Objective assessment of the effects of opicapone in Parkinson's disease through kinematic analysis

BACKGROUND

Opicapone (OPC) is a third-generation, selective peripheral COMT inhibitor that improves peripheral L-DOPA bioavailability and reduces OFF time and end-of-dose motor fluctuations in Parkinson's disease (PD) patients.

OBJECTIVES

In this study, we objectively assessed the effects of adding OPC to L-DOPA on bradykinesia in PD through kinematic analysis of finger movements.

METHODS

We enrolled 20 treated patients with PD and motor fluctuations. Patients underwent two experimental sessions (L-DOPA, L-DOPA + OPC), separated by at least 1 week. In each session, patients were clinically evaluated and underwent kinematic movement analysis of repetitive finger movements at four time points: (i) before their usual morning dose of L-DOPA (T0), (ii) 30 min (T1), (iii) 1 h and 30 min (T2), and (iv) 3 h and 30 min after the L-DOPA intake (T3).

RESULTS

Movement velocity and amplitude of finger movements were higher in PD patients during the session with OPC compared to the session without OPC at all the time points tested. Importantly, the variability of finger movement velocity and amplitude across T0-T3 was significantly lower in the L-DOPA + OPC than L-DOPA session.

CONCLUSIONS

This study is the first objective assessment of the effects of adding OPC to L-DOPA on bradykinesia in patients with PD and motor fluctuations. OPC, in addition to the standard dopaminergic therapy, leads to significant improvements in bradykinesia during clinically relevant periods associated with peripheral L-DOPA dynamics, i.e., the OFF state in the morning, delayed-ON, and wearing-OFF periods.

Intra and inter-rater remote assessment of bradykinesia in Parkinson's disease

INTRODUCTION

Reliable assessment of individuals with Parkinson's disease (PD) is essential for providing adequate treatment. Clinical assessment is a complex and time-consuming task, especially for bradykinesia, since its evaluation can be influenced by the degree of experience of the examiner, patient collaboration and individual bias. Improvement of the clinical evaluation can be obtained by considering assessments from several professionals. However, this is only true when inter and intra-rater agreement are high. Recently, the Movement Disorder Society highlighted, during the COVID-19 pandemic, the need to develop and validate technologies for remote assessment of the motor status of people with PD. Thus, this study introduces an objective strategy for the remote evaluation of bradykinesia using multi-specialist analysis.

METHODS

Twelve volunteers with PD participated and these were asked to execute finger tapping, hand opening/closing and pronation/supination movements. Each task was recorded and rated by fourteen PD health experts for each patient. The scores were assessed on an individual basis. Intra and inter-rater agreement and correlation were estimated.

RESULTS

The results showed that agreements and correlations between experienced examiners were high with low variability. In addition, group analysis was noted as possessing the potential to solve individual inconsistency bias.

CONCLUSION

Furthermore, this study demonstrated the need for a group with prior training and experience, along with indicating the importance for the development of a clinical protocol that can use telemedicine for the evaluation of individuals with PD, as well as the inclusion of a specialized mediating group. In Addition, this research helps to the development of a valid remote assessment of bradykinesia.

Functional interaction of abnormal beta and gamma oscillations on bradykinesia in parkinsonian rats

Bradykinesia, a debilitating symptom characterized by impaired movement initiation and reduced speed in Parkinson's disease (PD), is associated with abnormal oscillatory activity in the motor cortex-basal ganglia circuit. We investigated the interplay between abnormal beta and gamma oscillations in relation to bradykinesia in parkinsonian rats. Our findings showed reduced movement activities in parkinsonian rats, accompanied by enhanced high beta oscillations in the motor cortex, which are closely associated with movement transitional difficulties. Additionally, gamma oscillations correlated with movement velocity in control rats but not in parkinsonian rats. We observed selective coupling between high beta oscillation phase and gamma oscillation amplitude in PD, as well as cortical high beta-broadband gamma phase-amplitude coupling (PAC) negatively influencing locomotor activities in control and PD rats. These findings suggest a collaborative role of cortical beta and gamma oscillations in facilitating movement execution, with beta oscillations being linked to movement initiation and gamma oscillations associated with movement speed. Importantly, the aberrant alterations of these oscillations are closely related to the development of bradykinesia. Furthermore, PAC hold promise as a biomarker for comprehensive assessment of movement performance in PD.

Impaired performance of rapid grip in people with Parkinson's disease and motor segmentation

Bradykinesia, or slow movement, is a defining symptom of Parkinson's disease (PD), but the underlying neuromechanical deficits that lead to this slowness remain unclear. People with PD often have impaired rates of motor output accompanied by disruptions in neuromuscular excitation, causing abnormal, segmented, force-time curves. Previous investigations using single-joint models indicate that agonist electromyogram (EMG) silent periods cause motor segmentation. It is unknown whether motor segmentation is evident in more anatomically complex and ecologically important tasks, such as handgrip tasks. Aim 1 was to determine how handgrip rates of force change compare between people with PD and healthy young and older adults. Aim 2 was to determine whether motor segmentation is present in handgrip force and EMG measures in people with PD. Subjects performed rapid isometric handgrip pulses to 20-60% of their maximal voluntary contraction force while EMG was collected from the grip flexors and extensors. Dependent variables included the time to 90% peak force, the peak rate of force development, the duration above 90% of peak force, the number of segments in the force-time curve, the number of EMG bursts, time to relaxation from 90% of peak force, and the peak rate of force relaxation. People with PD had longer durations and lower rates of force change than young and older adults. Six of 22 people with PD had motor segmentation. People with PD had more EMG bursts compared to healthy adults and the number of EMG bursts covaried with the number of segments. Thus, control of rapid movement in Parkinson's disease can be studied using isometric handgrip. People with PD have impaired rate control compared to healthy adults and motor segmentation can be studied in handgrip.

Time-resolved quantification of fine hand movements as a proxy for evaluating bradykinesia-induced motor dysfunction

Bradykinesia is a behavioral manifestation that contributes to functional dependencies in later life. However, the current state of bradykinesia indexing primarily relies on subjective, time-averaged categorizations of motor deficits, which often yield poor reliability. Herein, we used time-resolved analyses of accelerometer recordings during standardized movements, data-driven factor analyses, and linear mixed effects models (LMEs) to quantitatively characterize general, task- and therapy-specific indices of motor impairment in people with Parkinson's disease (PwP) currently undergoing treatment for bradykinesia. Our results demonstrate that single-trial, accelerometer-based features of finger-tapping and rotational hand movements were significantly modulated by divergent therapeutic regimens. Further, these features corresponded well to current gold standards for symptom monitoring, with more precise predictive capacities of bradykinesia-specific declines achieved when considering kinematic features from diverse movement types together, rather than in isolation. Herein, we report data-driven, sample-specific kinematic profiles of diverse movement types along a continuous spectrum of motor impairment, which importantly, preserves the temporal scale for which biomechanical fluctuations in motor deficits evolve in humans. Therefore, this approach may prove useful for tracking bradykinesia-induced motor decline in aging populations the future.

The sound of Parkinson's disease: A model of audible bradykinesia

INTRODUCTION

Evaluation of bradykinesia is based on five motor tasks from the MDS-UPDRS. Visually scoring these motor tasks is subjective, resulting in significant interrater variability. Recent observations suggest that it may be easier to hear the characteristic features of bradykinesia, such as the decrement in sound intensity or force of repetitive movements. The objective is to evaluate whether audio signals derived during four MDS-UPDRS tasks can be used to detect and grade bradykinesia, using two machine learning models.

METHODS

54 patients with Parkinson's disease and 28 healthy controls were filmed while executing the bradykinesia motor tasks. Several features were extracted from the audio signal, including number of taps, speed, sound intensity, decrement and freezes. For each motor task, two supervised machine learning models were trained, Logistic Regression (LR) and Support Vector Machine (SVM).

RESULTS

Both classifiers were able to separate patients from controls reasonably well for the leg agility task, area under the receiver operating characteristic curve (AUC): 0.92 (95%CI: 0.78-0.99) for LR and 0.93 (0.81-1.00) for SVM. Also, models were able to differentiate less severe bradykinesia from severe bradykinesia, particularly for the pronation-supination motor task, with AUC: 0.90 (0.62-1.00) for LR and 0.82 (0.45-0.97) for SVM.

CONCLUSION

This audio-based approach discriminates PD from healthy controls with moderate-high accuracy and separated individuals with less severe bradykinesia from those with severe bradykinesia. Sound analysis may contribute to the identification and monitoring of bradykinesia.

Novel characteristics of the temporal transition to maximum tongue pressure in Parkinson's disease: A pilot study

Introduction

The reason why maximum tongue pressure (MTP) decreases in patients with Parkinson's disease (PD) remains unclear. Repeated measurements of isometric force and MTP may be useful for analyzing muscle wasting and force generation. The purpose of this pilot study was to evaluate the clinical characteristics and temporal transition of MTP in PD and normal control (NC) groups.

