Movement disorders induced by deep brain stimulation

Neuromodulation technologies improve functional recovery after brain injury: From bench to bedside

Spontaneous recovery frequently proves maladaptive or insufficient because the plasticity of the injured adult mammalian central nervous system is limited. This limited plasticity serves as a primary barrier to functional recovery after brain injury. Neuromodulation technologies represent one of the fastest-growing fields in medicine. These techniques utilize electricity, magnetism, sound, and light to restore or optimize brain functions by promoting reorganization or long-term changes that support functional recovery in patients with brain injury. Therefore, this review aims to provide a comprehensive overview of the effects and underlying mechanisms of neuromodulation technologies in supporting motor function recovery after brain injury. Many of these technologies are widely used in clinical practice and show significant improvements in motor function across various types of brain injury. However, studies report negative findings, potentially due to variations in stimulation protocols, differences in observation periods, and the severity of functional impairments among participants across different clinical trials. Additionally, we observed that different neuromodulation techniques share remarkably similar mechanisms, including promoting neuroplasticity, enhancing neurotrophic factor release, improving cerebral blood flow, suppressing neuroinflammation, and providing neuroprotection. Finally, considering the advantages and disadvantages of various neuromodulation techniques, we propose that future development should focus on closed-loop neural circuit stimulation, personalized treatment, interdisciplinary collaboration, and precision stimulation.

Will adaptive deep brain stimulation for Parkinson's disease become a real option soon? A Delphi consensus study

While conventional deep brain stimulation (cDBS) treatment delivers continuous electrical stimuli, new adaptive DBS (aDBS) technology provides dynamic symptom-related stimulation. Research data are promising, and devices are already available, but are we ready for it? We asked leading DBS experts worldwide (n = 21) to discuss a research agenda for aDBS research in the near future to allow full adoption. A 5-point Likert scale questionnaire, along with a Delphi method, was employed. In the next 10 years, aDBS will be clinical routine, but research is needed to define which patients would benefit more from the treatment; second, implantation and programming procedures should be simplified to allow actual generalized adoption; third, new adaptive algorithms, and the integration of aDBS paradigm with new technologies, will improve control of more complex symptoms. Since the next years will be crucial for aDBS implementation, the research should focus on improving precision and making programming procedures more accessible.

Stimulation-Induced Dyskinesia in STN DBS Patients

BACKGROUND

Stimulation-induced dyskinesia (SID) is a poorly studied and usually transient manifestation of subthalamic deep brain stimulation (STN DBS) for Parkinson's disease (PD), which can be troubling for patients.

OBJECTIVES

The aim of our study was to describe the features and management of SID in PD patients undergoing STN DBS.

METHODS

We conducted a retrospective study among 86 STN DBS patients. Clinical features and volume of tissue activated (VTA) were correlated to SID occurrence.

RESULTS

SID was identified in 28 (32.6%) patients and persisted for 6 months in six patients (7.0%). VTA overlap with the right motor STN was associated (P < 0.02) with SID. Weaning dopaminergic drugs and reducing the DBS amplitude were the most used strategies to control SID.

CONCLUSIONS

SID is a relatively common complication of STN DBS and can be persistent. It often requires specific postoperative management strategies.

Gait and balance worsening after bilateral deep brain stimulation of the subthalamic nucleus (STN-DBS) for Parkinson's disease: a systematic review

Background

Deep brain stimulation of the subthalamic nucleus (STN-DBS) is a widely applied therapy in Parkinson's disease (PD). Occasionally, postoperative worsening of gait or balance occurs, even in the face of a persistently gratifying appendicular symptom improvement. The characteristics vary considerably, and the risk factors for this postoperative gait or balance worsening are largely unknown. We systematically investigated the literature for all cases of gait or balance worsening after STN-DBS in PD and explored its characteristics and determinants. In consecutive populations with best medical treatment as the control group, we also explored its incidence.

Methods

We searched PubMed, Embase and Cochrane. We considered all cases occurring between 1 month after surgery (to exclude immediate postoperative complications as most likely cause) and 12 months after surgery (to exclude disease progression).

Results

From 2719 entries, we included 20 studies (n=1010 operated patients). Freezing of gait and falls were the most commonly reported symptoms. The first worsening of symptoms occurred between 3 and 6 months after surgery. Modulation of pedunculopontine afferents was more likely associated with worsening of gait and balance. In controlled trials with consecutive patients, 24 cases (15.9%) were reported, compared with 5.8% with best medical treatment (p=0.0013).

Conclusions

Gait or balance worsening after STN-DBS is a complex phenomenon that cannot readily be explained by mere disease progression. The multifactorial nature warrants further study in gait labs and through advanced imaging techniques. Future studies should also estimate the actual incidence, which we could not establish as we excluded cohorts without any reported cases.

Deep Brain Stimulation in Parkinson Disease: A Switch for On/Off Dystonia

BACKGROUND

Dystonia is common in Parkinson disease patients, affecting about 30% of them. Bilateral subthalamic nucleus deep brain stimulation (DBS) can sometimes lead to dystonia, but this relationship is not well understood. Our aim was to provide a better understanding of dystonia's causes and its connection to DBS.

METHODS

We conducted a retrospective analysis of clinical data from 80 Parkinson disease patients who underwent bilateral subthalamic nucleus stimulation, focusing on dystonia before and after surgery and its relation to medication state (on-dystonia/off-dystonia).

RESULTS

After DBS, off-dystonia had a higher recovery rate than on-dystonia (43.5% vs. 9.1%). Among patients suffering for on-dystonia, 74.4% had it for the first time after surgery; these patients assumed higher doses of levodopa before DBS.

CONCLUSIONS

Patients with off-dystonia before surgery tend to improve after DBS. Otherwise, DBS could have the role of "additive boost" in the process of sensitization of striato-pallidal pathways and lead to on-dystonia in particular patients.

Blepharospasm Secondary to Deep Brain Stimulation of the Subthalamic Nucleus in Parkinson Disease: Clinical Characteristics and Management Outcomes

BACKGROUND

Deep brain stimulation of the subthalamic nucleus (STN-DBS) is an effective treatment for patients with motor symptoms of Parkinson disease but can be complicated by disabling blepharospasm and apraxia of eyelid opening (ALO). Currently, there is no clear consensus on optimal management, and addressing these issues is further hindered by systemic morbidity and resistance to treatments. We aim to describe the different phenotypes of these eyelid movement disorders, to report our management approach and patient responses to treatment.

METHODS

A retrospective case series of all patients with blepharospasm/ALO secondary to STN-DBS that were treated at a tertiary center between 2011 and 2020. Data collected included date of Parkinson diagnosis, date of DBS surgery, date of development of blepharospasm/ALO symptoms, STN-DBS stimulation settings, and treatment given. Patients' symptoms before and after treatment were measured using the blepharospasm disability index and Jankovic Rating Scale.

RESULTS

Five patients were identified with eyelid movement disorders secondary to STN-DBS. All patients had moderate-to-severe symptoms at presentation. Four patients received periocular botulinum toxin injections. Three patients underwent surgery in the form of frontalis suspension or direct brow lift with or without upper lid blepharoplasty. All reported an improvement in symptoms following treatment.

