Postoperative gait deterioration after bilateral subthalamic nucleus stimulation in Parkinson's disease

The effect of deep brain stimulation on lower extremity dexterity in people with Parkinson's disease

PURPOSE

To examine the effect of deep brain stimulation (DBS) on lower extremity dexterity in people with Parkinson's disease (PwPD) and to investigate the relationship between this effect and the effect of DBS on measures of different walking characteristics, and other features of Parkinson's disease.

MATERIALS AND METHODS

Thirty-six PwPD were included. Assessment was performed twice with DBS "on" and DBS "off" state.

RESULTS

The LEDT scores of both extremities, the Unified Parkinson Disease Rating Scale-motor section (UPDRS-III), the 10-Meter Walk Test (TMWT), the Timed Up and Go Test (TUG), the Figure-of-Eight Walk Test (FEWT), and the Three-Meter Backward Walk Test (TMBWT) scores were significantly better in "on" DBS condition than "off" DBS condition. The effect of DBS on lower extremity dexterity is related to age and levodopa equivalent daily dosage (LEDD). The effect of DBS on lower extremity dexterity and the effect of DBS on the bradykinesia, TUG, the FEWT, and the TMBWT were also related.

CONCLUSIONS

DBS has a positive effect on lower extremity dexterity. Clinical characteristics such as age and LEDD and the effect of DBS on bradykinesia, walking with turning, curved walking, and backward walking is related with the effect of DBS on lower extremity dexterity.

Physical therapy in patients with Parkinson's disease treated with Deep Brain Stimulation: a Delphi panel study

Although deep brain stimulation of the subthalamic nucleus (STN-DBS) induces motor benefits in people with Parkinson's disease (PwPD), the size and duration of the effects of STN-DBS on motor axial (e.g., postural instability, trunk posture alterations) and gait impairments (e.g., freezing of gait - FOG) are still ambiguous. Physical therapy (PT) effectively complements pharmacological treatment to improve postural stability, gait performance, and other dopamine-resistant symptoms (e.g. festination, hesitation, axial motor dysfunctions, and FOG) in PwPD who are non-surgically treated. Despite the potential for positive adjuvant effects of PT following STN-DBS surgery, there is a paucity of science available on the topic. In such a scenario, gathering the opinion and expertise of leading investigators worldwide was pursued to study motor rehabilitation in PwPD following STN-DBS. After summarizing the few available findings through a systematic review, we identified clinical and academically experienced DBS clinicians (n=21) to discuss the challenges related to PT following STN-DBS. A 5-point Likert scale questionnaire was used and based on the results of the systematic review along with a Delphi method. Thirty-nine questions were submitted to the panel - half related to general considerations on PT following STN-DBS, half related to PT treatments. Despite the low-to-moderate quality, the few available rehabilitative studies suggested that PT could improve dynamic and static balance, gait performance and posture. Similarly, panellists strongly agreed that PT might help in improving motor symptoms and quality of life, and it may be possibly prescribed to maximize the effects of the stimulation. The experts agreed that physical therapists could be part of the multidisciplinary team taking care of the patients. Also, they agreed on prescribing of conventional PT, but not massage or manual therapy. Our results will inform the rehabilitation and the DBS community to engage, publish and deepen this area of research. Such efforts may spark guidelines for PT following STN-DBS.

Case report: Improvement of gait with adaptive deep brain stimulation in a patient with Parkinson's disease

Gait disturbance is a common and severe symptom of Parkinson's disease that severely impairs quality of life. Current treatments provide only partial benefits with wide variability in outcomes. Also, deep brain stimulation of the subthalamic nucleus (STN-DBS), a mainstay treatment for bradykinetic-rigid symptoms and parkinsonian tremor, is poorly effective on gait. We applied a novel DBS paradigm, adjusting the current amplitude linearly with respect to subthalamic beta power (adaptive DBS), in one parkinsonian patient with gait impairment and chronically stimulated with conventional DBS. We studied the kinematics of gait and gait initiation (anticipatory postural adjustments) as well as subthalamic beta oscillations with both conventional and adaptive DBS. With adaptive DBS, the patient showed a consistent and long-lasting improvement in walking while retaining benefits on other disease-related symptoms. We suggest that adaptive DBS can benefit gait in Parkinson's disease possibly by avoiding overstimulation and dysfunctional entrainment of the supraspinal locomotor network.

Deep Brain Stimulation Modulates the Visual Pathway to Improve Freezing of Gait in Parkinson's Disease Patients

OBJECTIVE

To investigate the involvement of the visual cortex in improving freezing of gait (FoG) after subthalamic nucleus (STN) deep brain stimulation (DBS) in Parkinson's disease (PD) patients using whole-brain seed-based functional connectivity.

METHODS

A total of 66 PD patients with FoG who underwent bilateral STN-DBS were included in our study. Patients were divided into a FoG responder group and an FoG nonresponder group according to whether FoG improved 1 year after DBS. We compared the differences in clinical characteristics, brain structural imaging, and seed-based functional connectivity between the 2 groups. The locations of active contacts were further analyzed.

RESULTS

All PD patients benefited from STN-DBS. No significant differences in the baseline characteristics or brain structures were found between the 2 groups. Seed-based functional connectivity analysis revealed that better connectivity in bilateral primary visual areas was associated with better clinical improvement in FoG (P < 0.05 familywise error corrected). Further analysis revealed that this disparity was associated with the location of the active contacts within the rostral region of the sensorimotor subregion in the FoG responder group, in contrast to the findings in the FoG nonresponder group.

CONCLUSIONS

This study suggested that DBS in the rostral region of the STN sensorimotor subregion may alleviate FoG by strengthening functional connectivity in primary visual areas, which has significant implications for guiding surgical strategies for FoG in the future.

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

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

Impact of deep brain stimulation on gait in Parkinson disease: A kinematic study

BACKGROUND

The effect of Deep Brain Stimulation (DBS) on gait in Parkinson's Disease (PD) is poorly understood. Kinematic studies utilizing quantitative gait outcomes such as speed, cadence, and stride length have shown mixed results and were done mostly before and after acute DBS discontinuation.

OBJECTIVE

To examine longitudinal changes in kinematic gait outcomes before and after DBS surgery.

METHOD

We retrospectively assessed changes in quantitative gait outcomes via motion capture in 22 PD patients before and after subthalamic (STN) or globus pallidus internus (GPi) DBS, in on medication state. Associations between gait outcomes and clinical variables were also assessed.

RESULT

Gait speed reduced from 110.7 ± 21.3 cm/s before surgery to 93.6 ± 24.9 after surgery (7.7 ± 2.9 months post-surgery, duration between assessments was 15.0 ± 3.8 months). Cadence, step length, stride length, and single support time reduced, while total support time, and initial double support time increased. Despite this, there was overall improvement in the Movement Disorder Society-Unified Parkinson Disease Rating Scale-Part III score "on medication/on stimulation" score (from 19.8 ± 10.7-13.9 ± 8.6). Change of gait speed was not related to changes in levodopa dosage, disease duration, unilateral vs bilateral stimulation, or target nucleus.

CONCLUSION

Quantitative gait outcomes in on medication state worsened after chronic DBS therapy despite improvement in other clinical outcomes. Whether these changes reflect the effects of DBS as opposed to ongoing disease progression is unknown.

Does Impaired Plantar Cutaneous Vibration Perception Contribute to Axial Motor Symptoms in Parkinson's Disease? Effects of Medication and Subthalamic Nucleus Deep Brain Stimulation

OBJECTIVE

To investigate whether impaired plantar cutaneous vibration perception contributes to axial motor symptoms in Parkinson's disease (PD) and whether anti-parkinsonian medication and subthalamic nucleus deep brain stimulation (STN-DBS) show different effects.

METHODS

Three groups were evaluated: PD patients in the medication "on" state (PD-MED), PD patients in the medication "on" state and additionally "on" STN-DBS (PD-MED-DBS), as well as healthy subjects (HS) as reference. Motor performance was analyzed using a pressure distribution platform. Plantar cutaneous vibration perception thresholds (VPT) were investigated using a customized vibration exciter at 30 Hz.