Methods

There were 18 participants in this study: 10 with PD and 8 NCs. The MTP was measured 20 times at regular intervals. The area under the curve of MTP temporal transitions, time to reach MTP, and total transition time of the tongue pressure (time to return to baseline) were compared between the groups.

Results

MTP decreased from baseline in PD subjects. Unlike NCs, PD subjects showed diverse and inconsistent temporal transitions. The decrease in MTP and delays in time to reach MTP and time to return to baseline were significantly greater in PD subjects (p < 0.05), while there was no group difference in area under the curve values. According to repeated-measures ANOVA, MTP was not different over time between PD subjects and NCs.

Conclusion

In this study, muscle fatigue did not affect the decrease in MTP seen in PD subjects, or the diversity and inconsistency of the temporal transition in MTP in that group. These findings indicate that the motor control needed for the repeated, identical movements associated with MTP generation may be impaired in PD patients.

Ucp4 Knockdown of Cerebellar Purkinje Cells Induces Bradykinesia

Although uncoupling protein 4 (UCP4) is the most abundant protein reported in the brain, the biological function of UCP4 in cerebellum and pathological outcome of UCP4 deficiency in cerebellum remain obscure. To evaluate the role of Ucp4 in the cerebellar Purkinje cells (PCs), we generated the conditional knockdown of Ucp4 in PCs (Pcp2cre;Ucp4fl/fl mice) by breeding Ucp4fl/fl mice with Pcp2cre mice. Series results by Western blot, immunofluorescent staining, and triple RNAscope in situ hybridization confirmed the specific ablation of Ucp4 in PCs in Pcp2cre;Ucp4fl/fl mice, but did not affect the expression of Ucp2, the analog of Ucp4. Combined behavioral tests showed that Pcp2cre;Ucp4fl/fl mice displayed a characteristic bradykinesia in the spontaneous movements. The electromyogram recordings detection excluded the possibility of hypotonia in Pcp2cre;Ucp4fl/fl mice. And the electrical patch clamp recordings showed the altered properties of PCs in Pcp2cre;Ucp4fl/fl mice. Moreover, transmission electron microscope (TEM) results showed the increased mitochondrial circularity in PCs; ROS probe imaging showed the increased ROS generation in molecular layer; and finally, microplate reader assay showed the significant changes of mitochondrial functions, including ROS, ATP, and MMP in the isolated cerebellum tissue. The results suggested that the specific knockdown of mitochondrial protein Ucp4 could damage PCs possibly by attacking their mitochondrial function. The present study is the first to report a close relationship between UCP4 deletion with PCs impairment, and suggests the importance of UCP4 in the substantial support of mitochondrial function homeostasis in bradykinesia. UCP4 might be a therapeutic target for the cerebellar-related movement disorder.

Subtle changes in central dopaminergic tone underlie bradykinesia in essential tremor

INTRODUCTION

In this research, our primary objective was to explore the correlation between basal ganglia dopaminergic neurotransmission, assessed using 123I-FP-CIT (DAT-SPECT), and finger movements abnormalities in patients with essential tremor (ET) and Parkinson's disease (PD).

METHODS

We enrolled 16 patients with ET, 17 with PD, and 18 healthy controls (HC). Each participant underwent comprehensive clinical evaluations, kinematic assessments of finger tapping. ET and PD patients underwent DAT-SPECT imaging. The DAT-SPECT scans were subjected to both visual and semi-quantitative analysis using DaTQUANT®. We then investigated the correlations between the clinical, kinematic, and DAT-SPECT data, in patients.

RESULTS

Our findings confirm that individuals with ET exhibited slower finger tapping than HC. Visual evaluation of radiotracer uptake in both striata demonstrated normal levels within the ET patient cohort, while PD patients displayed reduced uptake. However, there was notable heterogeneity in the quantification of uptake within the striata among ET patients. Additionally, we found a correlation between the amount of radiotracer uptake in the striatum and movement velocity during finger tapping in patients. Specifically, lower radioligand uptake corresponded to decreased movement velocity (ET: coef. = 0.53, p-adj = 0.03; PD: coef. = 0.59, p-adj = 0.01).

CONCLUSION

The study's findings suggest a potential link between subtle changes in central dopaminergic tone and altered voluntary movement execution, in ET. These results provide further insights into the pathophysiology of ET. However, longitudinal studies are essential to determine whether the slight reduction in dopaminergic tone observed in ET patients represents a distinct subtype of the disease or could serve as a predictor for the clinical progression into PD.

Gait video-based prediction of unified Parkinson's disease rating scale score: a retrospective study

BACKGROUND

The diagnosis of Parkinson's disease (PD) and evaluation of its symptoms require in-person clinical examination. Remote evaluation of PD symptoms is desirable, especially during a pandemic such as the coronavirus disease 2019 pandemic. One potential method to remotely evaluate PD motor impairments is video-based analysis. In this study, we aimed to assess the feasibility of predicting the Unified Parkinson's Disease Rating Scale (UPDRS) score from gait videos using a convolutional neural network (CNN) model.

METHODS

We retrospectively obtained 737 consecutive gait videos of 74 patients with PD and their corresponding neurologist-rated UPDRS scores. We utilized a CNN model for predicting the total UPDRS part III score and four subscores of axial symptoms (items 27, 28, 29, and 30), bradykinesia (items 23, 24, 25, 26, and 31), rigidity (item 22) and tremor (items 20 and 21). We trained the model on 80% of the gait videos and used 10% of the videos as a validation dataset. We evaluated the predictive performance of the trained model by comparing the model-predicted score with the neurologist-rated score for the remaining 10% of videos (test dataset). We calculated the coefficient of determination (R2) between those scores to evaluate the model's goodness of fit.

RESULTS

In the test dataset, the R2 values between the model-predicted and neurologist-rated values for the total UPDRS part III score and subscores of axial symptoms, bradykinesia, rigidity, and tremor were 0.59, 0.77, 0.56, 0.46, and 0.0, respectively. The performance was relatively low for videos from patients with severe symptoms.

CONCLUSIONS

Despite the low predictive performance of the model for the total UPDRS part III score, it demonstrated relatively high performance in predicting subscores of axial symptoms. The model approximately predicted the total UPDRS part III scores of patients with moderate symptoms, but the performance was low for patients with severe symptoms owing to limited data. A larger dataset is needed to improve the model's performance in clinical settings.

Nigral-specific increase in ser31 phosphorylation compensates for tyrosine hydroxylase protein and nigrostriatal neuron loss: Implications for delaying parkinsonian signs

Compensatory mechanisms that augment dopamine (DA) signaling are thought to mitigate onset of hypokinesia prior to major loss of tyrosine hydroxylase (TH) in striatum that occurs in Parkinson's disease. However, the identity of such mechanisms remains elusive. In the present study, the rat nigrostriatal pathway was unilaterally-lesioned with 6-hydroxydopamine (6-OHDA) to determine whether differences in DA content, TH protein, TH phosphorylation, or D1 receptor expression in striatum or substantia nigra (SN) aligned with hypokinesia onset and severity at two time points. In striatum, DA and TH loss reached its maximum (>90%) 7 days after lesion induction. However, in SN, no DA loss occurred, despite ∼60% TH loss. Hypokinesia was established at 21 days post-lesion and maintained at 28 days. At this time, DA loss was ∼60% in the SN, but still of lesser magnitude than TH loss. At day 7 and 28, ser31 TH phosphorylation increased only in SN, corresponding to less DA versus TH protein loss. In contrast, ser40 TH phosphorylation was unaffected in either region. Despite DA loss in both regions at day 28, D1 receptor expression increased only in lesioned SN. These results support the concept that augmented components of DA signaling in the SN, through increased ser31 TH phosphorylation and D1 receptor expression, contribute as compensatory mechanisms against progressive nigrostriatal neuron and TH protein loss, and may mitigate hypokinesia severity.

Facial and upper-limb movement abnormalities in individuals with psychotic-like experiences: a motion analysis study

Slow movements and irregular muscle contraction have been reported separately in different studies targeting individuals with psychotic-like experiences (PLEs). To date, it remains unknown whether these two movement abnormalities, possibly associated with hypo- and hyper-dopaminergia, respectively, co-existed in one sample with PLEs and interrelated in the early stage of psychotic progression. Therefore, this study was to examine if facial and upper-limb slow movements and irregular muscle contraction co-existed in individuals with PLEs, interrelated, and were associated with PLEs. A total of 26 individuals with PLEs, who were identified using the 16-item Prodromal Questionnaire, and 26 age- and gender-matched healthy controls received the facial and upper-limb movement measurement. A motion capture system was used to record the movement procedure and thus calculate kinematic variables that represented severity of slow movements and irregular muscle contraction. Results showed that facial and upper-limb slow movements and facial irregular muscle contraction existed in individuals with PLEs. For the total sample, slower facial movements were associated with less regular facial muscle contraction; slower upper-limb movements were associated with less regular upper-limb muscle contraction. Slower and less regular facial and upper-limb movements were associated with more severe PLEs. Compensatory changes in dopaminergic neural pathways in response to elevated dopamine might explain connection between slow movements and irregular muscle contraction. Because of the ability to detect facial and upper-limb movement abnormalities objectively and sensitively, motion analysis has great applicability to sensorimotor studies for people in the psychosis continuum.