CONCLUSIONS

A multimodality, patient-specific approach is required in the treatment of blepharospasm/ALO secondary to STN-DBS. Botulinum toxin injections can be effective, but patients may require surgery if toxin treatment alone becomes ineffective. Tailoring treatment to individual needs can result in a measurable improvement in symptoms.

Adaptive Deep Brain Stimulation in Parkinson's Disease: A Delphi Consensus Study

Importance

If history teaches, as cardiac pacing moved from fixed-rate to on-demand delivery in in 80s of the last century, there are high probabilities that closed-loop and adaptive approaches will become, in the next decade, the natural evolution of conventional Deep Brain Stimulation (cDBS). However, while devices for aDBS are already available for clinical use, few data on their clinical application and technological limitations are available so far. In such scenario, gathering the opinion and expertise of leading investigators worldwide would boost and guide practice and research, thus grounding the clinical development of aDBS.

Observations

We identified clinical and academically experienced DBS clinicians (n=21) to discuss the challenges related to aDBS. A 5-point Likert scale questionnaire along with a Delphi method was employed. 42 questions were submitted to the panel, half of them being related to technical aspects while the other half to clinical aspects of aDBS. Experts agreed that aDBS will become clinical practice in 10 years. In the present scenario, although the panel agreed that aDBS applications require skilled clinicians and that algorithms need to be further optimized to manage complex PD symptoms, consensus was reached on aDBS safety and its ability to provide a faster and more stable treatment response than cDBS, also for tremor-dominant Parkinson's disease patients and for those with motor fluctuations and dyskinesias.

Conclusions and Relevance

Despite the need of further research, the panel concluded that aDBS is safe, promises to be maximally effective in PD patients with motor fluctuation and dyskinesias and therefore will enter into the clinical practice in the next years, with further research focused on algorithms and markers for complex symptoms.

Perspectives on adaptive dynamical systems

Adaptivity is a dynamical feature that is omnipresent in nature, socio-economics, and technology. For example, adaptive couplings appear in various real-world systems, such as the power grid, social, and neural networks, and they form the backbone of closed-loop control strategies and machine learning algorithms. In this article, we provide an interdisciplinary perspective on adaptive systems. We reflect on the notion and terminology of adaptivity in different disciplines and discuss which role adaptivity plays for various fields. We highlight common open challenges and give perspectives on future research directions, looking to inspire interdisciplinary approaches.

Deep brain stimulation - New programming algorithms and teleprogramming

INTRODUCTION

Thanks to a variety of factors, the field of neuromodulation has evolved significantly over the past decade. Developments include new indications and innovations of hardware, software, and stimulation techniques leading to an expansion in scope and role of these techniques as powerful therapies. They also imply the realization that practical application involves new nuances that make patient selection, surgical technique and the programming process even more complex, requiring continuous education and an organized structured approach.

AREAS COVERED

In this review, the authors explore the developments in deep brain stimulation technology, including electrodes, implantable pulse generators, contact configurations (i.e, directional leads and independent current control), remote programming and sensing using local field potentials.

EXPERT OPINION

The innovations in the field of deep brain stimulation discussed in this review potentially provide increased effectiveness and flexibility not only to improve therapeutic response but also to address troubleshooting challenges seen in clinical practice. Directional leads and shorter pulse widths may broaden the therapeutic window of stimulation, avoiding current spread to structures that might trigger stimulation-related side effects. Similarly, independent control of current to individual contacts allows for the shaping of the electric field. Finally, sensing and remote programming represent important developments for more effective and individualized patient care.

Deep Brain Stimulation: When to Test Directional?

Background

Directional deep brain stimulation (DBS) allows for steering of the stimulation field, but extensive and time-consuming testing of all segmented contacts is necessary to identify the possible benefit of steering. It is therefore important to determine under which circumstances directional current steering is advantageous.

Methods

Fifty two Parkinson's disease patients implanted in the STN with a directional DBS system underwent a standardized monopolar programming session 5 to 9 months after implantation. Individual contacts were tested for a potential advantage of directional stimulation. Results were used to build a prediction model for the selection of ring levels that would benefit from directional stimulation.

Results

On average, there was no significant difference in therapeutic window between ring-level contact and best directional contact. However, according to our standardized protocol, 35% of the contacts and 66% of patients had a larger therapeutic window under directional stimulation compared to ring-mode. The segmented contacts warranting directional current steering could be predicted with a sensitivity of 79% and a specificity of 57%.

Conclusion

To reduce time required for DBS programming, we recommend additional directional contact testing initially only on ring-level contacts with a therapeutic window of less than 2.0 mA.

Efficacy of short pulse and conventional deep brain stimulation in Parkinson's disease: a systematic review and meta-analysis

BACKGROUND

Deep brain stimulation (DBS) is a common treatment for Parkinson's disease. However, the clinical efficacy of short pulse width DBS (spDBS) compared with conventional DBS (cDBS) is still unknown.

OBJECTIVE

This meta-analysis investigated the effectiveness of spDBS versus cDBS in patients with PD.

METHODS

Four databases (PubMed, Cochrane, Web of Science, and Embase) were independently searched until October 2021 by two reviewers. We utilized the following scales and items: therapeutic windows (TW), efficacy threshold, side effect threshold, Movement Disorder Society-Sponsored Revision Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part III off-medication score, Speech Intelligence Test (SIT), and Freezing of Gait Questionnaire (FOG-Q).

RESULTS

The analysis included seven studies with a total of 87 patients. The results indicated that spDBS significantly widened the therapeutic windows (0.99, 95% CI = 0.61 to 1.38) while increasing the threshold amplitudes of side effects (2.25, 95% CI = 1.69 to 2.81) and threshold amplitudes of effects (1.60, 95% CI = 0.84 to 2.36). There was no statistically significant difference in UPDRS part III, SIT, and FOG-Q scores between spDBS and cDBS groups, suggesting that treatment with both cDBS and spDBS may result in similar effects of improved dysarthria and gait disorders.

CONCLUSIONS

Compared with cDBS, spDBS is effective in expanding TW. Both types of deep brain stimulation resulted in improved gait disorders and speech intelligibility.

Directional Deep Brain Stimulation-A Step in the Right Direction? A Systematic Review of the Clinical and Therapeutic Efficacy of Directional Deep Brain Stimulation in Parkinson Disease

BACKGROUND

The use of directional deep brain stimulation (dDBS) electrodes for the treatment of movement disorders such as Parkinson disease (PD) has become relatively widespread. However, the efficacy of dDBS relative to its omnidirectional deep brain stimulation (oDBS) counterpart is not well characterized. This systematic review aims to synthesize the literature comparing clinical and therapeutic outcomes of dDBS relative to oDBS in patients with PD.

METHODS

A systematic literature search for studies with comparative clinical outcome data between dDBS and oDBS was performed across the PubMed, Ovid MEDLINE, and Web of Science databases. Data including therapeutic window (TW) and surrogate measures and the Unified Parkinson's Disease Rating Scale score were collected and summarized across multiple time periods.

RESULTS

Ten studies met the eligibility criteria. Three of these studies evaluated motor performance in the form of Unified Parkinson's Disease Rating Scale III, with none finding differences between dDBS and oDBS. Two studies assessed quality-of-life measures with neither finding differences between dDBS and oDBS. TW or a surrogate measure was assessed in 6 studies; 5 studies found an increase or strong trend toward increase in dDBS relative to oDBS.

