Freezing phenomenon in patients with parkinsonian syndromes

Validity, reliability, and measurement error of the Japanese version of the Freezing of Gait Questionnaire for patients with Parkinson's disease

BACKGROUND

The Freezing of Gait Questionnaire has been translated into several languages. However, it has not been translated into Japanese and its measurement error remains unclear.Objectives: This study aimed to translate the Freezing of Gait Questionnaire into Japanese, investigate its validity and reliability, and calculate its measurement errors.

METHODS

Thirty-five patients with Parkinson's disease participated in the study. The Freezing of Gait Questionnaire was translated into Japanese using a forward - backward translation method. Convergent validity was assessed using the Freezing of Gait Questionnaire and Unified Parkinson's Disease Rating Scale Part II(item 14-freezing). The content validity index was calculated using the Freezing of Gait Questionnaire score using correlation coefficients. Internal consistency was measured using Cronbach's alpha. The test - retest reliability was evaluated using the intraclass correlation coefficient(1,1). The Bland - Altman analysis was performed to detect the limits of agreement.

RESULTS

The mean Freezing of Gait Questionnaire score was 9.1 (5.0) points. Convergent validity was 0.655 and content validity index was 0.958. Cronbach's alpha was 0.958, intraclass correlation coefficient(1,1) was 0.951, and the limits of agreement ranged from - 4.9 to3.2 points.

CONCLUSIONS

The Japanese version of the Freezing of Gait Questionnaire is a valid and useful tool to evaluate patients with Parkinson's disease.

Hypokinetic-rigid gait disorders with balance impairment - A walk through clinical and pathophysiological definitions

Hypokinetic-rigid gait disorders with balance impairment are a common clinical phenotype of different syndromes and diseases. However, multiple designations are used across the literature with unclear definitions, which brings heterogeneity and subjectivity to the discussion of such gait disorders. Therefore, there is a need for clear concepts to increase accuracy in clinical diagnosis and allow consistent comparisons and reasoning within research data. We performed a review of concepts, including lower body parkinsonism (LBP), higher level gait disorders, frontal gait disorders, gait apraxia, senile gait and cautious gait. Additionally, we reviewed the basic pathophysiological mechanisms underlying these gait disorders. LBP was found to be mainly associated with dysfunction of the motor thalamocortical circuit and of the mesencephalic locomotor region. We propose that for research purposes, concepts with greater specificity, such as LBP, should be preferentially used to improve the accuracy of studies involving this population. Considering the significant phenotypic and pathophysiological overlap between hypokinetic-rigid gait disorders, a multi-modal approach would be more pertinent to optimize the differential diagnosis in both clinical and research settings.

Management of freezing of gait - mechanism-based practical recommendations

Freezing of gait (FOG) is a debilitating motor symptom that commonly occurs in Parkinson disease, atypical parkinsonism and other neurodegenerative conditions. Management of FOG is complex and requires a multifaceted approach that includes pharmacological, surgical and non-pharmacological interventions. In this Expert Recommendation, we provide state-of-the-art practical recommendations for the management of FOG, based on the latest insights into the pathophysiology of the condition. We propose two complementary treatment flows, both of which are linked to the pathophysiology and tailored to specific FOG phenotypes. The first workflow focuses on the reduction of excessive inhibitory outflow from the basal ganglia through use of dopaminergic medication or advanced therapies such as deep brain stimulation and infusion therapy. The second workflow focuses on facilitation of processing across cerebral compensatory networks by use of non-pharmacological interventions. We also highlight interventions that have potential for FOG but are not supported by sufficient evidence to recommend for clinical application. Our updated recommendations are intended to enable effective symptomatic relief once FOG has developed, but we also consider potential targets for preventive approaches. The recommendations are based on scientific evidence where available, supplemented with practice-based evidence informed by our clinical experience.

Wearable Surface Electromyography System to Predict Freeze of Gait in Parkinson's Disease Patients

Freezing of gait (FOG) is a disabling yet poorly understood paroxysmal gait disorder affecting the vast majority of patients with Parkinson's disease (PD) as they reach advanced stages of the disorder. Falling is one of the most disabling consequences of a FOG episode; it often results in injury and a future fear of falling, leading to diminished social engagement, a reduction in general fitness, loss of independence, and degradation of overall quality of life. Currently, there is no robust or reliable treatment against FOG in PD. In the absence of reliable and effective treatment for Parkinson's disease, alleviating the consequences of FOG represents an unmet clinical need, with the first step being reliable FOG prediction. Current methods for FOG prediction and prevention cannot provide real-time readouts and are not sensitive enough to detect changes in walking patterns or balance. To fill this gap, we developed an sEMG system consisting of a soft, wearable garment (pair of shorts and two calf sleeves) embedded with screen-printed electrodes and stretchable traces capable of picking up and recording the electromyography activities from lower limb muscles. Here, we report on the testing of these garments in healthy individuals and in patients with PD FOG. The preliminary testing produced an initial time-to-onset commencement that persisted > 3 s across all patients, resulting in a nearly 3-fold drop in sEMG activity. We believe that these initial studies serve as a solid foundation for further development of smart digital textiles with integrated bio and chemical sensors that will provide AI-enabled, medically oriented data.

Botulinum Toxin Effects on Freezing of Gait in Parkinson's Disease: A Systematic Review

Freezing of gait is a frequent phenomenon and can be one of the most debilitating motor impairments in Parkinson's disease, especially in the advanced stages. It is currently defined as a brief episodic absence or any marked reduction in the forward progression of the feet, despite the intention to walk. Greater severity of freezing of gait has been associated with more frequent falls, postural instability, and executive dysfunction. However, botulinum neurotoxin is one of the most widely administered therapies for motor and non-motor symptoms, including freezing of gait, in parkinsonism. To date, the literature has had conflicting results on the use of botulinum toxin in the treatment of freezing of gait in Parkinson's disease patients. In light of this, we reviewed the findings of past studies that specifically investigated the effects of botulinum toxin on freezing of gait in Parkinson's disease in order to better understand this issue.

Impacts of gait freeze on quality of life in Parkinson's disease, from the perspectives of patients and their carers

BACKGROUND

The World Health Organisation (WHO) reports that morbidity and mortality due to Parkinson's disease (PD) are increasing faster than for other neurodegenerative conditions. People with Parkinson's (PwP) present with a variety of motor symptoms, such as tremor, bradykinesia, and rigidity. Freezing of gait (FoG) is a significant motor symptom that manifests as temporary episodes of inability to move one's feet, despite the intention to walk.

AIMS

This study examined the impact of FoG on quality of life (QoL) within an Irish cohort of PwP, from the perspectives of both PwP and their carers, using validated questionnaires that had been adapted for online use.

METHODS

PwP and their carers were recruited by outreach to the Irish Parkinson's Community. Anonymous online questionnaires were distributed, which combined a demographic survey with several clinically validated surveys, including Freezing of Gait Questionnaire (FoG-Q), Parkinson's Disease Questionnaire 8 (PDQ-8), and Parkinson's Disease Carer Questionnaire (PDQ-C).

RESULTS

There was a strong correlation (p < 0.001) between severity of FoG and lower QoL among PwP. Significant correlation was also found between FoG severity and several motor symptoms, such as postural instability and difficulty with balance, and non-motor symptoms, such as cognitive changes and pain/discomfort. FoG severity correlated with disease progression. Significant correlation was also found between FoG and symptoms, as assessed from the perspective of the patients' carers.

CONCLUSIONS

This study shows that FoG is a significant detriment to the QoL of PwP, from the perspectives of patients and carers. This method of assessing FoG and QoL using online questionnaires has potential to enhance the reach and flexibility of this type of research. These findings will inform future studies on larger cohorts and highlight unmet clinical needs in PwP.

Freezing of gait in idiopathic normal pressure hydrocephalus

BACKGROUND

Reports of freezing of gait (FoG) in idiopathic normal pressure hydrocephalus (iNPH) are few and results are variable. This study's objective was to evaluate the frequency of FoG in a large cohort of iNPH patients, identify FoG-associated factors, and assess FoG's responsiveness to shunt surgery.