Effects of training involving patterned sensory enhancement on improving upper-limb movements in patients with Parkinson's disease: protocol of a randomised controlled trial

INTRODUCTION

Bradykinesia (ie, slow movements) is one of the most prominent symptoms of Parkinson's disease (PD) and has a negative impact on quality of life. Rhythmic auditory stimulation (RAS), a widely used and promising treatment technique, has been shown to effectively improve gait speed in patients with PD. The upper-limb movements, which also suffer from bradykinesia, are essential for daily life and directly impact quality of life. The term, patterned sensory enhancement (PSE) instead of RAS, is used when movement training targets the human body except lower limbs. Up until now, scarce studies have explored effects of training involving PSE on upper-limb movements. The purpose of this study is to investigate effects of movement training involving PSE on upper-limb movement speed and function in patients with PD.

METHODS AND ANALYSIS

A total of 138 patients with PD will be randomly assigned into two groups: the PSE group and the no-PSE group. A 21-day upper-limb training involving PSE (for the PSE group) or without PSE (for the no-PSE group) will be provided to the patients. An assessor will administer the box and block test and the Jebsen hand function test before and after training to assess upper-limb movement speed and function. The one-way analysis of covariance will be performed. This randomised controlled trial will provide evidence supporting effectiveness of upper-limb movement training involving PSE on reducing severity of bradykinesia in patients with PD.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from the Institutional Review Board of the Hong Kong Polytechnic University with the reference number HSEARS20221027005. Informed consent forms will be gathered from all patients before their participation. Study results will be disseminated through conferences and peer-reviewed academic journals.

TRIAL REGISTRATION NUMBER

NCT05637593.

Modulation of nigral dopamine signaling mitigates parkinsonian signs of aging: evidence from intervention with calorie restriction or inhibition of dopamine uptake

Identifying neurobiological mechanisms of aging-related parkinsonism, and lifestyle interventions that mitigate them, remain critical knowledge gaps. No aging study, from rodent to human, has reported loss of any dopamine (DA) signaling marker near the magnitude associated with onset of parkinsonian signs in Parkinson's disease (PD). However, in substantia nigra (SN), similar loss of DA signaling markers in PD or aging coincide with parkinsonian signs. Alleviation of these parkinsonian signs may be possible by interventions such as calorie restriction (CR), which augment DA signaling markers like tyrosine hydroxylase (TH) expression in the SN, but not striatum. Here, we interrogated respective contributions of nigral and striatal DA mechanisms to aging-related parkinsonian signs in aging (18 months old) rats in two studies: by the imposition of CR for 6 months, and inhibition of DA uptake within the SN or striatum by cannula-directed infusion of nomifensine. Parkinsonian signs were mitigated within 12 weeks after CR and maintained until 24 months old, commensurate with increased D₁ receptor expression in the SN alone, and increased GDNF family receptor, GFR-α1, in the striatum, suggesting increased GDNF signaling. Nomifensine infusion into the SN or striatum selectively increased extracellular DA. However, only nigral infusion increased locomotor activity. These results indicate mechanisms that increase components of DA signaling in the SN alone mitigate parkinsonian signs in aging, and are modifiable by interventions, like CR, to offset parkinsonian signs, even at advanced age. Moreover, these results give evidence that changes in nigral DA signaling may modulate some parameters of locomotor activity autonomously from striatal DA signaling.

May Bradykinesia Features Aid in Distinguishing Parkinson's Disease, Essential Tremor, And Healthy Elderly Individuals?

BACKGROUND

Bradykinesia is the hallmark feature of Parkinson's disease (PD); however, it can manifest in other conditions, including essential tremor (ET), and in healthy elderly individuals.

OBJECTIVE

Here we assessed whether bradykinesia features aid in distinguishing PD, ET, and healthy elderly individuals.

METHODS

We conducted simultaneous video and kinematic recordings of finger tapping in 44 PD patients, 69 ET patients, and 77 healthy elderly individuals. Videos were evaluated blindly by expert neurologists. Kinematic recordings were blindly analyzed. We calculated the inter-raters agreement and compared data among groups. Density plots assessed the overlapping in the distribution of kinematic data. Regression analyses and receiver operating characteristic curves determined how the kinematics influenced the likelihood of belonging to a clinical score category and diagnostic group.

RESULTS

The inter-rater agreement was fair (Fleiss K = 0.32). Rater found the highest clinical scores in PD, and higher scores in ET than healthy elderly individuals (p < 0.001). In regard to kinematic analysis, the groups showed variations in movement velocity, with PD presenting the slowest values and ET displaying less velocity than healthy elderly individuals (all ps < 0.001). Additionally, PD patients showed irregular rhythm and sequence effect. However, kinematic data significantly overlapped. Regression analyses showed that kinematic analysis had high specificity in differentiating between PD and healthy elderly individuals. Nonetheless, accuracy decreased when evaluating subjects with intermediate kinematic values, i.e., ET patients.

CONCLUSION

Despite a considerable degree of overlap, bradykinesia features vary to some extent in PD, ET, and healthy elderly individuals. Our findings have implications for defining bradykinesia and categorizing patients.

Real-time automated detection of older adults' hand gestures in home and clinical settings

There is an urgent need, accelerated by the COVID-19 pandemic, for methods that allow clinicians and neuroscientists to remotely evaluate hand movements. This would help detect and monitor degenerative brain disorders that are particularly prevalent in older adults. With the wide accessibility of computer cameras, a vision-based real-time hand gesture detection method would facilitate online assessments in home and clinical settings. However, motion blur is one of the most challenging problems in the fast-moving hands data collection. The objective of this study was to develop a computer vision-based method that accurately detects older adults' hand gestures using video data collected in real-life settings. We invited adults over 50 years old to complete validated hand movement tests (fast finger tapping and hand opening-closing) at home or in clinic. Data were collected without researcher supervision via a website programme using standard laptop and desktop cameras. We processed and labelled images, split the data into training, validation and testing, respectively, and then analysed how well different network structures detected hand gestures. We recruited 1,900 adults (age range 50-90 years) as part of the TAS Test project and developed UTAS7k-a new dataset of 7071 hand gesture images, split 4:1 into clear: motion-blurred images. Our new network, RGRNet, achieved 0.782 mean average precision (mAP) on clear images, outperforming the state-of-the-art network structure (YOLOV5-P6, mAP 0.776), and mAP 0.771 on blurred images. A new robust real-time automated network that detects static gestures from a single camera, RGRNet, and a new database comprising the largest range of individual hands, UTAS7k, both show strong potential for medical and research applications.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00521-022-08090-8.

A non-contact system for intraoperative quantitative assessment of bradykinesia in deep brain stimulation surgery

BACKGROUND AND OBJECTIVE

Deep brain stimulation (DBS) is an effective treatment for a number of neurological diseases, especially for the advanced stage of Parkinson's disease (PD). Objective assessment of patients' motor symptoms is crucial for accurate electrode targeting and treatment. Existing approaches suffer from subjective variability or interference with voluntary motion. This work is aimed to establish an objective assessment system to quantify bradykinesia in DBS surgery.

METHODS

Based on the analysis of the requirements for intraoperative assessment, we developed a system with non-contact measurement, online movement feature extraction, and interactive data analysis and visualization. An optical sensor, Leap Motion Controller (LMC), was taken to detect hand movement in three clinical tasks. A graphic user interface was designed to process, compare and visualize the collected data and assessment results online. Quantified movement features include amplitude, frequency, velocity, their decrement and variability, etc. Technical validation of the system was performed with a motion capture system (Mocap), with respect to data-level and feature-level accuracy and reliability. Clinical validation was conducted with 20 PD patients for intraoperative assessments in DBS surgery. Treatment responses with respect to the bradykinesia movement features were analyzed. Single case analysis and group statistical analysis were performed to examine the differences between preoperative and intraoperative performance, and the correlation between the clinical ratings and the quantified assessment was analyzed.

RESULTS

For the movements measured by LMC and Mocap, the average Pearson's correlation coefficient was 0.986, and the mean amplitude difference was 2.11 mm. No significant difference was found for all movement features quantified by LMC and Mocap. For the clinical tests, key movement features showed significant differences between the preoperative baseline and intraoperative performance when the brain stimulation was ON. The assessment results were significantly correlated with the MDS-UPDRS clinical ratings.

CONCLUSIONS

The proposed non-contact system has established itself as an objective intraoperative assessment, analysis, and visualization tool for DBS treatment of Parkinson's disease.

Clinical neurophysiology of Parkinson's disease and parkinsonism

•

This review is part of the series on the clinical neurophysiology of movement disorders and focuses on Parkinson’s disease and parkinsonism.

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The pathophysiology of cardinal parkinsonian motor symptoms and myoclonus are reviewed.