CONCLUSIONS

The current evidence, although limited by bias, does suggest that dDBS in the treatment of PD yields improvements in motor symptoms and quality of life that are comparable to oDBS; TW and surrogate measures are consistently improved in patients with PD under a directional configuration relative to omnidirectional.

Decoupling of interacting neuronal populations by time-shifted stimulation through spike-timing-dependent plasticity

The synaptic organization of the brain is constantly modified by activity-dependent synaptic plasticity. In several neurological disorders, abnormal neuronal activity and pathological synaptic connectivity may significantly impair normal brain function. Reorganization of neuronal circuits by therapeutic stimulation has the potential to restore normal brain dynamics. Increasing evidence suggests that the temporal stimulation pattern crucially determines the long-lasting therapeutic effects of stimulation. Here, we tested whether a specific pattern of brain stimulation can enable the suppression of pathologically strong inter-population synaptic connectivity through spike-timing-dependent plasticity (STDP). More specifically, we tested how introducing a time shift between stimuli delivered to two interacting populations of neurons can effectively decouple them. To that end, we first used a tractable model, i.e., two bidirectionally coupled leaky integrate-and-fire (LIF) neurons, to theoretically analyze the optimal range of stimulation frequency and time shift for decoupling. We then extended our results to two reciprocally connected neuronal populations (modules) where inter-population delayed connections were modified by STDP. As predicted by the theoretical results, appropriately time-shifted stimulation causes a decoupling of the two-module system through STDP, i.e., by unlearning pathologically strong synaptic interactions between the two populations. Based on the overall topology of the connections, the decoupling of the two modules, in turn, causes a desynchronization of the populations that outlasts the cessation of stimulation. Decoupling effects of the time-shifted stimulation can be realized by time-shifted burst stimulation as well as time-shifted continuous simulation. Our results provide insight into the further optimization of a variety of multichannel stimulation protocols aiming at a therapeutic reshaping of diseased brain networks.

Efficient suppression of parkinsonian beta oscillations in a closed-loop model of deep brain stimulation with amplitude modulation

Introduction

Parkinson's disease (PD) is a movement disorder characterized by the pathological beta band (15-30 Hz) neural oscillations within the basal ganglia (BG). It is shown that the suppression of abnormal beta oscillations is correlated with the improvement of PD motor symptoms, which is a goal of standard therapies including deep brain stimulation (DBS). To overcome the stimulation-induced side effects and inefficiencies of conventional DBS (cDBS) and to reduce the administered stimulation current, closed-loop adaptive DBS (aDBS) techniques were developed. In this method, the frequency and/or amplitude of stimulation are modulated based on various disease biomarkers.

Methods

Here, by computational modeling of a cortico-BG-thalamic network in normal and PD conditions, we show that closed-loop aDBS of the subthalamic nucleus (STN) with amplitude modulation leads to a more effective suppression of pathological beta oscillations within the parkinsonian BG.

Results

Our results show that beta band neural oscillations are restored to their normal range and the reliability of the response of the thalamic neurons to motor cortex commands is retained due to aDBS with amplitude modulation. Furthermore, notably less stimulation current is administered during aDBS compared with cDBS due to a closed-loop control of stimulation amplitude based on the STN local field potential (LFP) beta activity.

Discussion

Efficient models of closed-loop stimulation may contribute to the clinical development of optimized aDBS techniques designed to reduce potential stimulation-induced side effects of cDBS in PD patients while leading to a better therapeutic outcome.

Movement Disorders Associated With Radiotherapy and Surgical Procedures

Occasionally, movement disorders can occur following interventional procedures including but not limited to radiotherapy, dental procedures, and cardiac, cerebral and spinal surgeries. The majority of these disorders tend to be unexpected sequelae with variable phenomenology and latency, and they can often be far more disabling than the primary disease for which the procedure was performed. Owing to poor knowledge and awareness of the problem, delays in diagnosing the condition are common, as are misdiagnoses as functional movement disorders. This narrative review discusses the phenomenology, pathophysiology, and potential treatments of various movement disorders caused by interventional procedures such as radiotherapy and neurological and non-neurological surgeries and procedures.

Optimal Contact Position of Subthalamic Nucleus Deep Brain Stimulation for Reducing Restless Legs Syndrome in Parkinson's Disease Patients: One-Year Follow-Up with 33 Patients

Objectives: To determine the short- and medium-term therapeutic effects of subthalamic nucleus (STN) deep brain stimulation (DBS) on restless legs syndrome (RLS) in patients with Parkinson’s disease (PD) and to study the optimal position of activated contacts for RLS symptoms. Methods: We preoperatively and postoperatively assessed PD Patients with RLS undergoing STN-DBS. Additionally, we recorded the stimulation parameters that induced RLS or relieved RLS symptoms during a follow-up. Finally, we reconstructed the activated contacts’ position that reduced or induced RLS symptoms. Results: 363 PD patients were enrolled. At the 1-year follow-up, we found that the IRLS sum significantly decreased in the RLS group (preoperative 18.758 ± 7.706, postoperative 8.121 ± 7.083, p < 0.05). The results of the CGI score, MOS sleep, and RLS QLQ all showed that the STN-DBS improved RLS symptoms after one year. Furthermore, the activated contacts that relieved RLS were mainly located in the central sensorimotor region of the STN. Activated contacts in the inferior sensorimotor part of the STN or in the substantia nigra might have induced RLS symptoms. Conclusions: STN-DBS improved RLS in patients with PD in one year, which reduced their sleep disorders and increased their quality of life. Furthermore, the central sensorimotor region part of the STN is the optimal stimulation site.

Evoked potentials generated by deep brain stimulation for Parkinson's disease

BACKGROUND AND OBJECTIVES

The goal of this review is to describe the general features, mechanisms, technical recording factors, and clinical applications of brain evoked potentials (EPs) generated by deep brain stimulation (DBS) for Parkinson's disease (PD).

RESULTS

Evoked potentials in response to DBS pulses occur on the timescale of milliseconds and are found both locally at the site of stimulation and remotely in the cortex. DBS evoked potentials arise from a complex integration of antidromic and orthodromic conduction pathway responses, and provide information valuable for understanding the mechanisms and circuits involved in symptom treatment. Furthermore, these signals may provide biomarkers for improving DBS outcomes and function. For example, evoked potentials may have utility as control signals for DBS programming or adaptive DBS. Despite their promise there are still critical gaps in our understanding of the mechanisms by which evoked potentials arise and how these signals may be measured and applied in the clinical setting. Technical challenges of recording a highly transient signal at sufficient resolution without the interference of stimulation artifact present a barrier to understanding better DBS-induced EPs.

CONCLUSIONS

We describe the current scientific landscape of evoked potentials to facilitate and stimulate further investigation.

Surgical Outcomes in Rare Movement Disorders: A Report of Seventeen Patients from India and Review of Literature

Background:

Rare movement disorders (RMDs) throw remarkable challenges to their appropriate management particularly when they are medically refractory. We studied the outcome of functional neurosurgery among patients with RMDs.

