Modulation of specific components of sleep disturbances by simultaneous subthalamic and nigral stimulation in Parkinson's disease

Neuroprotective Effect of Melatonin on Sleep Disorders Associated with Parkinson's Disease

Parkinson's disease (PD) is a complex, multisystem disorder with both neurologic and systemic manifestations, which is usually associated with non-motor symptoms, including sleep disorders. Such associated sleep disorders are commonly observed as REM sleep behavior disorder, insomnia, sleep-related breathing disorders, excessive daytime sleepiness, restless legs syndrome and periodic limb movements. Melatonin has a wide range of regulatory effects, such as synchronizing circadian rhythm, and is expected to be a potential new circadian treatment of sleep disorders in PD patients. In fact, ongoing clinical trials with melatonin in PD highlight melatonin's therapeutic effects in this disease. Mechanistically, melatonin plays its antioxidant, anti-inflammatory, anti-excitotoxity, anti-synaptic dysfunction and anti-apoptotic activities. In addition, melatonin attenuates the effects of genetic variation in the clock genes of Baml1 and Per1 to restore the circadian rhythm. Together, melatonin exerts various therapeutic effects in PD but their specific mechanisms require further investigations.

Electrophysiologic Evidence That Directional Deep Brain Stimulation Activates Distinct Neural Circuits in Patients With Parkinson Disease

OBJECTIVES

Deep brain stimulation (DBS) delivered via multicontact leads implanted in the basal ganglia is an established therapy to treat Parkinson disease (PD). However, the different neural circuits that can be modulated through stimulation on different DBS contacts are poorly understood. Evidence shows that electrically stimulating the subthalamic nucleus (STN) causes a therapeutic effect through antidromic activation of the hyperdirect pathway-a monosynaptic connection from the cortex to the STN. Recent studies suggest that stimulating the substantia nigra pars reticulata (SNr) may improve gait. The advent of directional DBS leads now provides a spatially precise means to probe these neural circuits and better understand how DBS affects distinct neural networks.

MATERIALS AND METHODS

We measured cortical evoked potentials (EPs) using electroencephalography (EEG) in response to low-frequency DBS using the different directional DBS contacts in eight patients with PD.

RESULTS

A short-latency EP at 3 milliseconds originating from the primary motor cortex appeared largest in amplitude when stimulating DBS contacts closest to the dorsolateral STN (p < 0.001). A long-latency EP at 10 milliseconds originating from the premotor cortex appeared strongest for DBS contacts closest to the SNr (p < 0.0001).

CONCLUSIONS

Our results show that at the individual patient level, electrical stimulation of different nuclei produces distinct EP signatures. Our approach could be used to identify the functional location of each DBS contact and thus help patient-specific DBS programming.

CLINICAL TRIAL REGISTRATION

The ClinicalTrials.gov registration number for the study is NCT04658641.

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.

Combined Stimulation of the Substantia Nigra and the Subthalamic Nucleus for the Treatment of Refractory Gait Disturbances in Parkinson's Disease: A Preliminary Study

Deep brain stimulation of the subthalamic nucleus is efficient for the treatment of motor symptoms (i.e., tremors) in patients with Parkinson's disease. Gait disorders usually appear during advanced stages of idiopathic Parkinson's disease in up to 80% of patients and have an important impact on their quality of life. The effects of deep brain stimulation of the subthalamic nucleus on gait and balance are still controversial. For this reason, alternative targets have been considered, such as stimulation of the pedunculopontine nucleus and the pars reticulata of substantia nigra, involved in the integration of the functional connections for gait. Due to the proximity of the subthalamic nucleus to the substantia nigra, their combined stimulation is feasible and may lead to better outcomes, improving axial symptoms. Our objective was to prospectively compare simultaneous stimulation of both structures versus conventional subthalamic stimulation in improving gait disorders. In ten patients with advanced Parkinson's disease, deep brain stimulation leads (eight linear contacts) were implanted, and gait analysis was performed 6 months after surgery in off-stimulation and after 4 weeks of dual or single subthalamic stimulation. An improvement in gait parameters was confirmed with both stimulation conditions, with better results with combined substantia nigra and subthalamic stimulation compared with conventional subthalamic stimulation. Further studies are needed to determine if this effect remains after long-term dual-target stimulation.