•

The recordings from microelectrode and deep brain stimulation electrodes are reported in detail.

This review is part of the series on the clinical neurophysiology of movement disorders. It focuses on Parkinson’s disease and parkinsonism. The topics covered include the pathophysiology of tremor, rigidity and bradykinesia, balance and gait disturbance and myoclonus in Parkinson’s disease. The use of electroencephalography, electromyography, long latency reflexes, cutaneous silent period, studies of cortical excitability with single and paired transcranial magnetic stimulation, studies of plasticity, intraoperative microelectrode recordings and recording of local field potentials from deep brain stimulation, and electrocorticography are also reviewed. In addition to advancing knowledge of pathophysiology, neurophysiological studies can be useful in refining the diagnosis, localization of surgical targets, and help to develop novel therapies for Parkinson’s disease.

Neurophysiological assessment of juvenile parkinsonism due to primary monoamine neurotransmitter disorders

No studies have investigated voluntary movement abnormalities and their neurophysiological correlates in patients with parkinsonism due to inherited primary monoamine neurotransmitter (NT) disorders. Nine NT disorders patients and 16 healthy controls (HCs) were enrolled. Objective measurements of repetitive finger tapping were obtained using a motion analysis system. Primary motor cortex (M1) excitability was assessed by recording the input/output (I/O) curve of motor-evoked potentials (MEP) and using a conditioning test paradigm for short-interval intracortical inhibition (SICI) assessment. M1 plasticity-like mechanisms were indexed according to MEPs amplitude changes after the paired associative stimulation protocol. Patient values were considered abnormal if they were greater or lower than two standard deviations from the average HCs value. Patients with aromatic amino acid decarboxylase, tyrosine hydroxylase, and 6-pyruvoyl-tetrahydropterin synthase defects showed markedly reduced velocity (5/5 patients), reduced movement amplitude, and irregular rhythm (4/5 patients). Conversely, only 1 out of 3 patients with autosomal-dominant GTPCH deficiency showed abnormal movement parameters. Interestingly, none of the patients had a progressive reduction in movement amplitude or velocity during the tapping sequence (no sequence effect). Reduced SICI was the most prominent neurophysiological abnormality in patients (5/9 patients). Finally, the I/O curve slope correlated with movement velocity and rhythm in patients. We provided an objective assessment of finger tapping abnormalities in monoamine NT disorders. We also demonstrated M1 excitability changes possibly related to alterations in motor execution. Our results may contribute to a better understanding of the pathophysiology of juvenile parkinsonism due to dopamine deficiency.

Measures of motor segmentation from rapid isometric force pulses are reliable and differentiate Parkinson's disease from age-related slowing

Some people with Parkinson's disease (PD) have disruptions in motor output during rapid isometric muscle contractions. Measures of such disruptions (motor segmentation) may help clarify disease subtype, progression, or effects of therapeutic interventions. We investigated the potential utility of segmentation measures by testing two hypotheses that are fundamental to measurement and evaluation. First, measures of motor segmentation are reliable from day to day (intraclass correlation coefficient > 0.8). Second, that measures of motor segmentation have the sensitivity to differentiate between people with PD and older adults. 10 subjects with PD had a mean age of 70.1 years, Hoehn-Yahr stage < 3, and median levodopa equivalent daily dose of 350 mg. Older adult (mean age 81.9 years) reference data are from a previously published study. Each subject provided approximately 87 rapid isometric index finger abduction force pulses up to 65% of their maximal isometric force for calculation of force pulse measures. Measures were computed for the excitation, transition, and relaxation phases of each force pulse. Measures of motor segmentation had high reliability and presented large (Cohen's D > 0.8) and significant (p < 0.05) group differences. In bivariate plots of selected measures, motor segmentation marked a departure of PD from age-related slowing. Across all subjects, greater segmentation was associated with greater impairments in rate control and a longer time to reach peak force (all Spearman's ρ > 0.8). These results support the potential utility of the motor segmentation measures by satisfying requirements for reliability and the sensitivity to indicate deviations from age-related slowing in motor output.

Effects of rhythmic auditory stimulation on upper-limb movements in patients with Parkinson's disease

INTRODUCTION

Rhythmic auditory stimulation (RAS) is an effective technique extensively used to alleviate lower-limb bradykinesia in patients with Parkinson's disease (PD). However, RAS effects on upper-limb bradykinesia have not been well studied. This study investigated immediate effects of RAS on upper-limb movements in PD patients and healthy people.

METHODS

PD patients (n = 23) and age- and gender-matched healthy controls (n = 23) executed left-hand, right-hand, and both-hand movement tasks of the Purdue Pegboard Test when listening to the beats of RAS, including 100%, 110%, and 120% of the baseline tempo, which was fastest movement performance of each participant without the aid of RAS. Sequence of RAS and tasks was randomized for each participant.

RESULTS

PD patients had slower upper-limb movements than did health controls. An interaction was found between RAS and tasks. In both patients and controls and for all task conditions, 120%RAS induced higher scores than did 110% RAS, and the latter induced higher scores than did 100%RAS. In both patients and controls and for all RAS conditions, the right-hand condition induced higher scores than did the left-hand condition, and the latter induced higher scores than did the both-hand condition.

CONCLUSIONS

RAS was effective in regulating upper-limb movements in PD patients, which may be explained by rich neural connections between auditory and motor cortical areas in humans. Clinical practitioners should consider using RAS in clinical therapy. Future neuroimaging studies are needed to explore neural mechanisms of RAS in PD patients.

Subthalamic low beta bursts differ in Parkinson's disease phenotypes

OBJECTIVE

Parkinson's disease (PD) patients may be categorized into tremor-dominant (TD) and postural-instability and gait disorder (PIGD) motor phenotypes, but the dynamical aspects of subthalamic nucleus local field potentials (STN-LFP) and the neural correlates of this phenotypical classification remain unclear.

METHODS

35 STN-LFP (20 PIGD and 15 TD) were investigated through continuous wavelet transform and machine-learning-based methods. The beta oscillation - the main band associated with motor impairment in PD - dynamics was characterized through beta burst parameters across phenotypes and burst intervals under specific proposed criteria for optimal burst threshold definition.

RESULTS

Low-frequency (13-22 Hz) beta burst probability was the best predictor for PD phenotypes (75% accuracy). PIGD patients presented higher average burst duration (p = 0.018), while TD patients exhibited higher burst probability (p = 0.014). Categorization into shorter and longer than 400 ms bursts led to significant interaction between burst length categories and the phenotypes (p < 0.050) as revealed by mixed-effects models. Long burst durations and short bursts probability positively correlated, respectively, with rigidity-bradykinesia (p = 0.029) and tremor (p = 0.038) scores.

CONCLUSIONS

Subthalamic low-frequency beta bursts differed between TD and PIGD phenotypes and correlated with motor symptoms.

SIGNIFICANCE

These findings improve the PD phenotypes' electrophysiological characterization and may define new criteria for adaptive deep brain stimulation.

Cross-frequency phase-amplitude coupling in repetitive movements in patients with Parkinson's disease

Bradykinesia is a cardinal motor symptom in Parkinson’s disease (PD), the pathophysiology of which is not fully understood. We analyzed the role of cross-frequency coupling of oscillatory cortical activity in motor impairment in patients with PD and healthy controls. High-density EEG signals were recorded during various motor activities and at rest. Patients performed a repetitive finger-pressing task normally, but were slower than controls during tapping. Phase-amplitude coupling (PAC) between β (13–30 Hz) and broadband γ (50–150 Hz) was computed from individual EEG source signals in the premotor, primary motor, and primary somatosensory cortices, and the primary somatosensory complex. In all four regions, averaging the entire movement period resulted in higher PAC in patients than in controls for the resting condition and the pressing task (similar performance between groups). However, this was not the case for the tapping tasks where patients performed slower. This suggests the strength of state-related β-γ PAC does not determine Parkinsonian bradykinesia. Examination of the dynamics of oscillatory EEG signals during motor transitions revealed a distinctive motif of PAC rise and decay around press onset. This pattern was also present at press offset and slow tapping onset, linking such idiosyncratic PAC changes to transitions between different movement states. The transition-related PAC modulation in patients was similar to controls in the pressing task but flattened during slow tapping, which related to normal and abnormal performance, respectively. These findings suggest that the dysfunctional evolution of neuronal population dynamics during movement execution is an important component of the pathophysiology of Parkinsonian bradykinesia.

NEW & NOTEWORTHY Our findings using noninvasive EEG recordings provide evidence that PAC dynamics might play a role in the physiological cortical control of movement execution and may encode transitions between movement states. Results in patients with Parkinson’s disease suggest that bradykinesia is related to a deficit of the dynamic regulation of PAC during movement execution rather than its absolute strength. Our findings may contribute to the development of a new concept of the pathophysiology of bradykinesia.