Methods:

Retrospective chart-review from 2006 to 2021 of patients with RMDs who underwent either Deep brain Stimulation (DBS) or lesional surgeries in the department of Neurology and Neurosurgery at a tertiary care centre.

Results:

Seventeen patients were included. Generalized dystonia (11 patients, 64.7%) and tremor (5 patients, 29.4%) were the most common indication for surgery whereas, Wilson’s disease (8 patients, 47.1%) and Neurodegeneration with brain iron accumulation (5 patients, 29.4%) were the most common aetiology. Sixteen patients (94.1%) had objective clinical improvement. Significant improvement was noted in the dystonia motor scores both at 6-months and 12-months follow-up (n = 11, p-value of <0.01 and 0.01 respectively). Comparison between DBS and lesional surgery showed no significant difference in the outcomes (p = 0.95 at 6-months and p = 0.53 at 12-months), with slight worsening of scores in the DBS arm at 12-months. Among five patients of refractory tremor with Wilson’s disease, there was remarkable improvement in the tremor scores by 85.0 ± 7.8% at the last follow-up. Speech impairment was the main complication observed with most of the other adverse events either transient or reversible.

Discussion:

Surgical options should be contemplated among patients with disabling medically refractory RMDs irrespective of the aetiology. Key to success lies in appropriate patient selection. In situations when DBS is not feasible, lesional surgeries can offer an excellent alternative with comparable efficacy and safety.

Troubleshooting Gait Disturbances in Parkinson's Disease With Deep Brain Stimulation

Deep brain stimulation (DBS) of the subthalamic nucleus or the globus pallidus is an established treatment for Parkinson's disease (PD) that yields a marked and lasting improvement of motor symptoms. Yet, DBS benefit on gait disturbances in PD is still debated and can be a source of dissatisfaction and poor quality of life. Gait disturbances in PD encompass a variety of clinical manifestations and rely on different pathophysiological bases. While gait disturbances arising years after DBS surgery can be related to disease progression, early impairment of gait may be secondary to treatable causes and benefits from DBS reprogramming. In this review, we tackle the issue of gait disturbances in PD patients with DBS by discussing their neurophysiological basis, providing a detailed clinical characterization, and proposing a pragmatic programming approach to support their management.

Structural Connectivity of Subthalamic Nucleus Stimulation for Improving Freezing of Gait

BACKGROUND

Freezing of gait (FOG) is among the most common and disabling symptoms of Parkinson's disease (PD). Studies show that deep brain stimulation (DBS) of the subthalamic nucleus (STN) can reduce FOG severity. However, there is uncertainty about pathways that need to be modulated to improve FOG.

OBJECTIVE

To investigate whether STN-DBS effectively reduces FOG postoperatively and whether structural connectivity of the stimulated tissue explains variance of outcomes.

METHODS

We investigated 47 patients with PD and preoperative FOG. Freezing prevalence and severity was primarily assessed using the Freezing of Gait Questionnaire (FOG-Q). In a subset of 18 patients, provoked FOG during a standardized walking course was assessed. Using a publicly available model of basal-ganglia pathways we determined stimulation-dependent connectivity associated with postoperative changes in FOG. A region-of-interest analysis to a priori defined mesencephalic regions was performed using a disease-specific normative connectome.

RESULTS

Freezing of gait significantly improved six months postoperatively, marked by reduced frequency and duration of freezing episodes. Optimal stimulation volumes for improving FOG structurally connected to motor areas, the prefrontal cortex and to the globus pallidus. Stimulation of the lenticular fasciculus was associated with worsening of FOG. This connectivity profile was robust in a leave-one-out cross-validation. Subcortically, stimulation of fibers crossing the pedunculopontine nucleus and the substantia nigra correlated with postoperative improvement.

CONCLUSION

STN-DBS can alleviate FOG severity by modulating specific pathways structurally connected to prefrontal and motor cortices. More differentiated FOG assessments may allow to differentiate pathways for specific FOG subtypes in the future.

Clinical Efficacy and Dosing of Vibrotactile Coordinated Reset Stimulation in Motor and Non-motor Symptoms of Parkinson's Disease: A Study Protocol

Enhanced neuronal synchronization of the subthalamic nucleus (STN) is commonly found in PD patients and corresponds to decreased motor ability. Coordinated reset (CR) was developed to decouple synchronized states causing long lasting desynchronization of neural networks. Vibrotactile CR stimulation (vCR) was developed as non-invasive therapeutic that delivers gentle vibrations to the fingertips. A previous study has shown that vCR can desynchronize abnormal brain rhythms within the sensorimotor cortex of PD patients, corresponding to sustained motor relief after 3 months of daily treatment. To further develop vCR, we created a protocol that has two phases. Study 1, a double blinded randomized sham-controlled study, is designed to address motor and non-motor symptoms, sensorimotor integration, and potential calibration methods. Study 2 examines dosing effects of vCR using a remote study design. In Study 1, we will perform a 7-month double-blind sham-controlled study including 30 PD patients randomly placed into an active vCR or inactive (sham) vCR condition. Patients will receive stimulation for 4 h a day in 2-h blocks for 6 months followed by a 1-month pause in stimulation to assess long lasting effects. Our primary outcome measure is the Movement Disorders Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part III off medication after 6 months of treatment. Secondary measures include a freezing of gait (FOG) questionnaire, objective motor evaluations, sensorimotor electroencephalography (EEG) results, a vibratory temporal discrimination task (VTDT), non-motor symptom evaluations/tests such as sleep, smell, speech, quality of life measurements and Levodopa Equivalent Daily Dose (LEDD). Patients will be evaluated at baseline, 3, 6, and 7 months. In the second, unblinded study phase (Study 2), all patients will be given the option to receive active vCR stimulation at a reduced dose for an additional 6 months remotely. The remote MDS-UPDRS part III off medication will be our primary outcome measure. Secondary measures include sleep, quality of life, objective motor evaluations, FOG and LEDD. Patients will be evaluated in the same time periods as the first study. Results from this study will provide clinical efficacy of vCR and help validate our investigational vibrotactile device for the purpose of obtaining FDA clearance. Clinical Trial Registration: ClinicalTrials.gov, identifier: NCT04877015.

Suppression and Rebound of Pallidal Beta Power: Observation Using a Chronic Sensing DBS Device

Pallidal deep brain stimulation (DBS) is an increasingly used therapy for Parkinson’s disease (PD). Here, we study the effect of DBS on pallidal oscillatory activity as well as on symptom severity in an individual with PD implanted with a new pulse generator (Medtronic Percept system) which facilitates chronic recording of local field potentials (LFP) through implanted DBS lead. Pallidal LFPs were recorded while delivering stimulation in a monopolar configuration using stepwise increments (0.5 mA, every 20 s). At each stimulation amplitude, the power spectral density (PSD) was computed, and beta power (13–30 Hz) was calculated and correlated with the degree of bradykinesia. Pallidal beta power was reduced when therapeutic stimulation was delivered. Beta power correlated to the severity of bradykinesia. Worsening of parkinsonism when excessive stimulation was applied was associated with a rebound in the beta band power. These preliminary results suggest that pallidal beta power might be used as an objective marker of the disease state in PD. The use of brain sensing from implanted neural interfaces may in the future facilitate clinical programming. Detection of rebound could help to optimize benefits and minimize worsening from overstimulation.