METHODS

Videotaped standardized gait protocols with iNPH patients pre- and post-shunt surgery (n = 139; median age 75 (71-79) years; 48 women) were evaluated for FoG episodes by two observers (Cohens kappa = 0.9, p < 0.001). FoG episodes were categorized. Mini-mental state examination (MMSE) and MRI white matter hyperintensities (WMH) assessment using the Fazekas scale were performed. CSF was analyzed for Beta-amyloid, Tau, and Phospho-tau. Patients with and without FoG were compared.

RESULTS

Twenty-two patients (16%) displayed FoG at baseline, decreasing to seven (8%) after CSF shunt surgery (p = 0.039). The symptom was most frequently exhibited during turning (n = 16, 73%). Patients displaying FoG were older (77.5 vs. 74.6 years; p = 0.029), had a slower walking speed (0.59 vs. 0.89 m/s; p < 0.001), a lower Tinetti POMA score (6.8 vs. 10.8; p < 0.001), lower MMSE score (21.3 vs. 24.0; p = 0.031), and longer disease duration (4.2 vs. 2.3 years; p < 0.001) compared to patients not displaying FoG. WMH or CSF biomarkers did not differ between the groups.

CONCLUSIONS

FoG is occurring frequently in iNPH patients and may be considered a typical feature of iNPH. FoG in iNPH was associated with higher age, longer disease duration, worse cognitive function, and a more unstable gait. Shunt surgery seems to improve the symptom.

Atypical findings: Atypical parkinsonian syndromes or Atypical parkinsonian syndromes look-alikes

OBJECTIVE

In parkinsonian syndromes, presentations other than current diagnostic criteria are considered atypical findings. Our goal was to identify and describe the frequency and features of uncommon manifestations of atypical parkinsonian syndromes within our group.

METHODS

We retrospectively retrieved the medical records of all patients admitted to our clinic with parkinsonism between January 2011 and January 2022. We only included patients with atypical parkinsonian syndromes, in which the diagnosis was based on current clinical criteria. We retrospectively analyzed neurological, psychiatric, radiological, and electrophysiological characteristics. Typical and atypical features were classified according to the current clinical criteria and previous reports.

RESULTS

We determined 51 patients with atypical parkinsonian syndromes; 46 were included, whereas five were excluded due to insufficient follow-up. The probable diagnoses were multiple system atrophy (MSA, n = 19), dementia with Lewy bodies (DLB, n = 10), frontotemporal dementia (FTD, n = 10), corticobasal syndrome (CBS, n = 3), progressive supranuclear palsy (PSP, n = 4). The prevalence of atypical findings was similar among different types of atypical parkinsonian syndromes (p = 0.847). Atypical findings were eyelid myoclonus, double vision in MSA; ataxia, myoclonus, and a typical hummingbird sign on MRI in DLB; pyramidal findings and family history in FTD; early onset, family history, and onset with psychiatric findings in PSP-like phenotype. Genetic causes were identified in the FTD-like phenotype with pyramidal findings, whereas symptom onset was early with myoclonus in the PSP-like phenotype.

CONCLUSION

Atypical findings such as abnormal saccades, myoclonus, and ataxia may be a part of degenerative syndromes. However, family history, onset at an earlier age, and specific neurological findings suggest genetic syndromes.

FoGGAN: Generating Realistic Parkinson's Disease Freezing of Gait Data Using GANs

Data scarcity in the healthcare domain is a major drawback for most state-of-the-art technologies engaging artificial intelligence. The unavailability of quality data due to both the difficulty to gather and label them as well as due to their sensitive nature create a breeding ground for data augmentation solutions. Parkinson's Disease (PD) which can have a wide range of symptoms including motor impairments consists of a very challenging case for quality data acquisition. Generative Adversarial Networks (GANs) can help alleviate such data availability issues. In this light, this study focuses on a data augmentation solution engaging Generative Adversarial Networks (GANs) using a freezing of gait (FoG) symptom dataset as input. The data generated by the so-called FoGGAN architecture presented in this study are almost identical to the original as concluded by a variety of similarity metrics. This highlights the significance of such solutions as they can provide credible synthetically generated data which can be utilized as training dataset inputs to AI applications. Additionally, a DNN classifier's performance is evaluated using three different evaluation datasets and the accuracy results were quite encouraging, highlighting that the FOGGAN solution could lead to the alleviation of the data shortage matter.

Regional homogeneity and functional connectivity of freezing of gait conversion in Parkinson's disease

Background

Freezing of gait (FOG) is common in the late stage of Parkinson's disease (PD), which can lead to disability and impacts the quality of life. Therefore, early recognition is crucial for therapeutic intervention. We aimed to explore the abnormal regional homogeneity (ReHo) and functional connectivity (FC) in FOG converters and evaluate their diagnostic values.

Methods

The data downloaded from the Parkinson's Disease Progression Markers Project (PPMI) cohort was subdivided into PD-FOG converters (n = 16) and non-converters (n = 17) based on whether FOG appeared during the 3-year follow-up; 16 healthy controls were well-matched. ReHo and FC analyses were used to explore the variations in spontaneous activity and interactions between significant regions among three groups of baseline data. Correlations between clinical variables and the altered ReHo values were assessed in FOG converter group. Last, logistic regression and receiver operating characteristic curve (ROC) were used to predict diagnostic value.

Results

Compared with the non-converters, FOG converters had reduced ReHo in the bilateral medial superior frontal gyrus (SFGmed), which was negatively correlated with the postural instability and gait difficulty (PIGD) score. ReHo within left amygdala/olfactory cortex/putamen (AMYG/OLF/PUT) was decreased, which was correlated with anxiety and autonomic dysfunction. Also, increased ReHo in the left supplementary motor area/paracentral lobule was positively correlated with the rapid eye movement sleep behavior disorder screening questionnaire. FOG converters exhibited diminished FC in the basal ganglia, limbic area, and cognitive control cortex, as compared with non-converters. The prediction model combined ReHo of basal ganglia and limbic area, with PIGD score was the best predictor of FOG conversion.

Conclusion

The current results suggested that abnormal ReHo and FC in the basal ganglia, limbic area, and cognitive control cortex may occur in the early stage of FOG. Basal ganglia and limbic area dysfunction combined with higher PIGD score are useful for the early recognition of FOG conversion.

Intermittent theta-burst stimulation combined with physical therapy as an optimal rehabilitation in Parkinson's disease: study protocol for a randomised, double-blind, controlled trial

BACKGROUND

First-line rehabilitative strategies to improve motor deficits are based on functional training (physical or occupational therapy), which has been demonstrated to facilitate neural reorganisation. Accumulating evidence suggests that non-invasive brain stimulation techniques, such as repetitive TMS (rTMS), may enhance neuroplasticity, thereby facilitating neural reorganisation and recovery from Parkinson's disease. Evidence also shows that intermittent theta-burst stimulation (iTBS) can improve motor function and quality of life in patients by promoting the excitability and neural remodelling of cerebral cortex. We aimed to combine iTBS stimulation with physiotherapy to improve the rehabilitation effect compared to physiotherapy alone in patients with Parkinson's disease.

METHODS

This randomised, double-blind clinical trial will enrol 50 Parkinson's disease patients aged 45-70 years with Hoehn and Yahr scale scores of 1-3. Patients are randomly assigned to either the iTBS + physiotherapy or sham-iTBS + physiotherapy group. The trial consists of a 2-week double-blind treatment period and a 24-week follow-up period. iTBS and sham-iTBS will be administered twice daily for 10 days based on physiotherapy. The primary outcome will be the third part of Movement Disorders-Unified Parkinson's Disease Rating Scale (MDS-UPDRS III) from the baseline to the first 2 days following completion hospitalised intervention. The secondary outcome will be 39-item Parkinson's Disease Questionnaire (PDQ-39) at 4 weeks, 12 weeks and 24 weeks after intervention. Tertiary outcomes are clinical evaluations and mechanism study outcomes such as NMSS, 6MWD, 10MT, TUG, BBS, MRI, and EEG, the length of time between the drug needs to be adjusted when symptoms fluctuate.