RESULTS

Motor performance of PD-MED and PD-MED-DBS was characterized by greater postural sway, smaller limits of stability ranges, and slower gait due to shorter strides, fewer steps per minute, and broader stride widths compared to HS. Comparing patient groups, PD-MED-DBS showed better overall motor performance than PD-MED, particularly for the functional limits of stability and gait. VPTs were significantly higher for PD-MED compared to those of HS, which suggests impaired plantar cutaneous vibration perception in PD. However, PD-MED-DBS showed less impaired cutaneous vibration perception than PD-MED.

CONCLUSIONS

PD patients suffer from poor motor performance compared to healthy subjects. Anti-parkinsonian medication in tandem with STN-DBS seems to be superior for normalizing axial motor symptoms compared to medication alone. Plantar cutaneous vibration perception is impaired in PD patients, whereas anti-parkinsonian medication together with STN-DBS is superior for normalizing tactile cutaneous perception compared to medication alone. Consequently, based on our results and the findings of the literature, impaired plantar cutaneous vibration perception might contribute to axial motor symptoms in PD.

Frequency settings of subthalamic nucleus DBS for Parkinson's disease: A systematic review and network meta-analysis

INTRODUCTION

Deep Brain Stimulation (DBS) is an effective treatment for the motor symptoms of Parkinson's Disease. The targeted physiological structure for lead location is commonly the subthalamic nucleus (STN). The efficacy of DBS for improving motor symptoms is assessed via the Unified Parkinson's Disease Rating III Scale (UPDRS-III). In this study, we sought to compare the efficacy of frequency settings utilized for STN-DBS.

METHODS

Following PRISMA Guidelines, a search on PUBMED and MEDLINE was performed to include full-length randomized controlled trials evaluating STN-DBS. The frequency stimulation parameters and Unified Parkinson's Disease Rating Scale (UPDRS-III) outcomes were extracted in the search. High-frequency stimulation (HFS) was defined as ≥100 Hz and low-frequency stimulation (LFS) was defined as <100 Hz. A frequentist network meta-analysis was performed with odds ratios (OR) and pooling performed using the Mantel-Haenszel method. Statistics are presented as OR [95% CI].

RESULTS

15 studies consisting of 298 patients were included for analysis. Bilateral HFS -0.68 [-0.89; -0.46] was associated with better UPDRS-III scores compared to bilateral LFS. On the other hand, bilateral LFS with medications (MEDS) was favored over HFS with MEDS (-0.28 [-0.63; 0.07]). Bilateral LFS and MEDS, HFS and MEDS, stimulation (STIM) OFF MEDS ON, HFS, LFS, STIM OFF MEDS OFF UPDRS outcomes were ranked from best to worst outcomes.

DISCUSSION

The outcomes of this study suggest that bilateral HFS has better utility for those with no response to medication, while LFS has additive benefits to medication by improving unique symptoms via different neurophysiological mechanisms.

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

Objective

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

Methods

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

Results

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

Conclusion

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

Effect of subthalamic coordinated reset deep brain stimulation on Parkinsonian gait

Introduction

Coordinated Reset Deep Brain Stimulation (CR DBS) is a novel DBS approach for treating Parkinson's disease (PD) that uses lower levels of burst stimulation through multiple contacts of the DBS lead. Though CR DBS has been demonstrated to have sustained therapeutic effects on rigidity, tremor, bradykinesia, and akinesia following cessation of stimulation, i.e., carryover effect, its effect on Parkinsonian gait has not been well studied. Impaired gait is a disabling symptom of PD, often associated with a higher risk of falling and a reduced quality of life. The goal of this study was to explore the carryover effect of subthalamic CR DBS on Parkinsonian gait.

Methods

Three non-human primates (NHPs) were rendered Parkinsonian and implanted with a DBS lead in the subthalamic nucleus (STN). For each animal, STN CR DBS was delivered for several hours per day across five consecutive days. A clinical rating scale modified for NHP use (mUPDRS) was administered every morning to monitor the carryover effect of CR DBS on rigidity, tremor, akinesia, and bradykinesia. Gait was assessed quantitatively before and after STN CR DBS. The stride length and swing speed were calculated and compared to the baseline, pre-stimulation condition.

Results

In all three animals, carryover improvements in rigidity, bradykinesia, and akinesia were observed after CR DBS. Increased swing speed was observed in all the animals; however, improvement in stride length was only observed in NHP B2. In addition, STN CR DBS using two different burst frequencies was evaluated in NHP B2, and differential effects on the mUPDRS score and gait were observed.

Discussion

Although preliminary, our results indicate that STN CR DBS can improve Parkinsonian gait together with other motor signs when stimulation parameters are properly selected. This study further supports the continued development of CR DBS as a novel therapy for PD and highlights the importance of parameter selection in its clinical application.

Spinal cord stimulation for gait disturbances in Parkinson's disease

INTRODUCTION

Gait disturbances are a major contributor to the disability associated with Parkinson's disease. Although pharmacologic therapies and deep brain stimulation improve most motor parkinsonian features, their effects on gait are highly variable. Spinal cord stimulation, typically used for the treatment of chronic pain, has emerged as a potential therapeutic approach to improve gait disturbances in Parkinson's disease.

AREAS COVERED

The authors review the available evidence on the effects of spinal cord stimulation in patients with Parkinson's disease, targeting primarily gait abnormalities. They also discuss possible mechanisms, safety, and methodological implications for future clinical trials. This systematic review of originally published articles in English language was performed using The Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA).

WITHDRAWN: Laterality and frequency settings of subthalamic nucleus DBS for Parkinson's disease: A systematic review and network meta-analysis

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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.

Novel targets in deep brain stimulation for movement disorders

The neurosurgical treatment of movement disorders, primarily via deep brain stimulation (DBS), is a rapidly expanding and evolving field. Although conventional targets including the subthalamic nucleus (STN) and internal segment of the globus pallidus (GPi) for Parkinson's disease and ventral intermediate nucleus of the thalams (VIM) for tremor provide substantial benefit in terms of both motor symptoms and quality of life, other targets for DBS have been explored in an effort to maximize clinical benefit and also avoid undesired adverse effects associated with stimulation. These novel targets primarily include the rostral zona incerta (rZI), caudal zona incerta (cZI)/posterior subthalamic area (PSA), prelemniscal radiation (Raprl), pedunculopontine nucleus (PPN), substantia nigra pars reticulata (SNr), centromedian/parafascicular (CM/PF) nucleus of the thalamus, nucleus basalis of Meynert (NBM), dentato-rubro-thalamic tract (DRTT), dentate nucleus of the cerebellum, external segment of the globus pallidus (GPe), and ventral oralis (VO) complex of the thalamus. However, reports of outcomes utilizing these targets are scattered and disparate. In order to provide a comprehensive resource for researchers and clinicians alike, we have summarized the existing literature surrounding these novel targets, including rationale for their use, neurosurgical techniques where relevant, outcomes and adverse effects of stimulation, and future directions for research.

Subthalamic Deep Brain Stimulation Lead Asymmetry Impacts the Parkinsonian Gait Disorder

Background

The preferable position of Deep Brain Stimulation (DBS) electrodes is proposed to be located in the dorsolateral subthalamic nucleus (STN) to improve general motor performance. The optimal DBS electrode localization for the post-operative improvement of balance and gait is unknown.

Methods

In this single-center, retrospective analyses, 66 Parkinson’s disease (PD) patients (24 female, age 63 ± 7 years) were assessed pre- and post-operatively (8.45 ± 4.2 months after surgery) by using MDS-UPDRS, freezing of gait (FoG) score, Giladi’s gait and falls questionnaire and Berg balance scale. The clinical outcome was related to the DBS electrode coordinates in x, y, z plane as revealed by image-based reconstruction (SureTune™). Binomial generalized linear mixed models with fixed-effect variables electrode asymmetry, parkinsonian subtype, medication, age class and clinical DBS induced changes were analyzed.

Results

Subthalamic nucleus-deep brain stimulation improved all motor, balance and FoG scores in MED OFF condition, however there were heterogeneous results in MED ON condition. DBS electrode reconstructed coordinates impacted the responsiveness of axial symptoms. FoG and balance responders showed slightly more medially located STN electrode coordinates and less medio-lateral asymmetry of the electrode reconstructed coordinates across hemispheres compared to non-responders.