Long-Term Desynchronization by Coordinated Reset Stimulation in a Neural Network Model With Synaptic and Structural Plasticity

Several brain disorders are characterized by abnormal neuronal synchronization. To specifically counteract abnormal neuronal synchrony and, hence, related symptoms, coordinated reset (CR) stimulation was computationally developed. In principle, successive epochs of synchronizing and desynchronizing stimulation may reversibly move neural networks with plastic synapses back and forth between stable regimes with synchronized and desynchronized firing. Computationally derived predictions have been verified in pre-clinical and clinical studies, paving the way for novel therapies. However, as yet, computational models were not able to reproduce the clinically observed increase of desynchronizing effects of regularly administered CR stimulation intermingled by long stimulation-free epochs. We show that this clinically important phenomenon can be computationally reproduced by taking into account structural plasticity (SP), a mechanism that deletes or generates synapses in order to homeostatically adapt the firing rates of neurons to a set point-like target firing rate in the course of days to months. If we assume that CR stimulation favorably reduces the target firing rate of SP, the desynchronizing effects of CR stimulation increase after long stimulation-free epochs, in accordance with clinically observed phenomena. Our study highlights the pivotal role of stimulation- and dosing-induced modulation of homeostatic set points in therapeutic processes.

Long-Lasting Desynchronization Effects of Coordinated Reset Stimulation Improved by Random Jitters

Abnormally strong synchronized activity is related to several neurological disorders, including essential tremor, epilepsy, and Parkinson's disease. Chronic high-frequency deep brain stimulation (HF DBS) is an established treatment for advanced Parkinson's disease. To reduce the delivered integral electrical current, novel theory-based stimulation techniques such as coordinated reset (CR) stimulation directly counteract the abnormal synchronous firing by delivering phase-shifted stimuli through multiple stimulation sites. In computational studies in neuronal networks with spike-timing-dependent plasticity (STDP), it was shown that CR stimulation down-regulates synaptic weights and drives the network into an attractor of a stable desynchronized state. This led to desynchronization effects that outlasted the stimulation. Corresponding long-lasting therapeutic effects were observed in preclinical and clinical studies. Computational studies suggest that long-lasting effects of CR stimulation depend on the adjustment of the stimulation frequency to the dominant synchronous rhythm. This may limit clinical applicability as different pathological rhythms may coexist. To increase the robustness of the long-lasting effects, we study randomized versions of CR stimulation in networks of leaky integrate-and-fire neurons with STDP. Randomization is obtained by adding random jitters to the stimulation times and by shuffling the sequence of stimulation site activations. We study the corresponding long-lasting effects using analytical calculations and computer simulations. We show that random jitters increase the robustness of long-lasting effects with respect to changes of the number of stimulation sites and the stimulation frequency. In contrast, shuffling does not increase parameter robustness of long-lasting effects. Studying the relation between acute, acute after-, and long-lasting effects of stimulation, we find that both acute after- and long-lasting effects are strongly determined by the stimulation-induced synaptic reshaping, whereas acute effects solely depend on the statistics of administered stimuli. We find that the stimulation duration is another important parameter, as effective stimulation only entails long-lasting effects after a sufficient stimulation duration. Our results show that long-lasting therapeutic effects of CR stimulation with random jitters are more robust than those of regular CR stimulation. This might reduce the parameter adjustment time in future clinical trials and make CR with random jitters more suitable for treating brain disorders with abnormal synchronization in multiple frequency bands.

Structural Connectivity Patterns of Side Effects Induced by Subthalamic Deep Brain Stimulation for Parkinson's Disease

Background: Tractography based on diffusion-weighted magnetic resonance imaging (DWI) models the structural connectivity of the human brain. Deep brain stimulation (DBS) targeting the subthalamic nucleus is an effective treatment for advanced Parkinson's disease, but may induce adverse effects. This study investigated the relationship between structural connectivity patterns of DBS electrodes and stimulation-induced side effects. Materials and Methods: Twenty-one patients with Parkinson's disease treated with bilateral subthalamic DBS were examined. Overall, 168 electrode contacts were categorized as inducing or noninducing depending on their capability for inducing side effects such as motor effects, paresthesia, dysarthria, oculomotor effects, hyperkinesia, and other complications as assessed during the initial programming session. Furthermore, the connectivity of each contact with target regions was evaluated by probabilistic tractography based on DWI. Finally, stimulation sites and structural connectivity patterns of inducing and noninducing contacts were compared. Results: Inducing contacts differed across the various side effects and from those mitigating Parkinson's symptoms. Although contacts showed a largely overlapping spatial distribution within the subthalamic region, they could be distinguished by their connectivity patterns. In particular, inducing contacts were more likely connected with supplementary motor areas (hyperkinesia, dysarthria), frontal cortex (oculomotor), fibers of the internal capsule (paresthesia), and the basal ganglia-thalamo-cortical circuitry (dysarthria). Discussion: Side effects induced by DBS seem to be associated with distinct connectivity patterns. Cerebellar connections are hardly associated with side effects, although they seem relevant for mitigating motor symptoms in Parkinson's disease. A symptom-specific, connectivity-based approach for target planning in DBS may enhance treatment outcomes and reduce adverse effects.

The effects of transcranial direct current stimulation on gait in patients with Parkinson's disease: a systematic review

BACKGROUND

Gait problems are an important symptom in Parkinson's disease (PD), a progressive neurodegenerative disease. Transcranial direct current stimulation (tDCS) is a neuromodulatory intervention that can modulate cortical excitability of the gait-related regions. Despite an increasing number of gait-related tDCS studies in PD, the efficacy of this technique for improving gait has not been systematically investigated yet. Here, we aimed to systematically explore the effects of tDCS on gait in PD, based on available experimental studies.

METHODS

Using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) approach, PubMed, Web of Science, Scopus, and PEDro databases were searched for randomized clinical trials assessing the effect of tDCS on gait in patients with PD.

RESULTS

Eighteen studies were included in this systematic review. Overall, tDCS targeting the motor cortex and supplementary motor area bilaterally seems to be promising for gait rehabilitation in PD. Studies of tDCS targeting the dorosolateral prefrontal cortex or cerebellum showed more heterogeneous results. More studies are needed to systematically compare the efficacy of different tDCS protocols, including protocols applying tDCS alone and/or in combination with conventional gait rehabilitation treatment in PD.

CONCLUSIONS

tDCS is a promising intervention approach to improving gait in PD. Anodal tDCS over the motor areas has shown a positive effect on gait, but stimulation of other areas is less promising. However, the heterogeneities of methods and results have made it difficult to draw firm conclusions. Therefore, systematic explorations of tDCS protocols are required to optimize the efficacy.

Increased Subthalamic Nucleus Deep Brain Stimulation Amplitude Impairs Inhibitory Control of Eye Movements in Parkinson's Disease

BACKGROUND AND OBJECTIVES

Bilateral subthalamic nucleus deep brain stimulation (STN DBS) in Parkinson's disease (PD) can have detrimental effects on eye movement inhibitory control. To investigate this detrimental effect of bilateral STN DBS, we examined the effects of manipulating STN DBS amplitude on inhibitory control during the antisaccade task. The prosaccade error rate during the antisaccade task, that is, directional errors, was indicative of impaired inhibitory control. We hypothesized that as stimulation amplitude increased, the prosaccade error rate would increase.

