC group, PD participants in both ER and CR groups performed consistently poorer on cognitive and motor assessments. Significant improvements were observed in general motor function as assessed by the UPDRS-III in both ER and CR groups post-intervention. However, only the ER group showed improvements in gait parameters under ST and DT conditions post-intervention. Moreover, ER had a significant effect on cognition, which was reflected in increased MoCA, SDMT, and TMT scores post-intervention. MoCA, SDMT, and TMT scores were significantly different between ER and CR groups post-intervention. The RSFC analysis showed strengthened positive functional connectivity between the left DLPFC and other brain areas including the left insula and left inferior frontal gyrus (LIFG) post-ER. Conclusion: Our findings indicated that ER could serve as a potentially effective therapy for early-stage PD for improving gait performance and cognitive function. The underlying mechanism based on fMRI involved strengthened RSFC between the left DLPFC and other brain areas (e.g., the left insula and LIFG).

Biomechanical responses of Nordic walking in people with Parkinson's disease

In healthy adults, Nordic walking (NW) is known to increase the external mechanical energy fluctuations, though the external work is unaltered due to an improved pendulum-like recovery in comparison with free walking (FW). We aimed to compare mechanical, pendulum-like, and spatiotemporal parameters of gait at different speeds with and without NW poles in people with Parkinson's disease and healthy controls. The study included 11 people (aged 65.6 ± 7.0 years) with idiopathic Parkinson's disease, scoring between 1 and 1.5 on the Hoehn and Yahr scale (H&Y), and nine healthy controls (aged 70.0 ± 5.6 years). All the people were experienced Nordic walkers. Walking tests were performed at 1.8 km h^-1 and 4.7 km h^-1 , on eight 3D force platforms on a walkway. We found greater pendulum-like energy recovery (p < 0.05) in the Parkinson group during NW than in FW, while external mechanical work remained similar (p > 0.05). People with Parkinson's disease showed a major increase in vertical and forward energy fluctuations using poles than in healthy controls. In addition, the Parkinson group showed increased stride frequency and reduced stride length compared to controls in the NW and FW conditions. Our findings partly justify the lower walking economy in Parkinson's disease due to reduced pendulum-like mechanism at commonly used speeds. NW alters gait mechanics similarly in Parkinson group and healthy control, increasing the total mechanical work. Therefore, NW can be a compelling strategy for rehabilitation because of its potential for improving functional mobility, increasing pendulum-like mechanism in Parkinson's disease.

The effect of visual cues on muscular activation in the lower limbs of Parkinson's disease patients with freezing of gait: a preliminary study

Freezing of gait (FOG) is a disabling symptom of Parkinson's disease (PD) patients, especially in advanced stages. Visual cues, such as the laser, have been confirmed to improve kinematic performance and alleviate FOG incidences. However, the muscular effect is unknown. In this study, we aim to investigate the effect of visual cues on muscular activity in the lower limbs of PD patients with FOG. Surface EMG signals of the tibialis anterior (TA), lateral gastrocnemius (GL), rectus femoris (RF), and biceps femoris (BF) muscles were collected from eight patients (FOGer) and eight healthy elderly (HC) in both normal walking and walking with laser cues. Results showed that visual cues improved FOGer's muscular activation pattern towards normal. The RMS of TA was significantly increased in the loading response phase (p=0.02) and decreased in the pre-swing phase for FOGer (p=0.005) under visual cue. The RMS of GL in FOGer was considerably reduced in the loading response phase (p<0.001) and increased in the pre-swing phase (p=0.008) of their gait cycle. A significant strong correlation was also observed between the decrement in GL RMS during the loading response phase and the increment in GL RMS during the pre-swing phase (R=-0.952, p<0.001) incurred by visual cue in FOGer. These results indicate that the visual cues can help FOGer to modulate their muscular activation of ankle muscles, especially to normalize GL's activation distribution during stance. For clinical purposes, future rehabilitative strategies aimed at the modulation of ankle muscles are suggested.

Abnormal center of mass feedback responses during balance: A potential biomarker of falls in Parkinson's disease

Although Parkinson disease (PD) causes profound balance impairments, we know very little about how PD impacts the sensorimotor networks we rely on for automatically maintaining balance control. In young healthy people and animals, muscles are activated in a precise temporal and spatial organization when the center of body mass (CoM) is unexpectedly moved that is largely automatic and determined by feedback of CoM motion. Here, we show that PD alters the sensitivity of the sensorimotor feedback transformation. Importantly, sensorimotor feedback transformations for balance in PD remain temporally precise, but become spatially diffuse by recruiting additional muscle activity in antagonist muscles during balance responses. The abnormal antagonist muscle activity remains precisely time-locked to sensorimotor feedback signals encoding undesirable motion of the body in space. Further, among people with PD, the sensitivity of abnormal antagonist muscle activity to CoM motion varies directly with the number of recent falls. Our work shows that in people with PD, sensorimotor feedback transformations for balance are intact but disinhibited in antagonist muscles, likely contributing to balance deficits and falls.

Levodopa facilitates improvements in gait kinetics at the hip, not the ankle, in individuals with Parkinson's disease

Parkinson's disease symptoms impair gait, limit mobility, and reduce independence. Levodopa improves muscle activation, strength, and coordination; thus, facilitating increased step length, but few studies have evaluated the underlying forces associated with medication-induced gait improvements. Here, we assess the effects of levodopa on gait kinetics in persons with Parkinson's disease. Over two sessions, 13 participants with Parkinson's disease walked on a treadmill while both optimally medicated and after a 12-hour medication withdrawal. Walking was analyzed for spatiotemporal parameters, ranges of motion, anterior-posterior ground reaction forces, joint torques, and powers using an instrumented treadmill and motion capture system. When on medication, participants increased gait speed by significantly improving step length (p = .009) and time (p = .004). Peak propulsive force (p = .001) and hip flexion torques (p = .003) increased with medication while hip extensor and ankle plantarflexor torques did not. While differences in joint power were not significantly different, the optimal medication condition showed medium to large effects, with the largest effect at the hip (d_z = 0.84). Our findings suggest the underlying forces responsible for the increases in gait speed are primarily due to increases at the hip, with limited change at the ankle. Disproportionate use of muscle force may be a limiting factor for levodopa's use as an intervention for walking. Future interventions should consider targeting force production deficits during gait in those with Parkinson's disease.