Conclusion

Deep brain stimulation electrode reconstructed coordinates, particularly electrode asymmetry on the medio-lateral axis affected the post-operative responsiveness of balance and FoG symptoms in PD patients.

Combined Subthalamic and Nigral Stimulation Modulates Temporal Gait Coordination and Cortical Gait-Network Activity in Parkinson's Disease

Background

Freezing of gait (FoG) is a disabling burden for Parkinson's disease (PD) patients with poor response to conventional therapies. Combined deep brain stimulation of the subthalamic nucleus and substantia nigra (STN+SN DBS) moved into focus as a potential therapeutic option to treat the parkinsonian gait disorder and refractory FoG. The mechanisms of action of DBS within the cortical-subcortical-basal ganglia network on gait, particularly at the cortical level, remain unclear.

Methods

Twelve patients with idiopathic PD and chronically-implanted DBS electrodes were assessed on their regular dopaminergic medication in a standardized stepping in place paradigm. Patients executed the task with DBS switched off (STIM OFF), conventional STN DBS and combined STN+SN DBS and were compared to healthy matched controls. Simultaneous high-density EEG and kinematic measurements were recorded during resting-state, effective stepping, and freezing episodes.

Results

Clinically, STN+SN DBS was superior to conventional STN DBS in improving temporal stepping variability of the more affected leg. During resting-state and effective stepping, the cortical activity of PD patients in STIM OFF was characterized by excessive over-synchronization in the theta (4-8 Hz), alpha (9-13 Hz), and high-beta (21-30 Hz) band compared to healthy controls. Both active DBS settings similarly decreased resting-state alpha power and reduced pathologically enhanced high-beta activity during resting-state and effective stepping compared to STIM OFF. Freezing episodes during STN DBS and STN+SN DBS showed spectrally and spatially distinct cortical activity patterns when compared to effective stepping. During STN DBS, FoG was associated with an increase in cortical alpha and low-beta activity over central cortical areas, while with STN+SN DBS, an increase in high-beta was prominent over more frontal areas.

Conclusions

STN+SN DBS improved temporal aspects of parkinsonian gait impairment compared to conventional STN DBS and differentially affected cortical oscillatory patterns during regular locomotion and freezing suggesting a potential modulatory effect on dysfunctional cortical-subcortical communication in PD.

Targeted activation of midbrain neurons restores locomotor function in mouse models of parkinsonism

The pedunculopontine nucleus (PPN) is a locomotor command area containing glutamatergic neurons that control locomotor initiation and maintenance. These motor actions are deficient in Parkinson’s disease (PD), where dopaminergic neurodegeneration alters basal ganglia activity. Being downstream of the basal ganglia, the PPN may be a suitable target for ameliorating parkinsonian motor symptoms. Here, we use in vivo cell-type specific PPN activation to restore motor function in two mouse models of parkinsonism made by acute pharmacological blockage of dopamine transmission. With a combination of chemo- and opto-genetics, we show that excitation of caudal glutamatergic PPN neurons can normalize the otherwise severe locomotor deficit in PD, whereas targeting the local GABAergic population only leads to recovery of slow locomotion. The motor rescue driven by glutamatergic PPN activation is independent of activity in nearby locomotor promoting glutamatergic Cuneiform neurons. Our observations point to caudal glutamatergic PPN neurons as a potential target for neuromodulatory restoration of locomotor function in PD.

Here, the authors use cell-type specific stimulation of brainstem neurons within the caudal pedunculopontine nucleus to show that activation of excitatory neurons can normalize severe locomotor deficit in mouse models of parkinsonism. The study defines a potential target for neuromodulatory restoration of locomotor function in Parkinson’s disease.

Short- and Long-Term Effects of DBS on Gait in Parkinson's Disease

The aim was to compare the short and long-term effects of subthalamic nucleus (STN) deep brain stimulation (DBS) on gait dysfunction and other cardinal symptoms of Parkinson's disease (PD). Two groups of patients were studied. The first group (short-term DBS, n = 8) included patients recently implanted with STN DBS (mean time since DBS 15.8 months, mean age 58.8 years, PD duration 13 years); the second group (long-term DBS, n = 10) included patients with at least 5 years of DBS therapy (mean time since DBS 67.6 months, mean age 61.7 years, PD duration 17.1 years). Both groups were examined using the Unified Parkinson's Disease Rating Scale (UPDRS) and Gait and Balance scale (GABS) during four stimulation/medication states (ON/OFF; OFF/OFF; OFF/ON; ON/ON). Data were analyzed using repeated measures ANOVA with time since implantation (years) between groups and medication or DBS effect (ON, OFF) within groups. In the short-term DBS group, stimulation improved all UPDRS subscores similar to dopaminergic medications. In particular, average gait improvement was over 40% (p = 0.01), as measured by the UPDRS item 29 and GABS II. In the long-term DBS group, stimulation consistently improved all clinical subscores with the exception of gait and postural instability. In these patients, the effect of levodopa on gait was partially preserved. Short-term improvement of gait abnormalities appears to significantly decline after 5 years of STN DBS in PD patients, while effectiveness for other symptoms remains stable. Progressive non-dopaminergic (non-DBS responsive) mechanisms or deleterious effects of high frequency STN stimulation on gait function may play a role.

Does Subthalamic Deep Brain Stimulation Impact Asymmetry and Dyscoordination of Gait in Parkinson's Disease?

Background. Subthalamic deep brain stimulation (STN-DBS) is an effective treatment for selected Parkinson's disease (PD) patients. Gait characteristics are often altered after surgery, but quantitative therapeutic effects are poorly described. Objective. The goal of this study was to systematically investigate modifications in asymmetry and dyscoordination of gait 6 months postoperatively in patients with PD and compare the outcomes with preoperative baseline and to asymptomatic controls without PD. Methods. A convenience sample of thirty-two patients with PD (19 with postural instability and gait disorder (PIGD) type and 13 with tremor dominant disease) and 51 asymptomatic controls participated. Parkinson patients were tested prior to the surgery in both OFF and ON medication states, and 6-months postoperatively in the ON stimulation condition. Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) I to IV and medication were compared to preoperative conditions. Asymmetry ratios, phase coordination index, and walking speed were assessed. Results. MDS-UPDRS I to IV at 6 months improved significantly, and levodopa equivalent daily dosages significantly decreased. STN-DBS increased step time asymmetry (hedges' g effect sizes [95% confidence interval] between pre- and post-surgery: .27 [-.13, .73]) and phase coordination index (.29 [-.08, .67]). These effects were higher in the PIGD subgroup than the tremor dominant (step time asymmetry: .38 [-.06, .90] vs .09 [-.83, 1.0] and phase coordination index: .39 [-.04, .84] vs .13 [-.76, .96]). Conclusions. This study provides objective evidence of how STN-DBS increases asymmetry and dyscoordination of gait in patients with PD and suggests motor subtypes-associated differences in the treatment response.

3D visual cueing shortens the double support phase of the gait cycle in patients with advanced Parkinson's disease treated with DBS of the STN

Background

Gait disturbances have emerged as some of the main therapeutic concerns in late-stage Parkinson’s disease (PD) treated with dopaminergic therapy and deep brain stimulation (DBS). External cues may help to overcome freezing of gait (FOG) and improve some of the gait parameters.

Aim

To evaluate the effect of 3D visual cues and STN-DBS on gait in PD group.

Methods

We enrolled 35 PD patients treated with DBS of nucleus subthalamicus (STN-DBS). Twenty-five patients (5 females; mean age 58.9 ±6.3) and 25 sex- and age-matched controls completed the gait examination. The gait in 10 patients deteriorated in OFF state. The severity of PD was evaluated using the Unified Parkinson's Disease Rating Scale (UPDRS) and Hoehn and Yahr (HY). The PD group filled the Falls Efficacy Scale-International (FES) and Freezing of Gait Questionnaire (FOGQ). Gait was examined using the GaitRite Analysis System, placed in the middle of the 10m marked path. The PD group was tested without dopaminergic medication with and without visual cueing together with the DBS switched ON and OFF. The setting of DBS was double-blind and performed in random order.