MATERIALS AND METHODS

Ten participants with bilateral STN DBS completed the antisaccade task on six different stimulation amplitudes (including zero amplitude) after a 12-hour overnight withdrawal from antiparkinsonian medication.

RESULTS

We found that the prosaccade error rate increased as stimulation amplitude increased (p < 0.01). Additionally, prosaccade error rate increased as the modeled volume of tissue activated (VTA) and STN overlap decreased, but this relationship depended on stimulation amplitude (p = 0.04).

CONCLUSIONS

Our findings suggest that higher stimulation amplitude settings can be modulatory for inhibitory control. Some individual variability in the effect of stimulation amplitude can be explained by active contact location and VTA-STN overlap. Higher stimulation amplitudes are more deleterious if the active contacts fall outside of the STN resulting in a smaller VTA-STN overlap. This is clinically significant as it can inform clinical optimization of STN DBS parameters. Further studies are needed to determine stimulation amplitude effects on other aspects of cognition and whether inhibitory control deficits on the antisaccade task result in a meaningful impact on the quality of life.

Apraxia of Lid Opening in Subthalamic Nucleus Deep Brain Stimulation for Parkinson's Disease-Frequency, Risk Factors and Response to Treatment

Background

New-onset apraxia of lid opening (ALO) is reported to occur in Parkinson's disease (PD) patients following Deep Brain Stimulation (DBS). There are only few systematic studies on this uncommon disorder of eyelid movements.

Objectives

We aimed to examine the frequency, temporal evolution, predisposing factors and response to treatment, of new-onset ALO in PD patients who underwent bilateral subthalamic nucleus (STN) DBS.

Methods

We retrospectively reviewed the data of patients who underwent STN DBS at our centre between 1999 and 2017, with a minimum of 2 years of follow up after surgery.

Results

New-onset ALO was seen in 17 (9.1%) of the 187 patients after an average of 16.9 months (Range - 6-36 months). Comparison of the groups with and without ALO revealed that ALO occurred more often in older patients, both at the onset of PD symptoms and at surgery and in those with non-tremor dominant subtypes of PD and freezing of gait at baseline. The extent of levodopa dose reduction after surgery and the pre-operative severity of motor symptoms were not risk factors. Response to adjustments of dopaminergic medications and stimulation parameters was ill-sustained or nil. Botulinum toxin therapy resulted in satisfactory improvement in the majority.

Conclusions

New-onset ALO is an uncommon phenomenon that manifests months after STN DBS. Development of ALO is likely to be due to the effects of chronic stimulation of basal ganglia-thalamo-cortical or brain stem circuits controlling lid movements in susceptible patients. Botulinum toxin therapy offers relatively better relief of symptoms than other strategies.

Evaluation of the Direct Effect of Bilateral Deep Brain Stimulation of the Subthalamic Nucleus on Levodopa-Induced On-Dyskinesia in Parkinson's Disease

Objective: This study aimed to evaluate the direct anti-dyskinesia effect of deep brain stimulation (DBS) of subthalamic nucleus (STN) on levodopa-induced on-dyskinesia in Parkinson's disease (PD) patients during the early period after surgery without reducing the levodopa dosage.

Methods: We retrospectively reviewed PD patients who underwent STN-DBS from January 2017 to October 2019 and enrolled patients with levodopa-induced on-dyskinesia before surgery and without a history of thalamotomy or pallidotomy. The Unified Dyskinesia Rating Scale (UDysRS) parts I+III+IV and the Unified Parkinson's Disease Rating Scale part III (UPDRS-III) were monitored prior to surgery, and at the 3-month follow-up, the location of active contacts was calculated by postoperative CT–MRI image fusion to identify stimulation sites with good anti-dyskinesia effect.

Results: There were 41 patients enrolled. The postoperative levodopa equivalent daily dose (LEDD) (823.1 ± 201.5 mg/day) was not significantly changed from baseline (844.6 ± 266.1 mg/day, P = 0.348), while the UDysRS on-dyskinesia subscores significantly decreased from 24 (10–58) to 0 (0–18) [median (range)] after STN stimulation (P < 0.0001). The levodopa-induced on-dyskinesia recurred in stimulation-off/medication-on state in all the 41 patients and disappeared in 39 patients when DBS stimulation was switched on at 3 months of follow-up. The active contacts which correspond to good effect for dyskinesia were located above the STN, and the mean coordinate was 13.05 ± 1.24 mm lateral, −0.13 ± 1.16 mm posterior, and 0.72 ± 0.78 mm superior to the midcommissural point.

Conclusions: High-frequency electrical stimulation of the area above the STN can directly suppress levodopa-induced on-dyskinesia.

Jules Bernard Luys: from a description of the subthalamic nucleus to hypnotism

The authors review the role of Jules Bernard Luys in the discovery of the subthalamic nucleus (STN) over 150 years ago. The relationships between the STN and movement disorders, particularly hemiballismus and Parkinson's disease, are well known. The academic life of Jules Bernard Luys can be divided into two periods: a brilliant start as a neuroanatomist, culminating in the discovery of the STN, followed by a second period marked by a shift in his academic activity and an increased interest in topics such as hysteria, hypnotism and, eventually, esotericism.

Application of Remote Deep Brain Stimulation Programming for Parkinson's Disease Patients

BACKGROUND

Deep brain stimulation (DBS) is an important treatment for patients with advanced Parkinson's disease (PD). Patients after DBS implantation need specialized programming to get optimal outcomes. However, access to timely and economical postoperative programming for many patients living in remote areas is limited. Teleprogramming, which refers to deliver real-time remote programming through Internet, can help to address this gap.

OBJECTIVE

We aimed to evaluate the clinical application of remote programming for PD patients with DBS.

METHODS

We retrospectively studied 90 patients with PD who received remote DBS programming after implantation at Yuquan Hospital (Beijing, China) between March 2016 and June 2018. Patients' medical records were reviewed in an electronic database. A self-designed questionnaire was performed on all patients by phone.

RESULTS

Over a mean follow-up period of 27.0 months, 90 patients underwent a total of 386 remote programming visits, of which the average frequency within 6 months after DBS was 2.27 times/person. The average distance between the patients' residences and Yuquan Hospital was 1243.8 ± 746.5 km. The questionnaire survey showed that each remote programming visit saved ≥2000¥ for 76.7% of the patients and ≥12 hours for 90.0% of the patients, compared with the on-site programming visit. The acceptability of the remote programming platform was highly rated. Transient side effects related to programming were reported and were relieved after adjustments of parameters.

CONCLUSIONS

Remote programming may offer a feasible and acceptable approach to timely and economic management in patients with PD after DBS implantation.

Management of Parkinson's disease patients after DBS by remote programming: preliminary application of single center during quarantine of 2019-nCoV

Introduction

Deep brain stimulation (DBS) is an effective treatment for patients with Parkinson’s disease (PD). On time follow-up and timely programing of symptoms are important measures to maintain the effectiveness of DBS. Due to the highly contagious nature of 2019-nCoV, patients were quarantined. With the help of Internet technologies, we continued to provide motor and non-motor symptom assessment and remote programming services for postsurgical PD-DBS patients during this extraordinary period.