DISCUSSION

The aim of this study is to demonstrate that iTBS can promote overall function and quality of life in Parkinson's disease patients using physiotherapy and that this efficacy may be associated with altered neuroplasticity in exercise-related brain regions. The iTBS combined with physiotherapy training model will be evaluated during a 6-month follow-up period. With significant improvement in quality of life and motor function, iTBS combined with physiotherapy can be considered as a first-line rehabilitation option for Parkinson's disease. The potential of iTBS to enhance neuroplasticity in the brain should have a more positive impact in increasing the generality and efficiency of physiotherapy, improving the quality of life and overall functional status of patients with Parkinson's disease.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2200056581. Registered on 8 February 2022.

Freezing of gait in Chinese patients with multiple system atrophy: prevalence and risk factors

Objective

Freezing of gait (FOG) is common in neurodegenerative forms of atypical parkinsonism, but few studies have examined FOG in multiple system atrophy (MSA). In this study, we examined the prevalence of freezing of gait and its relationship to clinical features in a large cohort of Chinese MSA patients.

Methods

This exploratory study included 202 Chinese patients with probable MSA. FOG was defined as a score ≥ 1 on item 14 of the Unified Parkinson's Disease Rating Scale. Patients with or without FOG were compared in terms of the Unified MSA Rating Scale (UMSARS) as well as cognitive and neuropsychiatric assessments.

Results

The frequency of FOG was 48.0, 52.1, and 38.7% in MSA, MSA with predominant parkinsonism (MSA-P), and MSA with predominant cerebellar ataxia (MSA-C), respectively. FOG was associated with worse subscores on parts I, II and IV of the UMSARS as well as worse total UMSARS score; greater likelihood of speech difficulties, falls, gait impairment and balance disorder; more severe symptoms of anxiety and depression; and lower activities of daily living. The binary logistic regression model indicated that higher total UMSARS scores were associated with FOG in MSA, MSA-P, and MSA-C patients.

Conclusion

Freezing of gait may be common among Chinese MSA patients, FOG may correlate with severe motor symptoms, anxiety, depression and activities of daily living. Total UMSARS score may be an independent risk factor for FOG.

Techniques for the detection and management of freezing of gait in Parkinson's disease - A systematic review and future perspectives

Freezing of Gait (FoG) is one of the most critical debilitating motor symptoms of advanced Parkinson's disease (PD) with a higher rate of occurrence in aged people. PD affects the cardinal motor functioning and leads to non-motor symptoms, including cognitive and neurobehavioral abnormalities, autonomic dysfunctions and sleep disorders. Since its pathogenesis is complex and unclear yet, this paper targets the studies done on the pathophysiology and epidemiology of FoG in PD. Gait disorder and cardinal features vary from festination (involuntary hurrying in walking) to freezing of gait (breakdown of repetitive movement of steps despite the intention to walk) in patients. Hence, it is difficult to assess the FoG in clinical trials. Therefore, the current research emphasizes wearable sensor-based systems over pharmacology and surgical methods.•This paper presents a technological review of various techniques used for the assessment of FoG with a comprehensive comparison.•Researchers are aiming at the development of wireless sensor-based assistive devices to (a) predict the FoG episode in a different environment, (b) acquire the long-term data for real-time analysis, and (c) cue the FoG patients.•We summarize the work done till now and future research directions needed for a suitable cueing mechanism to overcome FoG.

Stepping up to meet the challenge of freezing of gait in Parkinson's disease

There has been a growing appreciation for freezing of gait as a disabling symptom that causes a significant burden in Parkinson’s disease. Previous research has highlighted some of the key components that underlie the phenomenon, but these reductionist approaches have yet to lead to a paradigm shift resulting in the development of novel treatment strategies. Addressing this issue will require greater integration of multi-modal data with complex computational modeling, but there are a number of critical aspects that need to be considered before embarking on such an approach. This paper highlights where the field needs to address current gaps and shortcomings including the standardization of definitions and measurement, phenomenology and pathophysiology, as well as considering what available data exist and how future studies should be constructed to achieve the greatest potential to better understand and treat this devastating symptom.

Freezing of Gait in Multiple System Atrophy

Background and Purpose

Freezing of gait (FOG) is a common gait disturbance phenomenon in multiple system atrophy (MSA) patients. The current investigation assessed the incidence FOG in a cross-sectional clinical study, and clinical correlations associated with it.

Methods

Ninety-nine MSA patients from three hospitals in China were consecutively enrolled in the study. Eight patients were subsequently excluded from the analysis due to incomplete information. The prevalence of FOG symptoms in the MSA cohort was determined, and clinical manifestations in MSA patients with and without FOG were assessed.

Results

Of 91 MSA patients, 60 (65.93%) exhibited FOG. The incidence of FOG increased with disease duration and motor severity and was correlated with modified Hoehn and Yahr (H-Y) stages [odds ratio (OR), 0.54; 95% confidence interval (CI), 0.33–3.92], longer disease duration (OR, 0.54, 95% CI, 0.37–0.78), higher Unified Multiple System Atrophy Rating Scale (UMSARS) score (OR, 0.96, 95% CI, 0.93–0.99), MSA-cerebellum subtype (OR, 2.99, 95% CI, 1.22–7.33), levodopa-equivalent dose (LDED) (OR, 0.998, 95% CI, 0.997–1.00), and higher Scale for the Assessment and Rating of Ataxia (SARA) score (OR, 0.80, 95% CI, 0.72–0.89) (logistic regression). Motor dysfunction was significantly positively associated with lower quality of life scores (p &lt; 0.01).

Conclusion

FOG is a common symptom in MSA patients and it is correlated with poor quality of life, disease progression and severity, levodopa-equivalent dose, and cerebellum impairment.

Levodopa-Carbidopa Intestinal Gel may improve treatment-resistant freezing of gait in Parkinson’s disease

•

Freezing of gait (FOG) in Parkinson’s Disease (PD) is difficult to control with oral levodopa.

•

Levodopa-Carbidopa Intestinal Gel (LCIG) may be a therapeutic option for patients with FOG.

•

This review examines the current literature on LCIG as a therapy for FOG.

Introduction

Freezing of gait (FOG) is a highly disabling symptom in Parkinson’s Disease (PD) with varying degree of benefits from oral dopaminergic medications and several subtypes that present with different medication states (e.g., off FOG, on FOG, pseudo-on FOG, supra-on FOG). Levodopa-Carbidopa Intestinal Gel (LCIG) greately reduces the variability of cerebral dopamine replacement inherent to oral therapies by continuous levodopa intestinal infusion. While LCIG may be superior to oral therapy in its ability to treat motor fluctuations and minimize off-time, there is no consensus regarding the overall effectiveness of LCIG specifically for the treatment of FOG in PD patients.

Methods

A systematic literature review was conducted to understand the efficacy of LCIG to treat FOG in PD patients. A PubMed search was conducted using the search query “Intestinal AND (Levodopa OR L-dopa) AND Freezing of Gait AND Parkinson.” Additional eligibility criteria included articles written in English and currently published journal articles. Articles were excluded if they did not have a clinical design or if they did not yield reportable data on FOG.

Results

The literature search yielded 16 articles, of which 10 articles were included. Of the 10 studies included, there were 3 retrospective studies, 6 case reports or case series, and 1 open-label study. (n = 449 patients total and 318 FOG patients). Nine of the 10 studies concluded that LCIG has a favorable effect on FOG, though the metrics to evaluate benefits of LCIG on FOG varied among the articles.

Conclusion

LCIG may be an effective treatment for PD patients suffering from FOG including those with poor response to oral medication, likely because of its ability to maintain steadier dopamine levels. Further research is necessary on LCIG as a therapy for refractory FOG, with particular attention to the different subtypes of FOG.

Parkinsonism and cerebrospinal fluid disorders

BACKGROUND

Although various motor manifestations can be seen in patients with cerebrospinal fluid (CSF) disorders, such as hydrocephalus or intracranial hypotension, the clinical presentation with parkinsonism is not clearly elucidated.

METHODS

We searched the literature for studies describing the occurrence of parkinsonism in subjects with normal pressure hydrocephalus (NPH), obstructive hydrocephalus, and intracranial hypotension. We analyzed the clinical presentation (particularly with respect to bradykinesia, rigidity, rest tremor, and gait disturbance/postural instability) as well as the response to treatment.