Results

The UPDRS was 21.9 ±9.5 in DBS ON state and 41.3 ±13.7 in DBS OFF state. HY was 2.5 ±0.6, FES 12.4 ±4.1 and FOGQ 9.4 ±5.7. In the DBS OFF state, PD group walked more slowly with shorter steps, had greater step length variability and longer duration of the double support phase compared to healthy controls. The walking speed and step length increased in the DBS ON state. The double support phase was reduced with 3D visual cueing and DBS; the combination of both cueing and DBS was even more effective.

Conclusion

Cueing with 3D visual stimuli shortens the double support phase in PD patients treated with DBS-STN. The DBS is more effective in prolonging step length and increasing gait speed. We conclude that 3D visual cueing can improve walking in patients with DBS.

Long-term Effects of Bilateral Subthalamic Deep Brain Stimulation on Postural Instability and Gait Difficulty in Patients with Parkinson's Disease

Objective

The long-term effects of bilateral subthalamic nucleus deep brain stimulation (STN-DBS) on postural instability and gait difficulty (PIGD) in patients with Parkinson’s disease (PD) remain unclear. In this study, we aimed to evaluate the longterm effects of STN-DBS surgery on PIGD symptoms in patients with advanced-stage PD.

Methods

This study included 49 consecutively included patients with PD who underwent bilateral STN-DBS. The Unified Parkinson’s Disease Rating Scale (UPDRS) scores and subscores for PIGD were assessed at baseline and at 1, 3, and 5 years postoperatively. The PIGD subscore was divided into PIGD-motor and PIGD-activities of daily living (ADL) scores according to parts III and II of the UPDRS, respectively.

Results

The PIGD-motor and PIGD-ADL scores at the “medication-off” state improved at 3 and 5 years, respectively. Overall, the UPDRS III and II scores at “medication-off” improved at 5 years. The UPDRS IV score also significantly improved and the levodopa equivalent daily dosage decreased at all follow-ups. Finally, the PIGD-motor score at baseline was able to predict long-term improvement in the PIGD-motor score at the 5-year follow-up.

Conclusion

The STN-DBS has both short- and long-term effects on PIGD, as well as overall motor function, in patients with advanced PD. The degree of PIGD at the preoperative evaluation can be used to predict long-term outcomes after STN-DBS surgery.

Intestinal Levodopa/Carbidopa Infusion as a Therapeutic Option for Unresponsive Freezing of Gait after Deep Brain Stimulation in Parkinson's Disease

Background

Treatment of freezing of gait (FOG) is always challenging because of its unpredictable nature and multifactorial physiopathology. Intestinal levodopa infusion has been proposed in recent years as a valuable option for its improvement. FOG in Parkinson's disease (PD) can appear after deep brain stimulation in patients who never had gait symptoms.

Objective

To study the effects of intestinal levodopa/carbidopa infusion in unresponsive-FOG that appears in PD patients treated with subthalamic nucleus deep brain stimulation.

Methods

We retrospectively collected and analyzed demographic, clinical, and therapeutic data from five PD patients treated with subthalamic nucleus stimulation who developed unresponsive-FOG and received intestinal levodopa/carbidopa infusion as an alternative therapy. FOG was measured based on scores in item 14 of the Unified Parkinson's Disease Rating Scale before and after intestinal levodopa infusion.

Results

Administration of intestinal levodopa caused improvement of FOG in the “ON” state in four patients (80%) by 2 or more points in item 14 of the Unified Parkinson's Disease Rating Scale. The improvement was maintained for at least 12 months.

Conclusions

Intestinal levodopa infusion may be a valuable therapeutic option for unresponsive-FOG developed after subthalamic nucleus deep brain stimulation.

Freezing of gait in Parkinson's disease: pathophysiology, risk factors and treatments

Background

Freezing of gait (FOG) is a common, disabling symptom of Parkinson's disease (PD), but the mechanisms and treatments of FOG remain great challenges for clinicians and researchers. The main focus of this review is to summarize the possible mechanisms underlying FOG, the risk factors for screening and predicting the onset of FOG, and the clinical trials involving various therapeutic strategies. In addition, the limitations and recommendations for future research design are also discussed.

Main body

In the mechanism section, we briefly introduced the physiological process of gait control and hypotheses about the mechanism of FOG. In the risk factor section, gait disorders, PIGD phenotype, lower striatal DAT uptake were found to be independent risk factors of FOG with consistent evidence. In the treatment section, we summarized the clinical trials of pharmacological and non-pharmacological treatments. Despite the limited effectiveness of current medications for FOG, especially levodopa resistant FOG, there were some drugs that showed promise such as istradefylline and rasagiline. Non-pharmacological treatments encompass invasive brain and spinal cord stimulation, noninvasive repetitive transcranial magnetic stimulation (rTMS) or transcranial direct current stimulation (tDCS) and vagus nerve stimulation (VNS), and physiotherapeutic approaches including cues and other training strategies. Several novel therapeutic strategies seem to be effective, such as rTMS over supplementary motor area (SMA), dual-site DBS, spinal cord stimulation (SCS) and VNS. Of physiotherapy, wearable cueing devices seem to be generally effective and promising.

Conclusion

FOG model hypotheses are helpful for better understanding and characterizing FOG and they provide clues for further research exploration. Several risk factors of FOG have been identified, but need combinatorial optimization for predicting FOG more precisely. Although firm conclusions cannot be drawn on therapeutic efficacy, the literature suggested that some therapeutic strategies showed promise.

Falls in Synucleinopathies

Parkinson's disease (PD) and other synucleinopathies, namely dementia with Lewy bodies (DLB) and multiple system atrophy (MSA), are common degenerative neurological disorders that share synuclein pathology. Although certain cardinal features of parkinsonism, including bradykinesia and rigidity, respond well to levodopa, axial features, such as gait and balance impairment, are less reliably responsive to dopaminergic therapy and surgical interventions. Consequently, falls are common in PD and other synucleinopathies and are a major contributor toward injury and loss of independence. This underscores the need for appropriate fall risk assessment and implementation of preventative measures in all patients with parkinsonism. The aim of this review is therefore to explore modifiable and non-modifiable risk factors for falls in synucleinopathies. We next review and evaluate the evidence for pharmacological, nonpharmacological, and surgical approaches for fall prevention, and emphasize individualized and multifaceted approaches.

[Deep brain stimulation effect on postural instability and gait disorders in Parkinson's disease]

An effect of deep brain stimulation on postural instability and gait disorders in Parkinson's disease S.G. Sultanova, N.V. Fedorova, E.V. Bril, A.A. Gamaleya, A.A. Tomskiy During the last time, surgical treatment of patients with Parkinson's disease has firmly taken its place in the general algorithm for managing patients with this pathology. Deep brain electrostimulation is the most advanced and promising method, which allows the reduction in the severity of main clinical manifestations of the disease, including axial symptoms. It is noted that certain temporal aspects of parkinsonian gait disorder remain therapeutically resistant. Subthalamic nucleus stimulation was also reported to improve levodopa-responsive freezing of gait. In this review, the authors summarize the effects of deep brain stimulation on gait and postural symptoms.

Deep brain stimulation in Parkinson's disease: A multicentric, long-term, observational pilot study

BACKGROUND

The impact of deep brain stimulation (DBS) on cognitive and urinary disorders, falls, and eventually hospitalizations and mortality in Parkinson's disease (PD) is still debated.

OBJECTIVE

We compared the rates of dementia, mild cognitive impairment (MCI), urinary incontinence, nocturia, falls, hospitalizations, and mortality in a cohort of PD patients undergoing DBS with a cohort of medically-treated patients chosen as controls.

METHODS

We conducted a retrospective pilot study in six Italian DBS centers. 91 PD patients receiving DBS and 91 age- and gender-matched controls receiving the best medical treatment alone with a minimum follow-up of one year were enrolled. Clinical data were collected from baseline to the last follow-up visit using an ad-hoc developed web-based system.

RESULTS

The risk of dementia was similar in the two groups while patients in the surgical cohort had lower rates of MCI, urinary incontinence, nocturia, and falls. In contrast, the risk of hospital admissions related to PD was higher in the surgical cohort. However, when excluding hospitalizations related to DBS surgery, the difference between the two cohorts was not significant. The surgical cohort had a lower number of hospitalizations not related to PD. The risk of death was similar in the two groups.