Motor and behavioral phenotype of Dravet syndrome in adulthood

In a comparative cross-sectional study, 26 adult individuals with clinically typical, genetically confirmed Dravet syndrome (DS) and an equal number of individuals with early onset, problematic epilepsy, and intellectual disability (ID) of comparable severity were included. The aim of the study was to find out whether patients with DS could be clearly distinguished from the comparison group with regard to neurological and behavioral symptoms. Significant differences were found in that individuals with DS clearly more frequently exhibited a symptom cluster characterized by bradykinesia, hypomimia, hypophonia, (spastic) increased muscle tone, ataxia, sthenic perseveration, and a special interest in colors. To these symptoms must be added, according to the findings of previous examinations, mastication, camptocormia/antecollis on the one hand, and the tendency to visual hallucinations on the other hand, in order to define one neuropsychiatric phenotype of DS in adulthood. To these symptoms must be added, according to the findings of previous investigations, crouch gait with camptocormia/antecollis on the one hand, and the tendency to visual hallucinations on the other hand, in order to define one outlined neuropsychiatric phenotype of DS in adulthood.

Adaptive deep brain stimulation: Retuning Parkinson's disease

A brain-machine interface represents a promising therapeutic avenue for the treatment of many neurologic conditions. Deep brain stimulation (DBS) is an invasive, neuro-modulatory tool that can improve different neurologic disorders by delivering electric stimulation to selected brain areas. DBS is particularly successful in advanced Parkinson's disease (PD), where it allows sustained improvement of motor symptoms. However, this approach is still poorly standardized, with variable clinical outcomes. To achieve an optimal therapeutic effect, novel adaptive DBS (aDBS) systems are being developed. These devices operate by adapting stimulation parameters in response to an input signal that can represent symptoms, motor activity, or other behavioral features. Emerging evidence suggests greater efficacy with fewer adverse effects during aDBS compared with conventional DBS. We address this topic by discussing the basics principles of aDBS, reviewing current evidence, and tackling the many challenges posed by aDBS for PD.

Disorders of Movement due to Acquired and Traumatic Brain Injury

Purpose of Review

Both traumatic and acquired brain injury can result in diffuse multifocal injury affecting both the pyramidal and extrapyramidal tracts. Thus, these patients may exhibit signs of both upper motor neuron syndrome and movement disorder simultaneously which can further complicate diagnosis and management. We will be discussing movement disorders following acquired and traumatic brain injury.

Recent Findings

Multiple functions including speech, swallowing, posture, mobility, and activities of daily living can all be affected. Medical treatment and rehabilitation-based therapy can be especially challenging due to accompanying cognitive deficits and severity of the disorder which can involve multiple limbs in addition to muscles of the face and axial skeleton. Tremor and dystonia are the most reported movement disorders following traumatic brain injury. Dystonia and myoclonus are well documented following hypoxic ischemic brain injuries. Electrophysiological studies such as dynamic surface poly-electromyography can assist with identifying phenomenology, especially differentiating between jerk-like phenomenon and help guide further work up and management. Management with medications remains challenging due to potential adverse effects. Surgical interventions including stereotactic surgery, deep brain stimulation, and intrathecal baclofen pumps have been reported, but most of the evidence supporting them has been limited to primarily case reports except for post-traumatic tremor.

Summary

Brain injury can lead to motor disorders, movement disorders, visual (processing) deficits, and vestibular deficits which often coexist with cognitive deficits making it challenging to treat and rehabilitate these patients. Unfortunately, the evidence regarding the medical management and rehabilitation of brain injury patients with movement disorders is sparse and leaves much to be desired.

Video-Based Automated Assessment of Movement Parameters Consistent with MDS-UPDRS III in Parkinson's Disease

BACKGROUND

Among motor symptoms of Parkinson's disease (PD), including rigidity and resting tremor, bradykinesia is a mandatory feature to define the parkinsonian syndrome. MDS-UPDRS III is the worldwide reference scale to evaluate the parkinsonian motor impairment, especially bradykinesia. However, MDS-UPDRS III is an agent-based score making reproducible measurements and follow-up challenging.

OBJECTIVE

Using a deep learning approach, we developed a tool to compute an objective score of bradykinesia based on the guidelines of the gold-standard MDS-UPDRS III.

METHODS

We adapted and applied two deep learning algorithms to detect a two-dimensional (2D) skeleton of the hand composed of 21 predefined points, and transposed it into a three-dimensional (3D) skeleton for a large database of videos of parkinsonian patients performing MDS-UPDRS III protocols acquired in the Movement Disorder unit of Avicenne University Hospital.

RESULTS

We developed a 2D and 3D automated analysis tool to study the evolution of several key parameters during the protocol repetitions of the MDS-UPDRS III. Scores from 2D automated analysis showed a significant correlation with gold-standard ratings of MDS-UPDRS III, measured with coefficients of determination for the tapping (0.609) and hand movements (0.701) protocols using decision tree algorithms. The individual correlations of the different parameters measured with MDS-UPDRS III scores carry meaningful information and are consistent with MDS-UPDRS III guidelines.

CONCLUSION

We developed a deep learning-based tool to precisely analyze movement parameters allowing to reliably score bradykinesia for parkinsonian patients in a MDS-UPDRS manner.

Characterization and localization of upper and lower extremity motor improvements in STN DBS for Parkinson's disease

INTRODUCTION

Subthalamic deep brain stimulation (STN DBS) may have differential effects on cardinal motor signs of Parkinson's disease (PD) in the upper and lower extremities. In addition, sites of maximally effective DBS for each sign and extremity may be distinct. Our study seeks to elucidate these structure-function relationships.

METHODS

We applied an ordinary least squares linear regression model to measure motor effects of STN DBS on upper (UE) and lower (LE) extremity tremor, rigidity, and bradykinesia. We then applied an atlas-independent electrical-field model to identify sites of maximally effective stimulation for each sign and each extremity. Distances between sites and statistical power to resolve differences were calculated.

RESULTS

In our study population (n = 78 patients), STN DBS improved all cardinal motor signs (β = 0.64, p < .05). Improvement magnitudes were tremor > rigidity > bradykinesia. Effects of STN DBS on UE versus LE signs were statistically equal for tremor and bradykinesia, but greater for UE rigidity than LE rigidity (β = 0.19, p < .05). UE maximal-effect loci were lateral, anterior, and dorsal to LE loci, but were not statistically resolved, despite sufficient statistical power to resolve differences of ≤0.48 mm (p < .05) between maximally effective loci of stimulation.

CONCLUSION

STN DBS produces differential effects on UE and LE rigidity, but not for tremor or bradykinesia. This finding is not explained by distinct UE and LE loci of maximally effective stimulation. Instead, we hypothesize that downstream effects of STN DBS on motor networks and limb biomechanics are responsible for observed differences in UE and LE responses.

Proposal of a simple bedside test

BACKGROUND

Bradykinesia, dysrhythmia, and decrement in hand movements (HM) are core symptoms of Parkinson's disease (PD). The maximal rate of repetitive rhythm-preserving HM can be a diagnostic tool for PD bradykinesia.

OBJECTIVES

To improve the clinical diagnosis of bradykinesia by identifying the frequencies at which rhythmic HM become irregular in PD patients compared to healthy age-matched controls.

METHOD

Forty PD patients and 16 controls were asked to alternately perform left and right hand movements following the rate of a metronome with sound stimulation beginning at 85 beats per minute (BPM) and increasing in increments of 15 BPM up to 355 BPM. The rhythm of the HM for each rate was assessed visually, and the threshold frequency at which the subject could no longer rhythmically continue HM was measured by the metronome. The increasing rates of HM until reaching that threshold were compared between patients with PD and controls.

RESULTS

The mean rates of a metronome in PD vs. healthy subjects were 173.3 ± 42.0 vs. 248.8 ± 48.5 BPM (p < 0.001) and 164.8 ± 34.2 vs. 241.2 ± 40.1 BPM (p < 0.001) for the dominant and non-dominant hands, respectively. The areas under the ROC curve were 0.929 [95%CI: (0.86-0.99)] for the dominant hand and 0.947 [95%CI: (0.88-1.0)] for the non-dominant hand. The BMP score cut-off value was 208 (sensitivity 72.7%, specificity 100%) for the dominant hand and 206 (sensitivity 87.5%, specificity 95%) for the non-dominant hand.

CONCLUSIONS

The proposed test quantified the frequencies of rhythmic HMs in PD patients vs. controls and improved the diagnosis of bradykinesia in PD patients.

Frequency-specific network activity predicts bradykinesia severity in Parkinson's disease

OBJECTIVE

Bradykinesia has been associated with beta and gamma band interactions in the basal ganglia-thalamo-cortical circuit in Parkinson's disease. In this present cross-sectional study, we aimed to search for neural networks with electroencephalography whose frequency-specific actions may predict bradykinesia.