RESULTS

Parkinsonism was most commonly reported in NPH patients. Although gait disturbance/postural instability is a well-known motor symptom of NPH, other cardinal signs include upper limb involvement or asymmetric presentation. As for obstructive hydrocephalus, parkinsonism was mainly observed in subjects with aqueductal stenosis and more often after shunt surgery. Patients with NPH or obstructive hydrocephalus rarely improved with levodopa therapy, while most subjects only improved with shunt surgery. Although the mechanism is still controversial, a functional involvement of nigrostriatal pathway has been hypothesized based on imaging studies and case reports. Brain imaging is also helpful for atypical cases of intracranial hypotension presenting with parkinsonism. Parkinsonism improved after treatment in such cases as well.

CONCLUSIONS

Studies exploring the relationship between CSF disorders and parkinsonism are mainly descriptive and their quality is generally poor. However, considering that these disorders can be treated, clinicians' awareness of the differential diagnosis is important and future studies better exploring the underlying pathophysiological mechanisms are warranted. This article is part of the Special Issue "Parkinsonism across the spectrum of movement disorders and beyond" edited by Joseph Jankovic, Daniel D. Truong and Matteo Bologna.

Identification of EEG Dynamics During Freezing of Gait and Voluntary Stopping in Patients With Parkinson's Disease

Mobility is severely impacted in patients with Parkinson's disease (PD), who often experience involuntary stopping from the freezing of gait (FOG). Understanding the neurophysiological difference between "voluntary stopping" and "involuntary stopping" caused by FOG is vital for the detection of and potential intervention for FOG in the daily lives of patients. This study characterised the electroencephalographic (EEG) signature associated with FOG in contrast to voluntary stopping. The protocol consisted of a timed up-and-go (TUG) task and an additional TUG task with a voluntary stopping component, where participants reacted to verbal "stop" and "walk" instructions by voluntarily stopping or walking. Event-related spectral perturbation (ERSP) analysis was performed to study the dynamics of the EEG spectra induced by different walking phases, including normal walking, voluntary stopping and episodes of involuntary stopping (FOG), as well as the transition windows between normal walking and voluntary stopping or FOG. These results demonstrate for the first time that the EEG signal during the transition from walking to voluntary stopping is distinguishable from that during the transition to involuntary stopping caused by FOG. The EEG signature of voluntary stopping exhibits a significantly decreased power spectrum compared with that of FOG episodes, with distinctly different patterns in the delta and low-beta power in the central area. These findings suggest the possibility of a practical EEG-based tool that can accurately predict FOG episodes, excluding the potential confounding of voluntary stopping.

Positive impact of short-term gait rehabilitation in Parkinson patients: a combined approach based on statistics and machine learning

Parkinson's disease is the second most common neurodegenerative disorder in the world. Assumed that gait dysfunctions represent a major motor symptom for the pathology, gait analysis can provide clinicians quantitative information about the rehabilitation outcome of patients. In this scenario, wearable inertial systems for gait analysis can be a valid tool to assess the functional recovery of patients in an automatic and quantitative way, helping clinicians in decision making. Aim of the study is to evaluate the impact of the short-term rehabilitation on gait and balance of patients with Parkinson's disease. A cohort of 12 patients with Idiopathic Parkinson's disease performed a gait analysis session instrumented by a wearable inertial system for gait analysis: Opal System, by APDM Inc., with spatial and temporal parameters being analyzed through a statistic and machine learning approach. Six out of fourteen motion parameters exhibited a statistically significant difference between the measurements at admission and at discharge of the patients, while the machine learning analysis confirmed the separability of the two phases in terms of Accuracy and Area under the Receiving Operating Characteristic Curve. The rehabilitation treatment especially improved the motion parameters related to the gait. The study shows the positive impact on the gait of a short-term rehabilitation in patients with Parkinson's disease and the feasibility of the wearable inertial devices, that are increasingly spreading in clinical practice, to quantitatively assess the gait improvement.

Freezing of Gait in Parkinson's Disease: Invasive and Noninvasive Neuromodulation

INTRODUCTION

Freezing of gait (FoG) is one of the most disabling yet poorly understood symptoms of Parkinson's disease (PD). FoG is an episodic gait pattern characterized by the inability to step that occurs on initiation or turning while walking, particularly with perception of tight surroundings. This phenomenon impairs balance, increases falls, and reduces the quality of life.

MATERIALS AND METHODS

Clinical-anatomical correlations, electrophysiology, and functional imaging have generated several mechanistic hypotheses, ranging from the most distal (abnormal central pattern generators of the spinal cord) to the most proximal (frontal executive dysfunction). Here, we review the neuroanatomy and pathophysiology of gait initiation in the context of FoG, and we discuss targets of central nervous system neuromodulation and their outcomes so far. The PubMed database was searched using these key words: neuromodulation, freezing of gait, Parkinson's disease, and gait disorders.

CONCLUSION

Despite these investigations, the pathogenesis of this process remains poorly understood. The evidence presented in this review suggests FoG to be a heterogenous phenomenon without a single unifying pathologic target. Future studies rigorously assessing targets as well as multimodal approaches will be essential to define the next generation of therapeutic treatments.

The Transition from Standing to Walking Is Affected in People with Parkinson's Disease and Freezing of Gait

BACKGROUND

It has been hypothesized that freezing of gait (FOG) in people with Parkinson's disease (PD) is due to abnormal coupling between posture and gait.

OBJECTIVE

In this study, we examined the relationship between anticipatory postural adjustments (APAs) preceding gait initiation and the kinematics of the first two steps between people with FOG and without FOG.

METHODS

The kinetics and kinematics of self-initiated gait were recorded in 25 people with PD (11 with FOG, 14 without FOG). Outcome variables included the amplitude and timing of the ground reaction forces (GRFs), center of pressure (CoP) shifts and the spatial and temporal characteristics of the first and second steps.

RESULTS

The magnitude and timing of the APA phase of gait initiation were not significantly different between participants with and without FOG, yet the first step in the FOG group was distinguished by a significantly wider and less variable first step width, followed by a subsequent wider and shortened second step with reduced toe clearance. Multiple linear regression showed that the relationship between the initial conditions (stance width), APAs (posterior shift of the CoP) and the kinematics of the first step were different between groups with a significantly increased slope in the FOG group.

CONCLUSION

These findings demonstrate that the transition from standing to walking is different between those with and without FOG and that alterations in the initial conditions or APAs are more likely to impact the execution of the two steps in people with FOG.

Prediction of Freezing of Gait in Parkinson's Disease Using Wearables and Machine Learning

Freezing of gait (FOG) is one of the most troublesome symptoms of Parkinson’s disease, affecting more than 50% of patients in advanced stages of the disease. Wearable technology has been widely used for its automatic detection, and some papers have been recently published in the direction of its prediction. Such predictions may be used for the administration of cues, in order to prevent the occurrence of gait freezing. The aim of the present study was to propose a wearable system able to catch the typical degradation of the walking pattern preceding FOG episodes, to achieve reliable FOG prediction using machine learning algorithms and verify whether dopaminergic therapy affects the ability of our system to detect and predict FOG. Methods: A cohort of 11 Parkinson’s disease patients receiving (on) and not receiving (off) dopaminergic therapy was equipped with two inertial sensors placed on each shin, and asked to perform a timed up and go test. We performed a step-to-step segmentation of the angular velocity signals and subsequent feature extraction from both time and frequency domains. We employed a wrapper approach for feature selection and optimized different machine learning classifiers in order to catch FOG and pre-FOG episodes. Results: The implemented FOG detection algorithm achieved excellent performance in a leave-one-subject-out validation, in patients both on and off therapy. As for pre-FOG detection, the implemented classification algorithm achieved 84.1% (85.5%) sensitivity, 85.9% (86.3%) specificity and 85.5% (86.1%) accuracy in leave-one-subject-out validation, in patients on (off) therapy. When the classification model was trained with data from patients on (off) and tested on patients off (on), we found 84.0% (56.6%) sensitivity, 88.3% (92.5%) specificity and 87.4% (86.3%) accuracy. Conclusions: Machine learning models are capable of predicting FOG before its actual occurrence with adequate accuracy. The dopaminergic therapy affects pre-FOG gait patterns, thereby influencing the algorithm’s effectiveness.