CONCLUSION

Despite a higher risk of hospitalization, patients receiving DBS had a lower rate of MCI, urinary incontinence, nocturia and falls, without evidence of an increased risk of dementia and mortality. Although these findings need to be confirmed in prospective studies, they seem to suggest that DBS may play a significant role in the management of non-motor symptoms and common complications of advanced PD.

Deep Brain Stimulation for Parkinson Disease Does not Worsen or Improve Postural Instability: A Prospective Cohort Trial

BACKGROUND

Falls and postural instability (PI) are major sources of morbidity in Parkinson disease (PD). Deep brain stimulation (DBS) is a major therapy for PD. The effects of DBS on PI and falls remain controversial.

OBJECTIVE

To study if DBS worsens PI, validated measures of PI (Timed Up and Go, Berg Balance Scale, Unified Parkinson's Disease Rating Scale 3.12 [Pull Test], and the Biodex Sway Index with eyes closed on a firm and soft surface) and reported falls were used to prospectively evaluate the effect of DBS on PI at 3 and 12 mo postoperatively compared to baseline measurements. The primary outcomes were a positive result on 4 out of the 5 PI tests and falls.

METHODS

Patients presenting for DBS were prospectively enrolled and evaluated at presentation and, 3 and 12 mo postoperatively. All tests were performed at each visit.

RESULTS

At 3 mo 4 of 5 positive showed noninferiority to baseline, with a rate of 28% vs 41% (relative risk [RR] 0.8 [0.5-1.3]). At 12 mo, 4 of 5 positive had a rate of 35% vs 30% (RR 1.2 [0.8-1.8]) and falls had a rate of 54% vs 46% (RR 1.2 [0.6-2.3]). These did not meet criteria to prove noninferiority. Sensitivity analysis at 12 mo showed noninferiority for 4 of 5 (RR 0.9 [0.6-1.5]) but not falls (RR 1.1 [0.5-2.3]).

CONCLUSION

This evidence is consistent with the hypothesis that DBS does not worsen PI when measured at 3 and 12 mo postoperatively.

Proceedings of the Sixth Deep Brain Stimulation Think Tank Modulation of Brain Networks and Application of Advanced Neuroimaging, Neurophysiology, and Optogenetics

The annual deep brain stimulation (DBS) Think Tank aims to create an opportunity for a multidisciplinary discussion in the field of neuromodulation to examine developments, opportunities and challenges in the field. The proceedings of the Sixth Annual Think Tank recapitulate progress in applications of neurotechnology, neurophysiology, and emerging techniques for the treatment of a range of psychiatric and neurological conditions including Parkinson’s disease, essential tremor, Tourette syndrome, epilepsy, cognitive disorders, and addiction. Each section of this overview provides insight about the understanding of neuromodulation for specific disease and discusses current challenges and future directions. This year’s report addresses key issues in implementing advanced neurophysiological techniques, evolving use of novel modulation techniques to deliver DBS, ans improved neuroimaging techniques. The proceedings also offer insights into the new era of brain network neuromodulation and connectomic DBS to define and target dysfunctional brain networks. The proceedings also focused on innovations in applications and understanding of adaptive DBS (closed-loop systems), the use and applications of optogenetics in the field of neurostimulation and the need to develop databases for DBS indications. Finally, updates on neuroethical, legal, social, and policy issues relevant to DBS research are discussed.

Postural instability and gait disorders after subthalamic nucleus deep brain stimulation in Parkinson's disease: a PET study

INTRODUCTION

Patients with Parkinson's disease sometimes report postural instability and gait disorders (PIGD) after subthalamic nucleus deep brain stimulation (STN-DBS). Whether this is the direct consequence of DBS or the result of natural disease progression is still subject to debate.

OBJECTIVE

To compare changes in brain metabolism during STN-DBS between patients with and without PIGD after surgery.

METHODS

We extracted consecutive patients from a database where all Rennes Hospital patients undergoing STN-DBS are registered, with regular prospective updates of their clinical data. Patients were divided into two groups (PIGD and No PIGD) according to changes after surgery, as measured with a composite score based on the selected Unified Parkinson's Disease Rating Scale items. All patients underwent positron emission tomography with ¹⁸[F]-fluorodeoxyglucose 3 months before and after surgery. We ran an ANOVA with two factors (group: PIGD vs. No PIGD; and phase: preoperative vs. postoperative) on SPM8 to compare changes in brain metabolism between the two groups.

RESULTS

Participants were 56 patients, including 10 in the PIGD group. The two groups had similar baseline (i.e., before surgery) characteristics. We found two clusters of increased metabolism in the PIGD group relative to the No PIGD group: dorsal midbrain/pons, including locomotor mesencephalic region and reticular pontine formation, and right motor cerebellum.

CONCLUSION

We found different metabolic changes during DBS-STN among patients with PIGD, concerning brain regions that are already known to be involved in gait disorders in Parkinson's disease, suggesting that DBS is responsible for the appearance of PIGD.

Acute Effects of Subthalamic Deep Brain Stimulation on Motor Outcomes in Parkinson's Disease; 13 Year Follow Up

Objective: Deep brain stimulation of the Subthalamic nucleus (STN-DBS) is a safe and well-established therapy for the management of refractory motor symptoms in Parkinson's disease (PD). Marked improvement in axial symptoms has been reported in the short term with STN-DBS but questions remain regarding the long-term efficacy of this intervention. We assessed the acute ON and OFF effects of STN-DBS in PD patients who have been treated with STN-DBS for over a decade.

Methods: We assessed 11 patients with early-onset PD (9 men, 2 women; mean age, 57.1 ± 7.2 y; mean age at illness onset, 38.9 ± 7.5 y) managed with long-term bilateral STN-DBS (mean treatment duration, 13.4 ± 1.3 y). Motor symptoms were assessed by means of the Unified Parkinson's Disease Rating Scale (UPDRS)-III, Timed Up and Go test (TUG), and Hoehn-Yahr scale. Motor assessments in the medication ON and OFF states with stimulation ON and OFF conditions were documented and video recorded.

Results: Patients showed a significant improvement in motor symptoms both in the off-medication and on-medication state by a 54% reduction (off-medication/on-stimulation vs. off-medication/off-stimulation) and a 48% reduction (on-medication/on-stimulation vs. on-medication/off-stimulation) in the total UPDRS-III score. Specifically, improvement in axial symptoms (off-medication: 51% reduction; on-medication: 44% reduction), including gait but not posture. Similarly, STN-DBS reduced TUG scores (off-medication: 70% reduction; on-medication: 47% reduction).

Conclusions: On stimulation long-term, bilateral STN-DBS can improve appendicular and axial symptoms of patients with early-onset PD in the acute setting.

Short-Term Dosage Regimen for Stimulation-Induced Long-Lasting Desynchronization

In this paper, we computationally generate hypotheses for dose-finding studies in the context of desynchronizing neuromodulation techniques. Abnormally strong neuronal synchronization is a hallmark of several brain disorders. Coordinated Reset (CR) stimulation is a spatio-temporally patterned stimulation technique that specifically aims at disrupting abnormal neuronal synchrony. In networks with spike-timing-dependent plasticity CR stimulation may ultimately cause an anti-kindling, i.e., an unlearning of abnormal synaptic connectivity and neuronal synchrony. This long-lasting desynchronization was theoretically predicted and verified in several pre-clinical and clinical studies. We have shown that CR stimulation with rapidly varying sequences (RVS) robustly induces an anti-kindling at low intensities e.g., if the CR stimulation frequency (i.e., stimulus pattern repetition rate) is in the range of the frequency of the neuronal oscillation. In contrast, CR stimulation with slowly varying sequences (SVS) turned out to induce an anti-kindling more strongly, but less robustly with respect to variations of the CR stimulation frequency. Motivated by clinical constraints and inspired by the spacing principle of learning theory, in this computational study we propose a short-term dosage regimen that enables a robust anti-kindling effect of both RVS and SVS CR stimulation, also for those parameter values where RVS and SVS CR stimulation previously turned out to be ineffective. Intriguingly, for the vast majority of parameter values tested, spaced multishot CR stimulation with demand-controlled variation of stimulation frequency and intensity caused a robust and pronounced anti-kindling. In contrast, spaced CR stimulation with fixed stimulation parameters as well as singleshot CR stimulation of equal integral duration failed to improve the stimulation outcome. In the model network under consideration, our short-term dosage regimen enables to robustly induce long-term desynchronization at comparably short stimulation duration and low integral stimulation duration. Currently, clinical proof of concept is available for deep brain CR stimulation for Parkinson's therapy and acoustic CR stimulation for tinnitus therapy. Promising first in human data is available for vibrotactile CR stimulation for Parkinson's treatment. For the clinical development of these treatments it is mandatory to perform dose-finding studies to reveal optimal stimulation parameters and dosage regimens. Our findings can straightforwardly be tested in human dose-finding studies.