METHODS

Twenty Parkinsonian patients treated with bilateral subthalamic stimulation were first prescreened while we selected four levels of contralateral stimulation (0: OFF, 1-3: decreasing symptoms to ON state) individually, based on kinematics. In the screening period, we performed 64-channel electroencephalography measurements simultaneously with electromyography and motion detection during a resting state, finger tapping, hand grasping tasks, and pronation-supination of the arm, with the four levels of contralateral stimulation. We analyzed spectral power at the low (13-20 Hz) and high (21-30 Hz) beta frequency bands and low (31-60 Hz) and high (61-100 Hz) gamma frequency bands using the dynamic imaging of coherent sources. Structural equation modelling estimated causal relationships between the slope of changes in network beta and gamma activities and the slope of changes in bradykinesia measures.

RESULTS

Activity in different subnetworks, including predominantly the primary motor and premotor cortex, the subthalamic nucleus predicted the slopes in amplitude and speed while switching between stimulation levels. These subnetwork dynamics on their preferred frequencies predicted distinct types and parameters of the movement only on the contralateral side.

DISCUSSION

Concurrent subnetworks affected in bradykinesia and their activity changes in the different frequency bands are specific to the type and parameters of the movement; and the primary motor and premotor cortex are common nodes.

Intra and inter-rater remote assessment of bradykinesia in Parkinson's disease

INTRODUCTION

Reliable assessment of individuals with Parkinson's disease (PD) is essential for providing adequate treatment. Clinical assessment is a complex and time-consuming task, especially for bradykinesia, since its evaluation can be influenced by the degree of experience of the examiner, patient collaboration and individual bias. Improvement of the clinical evaluation can be obtained by considering assessments from several professionals. However, this is only true when inter and intra-rater agreement are high. Recently, the Movement Disorder Society highlighted, during the COVID-19 pandemic, the need to develop and validate technologies for remote assessment of the motor status of people with PD. Thus, this study introduces an objective strategy for the remote evaluation of bradykinesia using multi-specialist analysis.

METHODS

Twelve volunteers with PD participated and these were asked to execute finger tapping, hand opening/closing and pronation/supination movements. Each task was recorded and rated by fourteen PD health experts for each patient. The scores were assessed on an individual basis. Intra and inter-rater agreement and correlation were estimated.

RESULTS

The results showed that agreements and correlations between experienced examiners were high with low variability. In addition, group analysis was noted as possessing the potential to solve individual inconsistency bias.

CONCLUSION

Furthermore, this study demonstrated the need for a group with prior training and experience, along with indicating the importance for the development of a clinical protocol that can use telemedicine for the evaluation of individuals with PD, as well as the inclusion of a specialized mediating group. In Addition, this research helps to the development of a valid remote assessment of bradykinesia.

Bradykinesia in motoneuron diseases

OBJECTIVE

Only few studies investigated voluntary movement abnormalities in patients with motoneuron diseases (MNDs) or their neurophysiological correlates. We aimed to kinematically assess finger tapping abnormalities in patients with amyotrophic lateral sclerosis (ALS) and primary lateral sclerosis (PLS), as compared to healthy controls (HCs), and their relationship with motoneuron involvement.

METHODS

Fourteen ALS and 5 PLS patients were enrolled. Finger tapping was assessed by a motion analysis system. Patients underwent a central motor conduction time assessment, a motor nerve conduction study, and needle electromyography. Data were compared to those of 79 HCs using non-parametric tests. Possible relationships between clinical, kinematic, and neurophysiological data were assessed in patients.

RESULTS

As a major finding, ALS and PLS patients performed finger tapping slower than HCs. In both conditions, movement slowness correlated with muscle strength. In ALS, movement slowness also correlated with the amplitude of the compound muscle action potential recorded from the muscles involved in the task and with denervation activity. No correlations were found between slowness, measures of upper motoneuron involvement, and other clinical and neurophysiological data.

CONCLUSIONS

This study provides novel information on voluntary movement abnormalities in MNDs.

SIGNIFICANCE

The results highlight the pathophysiological role of motoneurons in generating movement slowness.

Transcranial direct current stimulation of supplementary motor area improves upper limb kinematics in Parkinson's disease

OBJECTIVE

Bradykinesia, defined as slowness of movements, is among the most functionally debilitating symptoms of Parkinson's disease (PD). Hypoactivation of cortical neurons in supplementary motor area (SMA) has been linked to the progression of bradykinesia symptoms. This study investigated the influence of transcranial direct current stimulation (tDCS) applied over SMA on upper limb movement for individuals diagnosed with PD.

METHODS

Thirteen individuals with PD performed a simple reaction time (RT) task involving elbow extension following an auditory go-signal. Sham or anodal tDCS was then applied over SMA for 10 minutes before participants repeated the simple RT task. Participants were unaware of which stimulation they received in each testing session. Electromyography (EMG) and kinematic data were recorded on all trials.

RESULTS

While there were no significant differences in premotor RT, anodal tDCS applied over SMA led to significantly shorter time to peak displacement (p = .015) and movement time (p = .003) compared to pre-tDCS trials, whereas sham stimulation had no impact on these variables.

CONCLUSIONS

These results provide evidence that anodal tDCS applied over SMA contributes to improvements in movement kinematics of an upper limb simple RT task.

SIGNIFICANCE

Anodal tDCS over SMA could be a useful therapy to mitigate bradykinesia associated with PD.

Association of Helicobacter pylori treatment with Parkinsonism and related disorders: A systematic review and meta-analysis

AIMS

Previous studies have suggested that Helicobacter pylori (H. pylori) infections may be the cause of or worsen Parkinson's disease symptoms. In this meta-analysis, all relevant studies were reviewed to assess whether H. pylori treatment would benefit patients with Parkinson's disease.

MAIN METHODS

Systemically searches were carried out in MEDLINE and other popular databases. The software RevMan 5.2 was used for meta-analysis. The mean difference (MD) was used as the effect size to draw forest plots.

KEY FINDINGS

A total of 10 qualified studies were included. For bradykinesia, the pooled MD value of stride length was -75.76, 95% CI [-109.37, -42.15, P < 0.05]; for myotonia, the pooled MD value of torque to flex was 75.24, 95% CI [27.36, 123.13, P < 0.05]. The pooled MD value of Unified Parkinson's Disease Rating Scale (UPDRS)-III scores before and after treatment was 6.27, 95% CI [1.30, 11.24, P < 0.05], suggesting that UPDRS-III scores improved in response to H. pylori treatment. The pooled MD value of levodopa onset time (min) was 14.91, 95% CI [8.92, 20.90, P < 0.05].

SIGNIFICANCE

H. pylori treatment may improve the stride length in the bradykinesia index and significantly improve UPDRS-III scores.

Beta power and movement-related beta modulation as hallmarks of energy for plasticity induction: Implications for Parkinson's disease

Extensive work on movement-related beta oscillations (~13-30 Hz) over the sensorimotor areas in both humans and animals has demonstrated that sensorimotor beta power decreases during movement and transiently increases after movement. This beta power modulation has been interpreted as reflecting interactions between sensory and motor cortical areas with attenuation of sensory afferents during movement and their subsequent re-activation for internal models updating. More recent studies in neurologically normal subjects have demonstrated that this movement-related modulation as well as mean beta power at rest increase with practice and that previous motor learning enhances such increases. Conversely, patients with Parkinson's disease (PD) do not show such practice-related increases. Interestingly, a 2-h inactivity period without sleep can restore beta power values to baseline in normal subjects. Based on these results and on those of biochemical and electrophysiological studies in animals, we expand the current interpretation of beta activity and propose that the practice-related increases of beta power over sensorimotor areas are local indices of energy used for engaging plasticity-related activity. This paper provides some preliminary evidence in this respect linking findings of biochemical and electrophysiological studies in both humans and animals. This novel interpretation may explain the high level of beta power at rest, the deficient modulation during movement as well as the decreased skill formation in PD as resulting from deficiency in energy consumption, availability and regulation that are altered in this disease.

Face pareidolia is associated with right striatal dysfunction in drug-naïve patients with Parkinson's disease

BACKGROUND AND AIM

Some patients with Parkinson's disease (PD) present with pareidolia, an illusion of a meaningless stimulus as a familiar object known to the observer. Since the striatum is associated with processing of visual information, we investigated correlations of pareidolia with motor symptoms and striatal dopaminergic function.

METHOD

A noise pareidolia test, assessment of motor symptoms using MDS-UPDRS and ¹²³I-Ioflupane SPECT were performed in 58 drug-naïve PD patients. A number of images in which a participant noticed an illusory face (number of illusory responses) were compared with motor assessment scores and uptake of ¹²³I-ioflupane in the striatum.

RESULTS

Of the 58 participants, 22 had at least one illusory response. Mean scores for MDS-UPDRS part III (p<0.05), rigidity (p<0.05), and rigidity on the left side of the body (p<0.01) in patients with pareidolia were significantly higher than those in patients without pareidolia. Uptake of ¹²³I-ioflupane in the right caudate nucleus (p<0.05), anterior putamen (p<0.01), and posterior putamen (p<0.01) in patients with pareidolia was significantly lower than in patients without pareidolia. In the 22 patients with pareidolia, the number of illusory responses was significantly correlated with total scores for MDS-UPDRS part III (r=0.443, p<0.05) and subscores for bradykinesia (r=0.440, p<0.05) and bradykinesia on the left side of the body (r=0.564, p<0.01). The prevalence of pareidolia in left-dominant parkinsonism (16/30 patients) was higher than that in right-dominant parkinsonism (6/28 patients) (p<0.05 by chi-square test).