Defective corticomuscular connectivity during walking in patients with Parkinson's disease

Gait disturbances are common in individuals with Parkinson's disease (PD). Although the basic patterns of walking are thought to be controlled by the brainstem and spinal networks, recent studies have found significant corticomuscular coherence in healthy individuals during walking. However, it still remains unknown how PD affects the cortical control of muscles during walking. As PD typically develops in older adults, it is important to investigate the effects of both aging and PD when examining disorders in patients with PD. Here, we assessed the effects of PD and aging on corticomuscular communication during walking by investigating corticomuscular coherence. We recorded electroencephalographic and electromyographic signals in 10 individuals with PD, 9 healthy older individuals, and 15 healthy young individuals. We assessed the corticomuscular coherence between the motor cortex and two lower leg muscles, tibialis anterior (TA) and medial gastrocnemius, during walking. Older and young groups showed sharp peaks in muscle activation patterns at specific gait phases, whereas the PD group showed prolonged patterns. Smaller corticomuscular coherence was found in the PD group compared with the healthy older group in the α band (8-12 Hz) for both muscles, and in the β band (16-32 Hz) for TA. Older and young groups did not differ in the magnitude of corticomuscular coherence. Our results indicated that PD decreased the corticomuscular coherence during walking, whereas it was not affected by aging. This lower corticomuscular coherence in PD may indicate lower-than-normal corticomuscular communication, although direct or indirect communication is unknown, and may cause impaired muscle control during walking.NEW & NOTEWORTHY Mechanisms behind how Parkinson's disease (PD) affects cortical control of muscles during walking remain unclear. As PD typically develops in the elderly, investigation of aging effects is important to examine deficits regarding PD. Here, we demonstrated that PD causes weak corticomuscular synchronization during walking, but aging does not. This lower-than-normal corticomuscular communication may cause impaired muscle control during walking.

Freezing of gait: understanding the complexity of an enigmatic phenomenon

Diverse but complementary methodologies are required to uncover the complex determinants and pathophysiology of freezing of gait. To develop future therapeutic avenues, we need a deeper understanding of the disseminated functional-anatomic network and its temporally associated dynamic processes. In this targeted review, we will summarize the latest advances across multiple methodological domains including clinical phenomenology, neurogenetics, multimodal neuroimaging, neurophysiology, and neuromodulation. We found that (i) locomotor network vulnerability is established by structural damage, e.g. from neurodegeneration possibly as result from genetic variability, or to variable degree from brain lesions. This leads to an enhanced network susceptibility, where (ii) modulators can both increase or decrease the threshold to express freezing of gait. Consequent to a threshold decrease, (iii) neuronal integration failure of a multilevel brain network will occur and affect one or numerous nodes and projections of the multilevel network. Finally, (iv) an ultimate pathway might encounter failure of effective motor output and give rise to freezing of gait as clinical endpoint. In conclusion, we derive key questions from this review that challenge this pathophysiological view. We suggest that future research on these questions should lead to improved pathophysiological insight and enhanced therapeutic strategies.

Unsupervised clustering of dopamine transporter PET imaging discovers heterogeneity of parkinsonism

Parkinsonism has heterogeneous nature, showing distinctive patterns of disease progression and prognosis. We aimed to find clusters of parkinsonism based on ¹⁸F‐fluoropropyl‐carbomethoxyiodophenylnortropane (FP‐CIT) PET as a data‐driven approach to evaluate heterogenous dopaminergic neurodegeneration patterns. Two different cohorts of patients who received FP‐CIT PET were collected. A labeled cohort (n = 94) included patients with parkinsonism who underwent a clinical follow‐up of at least 3 years (mean 59.0 ± 14.6 months). An unlabeled cohort (n = 813) included all FP‐CIT PET data of a single‐center. All PET data were clustered by a dimension reduction method followed by hierarchical clustering. Four distinct clusters were defined according to the imaging patterns. When the diagnosis of the labeled cohort of 94 patients was compared with the corresponding cluster, parkinsonism patients were mostly included in two clusters, cluster “0” and “2.” Specifically, patients with progressive supranuclear palsy were significantly more included in cluster 0. The two distinct clusters showed significantly different clinical features. Furthermore, even in PD patients, two clusters showed a trend of different clinical features. We found distinctive clusters of parkinsonism based on FP‐CIT PET‐derived heterogeneous neurodegeneration patterns, which were associated with different clinical features. Our results support a biological underpinning for the heterogeneity of neurodegeneration in parkinsonism.

Freezing of Speech Single Questionnaire as a Screening Tool for Cognitive Dysfunction in Patients With Dementia With Lewy Bodies

Introduction

Freezing phenomenon is a striking feature of Parkinson's disease. However, it has never been studied in people with dementia with Lewy bodies (DLB). We designed a freezing of speech single questionnaire (FOSSQ) and investigated the frequency and association of freezing of speech (FOS) in patients with DLB and other types of dementia.

Methods

This is a retrospective analysis of data from the project of history-based artificial intelligent computerized dementia diagnostic system. We compared the frequencies of FOS among non-demented (ND) participants, patients with Alzheimer's disease (AD), vascular dementia (VaD), and DLB. Further, we explored the association factors of FOS in all the participants.

Results

We enrolled 666 individuals with the following disease distribution: 190, ND; 230, AD; 183, VaD; and 63, DLB. Compared to individuals with ND (2.1%), patients with AD (6.1%), or VaD (18.0%), DLB (54.0%) showed a significantly higher frequency of positive FOS (all p < 0.001). The association factors of FOS were older age, more severe dementia, more severe motor dysfunction, fluctuating cognition, visual hallucinations, parkinsonism, rapid eye movement sleep behavior disorder, attention, mental manipulation, and language.

Conclusion

Our study showed that the informant-based FOSSQ may be a practical screening tool for discriminating DLB from individuals with ND or other forms of dementia. The FOSSQ can be applied in clinical practice as well as on the artificial intelligent platform.

Comparison of predicted kinetic variables between Parkinson's disease patients and healthy age-matched control using a depth sensor-driven full-body musculoskeletal model

BACKGROUND

Abnormalities in gait kinetics in patients with Parkinson's disease (PD) who have suffer from gait impairment have been noted using a conventional inverse dynamic analysis derived by marker-based motion capture system and force plate, which are typically mounted in the laboratory floor. Despite the high accuracy of this approach in tracking markers' trajectories and acquiring ground reaction forces (GRFs), its dependence on laboratory-mounted equipment restricts its potential use in wider variety of clinical applications.

RESEARCH QUESTION

Would a full-body musculoskeletal model driven by a single depth sensor data only produce comparable gait kinetic parameters, including GRFs and lower extremity joints moments, for elderly participants, both healthy and those diagnosed with PD?

METHODS

Nine patients diagnosed with PD and 11 healthy age-matched control participants performed three over-ground gait trials. Full-body kinematic data were collected using a depth sensor and a musculoskeletal model have been constructed using AnyBody musculoskeletal modeling system to predict the three-dimensional GRFs and lower extremity joint moments. Predicted kinetic parameters for both PD and control groups were compared during the braking and propulsive phases of the gait cycle. In addition, ensemble curve analysis with 90% confidence intervals were constructed to compare between group differences across the stance phase of the gait cycle.

RESULTS

The findings of this study showed that the PD exhibited a significantly lower braking peak vertical GRF and propulsion peak horizontal GRF while no significant between-group differences were found in peak lower extremity joint moments. However, the PD showed significant alterations in lower extremity joint moments during the early and late phases of stance, which indicate a difference in ambulation strategy.

SIGNIFICANCE

The proposed method adopting full-body musculoskeletal model driven by a depth sensor data proves that it has the potential to be a portable and cost-effective gait analysis tool in the clinical setting.