Physical therapy and deep brain stimulation in Parkinson's Disease: protocol for a pilot randomized controlled trial

BACKGROUND

Subthalamic nucleus deep brain stimulation (STN-DBS) reduces tremor, muscle stiffness, and bradykinesia in people with Parkinson's Disease (PD). Walking speed, known to be reduced in PD, typically improves after surgery; however, other important aspects of gait may not improve. Furthermore, balance may worsen and falls may increase after STN-DBS. Thus, interventions to improve balance and gait could reduce morbidity and improve quality of life following STN-DBS. Physical therapy (PT) effectively improves balance and gait in people with PD, but studies on the effects of PT have not been extended to those treated with STN-DBS. As such, the efficacy, safety, and feasibility of PT in this population remain to be determined. The purpose of this pilot study is to address these unmet needs. We hypothesize that PT designed to target balance and gait impairment will be effective, safe, and feasible in this population.

METHODS/DESIGN

Participants with PD treated with STN-DBS will be randomly assigned to either a PT or control group. Participants assigned to PT will complete an 8-week, twice-weekly PT program consisting of exercises designed to improve balance and gait. Control group participants will receive the current standard of care following STN-DBS, which does not include prescription of PT. The primary aim is to assess preliminary efficacy of PT on balance (Balance Evaluation Systems Test). A secondary aim is to assess efficacy of PT on gait (GAITRite instrumented walkway). Participants will be assessed OFF medication/OFF stimulation and ON medication/ON stimulation at baseline and at 8 and 12 weeks after baseline. Adverse events will be measured over the duration of the study, and adherence to PT will be measured to determine feasibility.

DISCUSSION

To our knowledge, this will be the first study to explore the preliminary efficacy, safety, and feasibility of PT for individuals with PD with STN-DBS. If the study suggests potential efficacy, then this would justify larger trials to test effectiveness and safety of PT for those with PD with STN-DBS.

TRIAL REGISTRATION

NCT03181282 (clinicaltrials.gov). Registered on 7 June 2017.

Multisite Delayed Feedback for Electrical Brain Stimulation

Demand-controlled deep brain stimulation (DBS) appears to be a promising approach for the treatment of Parkinson's disease (PD) as revealed by computational, pre-clinical and clinical studies. Stimulation delivery is adapted to brain activity, for example, to the amount of neuronal activity considered to be abnormal. Such a closed-loop stimulation setup might help to reduce the amount of stimulation current, thereby maintaining therapeutic efficacy. In the context of the development of stimulation techniques that aim to restore desynchronized neuronal activity on a long-term basis, specific closed-loop stimulation protocols were designed computationally. These feedback techniques, e.g., pulsatile linear delayed feedback (LDF) or pulsatile nonlinear delayed feedback (NDF), were computationally developed to counteract abnormal neuronal synchronization characteristic for PD and other neurological disorders. By design, these techniques are intrinsically demand-controlled methods, where the amplitude of the stimulation signal is reduced when the desired desynchronized regime is reached. We here introduce a novel demand-controlled stimulation method, pulsatile multisite linear delayed feedback (MLDF), by employing MLDF to modulate the pulse amplitude of high-frequency (HF) DBS, in this way aiming at a specific, MLDF-related desynchronizing impact, while maintaining safety requirements with the charge-balanced HF DBS. Previously, MLDF was computationally developed for the control of spatio-temporal synchronized patterns and cluster states in neuronal populations. Here, in a physiologically motivated model network comprising neurons from subthalamic nucleus (STN) and external globus pallidus (GPe), we compare pulsatile MLDF to pulsatile LDF for the case where the smooth feedback signals are used to modulate the amplitude of charge-balanced HF DBS and suggest a modification of pulsatile MLDF which enables a pronounced desynchronizing impact. Our results may contribute to further clinical development of closed-loop DBS techniques.

A meta-analysis of the pedunculopontine nucleus deep-brain stimulation effects on Parkinson's disease

Postural instability and gait disturbance (PIGD) are common symptoms in patients with advanced Parkinson's disease (PD). The deep-brain stimulation (DBS) of the pedunculopontine nucleus (PPN) shows a promising effect on PIGD. However, the quantitative effects of PPN DBS for PD, especially for PIGD, and the efficacy of PPN DBS combined with levodopa are controversial and ambiguous to clinical practice. We carried out a meta-analysis of original researches on PPN to PIGD/PD from the electronic databases MEDLINE and EMBASE. The scores of united Parkinson's disease rating scores (UPDRS) III were used to evaluate the improvement in motor function and the scores of UPDRS III subitems 27-30 were used to evaluate the improvement in PIGD. The outcome was expressed as the mean difference and the percentage change between the scores of baseline and end point. The quality of studies was assessed using the 'assessing risk of bias' table. Overall, 909 articles were screened and seven studies were included with a total of 45 patients. The improvement in PIGD was significant, but there were no such effects on motor function. All the differences in PIGD scores were greater in the OFF medicine state rather than the ON medicine state, especially in the comparison between postsurgery ON stimulation and presurgery. PPN DBS indeed improved PIGD in advanced PD patients. This result could inspire more researchers to focus on its clinical application.

Asymmetric neuromodulation of motor circuits in Parkinson's disease: The role of subthalamic deep brain stimulation

Whereas hemispheric dominance is well-established for appendicular motor control in humans, the evidence for dominance in axial motor control is still scarce. In Parkinson's disease (PD), unilateral (UL) onset of appendicular motor symptoms corresponds with asymmetric neurodegeneration predominantly affecting contralateral nigrostriatal circuits. Disease progression yields bilateral and axial motor symptoms but the initial appendicular asymmetry usually persists. Furthermore, there is evidence for hemispheric dominance for axial motor dysfunction in some of these patients. Dopaminergic medications improve appendicular symptoms but can also produce motor complications over time. Once these complications develop, bilateral (BL) deep brain stimulation (DBS) of the subthalamic nuclei (STN) can significantly improve appendicular symptoms while reducing medication doses and motor complications. Conversely, axial motor symptoms remain a significant source of disability, morbidity, and mortality for patients with PD. These axial symptoms do not necessarily improve with dopaminergic therapy, might not respond, and could even worsen after BL-DBS. In contrast to medications, DBS provides the opportunity to modify stimulation parameters for each cerebral hemisphere. Identical, BL-DBS of motor circuits with hemispheric dominance in PD might produce overstimulation on one side and/or understimulation on the other side, which could contribute to motor dysfunction. Several studies based on asymmetry of appendicular motor symptoms already support an initial UL rather than BL approach to DBS in some patients. The response of axial motor symptoms to UL versus BL-DBS remains unclear. Nonetheless, UL-DBS, staged BL-DBS, or asymmetric programming of BL-DBS could also be considered in patients with PD.

Deep Brain Stimulation in Parkinson's Disease: New and Emerging Targets for Refractory Motor and Nonmotor Symptoms

Parkinson's disease (PD) is a progressive neurodegenerative condition characterized by bradykinesia, tremor, rigidity, and postural instability (PI), in addition to numerous nonmotor manifestations. Many pharmacological therapies now exist to successfully treat PD motor symptoms; however, as the disease progresses, it often becomes challenging to treat with medications alone. Deep brain stimulation (DBS) has become a crucial player in PD treatment, particularly for patients who have disabling motor complications from medical treatment. Well-established DBS targets include the subthalamic nucleus (STN), the globus pallidus pars interna (GPi), and to a lesser degree the ventral intermediate nucleus (VIM) of the thalamus. Studies of alternative DBS targets for PD are ongoing, the majority of which have shown some clinical benefit; however, more carefully designed and controlled studies are needed. In the present review, we discuss the role of these new and emerging DBS targets in treating refractory axial motor symptoms and other motor and nonmotor symptoms (NMS).