CONCLUSION

Pareidolia in PD patients is associated with dysfunction in the right striatum.

Association of freezing of gait and clinical features in patients with Parkinson's disease

Freezing of gait (FOG) is a disabling symptom that affects the quality of life of patients with Parkinson's disease (PD) and its pathophysiology is not fully understood yet. The aim of the present study is to evaluate the relationship between FOG and other clinical characteristics in patients with PD. The clinical characteristics, modified Hoehn and Yahr (mHY) stages, Unified Parkinson's Disease Rating Scale (UPDRS) scores, and total Freezing of Gait Questionnaire (FOG-Q) scores of the patients with PD were recorded. FOG-Q item 1.3 was used to evaluate patients with or without FOG. A total of 65 patients with PD (32 with FOG and 33 without FOG) were included to the study. Disease duration was longer, mHY stages were higher, bradykinesia and dyskinesia were more common in patients with FOG compared to patients without (p = 0.001, p = 0.036, p = 0.019 and p = 0.021; respectively). Patients with FOG had lower UPDRS part III tremor subscores (p = 0.020), although gait, postural balance subscores and part IV motor fluctuations scores were higher (p = 0.003, p = 0.023 and p < 0.001; respectively). A positive correlation was found between FOG-Q scores and mHY stages (p < 0.001), UPDRS part II and III total scores (p = 0.020 and p = 0.001) and part III bradykinesia, and gait and postural balance subscores (p = 0.003, p = 0.036 and p = 0.003, respectively), and part IV motor fluctuation scores (p = 0.006). The results of the present study point to an association between FOG and bradykinesia rather than tremor, prolonged disease duration and advanced disease stage reflecting its association with more severe and extensive neurodegenerative processes.

Multiple Pathways of LRRK2-G2019S/Rab10 Interaction in Dopaminergic Neurons

BACKGROUND

Inherited mutations in the LRRK2 protein are common causes of Parkinson's disease, but the mechanisms by which increased kinase activity of mutant LRRK2 leads to pathological events remain to be determined. In vitro assays (heterologous cell culture, phospho-protein mass spectrometry) suggest that several Rab proteins might be directly phosphorylated by LRRK2-G2019S. An in vivo screen of Rab expression in dopaminergic neurons in young adult Drosophila demonstrated a strong genetic interaction between LRRK2-G2019S and Rab10.

OBJECTIVE

To determine if Rab10 is necessary for LRRK2-induced pathophysiological responses in the neurons that control movement, vision, circadian activity, and memory. These four systems were chosen because they are modulated by dopaminergic neurons in both humans and flies.

METHODS

LRRK2-G2019S was expressed in Drosophila dopaminergic neurons and the effects of Rab10 depletion on Proboscis Extension, retinal neurophysiology, circadian activity pattern ('sleep'), and courtship memory determined in aged flies.

RESULTS

Rab10 loss-of-function rescued LRRK2-G2019S induced bradykinesia and retinal signaling deficits. Rab10 knock-down, however, did not rescue the marked sleep phenotype which results from dopaminergic LRRK2-G2019S. Courtship memory is not affected by LRRK2, but is markedly improved by Rab10 depletion. Anatomically, both LRRK2-G2019S and Rab10 are seen in the cytoplasm and at the synaptic endings of dopaminergic neurons.

CONCLUSION

We conclude that, in Drosophila dopaminergic neurons, Rab10 is involved in some, but not all, LRRK2-induced behavioral deficits. Therefore, variations in Rab expression may contribute to susceptibility of different dopaminergic nuclei to neurodegeneration seen in people with Parkinson's disease.

Supervised classification of bradykinesia in Parkinson's disease from smartphone videos

BACKGROUND

Slowness of movement, known as bradykinesia, is the core clinical sign of Parkinson's and fundamental to its diagnosis. Clinicians commonly assess bradykinesia by making a visual judgement of the patient tapping finger and thumb together repetitively. However, inter-rater agreement of expert assessments has been shown to be only moderate, at best.

AIM

We propose a low-cost, contactless system using smartphone videos to automatically determine the presence of bradykinesia.

METHODS

We collected 70 videos of finger-tap assessments in a clinical setting (40 Parkinson's hands, 30 control hands). Two clinical experts in Parkinson's, blinded to the diagnosis, evaluated the videos to give a grade of bradykinesia severity between 0 and 4 using the Unified Pakinson's Disease Rating Scale (UPDRS). We developed a computer vision approach that identifies regions related to hand motion and extracts clinically-relevant features. Dimensionality reduction was undertaken using principal component analysis before input to classification models (Naïve Bayes, Logistic Regression, Support Vector Machine) to predict no/slight bradykinesia (UPDRS = 0-1) or mild/moderate/severe bradykinesia (UPDRS = 2-4), and presence or absence of Parkinson's diagnosis.

RESULTS

A Support Vector Machine with radial basis function kernels predicted presence of mild/moderate/severe bradykinesia with an estimated test accuracy of 0.8. A Naïve Bayes model predicted the presence of Parkinson's disease with estimated test accuracy 0.67.

CONCLUSION

The method described here presents an approach for predicting bradykinesia from videos of finger-tapping tests. The method is robust to lighting conditions and camera positioning. On a set of pilot data, accuracy of bradykinesia prediction is comparable to that recorded by blinded human experts.

Genetics of Parkinson's disease

Less than a quarter century after the discovery of SNCA as the first attributable gene in Parkinson's disease (PD), our knowledge of the genetic architecture underlying this disease has improved by leaps and bounds. About 5-10% of all patients suffer from a monogenic form of PD where mutations in autosomal-dominant (AD) genes-SNCA, LRRK2, and VPS35 and autosomal recessive (AR) genes-PINK1, DJ-1, and Parkin cause the disease. Whole-exome sequencing has described AR DNAJC6 mutations not only in predominantly atypical, but also in patients with typical PD. Majority of PD is genetically complex, caused by the combination of common genetic variants in concert with environmental factors. Genome-wide association studies have identified twenty six PD risk loci till date; however, these show only moderate effects on the risk for PD. The validation of novel genes and its association with PD remains extremely challenging as families harboring rare genetic variants are sparse and globally widespread. This review article aims to provide a comprehensive overview on PD genetics.

Wearable technology to assess bradykinesia and immobility in patients with severe depression undergoing electroconvulsive therapy: A pilot study

The psychomotor retardation that may be seen in major depression represents an interesting parallel to bradykinesia, a core feature of Parkinson's disease. Psychomotor retardation has been correlated with the severity of depression and is a predictor of response to electroconvulsive therapy (ECT). Psychomotor retardation has typically been assessed by subjective clinical judgement including clinical rating scales. Gross activity levels have also been measured with actigraphy previously. The Parkinson's KinetiGraph (PKG) was developed to assess bradykinesia, dyskinesia and tremor in Parkinson's disease and allows for an objective assessment of motor symptoms over time. It has not been used previously to assess motor symptoms in depression. The aim of the current pilot study was to use the PKG to objectively measure both bradykinesia and immobility in depressed inpatients undergoing ECT before, during and at the end of therapy and review correlations with depressive symptomatology and treatment response. The majority of patients (9/12) had PKG defined bradykinesia at baseline and 7/9 of these improved with ECT. All patients with bradykinesia who remitted clinically demonstrated improvements in bradykinesia scores. PKG defined immobility was present at baseline in 11/12 total patients and improved in the majority of these patients (9/11) post ECT. Correlations between clinically assessed melancholia and PKG measures were significant (r = 0.701, p 0.011 at baseline to r_s = 0.655, p 0.021 at end). A strong association between bradykinesia and immobility scores and depression severity was not seen. The PKG is a potentially useful wearable technology to objectively assess motor symptoms in depression.

Playback of 50-kHz ultrasonic vocalizations overcomes psychomotor deficits induced by sub-chronic haloperidol treatment in rats

RATIONALE

In rodents, acute haloperidol treatment induces psychomotor impairments known as catalepsy, which models akinesia in humans and is characterized as an animal model of acute Parkinsonism, whereas sub-chronic haloperidol reduces exploratory behavior, which resembles bradykinesia. Haloperidol-induced catalepsy in rats can be ameliorated by playback of 50-kHz ultrasonic vocalizations (USV), an emotionally and motivationally relevant appetitive auditory stimulus, representing an animal model of paradoxical kinesia. In a condition like PD where patients suffer from chronic motor impairments, it is paramount to assess the long-term symptom relief in an animal model of Parkinsonism.

OBJECTIVES

We investigated whether 50-kHz USV playback ameliorates psychomotor deficits induced by haloperidol in a sub-chronic dosing regimen.