Parkinsonism in the psychiatric setting: an update on clinical differentiation and management

Parkinsonism is seen frequently in patients with psychiatric conditions. Drug-induced parkinsonism (DIP) is the second most common cause of parkinsonism in the general population after Parkinson’s disease (PD) but a range of rarer aetiologies, some of them reversible, should also be considered in patients of all ages. DIP is more common in older patients, as are neurodegenerative diseases that may produce parkinsonism and it is relatively more likely that drug exposure could be unmasking an underlying process in this population. There is an extensive literature on differentiating DIP from PD but clinical features can be indistinguishable and many proposed investigations are not readily available. Aside from cessation of the responsible medication, there is no clear consensus on treatment strategies or duration of treatment. Practically, a delicate balance must be achieved between ameliorating parkinsonism and avoiding recurrent psychosis. Long-term prognosis in the setting of DIP remains unclear. We review the features that may differentiate DIP from other causes of parkinsonism in patients with psychiatric illness, provide an update on relevant investigations and discuss management strategies. The use of atypical antipsychotics for a broad range of indications highlights the ongoing relevance of DIP.

Relationship between Freezing of Gait and Anxiety in Parkinson's Disease Patients: A Systemic Literature Review

Freezing of gait (FOG) is experienced by a significant number of patients with Parkinson's disease (PD). The pathophysiology of this disabling motor symptom remains unclear, and there are no effective therapies. Anxiety has previously been posited as a contributing factor to gait freezing. There have been few studies directly investigating this topic, and a comprehensive literature review is lacking. The objective of this paper was to systematically review the evidence associating anxiety with the presence, severity, and progression of FOG in PD patients. The PubMed, EMBASE, and PsycINFO databases were searched up to September 19, 2018, for English-language, peer-reviewed articles that explored anxiety and FOG as outcome measures in a PD population base. Review articles, case reports, and articles that assessed gait disorders other than FOG were excluded, yielding a total of 26 articles in the final analysis. Of these 26 studies, 16 had a significant relationship between anxiety outcome measure and either presence or severity of FOG. There was great variability among studies in terms of outcome measures for both FOG and anxiety. Despite this heterogeneity, most studies relate anxiety and FOG. Standardized, high-validity outcome measures of anxiety and FOG are needed. Future exploration should aim to clarify the role of anxiety in FOG as a causal factor, pathophysiological marker, and manifestation of a common pathophysiological process versus a consequence of FOG itself. Clarifying the relationship between anxiety and FOG could reveal anxiety reduction as a therapy for FOG.

Freezing of gait and dementia in parkinsonism: A retrospective case-control study

OBJECTIVES

To support the cognitive model of Freezing of Gait (FoG) we investigated FoG in a cohort of patients with Dementia with Lewy Bodies (DLB).

MATERIALS AND METHODS

We assessed FoG frequency in 19 DLB patients compared to 19 control PD patients within 2 years from symptom onset and with at least 5 years follow-up. The two groups were matched by age and motor presentation at onset, severity of parkinsonism and disease duration. The presence and severity of FoG was identified as those with a score of 1 or greater on subitem 14 of the Unified Parkinson's Disease Rating Scale Part II  (UPDRS II).

RESULTS

At T0, 68.4% DLB and 10.5% PD patients experienced FoG ≥1. The prevalence of FoG increased with disease progression (94.7% DLB and 47.3% PD subjects had FoG ≥1 at T5). DLB also showed a more severe FoG (FoG ≥2) than PD (21% vs. 0% at T0 and 52.6% vs. 10.5% at T5), consistently with previous studies reporting FoG prevalence in DLB.

CONCLUSION

This is the first study looking specifically at FoG in DLB, identifying it as a frequent and early feature of DLB and emphasizing the crucial role of cognitive impairment in the occurrence of this mysterious phenomenon.

Gait and postural disorders in parkinsonism: a clinical approach

Disturbances of balance, gait and posture are a hallmark of parkinsonian syndromes. Recognition of these axial features can provide important and often early clues to the nature of the underlying disorder, and, therefore, help to disentangle Parkinson’s disease from vascular parkinsonism and various forms of atypical parkinsonism, including multiple system atrophy, progressive supranuclear palsy, and corticobasal syndrome. Careful assessment of axial features is also essential for initiating appropriate treatment strategies and for documenting the outcome of such interventions. In this article, we provide an overview of balance, gait and postural impairment in parkinsonian disorders, focusing on differential diagnostic aspects.

A Multi-Layer Gaussian Process for Motor Symptom Estimation in People With Parkinson's Disease

The assessment of Parkinson's disease (PD) poses a significant challenge, as it is influenced by various factors that lead to a complex and fluctuating symptom manifestation. Thus, a frequent and objective PD assessment is highly valuable for effective health management of people with Parkinson's disease (PwP). Here, we propose a method for monitoring PwP by stochastically modeling the relationships between wrist movements during unscripted daily activities and corresponding annotations about clinical displays of movement abnormalities. We approach the estimation of PD motor signs by independently modeling and hierarchically stacking Gaussian process models for three classes of commonly observed movement abnormalities in PwP including tremor, (non-tremulous) bradykinesia, and (non-tremulous) dyskinesia. We use clinically adopted severity measures as annotations for training the models, thus allowing our multi-layer Gaussian process prediction models to estimate not only their presence but also their severities. The experimental validation of our approach demonstrates strong agreement of the model predictions with these PD annotations. Our results show that the proposed method produces promising results in objective monitoring of movement abnormalities of PD in the presence of arbitrary and unknown voluntary motions, and makes an important step toward continuous monitoring of PD in the home environment.

Neuroimaging and neuropsychological assessment of freezing of gait in Parkinson's disease

Introduction

Freezing of gait (FOG) is a disabling phenomenon characterized by a brief, episodic absence or reduction of forward progression of the feet despite the intention to walk. It is a common cause of falls and mortality in cases with Parkinson's disease (PD). This article reviews neuropsychological and neuroimaging studies to date and introduces a new study of multimodal imaging and cognition in PD-FOG.

Methods

A comprehensive literature search identified studies using neuropsychological evaluation and/or neuroimaging to evaluate PD-FOG.

Results

Several studies have evaluated PD-FOG, but few have combined neuropsychological and comprehensive neuroimaging and none longitudinally.

Discussion

A study using a combined approach longitudinally evaluating cognitive dysfunction and underlying neural networks in FOG is needed. We introduce the framework of a study which demonstrates the use of establishing an infrastructure for studying neurodegenerative disorders using the National Institutes of Health/National Institute of General Medical Science Center of Biomedical Research Excellence grant mechanism.

Neuromodulation targets pathological not physiological beta bursts during gait in Parkinson's disease

Freezing of gait (FOG) is a devastating axial motor symptom in Parkinson's disease (PD) leading to falls, institutionalization, and even death. The response of FOG to dopaminergic medication and deep brain stimulation (DBS) is complex, variable, and yet to be optimized. Fundamental gaps in the knowledge of the underlying neurobiomechanical mechanisms of FOG render this symptom one of the unsolved challenges in the treatment of PD. Subcortical neural mechanisms of gait impairment and FOG in PD are largely unknown due to the challenge of accessing deep brain circuitry and measuring neural signals in real time in freely-moving subjects. Additionally, there is a lack of gait tasks that reliably elicit FOG. Since FOG is episodic, we hypothesized that dynamic features of subthalamic (STN) beta oscillations, or beta bursts, may contribute to the Freezer phenotype in PD during gait tasks that elicit FOG. We also investigated whether STN DBS at 60 Hz or 140 Hz affected beta burst dynamics and gait impairment differently in Freezers and Non-Freezers. Synchronized STN local field potentials, from an implanted, sensing neurostimulator (Activa® PC + S, Medtronic, Inc.), and gait kinematics were recorded in 12 PD subjects, off-medication during forward walking and stepping-in-place tasks under the following randomly presented conditions: NO, 60 Hz, and 140 Hz DBS. Prolonged movement band beta burst durations differentiated Freezers from Non-Freezers, were a pathological neural feature of FOG and were shortened during DBS which improved gait. Normal gait parameters, accompanied by shorter bursts in Non-Freezers, were unchanged during DBS. The difference between the mean burst duration between hemispheres (STNs) of all individuals strongly correlated with the difference in stride time between their legs but there was no correlation between mean burst duration of each STN and stride time of the contralateral leg, suggesting an interaction between hemispheres influences gait. These results suggest that prolonged STN beta burst durations measured during gait is an important biomarker for FOG and that STN DBS modulated long not short burst durations, thereby acting to restore physiological sensorimotor information processing, while improving gait.