Methods

A retrospective analysis was performed on postsurgical PD-DBS patients who could not come to our hospital for programming due to the impact of the 2019-nCoV. The differences between the pre- and post-programming groups were analyzed. We designed a 5-level Likert rating scale to evaluate the effects and convenience of the remote programming and Internet self-evaluation procedures.

Results

Of the 36 patients engaged in the remote programming, 32 patients met the inclusion criteria. Four of the 32 patients set initiated stimulation parameters, and the other 28 patients had significant improvement in UPDRS-III. Nearly all the 28 patients were satisfied with the effect of the remote programming. Most of the patients were willing to use remote programming again.

Conclusion

Remote programming based on the online evaluation of patient’s symptoms can help improve motor symptoms of postsurgical DBS patients with PD during the quarantine period caused by 2019-nCoV.

Electronic supplementary material

The online version of this article (10.1007/s00415-020-10273-z) contains supplementary material, which is available to authorized users.

Stimulation-Induced Dyskinesia After Subthalamic Nucleus Deep Brain Stimulation in Patients With Meige Syndrome

OBJECTIVES

Deep brain stimulation of the subthalamic nucleus (STN-DBS) is increasingly used to treat Meige syndrome (MS) and markedly improves symptoms. Stimulation-induced dyskinesia (SID), which adversely affects surgical outcomes and patient satisfaction, may, however, occur in some patients. This study attempts to explore possible causes of SID.

MATERIALS AND METHODS

Retrospectively collected clinical data on 32 patients who underwent STN-DBS between October 2016 and April 2019 were analyzed. Clinical outcomes were assessed pre- and post-surgery, using the Burke-Fahn-Marsden dystonia rating scale (BFMDRS). Patients were divided into a dyskinesia group and a non-dyskinesia group, according to whether or not they experienced persistent SID during follow-up. The coordinates of the active contacts were calculated from post-operative computerized tomography or magnetic resonance imaging, using the inter-commissural line as a reference. At final follow-up, the main stimulatory parameters for further study included pulse width, voltage, and frequency.

RESULTS

At final follow-up (mean = 16.3 ± 7.2 months), MS patients had improved BFMDRS total scores compared with pre-surgical scores (mean improvement = 79.0%, p < 0.0001). The mean improvement in BFMDRS total scores in the dyskinesia (n = 10) and non-dyskinesia (n = 22) groups were 81.6 ± 8.8% and 77.9 ± 14.2%, respectively. The mean minimum voltage to induce dyskinesia was 1.7 ± 0.3 V. The programmed parameters of both groups were similar. When compared with the non-dyskinesia group, active stimulatory contact coordinates in the dyskinesia group were inferior (mean left side: z = -2.3 ± 1.7 mm vs. z = -1.2 ± 1.5 mm; p = 0.0282; mean right side: z = -2.7 ± 1.9 mm vs. z = -2.3 ± 1.7 mm; p = 0.0256). The x and y coordinates were similar.

CONCLUSION

STN-DBS is an effective intervention for MS, providing marked improvements in clinical symptoms; SID may, however occur in the subsequent programming control process. Comparing patients with/without dyskinesia, the active contacts were located closer to the inferior part of the STN in patients with dyskinesia, which may provide an explanation for the dyskinesia.

Lateralized Connectivity between Globus Pallidus and Motor Cortex is Associated with Freezing of Gait in Parkinson's Disease

Freezing of gait (FoG) is a brief, episodic absence or marked reduction of forward progression of the feet, despite the intention to walk, that is common in people with Parkinson's disease (PD). We hypothesized that not only motor, but higher level cognitive and attention areas may be impaired in freezers. In this study, we aimed to characterize differences in cortical and subcortical functional connectivity specific to FoG. We examined resting state neuroimaging and objective measures of FoG severity and gait from 103 individuals (28 PD + FoG, 36 PD - FoG and 39 healthy controls). Inertial sensors were used to quantify freezing severity and gait. Groups with and without FoG were matched on age, disease severity, cognitive status, and levodopa medication. MRI data was processed using surface-based registration. High-quality imaging data were used to characterize differences in connectivity specific to FoG using a pre-defined set of Regions of Interest (ROIs) and validated using whole-brain connectivity analysis. Associations between functional connectivity and objective measures of FoG were determined via predictive modeling using hold-out cross validation. We found that connectivity between the left globus pallidus (GP) and left somatosensory cortex and between two brain areas in the default and insular/vestibular networks exhibited significant differences specific to FoG and were also strong and significant predictors of FoG severity. Our findings suggest that the interplay among motor, default and vestibular areas of the left cortex are critical in the pathology of FoG.

A Framework for Adapting Deep Brain Stimulation Using Parkinsonian State Estimates

The mechanisms underlying the beneficial effects of deep brain stimulation (DBS) for Parkinson's disease (PD) remain poorly understood and are still under debate. This has hindered the development of adaptive DBS (aDBS). For further progress in aDBS, more insight into the dynamics of PD is needed, which can be obtained using machine learning models. This study presents an approach that uses generative and discriminative machine learning models to more accurately estimate the symptom severity of patients and adjust therapy accordingly. A support vector machine is used as the representative algorithm for discriminative machine learning models, and the Gaussian mixture model is used for the generative models. Therapy is effected using the state estimates obtained from the machine learning models together with a fuzzy controller in a critic-actor control approach. Both machine learning model configurations achieve PD suppression to desired state in 7 out of 9 cases; most of which settle in under 2 s.

Long-term effect of subthalamic nucleus deep brain stimulation on freezing of gait in Parkinson's disease

OBJECTIVE

Subthalamic nucleus deep brain stimulation (STN DBS) is effective against freezing of gait (FOG) in Parkinson's disease (PD); however, whether this effect persists over the long term is debated. The aim of the current study was to investigate the long-term effect of STN DBS on FOG in patients with PD.

METHODS

Data on 52 cases in which PD patients received bilateral STN DBS were obtained from a prospective registry. The authors blindly analyzed FOG incidence and its severity from the videotapes of a 5-m walking task at the baseline and at the 1-, 2-, and 5- or 7-year follow-up visits. They also compared the axial score from the Unified Parkinson's Disease Rating Scale (UPDRS) part III, UPDRS part II (UPDRS-II) item 14, and the FOG questionnaire (FOG-Q). Postoperatively, video-based FOG analysis and the axial score were evaluated under 4 conditions (off-medication/off-stimulation, off-medication/on-stimulation, on-medication/off-stimulation, and on-medication/on-stimulation), and UPDRS-II item 14 and the FOG-Q score were evaluated under 2 conditions (off-medication/on-stimulation and on-medication/on-stimulation).

RESULTS

During the off-medication state, the on-stimulation condition improved FOG outcomes, except for video-based FOG severity, up to the last follow-up compared with the baseline. Video-based FOG outcomes and the axial score during the off-medication state were improved with the on-stimulation condition up to the last follow-up compared with the off-stimulation condition. During the on-medication state, the on-stimulation condition did not improve any FOG outcome compared with the baseline; however, it improved video-based FOG outcomes up to the 2-year follow-up and the axial score up to the last follow-up compared with the off-stimulation condition.