Adverse events in deep brain stimulation: A retrospective long-term analysis of neurological, psychiatric and other occurrences

Background and objective

The extent to which deep brain stimulation (DBS) can improve quality of life may be perceived as a permanent trade-off between neurological improvements and complications of therapy, comorbidities, and disease progression.

Patients and methods

We retrospectively investigated 123 consecutive and non-preselected patients. Indications for DBS surgery were Parkinson's disease (82), dystonia (18), tremor of different etiology (21), Huntington's disease (1) and Gilles de la Tourette syndrome (1). AEs were defined as any untoward clinical occurrence, sign or patient complaint or unintended disease if related or unrelated to the surgical procedures, implanted devices or ongoing DBS therapy.

Results

Over a mean/median follow-up period of 4.7 years (578 patient-years) 433 AEs were recorded in 106 of 123 patients (86.2%). There was no mortality or persistent morbidity from the surgical procedure. All serious adverse events (SAEs) that occurred within 4 weeks of surgery were reversible. Neurological AEs (193 in 85 patients) and psychiatric AEs (78 in 48 patients) were documented most frequently. AEs in 4 patients (suicide under GPI stimulation, weight gain >20 kg, impairment of gait and speech, cognitive decline >2 years following surgery) were severe or worse, at least possibly related to DBS and non reversible. In PD 23.1% of the STN-stimulated patients experienced non-reversible (or unknown reversibility) AEs that were at least possibly related to DBS in the form of impaired speech or gait, depression, weight gain, cognitive disturbances or urinary incontinence (severity was mild or moderate in 15 of 18 patients). Age and Hoehn&Yahr stage of STN-simulated PD patients, but not preoperative motor impairment or response to levodopa, showed a weak correlation (r = 0.24 and 0.22, respectively) with the number of AEs.

Conclusions

DBS-related AEs that were severe or worse and non-reversible were only observed in PD (4 of 82 patients; 4.9%), but not in other diseases. PD patients exhibited a significant risk for non-severe AEs most of which also represented preexisting and progressive axial and non-motor symptoms of PD. Mild gait and/or speech disturbances were rather frequent complaints under VIM stimulation. GPI stimulation for dystonia could be applied with negligible DBS-related side effects.

Comparison of Pallidal and Subthalamic Deep Brain Stimulation in Parkinson's Disease: Therapeutic and Adverse Effects

OBJECTIVE

To compare the therapeutic and adverse effects of globus pallidus interna (GPi) and subthalamic nucleus (STN) deep brain stimulation (DBS) for the treatment of advanced Parkinson's disease (PD).

METHODS

We retrospectively analyzed the clinical data of patients with PD who underwent GPi (n = 14) or STN (n = 28) DBS surgery between April 2002 and May 2014. The subjects were matched for age at surgery and disease duration. The Unified Parkinson's Disease Rating Scale (UPDRS) scores and levodopa equivalent dose (LED) at baseline and 12 months after surgery were used to assess the therapeutic effects of DBS. Adverse effects were also compared between the two groups.

RESULTS

At 12 months, the mean changes in the UPDRS total and part I-IV scores did not differ significantly between the two groups. However, the subscores for gait disturbance/postural instability and dyskinesia were significantly more improved after GPi DBS than those after STN DBS (p = 0.024 and 0.016, respectively). The LED was significantly more reduced in patients after STN DBS than that after GPi DBS (p = 0.004). Serious adverse effects did not differ between the two groups (p = 0.697).

CONCLUSION

The patients with PD showed greater improvement in gait disturbance/postural instability and dyskinesia after GPi DBS compared with those after STN DBS, although the patients had a greater reduction in LED after STN DBS. These results may provide useful information for optimal target selection for DBS in PD.

Stratifying Parkinson's Patients With STN-DBS Into High-Frequency or 60 Hz-Frequency Modulation Using a Computational Model

OBJECTIVE

High frequency stimulation (HFS) of the subthalamic nucleus (STN) is a well-established therapy for Parkinson's disease (PD), particularly the cardinal motor symptoms and levodopa induced motor complications. Recent studies have suggested the possible role of 60 Hz stimulation in STN-deep brain stimulation (DBS) for patients with gait disorder. The objective of this study was to develop a computational model, which stratifies patients a priori based on symptomatology into different frequency settings (i.e., high frequency or 60 Hz).

METHODS

We retrospectively analyzed preoperative MDS-Unified Parkinson's Disease Rating Scale III scores (32 indicators) collected from 20 PD patients implanted with STN-DBS at Mount Sinai Medical Center on either 60 Hz stimulation (ten patients) or HFS (130-185 Hz) (ten patients) for an average of 12 months. Predictive models using the Random Forest classification algorithm were built to associate patient/disease characteristics at surgery to the stimulation frequency. These models were evaluated objectively using leave-one-out cross-validation approach.

RESULTS

The computational models produced, stratified patients into 60 Hz or HFS (130-185 Hz) with 95% accuracy. The best models relied on two or three predictors out of the 32 analyzed for classification. Across all predictors, gait and rest tremor of the right hand were consistently the most important.

CONCLUSIONS

Computational models were developed using preoperative clinical indicators in PD patients treated with STN-DBS. These models were able to accurately stratify PD patients into 60 Hz stimulation or HFS (130-185 Hz) groups a priori, offering a unique potential to enhance the utilization of this therapy based on clinical subtypes.

Current Practice and the Future of Deep Brain Stimulation Therapy in Parkinson's Disease

Deep brain stimulation (DBS) is an effective therapy for Parkinson's disease patients experiencing motor fluctuations, medication-resistant tremor, and/or dyskinesia. Currently, the subthalamic nucleus and the globus pallidus internus are the two most widely used targets, with individual advantages and disadvantages influencing patient selection. Potential DBS patients are selected using the few existing guidelines and the available DBS literature, and many centers employ an interdisciplinary team review of the individual's risk-benefit profile. Programmed settings vary based on institution- or physician-specific protocols designed to maximize benefits and limit adverse effects. Expectations should be realistic and clearly defined during the evaluation process, and each bothersome symptom should be addressed in the context of building the risk-benefit profile. Current DBS research is focused on improved symptom control, the development of newer technologies, and the improved efficiency of stimulation delivery. Techniques deliver stimulation in a more personalized way, and methods of adaptive DBS such as closed-loop approaches are already on the horizon.

Pulsatile desynchronizing delayed feedback for closed-loop deep brain stimulation

High-frequency (HF) deep brain stimulation (DBS) is the gold standard for the treatment of medically refractory movement disorders like Parkinson’s disease, essential tremor, and dystonia, with a significant potential for application to other neurological diseases. The standard setup of HF DBS utilizes an open-loop stimulation protocol, where a permanent HF electrical pulse train is administered to the brain target areas irrespectively of the ongoing neuronal dynamics. Recent experimental and clinical studies demonstrate that a closed-loop, adaptive DBS might be superior to the open-loop setup. We here combine the notion of the adaptive high-frequency stimulation approach, that aims at delivering stimulation adapted to the extent of appropriately detected biomarkers, with specifically desynchronizing stimulation protocols. To this end, we extend the delayed feedback stimulation methods, which are intrinsically closed-loop techniques and specifically designed to desynchronize abnormal neuronal synchronization, to pulsatile electrical brain stimulation. We show that permanent pulsatile high-frequency stimulation subjected to an amplitude modulation by linear or nonlinear delayed feedback methods can effectively and robustly desynchronize a STN-GPe network of model neurons and suggest this approach for desynchronizing closed-loop DBS.