Quantitative Analysis of Relationship Between Hypokinetic Dysarthria and the Freezing of Gait in Parkinson's Disease

Hypokinetic dysarthria (HD) and freezing of gait (FOG) are both axial symptoms that occur in patients with Parkinson's disease (PD). It is assumed they have some common pathophysiological mechanisms and therefore that speech disorders in PD can predict FOG deficits within the horizon of some years. The aim of this study is to employ a complex quantitative analysis of the phonation, articulation and prosody in PD patients in order to identify the relationship between HD and FOG, and establish a mathematical model that would predict FOG deficits using acoustic analysis at baseline. We enrolled 75 PD patients who were assessed by 6 clinical scales including the Freezing of Gait Questionnaire (FOG-Q). We subsequently extracted 19 acoustic measures quantifying speech disorders in the fields of phonation, articulation and prosody. To identify the relationship between HD and FOG, we performed a partial correlation analysis. Finally, based on the selected acoustic measures, we trained regression models to predict the change in FOG during a 2-year follow-up. We identified significant correlations between FOG-Q scores and the acoustic measures based on formant frequencies (quantifying the movement of the tongue and jaw) and speech rate. Using the regression models, we were able to predict a change in particular FOG-Q scores with an error of between 7.4 and 17.0 %. This study is suggesting that FOG in patients with PD is mainly linked to improper articulation, a disturbed speech rate and to intelligibility. We have also proved that the acoustic analysis of HD at the baseline can be used as a predictor of the FOG deficit during 2 years of follow-up. This knowledge enables researchers to introduce new cognitive systems that predict gait difficulties in PD patients.

Movement Disorders Associated With Antipsychotic Medication in People With Schizophrenia: An Overview of Cochrane Reviews and Meta-Analysis

Movement disorders associated with antipsychotic medications are relatively common, stigmatising, and potentially disabling. Their prevalence in people with psychosis who are prescribed second-generation antipsychotics (SGAs) is uncertain, as is their level of recognition by clinicinas. We conducted meta-analyses of randomised controlled trials included in the Cochrane Database of Systematic Reviews on schizophrenia and schizophrenia-like psychoses to estimate the prevalence of new-onset dystonia, akathisia, parkinsonism, and tremor with SGAs (amisulpride, asenapine, aripiprazole, clozapine, olanzapine, paliperidone, quetiapine, risperidone, L-sulpiride, and ziprasidone) approved in Canada and the UK, comparing them with haloperidol and chlorpromazine. We used a random effects model because of the heterogeneity between-studies in drug dosage and method of ascertainment of movement disorders. Our systematic search yielded 37 Cochrane systematic reviews (28 for SGAs), which generated 316 informative randomised controlled trials (243 for SGAs). With respect to SGAs, prevalence estimates ranged from 1.4% (quetiapine) to 15.3% (L-sulpiride) for dystonia, 3.3% (paliperidone) to 16.4% (L-sulpiride) for akathisia, 2.4% (asenapine) to 29.3% (L-sulpiride) for parkinsonism, and 0.2% (clozapine) to 28.2% (L-sulpiride) for tremor. Prevalence estimates were not influenced by treatment duration, the use of a flexible or fixed dosing scheme, or whether studies used validated instruments for the screening/rating of movement disorders. Overall, we found high overlap on the prevalence of new-onset movement disorders across different SGAs precribed for established psychoses. Variations in prevalence figures across antipsychotic medications were observed for the different movement disorders. Differences in pharmacological properties, such as for the dopamine D2 R association rate and serotonin 5-HT2A antagonism, could contribute to this variation.

Effects of intestinal Levodopa infusion on freezing of gait in Parkinson disease

OBJECTIVE

To determine the impact of levodopa-carbidopa intestinal gel (LCIG) infusion on different subtypes of freezing of gait (FoG) classified according to levodopa responsiveness in advanced Parkinson disease (PD) patients.

METHODS

We retrospectively assessed the presence and severity of FoG in 32 advanced PD patients based on the Unified PD Rating Scale (UPDRS) item 14 score. Different FoG subtypes were inferred from the score variation with oral dopaminergic medications. Modifications following long-term LCIG infusion were analysed. Motor symptoms and motor complications were assessed by UPDRS part III and IV respectively.

RESULTS

FoG related UPDRS score varied from 2.6±0.9 in OFF condition to 0.9±0.8 in the ON condition at baseline and improved to 0.6±0.7 with LCIG infusion (p=0.027). After a mean of 2.59±1.12years of continuous LCIG infusion, Pseudo-ON-FoG improved to a greater extent with LCIG infusion than with oral therapy in 12 patients (38%) and equally well in 8 patients (25%), OFF-type-FoG was controlled equally well in 8 patients (25%) and worsened slightly in 3 patients (9%). Unresponsive-FoG, present in one patient (3%), was unmodified by LCIG infusion.

CONCLUSIONS

Even though limited by the subjective simple measure of FoG, this study suggests that patients undergoing LCIG infusion maintain a good long-term control of FoG. Pseudo-on-FoG improves in a considerable percentage of patients and OFF-type-FoG remains well controlled with LCIG infusion. Further studies with a larger number of patients and objective measures of FoG are needed to confirm these findings.

Parkinson's Disease Subtypes Show Distinct Tradeoffs Between Response Initiation and Inhibition Latencies

OBJECTIVES

In unpredictable situations, individuals often show tradeoffs between response initiation and inhibition speeds. We tested the hypothesis that Parkinson's disease (PD) motor subtypes differentially impact tradeoffs between these two action-oriented processes. We predicted that, compared to tremor dominant (TD) patients, predominant postural instability and gait dysfunction (PIGD) patients would show exacerbated tradeoffs between response initiation and inhibition in situations requiring the sudden potential need to interrupt an action.

METHODS

Fifty-one PD patients (subdivided into PIGD [n=27] and TD [n=24]) and 21 healthy controls (HCs) completed a choice reaction task to establish baseline response initiation speed between groups. Subsequently, participants completed a stop-signal task which introduced an occasional, unpredictable stop stimulus. We measured changes in initiation speed in preparation of an unpredictable stop (i.e., proactive slowing) and inhibition latency (i.e., stop-signal reaction time).

RESULTS

Compared to HCs, PD patients showed slower response initiation speeds in the choice reaction task. All groups showed proactive slowing in the stop-signal task but the magnitude was considerably larger in PIGD patients, almost twice as large as TD patients. PD patients, irrespective of motor subtype, showed longer inhibition latencies than HCs.

CONCLUSIONS

PIGD and TD subtypes both showed exacerbated response inhibition deficits. However, PIGD patients showed much more pronounced proactive slowing in situations with an expected yet unpredictable need to stop action abruptly. This suggests that PIGD is accompanied by exaggerated tradeoffs between response initiation and inhibition processes to meet situational action demands. We discuss putative neural mechanisms and clinical implications of these findings. (JINS, 2017, 23, 665-674).

Spatial constraints evoke increased number of steps during turning in Parkinson's disease

OBJECTIVE

Turning and limitations to step length were shown to trigger progressive shortening of steps, which can lead to freezing of gait. By reducing the base area in which the turn had to take place, we aimed to evaluate the contribution of spatial constraints on 360° axial turns in people with Parkinson's disease with and without freezing.

METHODS

We evaluated 40 patients with and without freezing and 16 age-matched healthy subjects. We assessed clinical data, and used body-worn inertial sensors to describe stepping and turn duration of 360° in quadratic squares of different sizes marked on the floor.

RESULTS

We found that, when subjects had to perform turns in smaller as compared to larger squares, this spatial constraint strongly affected the turning behavior, i.e. increased the number of steps, and the duration of turns. However, turning was significantly more impaired in patients as compared to controls, and patients with freezing were significantly worse as patients without freezing.

CONCLUSION

Our data show that spatial constraint during axial turning has the potential to deteriorate stepping performance, especially in patients reporting freezing of gait.

SIGNIFICANCE

The size of the base area needs to be defined in any item or scale that makes diagnostic use of turning.