CONCLUSIONS

Our findings suggest that STN DBS has a long-term effect on FOG in the off-medication state. However, STN DBS did not show a long-term effect on FOG in the on-medication state, although it had a short-term effect until the 2-year follow-up.

Deep Brain Stimulation for Freezing of Gait in Parkinson's Disease With Early Motor Complications

BACKGROUND

Effects of DBS on freezing of gait and other axial signs in PD patients are unclear.

OBJECTIVE

Secondary analysis to assess whether DBS affects these symptoms within a large randomized controlled trial comparing DBS of the STN combined with best medical treatment and best medical treatment alone in patients with early motor complications (EARLYSTIM-trial).

METHODS

One hundred twenty-four patients were randomized in the stimulation group and 127 patients in the best medical treatment group. Presence of freezing of gait was assessed in the worst condition based on item-14 of the UPDRS-II at baseline and follow-up. The posture, instability, and gait-difficulty subscore of the UPDRS-III, and a gait test including quantification of freezing of gait and number of steps, were performed in both medication-off and medication-on conditions.

RESULTS

Fifty-two percent in both groups had freezing of gait at baseline based on UPDRS-II. This proportion decreased in the stimulation group to 34%, but did not change in the best medical treatment group at 24 months (P = 0.018). The steps needed to complete the gait test decreased in the stimulation group and was superior to the best medical treatment group (P = 0.016). The axial signs improved in the stimulation group compared to the best medical treatment group (P < 0.01) in both medication-off and medication-on conditions.

CONCLUSIONS

Within the first 2 years of DBS, freezing of gait and other axial signs improved in the medication-off condition compared to best medical treatment in these patients. © 2019 International Parkinson and Movement Disorder Society.

Effects of virtual reality rehabilitation training on gait and balance in patients with Parkinson's disease: A systematic review

OBJECTIVE

In recent years, virtual reality (VR) has been tested as a therapeutic tool in neurorehabilitation research. However, the impact effectiveness of VR technology on for Parkinson's Disease (PD) patients is still remains controversial unclear. In order to provide a more scientific basis for rehabilitation of PD patients' modality, we conducted a systematic review of VR rehabilitation training for PD patients and focused on the improvement of gait and balance.

METHODS

An comprehensive search was conducted using the following databases: PubMed, Web of Science, Cochrane Library, CINHAL, Embase and CNKI (China National Knowledge Infrastructure).Articles published before 30 December 2018 and of a randomized controlled trial design to study the effects of VR for patients with PD were included. The study data were pooled and a meta-analysis was completed. This systematic review was conducted in accordance with the PRISMA guideline statement and was registered in the PROSPERO database (CRD42018110264).

RESULTS

A total of sixteen articles involving 555 participants with PD were included in our analysis. VR rehabilitation training performed better than conventional or traditional rehabilitation training in three aspects: step and stride length (SMD = 0.72, 95%CI = 0.40,1.04, Z = 4.38, P<0.01), balance function (SMD = 0.22, 95%CI = 0.01,0.42, Z = 2.09, P = 0.037), and mobility(MD = -1.95, 95%CI = -2.81,-1.08, Z = 4.41, P<0.01). There was no effect on the dynamic gait index (SMD = -0.15, 95%CI = -0.50,0.19, Z = 0.86, P = 0.387), and gait speed (SMD = 0.19, 95%CI = -0.03,0.40, Z = 1.71, P = 0.088).As for the secondary outcomes, compared with the control group, VR rehabilitation training demonstrated more significant effects on the improvement of quality of life (SMD = -0.47, 95%CI = -0.73,-0.22, Z = 3.64, P<0.01), level of confidence (SMD = -0.73, 95%CI = -1.43,-0.03, Z = 2.05, P = 0.040), and neuropsychiatric symptoms (SMD = -0.96, 95%CI = -1.27,-0.65, Z = 6.07, P<0.01), while it may have similar effects on global motor function (SMD = -0.50, 95%CI = -1.48,0.48, Z = 0.99, P = 0.32), activities of daily living (SMD = 0.25, 95%CI = -0.14,0.64, Z = 1.24, P = 0.216), and cognitive function (SMD = 0.21, 95%CI = -0.28,0.69, Z = 0.84, P = 0.399).During the included interventions, four patients developed mild dizziness and one patient developed severe dizziness and vomiting.

CONCLUSIONS

According to the results of this study, we found that VR rehabilitation training can not only achieve the same effect as conventional rehabilitation training. Moreover, it has better performance on gait and balance in patients with PD. Taken together, when the effect of traditional rehabilitation training on gait and balance of PD patients is not good enough, we believe that VR rehabilitation training can at least be used as an alternative therapy. More rigorous design of large-sample, multicenter randomized controlled trials are needed to provide a stronger evidence-based basis for verifying its potential advantages.

Dystonia and Parkinson's disease: What is the relationship?

Dystonia and Parkinson's disease are closely linked disorders sharing many pathophysiological overlaps. Dystonia can be seen in 30% or more of the patients suffering with PD and sometimes can precede the overt parkinsonism. The response of early dystonia to the introduction of dopamine replacement therapy (levodopa, dopamine agonists) is variable; dystonia commonly occurs in PD patients following levodopa initiation. Similarly, parkinsonism is commonly seen in patients with mutations in various DYT genes including those involved in the dopamine synthesis pathway. Pharmacological blockade of dopamine receptors can cause both tardive dystonia and parkinsonism and these movement disorders syndromes can occur in many other neurodegenerative, genetic, toxic and metabolic diseases. Pallidotomy in the past and currently deep brain stimulation largely involving the GPi are effective treatment options for both dystonia and parkinsonism. However, the physiological mechanisms underlying the response of these two different movement disorder syndromes are poorly understood. Interestingly, DBS for PD can cause dystonia such as blepharospasm and bilateral pallidal DBS for dystonia can result in features of parkinsonism. Advances in our understanding of these responses may provide better explanations for the relationship between dystonia and Parkinson's disease.

An Unusual Case of Essential Tremor Deep Brain Stimulation: Where is the Lead?

Clinical Vignette

A 73-year-old female with essential tremor (ET) underwent bilateral thalamic ventralis intermedius (Vim) deep brain stimulation (DBS) surgery. The leads provided tremor benefit, but the location was suboptimal and contributed to stimulation-induced hemichorea.

Clinical Dilemma

Can patients with ET derive benefit when stimulating outside the Vim? What do we know about stimulation-induced hemichorea in the setting of ET?

Clinical Solution

Lead localization combined with advanced programming strategies can be employed to troubleshoot DBS in settings when benefits are observed along with adverse effects.

Gap in Knowledge

Sparse information exists about DBS when applied to neuroanatomic regions outside the Vim for the management of ET. Subthalamic nucleus DBS-induced chorea has been reported in multiple movement disorders, but not in ET.

Blepharospasm as a Manifestation of Peak of Dose Dyskinesia in Parkinson Disease

OBJECTIVES

The aim of the study was to report 4 patients with Parkinson disease (PD) and On-period blepharospasm (BS).

METHODS

We analyzed patients with PD and motor fluctuations who developed BS in several different centers in Latin America.

RESULTS

Four patients had BS while in the ON periods.

CONCLUSIONS

Blepharospasm in the On period in patients with PD is extremely uncommon, and our series is the only one to describe such association.