Subthalamic nucleus stimulation and gait in Parkinson's Disease: a not always fruitful relationship

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) provides efficient treatment for the alleviation of motor signs in patients with advanced Parkinson's disease (PD), but its specific effects on gait is sometimes less successful as it may even lead to an aggravation of freezing of gait. To better understand when axial symptoms can be expected to improve and when they may worsen or be resistant to STN-DBS, we propose here a narrative review that considers the recent literature evidences based on instrumental gait analysis data. Our aim is to report about the efficacy of STN-DBS on PD gait, analyzing the clinical and procedural factors involved, and discussing the strategies for optimizing such effectiveness in patients with advanced PD.

Gait function and locus coeruleus Lewy body pathology in 51 Parkinson's disease patients

INTRODUCTION

Gait impairment in Parkinson's Disease (PD) is often severely disabling, yet frequently remains refractory to treatment. The locus coeruleus (LC) has diffuse noradrenergic projections that are thought to play a role in gait function. Enhancement of norepinephrine transmission may improve gait in some PD patients. We hypothesized that the severity of PD pathology, and more specifically, Lewy bodies and neuronal loss in the LC, would correlate with the severity of gait dysfunction in PD.

METHODS

Autopsy data from 51 patients, collected through the Morris K. Udall Parkinson's Disease Research Center, were correlated with clinical gait-related measures, including individual Unified Parkinson's Disease Rating Scale (UPDRS) Part II and III questions, total UPDRS Part III scores, and timed up-and-go speed (TUG).

RESULTS

Neither the presence nor degree of Lewy body pathology in the LC on autopsy was associated with a higher UPDRS part III gait score. LC tau deposition and frontal Lewy body deposition were not correlated with any of the assessed gait measures. The degree of Lewy body pathology, independent of Braak stage, was positively associated with the severity of motor symptoms overall (UPDRS Part III total score).

CONCLUSION

Neither the degree of Lewy body nor tau pathology in the LC is associated with severity of gait disorders in PD. This finding may have implications for targeted noradrenergic therapies in patients with refractory gait disorders.

Coordinated Reset Deep Brain Stimulation of Subthalamic Nucleus Produces Long-Lasting, Dose-Dependent Motor Improvements in the 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine Non-Human Primate Model of Parkinsonism

BACKGROUND

Novel deep brain stimulation (DBS) paradigms are being explored in an effort to further optimize therapeutic outcome for patients with Parkinson's disease (PD). One approach, termed 'Coordinated Reset' (CR) DBS, was developed to target pathological oscillatory network activity. with desynchronizing effects and associated therapeutic benefit hypothesized to endure beyond cessation of stimulus delivery.

OBJECTIVE

To characterize the acute and carry-over effects of low-intensity CR DBS versus traditional DBS (tDBS) in the region of the subthalamic nucleus (STN).

METHODS

A within-subject, block treatment design involving the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) non-human primate model of parkinsonism was used. Each treatment block consisted of five days of daily DBS delivery followed by a one week minimum post-treatment observation window. Motor behavior was quantified using a modified rating scale for both animals combined with an objective, upper-extremity reach task in one animal.

RESULTS

Both animals demonstrated significant motor improvements during acute tDBS; however, within-session and post-treatment carry-over was limited. Acute motor improvements were also observed in response to low-intensity CR DBS; however, both within- and between-session therapeutic carry-over enhanced progressively following each daily treatment. Moreover, in contrast to tDBS, five consecutive days of CR DBS treatment yielded carry-over benefits that persisted for up to two weeks without additional intervention. Notably, the magnitude and time-course of CR DBS' effects on each animal varied with daily dose-duration, pointing to possible interaction effects involving baseline parkinsonian severity.

CONCLUSION

Our results support the therapeutic promise of CR DBS for PD, including its potential to induce carryover while reducing both side effect risk and hardware power consumption.

Anti-kindling Induced by Two-Stage Coordinated Reset Stimulation with Weak Onset Intensity

Abnormal neuronal synchrony plays an important role in a number of brain diseases. To specifically counteract abnormal neuronal synchrony by desynchronization, Coordinated Reset (CR) stimulation, a spatiotemporally patterned stimulation technique, was designed with computational means. In neuronal networks with spike timing–dependent plasticity CR stimulation causes a decrease of synaptic weights and finally anti-kindling, i.e., unlearning of abnormally strong synaptic connectivity and abnormal neuronal synchrony. Long-lasting desynchronizing aftereffects of CR stimulation have been verified in pre-clinical and clinical proof of concept studies. In general, for different neuromodulation approaches, both invasive and non-invasive, it is desirable to enable effective stimulation at reduced stimulation intensities, thereby avoiding side effects. For the first time, we here present a two-stage CR stimulation protocol, where two qualitatively different types of CR stimulation are delivered one after another, and the first stage comes at a particularly weak stimulation intensity. Numerical simulations show that a two-stage CR stimulation can induce the same degree of anti-kindling as a single-stage CR stimulation with intermediate stimulation intensity. This stimulation approach might be clinically beneficial in patients suffering from brain diseases characterized by abnormal neuronal synchrony where a first treatment stage should be performed at particularly weak stimulation intensities in order to avoid side effects. This might, e.g., be relevant in the context of acoustic CR stimulation in tinnitus patients with hyperacusis or in the case of electrical deep brain CR stimulation with sub-optimally positioned leads or side effects caused by stimulation of the target itself. We discuss how to apply our method in first in man and proof of concept studies.

Subthalamic stimulation may inhibit the beneficial effects of levodopa on akinesia and gait

BACKGROUND

Gait and akinesia deterioration in PD patients during the immediate postoperative period of DBS has been directly related to stimulation in the subthalamic region. The underlying mechanisms remain poorly understood. The aim of the present study was to clinically and anatomically describe this side effect.

METHODS

PD patients presenting with a worsening of gait and/or akinesia following STN-DBS, that was reversible on stimulation arrest were included. The evaluation included (1) a Stand Walk Sit Test during a monopolar survey of each electrode in the on-drug condition; (2) a 5-condition test with the following conditions: off-drug/off-DBS, off-drug/on-best-compromise-DBS, on-drug/off-DBS, on-drug/on-best-compromise-DBS, and on-drug/on-worsening-DBS, which utilized the contact inducing the most prominent gait deterioration. The following scales were performed: UPDRSIII subscores, Stand Walk Sit Test, and dyskinesia and freezing of gait scales. Localization of contacts was performed using a coregistration method.

RESULTS

Twelve of 17 patients underwent the complete evaluation. Stimulation of the most proximal contacts significantly slowed down the Stand Walk Sit Test. The on-drug/on-worsening-DBS condition compared with the on-drug/off-DBS condition worsened akinesia (P = 0.02), Stand Walk Sit Test (P = 0.001), freezing of gait (P = 0.02), and improved dyskinesias (P = 0.003). Compared with the off-drug/off-DBS condition, the on-drug/on-worsening-DBS condition improved rigidity (P = 0.007) and tremor (P = 0.007). Worsening contact sites were predominantly dorsal and anterior to the STN in the anterior zona incerta and Forel fields H2.

CONCLUSIONS

A paradoxical deterioration of gait and akinesia is a rare side effect following STN-DBS. We propose that this may be related to misplaced contacts, and we discuss the pathophysiology and strategies to identify and manage this complication. © 2016 International Parkinson and Movement Disorder Society.

A Prospective Evaluation of an Outpatient Assessment of Postural Instability to Predict Risk of Falls in Patients with Parkinson's Disease Presenting for Deep Brain Stimulation

Background

Postural instability (PI) and falls, major causes of morbidity in patients with PD, are often overlooked. DBS is a mainstay therapy for Parkinson's disease (PD) and has been purported to both worsen and improve PI. An effective PI evaluation that can predict fall risk in patients with PD presenting for DBS is needed.

Methods

Forty-nine consecutive patients with PD were enrolled. Self-reported falls were the gold standard. Tests evaluated were the Berg Balance Scale (BBS), Timed-Up-and-Go (TUG), Pull Test, and Biodex Balance System Sway Index on firm (SI-FIRM) and soft (SI-SOFT) surfaces.

Results

The best single tests for fall risk were the BBS and SI-FIRM, each with sensitivities of 79% and specificities of 60% and 65%, respectively. When the evaluation was combined into a composite measure requiring four positive tests out of five, the sensitivity was 72% and specificity was 80%.

Conclusions

A simple, efficient outpatient physical therapy assessment is effective in diagnosing fall risk in patients with PD.