Contribution of the supplementary motor area and the cerebellum to the anticipatory postural adjustments and execution phases of human gait initiation

Several brain structures including the brainstem, the cerebellum and the frontal cortico-basal ganglia network, with the primary and premotor areas have been shown to participate in the functional organization of gait initiation and postural control in humans, but their respective roles remain poorly understood. The aim of this study was to better understand the role of the supplementary motor area (SMA) and posterior cerebellum in the gait initiation process. Gait initiation parameters were recorded in 22 controls both before and after continuous theta burst transcranial stimulation (cTBS) of the SMA and cerebellum, and were compared to sham stimulation, using a randomized double-blind design study. The two phases of gait initiation process were analyzed: anticipatory postural adjustments (APAs) and execution, with recordings of soleus and tibialis anterior muscles. Functional inhibition of the SMA led to a shortened APA phase duration with advanced and increased muscle activity; during execution, it also advanced muscle co-activation and decreased the duration of stance soleus activity. Cerebellar functional inhibition did not influence the APA phase duration and amplitude but increased muscle co-activation, it decreased execution duration and showed a trend to increase velocity, with increased swing soleus muscle duration and activity. The results suggest that the SMA contributes to both the timing and amplitude of the APAs with no influence on step execution and the posterior cerebellum in the coupling between the APAs and execution phases and leg muscle activity pattern during gait initiation.

Complexity Analysis of Electroencephalogram Dynamics in Patients with Parkinson's Disease

In this study, a new combination scheme has been proposed for detecting Parkinson's disease (PD) from electroencephalogram (EEG) signal recorded from normal subjects and PD patients. The scheme is based on discrete wavelet transform (DWT), sample entropy (SampEn), and the three-way decision model in analysis of EEG signal. The EEG signal is noisy and nonstationary, and, as a consequence, it becomes difficult to distinguish it visually. However, the scheme is a well-established methodology in analysis of EEG signal in three stages. In the first stage, the DWT was applied to acquire the split frequency information; here, we use three-level DWT to decompose EEG signal into approximation and detail coefficients; in this stage, we aim to remove the useless and noise information and acquire the effective information. In the second stage, as the SampEn has advantage in analyzing the EEG signal, we use the approximation coefficient to compute the SampEn values. Finally, we detect the PD patients using three-way decision based on optimal center constructive covering algorithm (O_CCA) with the accuracy about 92.86%. Without DWT as preprocessing step, the detection rate reduces to 88.10%. Overall, the combination scheme we proposed is suitable and efficient in analyzing the EEG signal with higher accuracy.

Freezing of Gait in Parkinson's Disease: Its Pathophysiology and Pragmatic Approaches to Management

Background

Freezing of gait (FOG) in Parkinson's disease (PD) is poorly understood; however, with the established understanding of basal ganglia function, its manifestations should be more easily interpretable. This review examines freezing of gait (FOG) from such a perspective.

Methods

A search of the MEDLINE and EMBASE databases from the year 2000 onward for review articles, focused on the pathophysiology of FOG, was used to determine current concepts. A previously established model of basal ganglia function was used to determine the concepts' validities. At the core of the model are deficits in motor set maintenance and timing cue production for automatic movement. It includes the shift between attention and automation to the predominant attention control of gait in PD.

Results

The difficulties of the found concepts to explain FOG stem from failure to characterize different FOG components, from the assumption that all components share a similar pathophysiology, from a failure to separate basic deficits from compensatory mechanisms, and from the assumption that cognitive deficits are the cause of FOG rather than representing an inadequate compensation to FOG. Pragmatic approaches to management use the attention shift, with the provision of visual information about correct amplitude of step to correct initiation deficits, and motor blocks during gait. It also emphasizes the need to prevent step length reduction on turns, environmental situations, and cognitive overload.

Conclusion

The concept of automatic deficits in set maintenance and cue production best describe FOG manifestations in PD and, with the use of attention, the concept also provides pragmatic strategies for management.

Freezing of gait in Parkinson's disease: from pathophysiology to emerging therapies

Freezing of gait (FOG) is 'an episodic inability to generate effective stepping in the absence of any known cause other than parkinsonism or high level gait disorders'. FOG is one of the most disabling symptoms in Parkinson's disease, especially in its more advanced stages. Early recognition is important as FOG is related to higher fall risk and poorer prognosis. Although specific treatments are still elusive, there have been recent advances in the development of new therapeutic approaches. The aim of this review is to present the latest knowledge regarding the phenomenology, pathogenesis, diagnostic assessment and conventional treatment of FOG in Parkinson's disease. A review of the evidence supporting noninvasive brain stimulation will follow to highlight the potential of these strategies.

Cognitive Contributions to Freezing of Gait in Parkinson Disease: Implications for Physical Rehabilitation

People with Parkinson disease (PD) who show freezing of gait also have dysfunction in cognitive domains that interact with mobility. Specifically, freezing of gait is associated with executive dysfunction involving response inhibition, divided attention or switching attention, and visuospatial function. The neural control impairments leading to freezing of gait have recently been attributed to higher-level, executive and attentional cortical processes involved in coordinating posture and gait rather than to lower-level, sensorimotor impairments. To date, rehabilitation for freezing of gait primarily has focused on compensatory mobility training to overcome freezing events, such as sensory cueing and voluntary step planning. Recently, a few interventions have focused on restitutive, rather than compensatory, therapy. Given the documented impairments in executive function specific to patients with PD who freeze and increasing evidence of overlap between cognitive and motor function, incorporating cognitive challenges with mobility training may have important benefits for patients with freezing of gait. Thus, a novel theoretical framework is proposed for exercise interventions that jointly address both the specific cognitive and mobility challenges of people with PD who freeze.

Freezing of gait in early Parkinson's disease: Nigral iron content estimated from magnetic resonance imaging

PURPOSE

Freezing of gait is a major source of disability associated with the progression of Parkinson's disease (PD). Our objective was to determine whether evolving changes in nigral iron content in association with declining motor function in early PD differentiates subjects who develop freezing from those who do not.

METHODS

A cohort of previously untreated individuals with early PD (n=19) was followed for 36 months clinically and with MRI. The cohort was divided into two groups based on the development of freezing during follow-up. A multiple gradient echo MRI sequence provided an index of basal ganglia iron content.

RESULTS

There were significant baseline differences between those who developed freezing (n=7) and those who did not (n=12) in Unified Parkinson's Disease Rating Scale motor scores, time to complete a 14 m walk and timed up and go. There was a significant correlation between the measured change in transverse relaxation in the lateral substantia nigra pars compacta and the change in motor score from baseline to 36 months (p=0.002). The freezing group showed a greater change in motor score and iron content than did the non-freezing group.

CONCLUSIONS

Individuals destined to develop freezing early in PD have more motor impairment at baseline, more rapid deterioration in motor function, and pars compacta changes suggestive of increased iron content in comparison to those who do not.

Generalized motor inhibitory deficit in Parkinson's disease patients who freeze

Freezing of gait is a disabling symptom of Parkinson's disease (PD) that involves failure to initiate and continue motor activity appropriately. PD disrupts fronto-basal ganglia circuitries that also implement the inhibition of responses, leading to the hypothesis that freezing of gait may involve fundamental changes in both initiation and inhibition of motor actions. We asked whether PD patients who show freezing of gait show selective deficits in their ability to inhibit upper and lower extremity reactions. We compared older healthy controls, older PD controls without freezing of gait, and older PD participants with freezing of gait, in stop-signal tasks that measured the initiation (go trials) and inhibition (stop trials) of both hand and foot responses. When only go trials were presented, all three groups showed similar initiation speeds across lower and upper extremity responses. When stop-signal trials were introduced, both PD groups slowed their reactions nearly twice as much as healthy controls. While this adjustment helped PD controls stop their actions as quickly as healthy controls, PD patients with freezing showed significantly delayed inhibitory control of both upper and lower extremities. When anticipating the need to stop their actions urgently, PD patients show greater adjustments (i.e., slowing) to reaction speed than healthy controls. Despite these proactive adjustments, PD patients who freeze show marked impairments in inhibiting both upper and lower extremity responses, suggesting that freezing may involve a fundamental disruption to the brain's inhibitory control system.