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.

Comparison of Shod and Unshod Gait in Patients With Parkinson's Disease With Subthalamic and Nigral Stimulation

Background: The Parkinsonian [i.e., Parkinson's disease (PD)] gait disorder represents a therapeutical challenge with residual symptoms despite the use of deep brain stimulation of the subthalamic nucleus (STN DBS) and medical and rehabilitative strategies. The aim of this study was to assess the effect of different DBS modes as combined stimulation of the STN and substantia nigra (STN+SN DBS) and environmental rehabilitative factors as footwear on gait kinematics.

Methods: This single-center, randomized, double-blind, crossover clinical trial assessed shod and unshod gait in patients with PD with medication in different DBS conditions (i.e., STIM OFF, STN DBS, and STN+SN DBS) during different gait tasks (i.e., normal gait, fast gait, and gait during dual task) and compared gait characteristics to healthy controls. Notably, 15 patients participated in the study, and 11 patients were analyzed after a dropout of four patients due to DBS-induced side effects.

Results: Gait was modulated by both factors, namely, footwear and DBS mode, in patients with PD. Footwear impacted gait characteristics in patients with PD similarly to controls with longer step length, lower cadence, and shorter single-support time. Interestingly, DBS exerted specific effects depending on gait tasks with increased cognitive load. STN+SN DBS was the most efficient DBS mode compared to STIM OFF and STN DBS with intense effects as step length increment during dual task.

Conclusion: The PD gait disorder is a multifactorial symptom, impacted by environmental factors as footwear and modulated by DBS. DBS effects on gait were specific depending on the gait task, with the most obvious effects with STN+SN DBS during gait with increased cognitive load.

The Impact of Deep Brain Stimulation on Sleep in Parkinson's Disease: An update

Background:

Parkinson’s disease (PD) can have a significant impact on sleep. Deep brain stimulation (DBS) is an effective treatment for motor features of PD, but less is understood about the impact DBS may have on sleep architecture and various sleep issues commonly seen in PD.

Objective:

To review the impact of DBS on various sleep issues in PD.

Methods:

We reviewed the literature regarding the impact of DBS on sleep patterns, nocturnal motor and non-motor symptoms, and sleep disorders in PD.

Results:

Objective sleep measures on polysomnography (PSG), including sleep latency and wake after sleep onset improve after subthalamic nucleus (STN) and globus pallidus interna (GPi) DBS. Subjective sleep measures, nocturnal motor symptoms, and some non-motor symptoms (nocturia) also may improve. Current evidence suggests STN DBS has no impact on Rapid Eye Movement Behavior Disorder (RBD), while STN DBS may improve symptoms of Restless Legs Syndrome (RLS). There are no studies that have evaluated the impact of GPi DBS on RBD, while it is unclear if GPi has an effect on RLS in PD.

Conclusion:

DBS therapy at either site appears to improve objective and subjective sleep parameters in patients with PD. Most likely, the improvement of motor and some non-motor nocturnal symptoms leads to an increase in total sleep time by up to an hour, as well as reduction of sleep fragmentation. DBS most likely has no impact on RBD, while there is evidence that STN DBS appears to help reduce RLS severity. Further studies are needed.

A quantitative analysis of the effect of bilateral subthalamic nucleus-deep brain stimulation on subjective and objective sleep parameters in Parkinson's disease

OBJECTIVE

To explore how subjective and objective sleep parameters respond to bilateral subthalamic nucleus-deep brain stimulation (STN-DBS) in patients with Parkinson's disease (PD).

METHODS

Thirty DBS sleep studies were included by searching PubMed, Embase, and the Cochrane Library, and only 21 prospectively designed studies, including 541 patients, were eligible for the main analysis. We evaluated sleep disturbance using 1 objective measurement, polysomnography (PSG), and 4 subjective scales, including PD Sleep Scale (PDSS), Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), and restless legs syndrome (RLS). We pooled data using the standard mean difference (SMD). The primary outcome was a change in sleep parameters 6 months postoperatively. Outcomes from <12 months to ≥12 months follow-up were compared in the subgroup analysis. Meta-regression was further conducted.