METHODS

In phase 1, distance traveled and number of rearing behavior were assessed in an activity chamber in order to investigate whether sub-chronic haloperidol treatment induced psychomotor impairments. In phase 2, we investigated whether 50-kHz USV playback could overcome these impairments by assessing exploratory behaviors and approach behavior towards the sound source in the 50-kHz USV radial maze playback paradigm.

RESULTS

Sub-chronic haloperidol treatment led to psychomotor deficits since the distance traveled and number of rearing behavior were reduced as compared to saline control group or baseline. These psychomotor impairments were ameliorated during playback of 50-kHz USV, with haloperidol treated rats showing a clear social approach behavior towards the sound source exclusively during playback.

CONCLUSIONS

This study provides evidence that 50-kHz USV playback induces paradoxical kinesia in rats exhibiting motor deficits after sub-chronic haloperidol, as we previously showed after acute haloperidol treatment.

Effects of high-frequency repetitive transcranial magnetic stimulation on reach-to-grasp performance in individuals with Parkinson's disease: a preliminary study

Individuals with Parkinson's disease (PD) have deficits in reach-to-grasp (RTG) execution and visuospatial processing which may be a result of dopamine deficiency in two brain regions: primary motor cortex (M1) and dorsolateral prefrontal cortex (DLPFC). We hypothesized that improvement following M1 stimulation would be the result of a direct impact on motor execution; whereas, DLPFC stimulation would improve the role of DLPFC in visuospatial processing. The aim of pilot study was to investigate the effects of HF-rTMS on RTG performance by stimulating either M1 or DLPFC. Thirty individuals with PD participated (H&Y stages I-III). All of them were more affected on the right side. Participants were allocated into three groups. The DLPFC group received HF-rTMS over left DLPFC; while, the M1 group received HF-rTMS over left M1 of extensor digitorum communis representational area. The control group received HF-rTMS over the vertex. Before and immediately post HF-rTMS, right-hand RTG performance was measured under no barrier and barrier conditions. Additionally, TMS measures including motor-evoked-potential (MEP) amplitude and cortical silent period (CSP) were determined to verify the effects of HF-rTMS. For the results, there were no significant differences among the three groups. However, only the M1 group showed a significant decrease in movement time immediately after HF-rTMS for a barrier condition. Moreover, the M1 group showed a near-significant increase in hand opening and transport velocity. As for the DLPFC group, there was a near-significant increase in temporal transport-grasp coordination and a significant increase in velocity. Increased MEP amplitudes and a significantly longer CSP in the M1 and DLPFC groups confirmed the effects of HF-rTMS. Regarding non-significant results among the three groups, it is still inconclusive whether there were different effects of the rTMS on the two stimulation areas. This is a preliminary study demonstrating that HF-rTMS to M1 may improve RTG execution; whereas, HF-rTMS to DLPFC may improve visuospatial processing demands of RTG.

Role of data measurement characteristics in the accurate detection of Parkinson's disease symptoms using wearable sensors

Background

Parkinson’s disease (PD) is a progressive neurological disease, with characteristic motor symptoms such as tremor and bradykinesia. There is a growing interest to continuously monitor these and other symptoms through body-worn sensor technology. However, limited battery life and memory capacity hinder the potential for continuous, long-term monitoring with these devices. There is little information available on the relative value of adding sensors, increasing sampling rate, or computing complex signal features, all of which may improve accuracy of symptom detection at the expense of computational resources. Here we build on a previous study to investigate the relationship between data measurement characteristics and accuracy when using wearable sensor data to classify tremor and bradykinesia in patients with PD.

Methods

Thirteen individuals with PD wore a flexible, skin-mounted sensor (collecting tri-axial accelerometer and gyroscope data) and a commercial smart watch (collecting tri-axial accelerometer data) on their predominantly affected hand. The participants performed a series of standardized motor tasks, during which a clinician scored the severity of tremor and bradykinesia in that limb. Machine learning models were trained on scored data to classify tremor and bradykinesia. Model performance was compared when using different types of sensors (accelerometer and/or gyroscope), different data sampling rates (up to 62.5 Hz), and different categories of pre-engineered features (up to 148 features). Performance was also compared between the flexible sensor and smart watch for each analysis.

Results

First, there was no effect of device type for classifying tremor symptoms (p > 0.34), but bradykinesia models incorporating gyroscope data performed slightly better (up to 0.05 AUROC) than other models (p = 0.01). Second, model performance decreased with sampling frequency (p < 0.001) for tremor, but not bradykinesia (p > 0.47). Finally, model performance for both symptoms was maintained after substantially reducing the feature set.

Conclusions

Our findings demonstrate the ability to simplify measurement characteristics from body-worn sensors while maintaining performance in PD symptom detection. Understanding the trade-off between model performance and data resolution is crucial to design efficient, accurate wearable sensing systems. This approach may improve the feasibility of long-term, continuous, and real-time monitoring of PD symptoms by reducing computational burden on wearable devices.

A sequential methodology for integral evaluation of motor and non-motor behaviors in parkinsonian rodents

An animal model, suitable for resembling Parkinson's disease (PD) progress, should show both, motor and non-motor alterations. However, these features have been scarcely evaluated or developed in parkinsonian models induced by neurotoxins. This protocol provides modifications to original methods, allowing six different motor and non-motor behavior tests, which adequately and timely emulate the main parkinsonian sensorimotor alterations in the rat or mouse: (1) bilateral sensorimotor alterations, examined by the vibrissae test; (2) balance and motor coordination, evaluated by the uncoordinated gait test; (3) locomotor asymmetry, analyzed by the cylinder test; (4) bradykinesia, as a locomotor alteration evidenced by the open field test; (5) depressive-like behavior, judged by the forced swimming test; and (6) hyposmia, assessed by the olfactory asymmetry test. Some advantages of using these behavioral tests over others include:•No sophisticated materials or equipment are required for their application and evaluation.•They are used in rodent models for parkinsonian research, but they can also be helpful for studying other movement disorders.•These tests can accurately discriminate the affected side from the healthy one, after unilateral injury of one hemisphere, resulting in sensorimotor, olfactory or locomotor asymmetry.

[Research Progress on Evaluation Method of Parkinson's Disease Bradykinesia Detection Based on Wearable Device]

Parkinson's Disease (PD) is a neurodegenerative disease that occurs in the middle-aged and elderly population and has dyskinesia as the main clinical symptom. Bradykinesia is a typical dyskinesia symptom of Parkinson's disease. The evaluation of bradykinesia based on wearable devices is an important support for individualized diagnosis and telemedicine. This paper focuses on the bradykinesia, expound the existing detection and evaluation techniques for wearable devices and data analysis methods. This paper also analyzes and discusses some current problems in the field and future research directions.

Parkinsonism in Huntington's disease

Huntington's disease (HD) is usually characterized by involuntary hyperkinetic movements, called chorea. The intensity of chorea exhibits a peak in middle stages of HD and then decreases as HD progresses. In contrast, Pakinsonian signs of HD are often less appreciated. They typically progress in a fairly linear pattern over time. In fact, bradykinesia is detectable early on in premanifest gene carriers up to two decades prior to the clinical manifestation of HD symptoms using quantitative motor (Q-Motor) assessments such as finger tapping (digitomotography). Other Parkinsonian symptoms besides bradykinesia are rigidity and postural instability. They typically results in falls and injuries in advanced stages of HD. A primarily Parkinsonian motor phenotype, often seen with little to no chorea, is characteristically observed in older, late manifesting patients and in pediatric HD subjects. Establishing a diagnosis of HD is difficult in these groups and patients are often misdiagnosed in early stages.

Impact of Subthalamic Deep Brain Stimulation Frequency on Upper Limb Motor Function in Parkinson's Disease

Background:

Whilst changes in the frequency of subthalamic deep brain stimulation (STN-DBS) have been proposed to improve control of tremor or axial motor features in Parkinson’s disease (PD), little is known about the effects of frequency changes on upper limb motor function, particularly bradykinesia.

Objective:

To investigate the acute effects of various STN-DBS frequencies (40–160 Hz, 40 Hz intervals) on upper limb motor function.

Methods:

We carried out a randomised, double-blind study on 20 PD patients with chronic STN-DBS using the Simple and Assembly components of the Purdue Pegboard (PP) test and a modified upper limb version of the UPDRS-III (UL-UPDRS-III).

Results:

There was no significant effect of frequency on bradykinesia on the Simple PP task or the UL-UPDRS-III. There was an effect of frequency on the Assembly PP score when comparing all frequencies (p = 0.019) and between 80 Hz and 130 Hz (p = 0.007), with lower frequencies yielding a better performance. Rigidity and Tremor scores were significantly reduced with higher (>80 Hz) compared to lower (40 Hz) frequencies.

Conclusions:

Our findings suggest that a wide range of frequencies are efficacious in improving acute upper-limb motor function. Reducing the frequency of stimulation down to 80 Hz is safe and has a similar clinical effect to higher frequencies. Therefore, a wider range of frequencies are available when it comes adjusting patients’ acute settings without the risk of worsening bradykinesia.