RESULTS

STN-DBS significantly improved all 4 subjective sleep scales in the 6-month follow-up: ESS (SMD = 0.234), PDSS (SMD = 0.724), PSQI (SMD = 1.374) and RLS (SMD = 1.086), while most PSG parameters remained unchanged, except for shortened rapid eye movement sleep latency (RSL) (SMD = 0.520). In the over-12-month follow-up, improvement persisted in PDSS but not in ESS. Dopamine drug reduction (p = 0.009) and motor improvement (p = 0.036) were correlated with ESS improvement and PDSS improvement, respectively.

CONCLUSIONS

Bilateral STN-DBS continuously improved subjective nocturnal sleep, while its effect on ESS lasted for only 1 year. Medication reduction and motor improvement may contribute to improved daytime sleepiness and better subjective nocturnal sleep, respectively. Except for a shortened RSL, STN-DBS did not change PSG parameters, including sleep efficiency and sleep architecture.

REGISTRATION

Open Science Framework: DOI 10.17605/OSF.IO/3EGRC.

6-Hydroxydopamine lesion and levodopa treatment modify the effect of buspirone in the substantia nigra pars reticulata

BACKGROUND AND PURPOSE

l-DOPA-induced dyskinesia (LID) is considered a major complication in the treatment of Parkinson's disease (PD). Buspirone (5-HT1A partial agonist) have shown promising results in the treatment of PD and LID, however no 5-HT-based treatment has been approved in PD. The present study was aimed to investigate how the substantia nigra pars reticulata (SNr) is affected by buspirone and whether it is a good target to study 5-HT antidyskinetic treatments.

EXPERIMENTAL APPROACH

Buspirone was studied using in vivo single-unit, electrocorticogram, local field potential recordings along with microdialysis and immunohistochemistry in naïve/sham, 6-hydroxydopamine (6-OHDA)-lesioned or 6-OHDA-lesioned and l-DOPA-treated (6-OHDA/l-DOPA) rats.

KEY RESULTS

Local buspirone inhibited SNr neuron activity in all groups. However, systemic buspirone reduced burst activity in 6-OHDA-lesioned rats (with or without l-DOPA treatment), whereas 8-OH-DPAT, a full 5-HT1A agonist induced larger inhibitory effects in sham animals. Neither buspirone nor 8-OH-DPAT markedly modified the low-frequency oscillatory activity in the SNr or synchronization within the SNr with the cortex. In addition, local perfusion of buspirone increased GABA and glutamate release in the SNr of naïve and 6-OHDA-lesioned rats but no effect in 6-OHDA/l-DOPA rats. In the 6-OHDA/l-DOPA group, increased 5-HT transporter and decreased 5-HT1A receptor expression was found.

CONCLUSIONS AND IMPLICATIONS

The effects of buspirone in SNr are influenced by dopamine loss and l-DOPA treatment. The present results suggest that the regulation of burst activity of the SNr induced by DA loss may be a good target to test new drugs for the treatment of PD and LID.

Improvement of Subthalamic Nucleus Deep Brain Stimulation in Sleeping Symptoms in Parkinson's Disease: A Meta-Analysis

Introduction

The aim of this meta-analysis was to evaluate the effects of STN DBS on sleep quality and restless leg symptoms in individuals with PD.

Methods

We searched the PubMed, Web of Science, EMBASE, CNKI, and WANFANG databases published between 1990 and 2019. The articles included were those that contained both pre- and postsurgery data acquired using International RLS Study Group criteria and the Pittsburgh sleep quality index (PSQI) questionnaire with patients' follow-up of at least three months. All studies that met the quality requirements were included in a meta-analysis performed using STATA 12.0 software.

Results

Of 73 articles identified, 7 studies comprising 82 patients were qualified for the current meta-analysis. After adjusting for heterogeneity in study effect sizes, the random effects meta-analysis indicated that STN DBS improved sleep quality and restless leg symptoms significantly (SMD = −1.111, 95% CI: −1.918∼−0.304, P=0.007). Subgroup analysis showed that different sleep scoring criteria had different effects on the condition of sleeping after surgery.

Conclusions

STN DBS is a powerful method in the management of sleep quality and restless leg symptoms in PD patients, but its long-term effects with larger populations must be thoroughly assessed.