Eleven-Year Outcomes of Deep Brain Stimulation in Early-Stage Parkinson Disease

Risk of fall with device-based advanced treatments in Parkinson's disease: a systematic review and network meta-analysis

BACKGROUND

Deep brain stimulation (DBS) and infusion therapies are effective treatments for the motor complications of Parkinson's disease (PD), but less established is their role in fall prevention. This systematic review and network meta-analysis (NMA) aimed to evaluate the risk of falls associated with advanced therapies in PD.

METHODS

Following PRISMA-NMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Network Meta-analyses) guidelines, we searched PubMed, Medline, Embase and CINAHL up to 20 March 2024. Eligibility criteria based on PICOS (Population Intervention Control Outcome Study design) framework were used for DBS of the subthalamic nucleus (STN) or globus pallidus pars interna (GPi), or infusion therapies, compared with best medical treatment (BMT) or sham stimulation. Pairwise meta-analysis was conducted using RevMan V.5.4, and NMA using the netmeta package in R software.

RESULTS

Fourteen studies were included. A higher number of falls were observed in the DBS group compared with BMT, although the difference was not significant. Sensitivity analysis excluding a heterogeneity-contributing study showed a significantly higher fall risk in the DBS group (Risk Ratio (RR)=2.74, 95% CI 1.60, 4.67, p=0.0002). Subgroup analyses indicated that levodopa-carbidopa intestinal gel tended towards increased fall risk, while continuous subcutaneous infusion of (fos)levodopa (CSCI) significantly decreased risk with high certainty of evidence. NMA showed CSCI as the most effective in reducing falls, while STN DBS was associated with the highest risk.

CONCLUSIONS

DBS, especially targeting the STN, may increase fall risk compared with other advanced non-DBS procedures. While LCIG might not alter fall risk, preliminary evidence suggests that CSCI positively affects fall prevention.

PROSPERO REGISTRATION NUMBER

CRD42023420637.

Deep brain stimulation halts Parkinson's disease-related immune dysregulation in the brain and peripheral blood

Immune dysregulation in the brain and periphery is thought to contribute to the detrimental neurodegeneration that occurs in Parkinson's disease (PD). Identifying mechanisms to reverse this dysregulation is key to developing disease-altering therapeutics for this currently incurable disease. Here we utilized the longitudinal data from the Parkinson's Progression Marker Initiative to demonstrate that circulating lymphocytes progressively decline in PD and can be used to predict future motor symptom progression. Deep brain stimulation (DBS), which is used as a symptomatic treatment, could halt this progressive decline. By analyzing specific immune populations from a second cohort of patients, we could show that DBS causes a shift from the pro-inflammatory CD4+ T helper 17 cells driving neurodegeneration to anti-inflammatory CD4+ regulatory T cells. RNA-sequencing and immunohistochemistry in the brain of the A53T alpha-synuclein rat model of PD revealed that DBS also decreases neuroinflammation. These data suggest a potential disease-altering role for DBS by halting inflammatory processes.

[Synergies Instead of Rivalries - Expert Opinion on the Misunderstood Roles of Continuous Intrajejunal Levodopa Therapy and Deep Brain Stimulation in the Treatment of Parkinson̓s Disease]

In the therapy of Parkinson̓s disease, both the intrajejunal administration of Levodopa/Carbidopa Intestinal Gel (LCIG) and, more recently, Levodopa/Carbidopa/Entacapone Intestinal Gel (LECIG), as well as deep brain stimulation (DBS), are employed. These approaches differ significantly in their efficacy and side effect profiles, as well as the timing of their use. Yet, the initiation of therapy for both methods is often simultaneously considered when patients have reached an advanced stage of the disease. From the authors' perspective, however, patients may reach the milestones for the indication of one of these respective treatments at different points in the course of the disease. Individual disease progression plays a pivotal role in this regard. The concept that all patients become candidates for a specific treatment at a predefined time appears erroneous to the authors. In the context of this review, therefore, the therapeutic modalities are presented in terms of their efficacy for different symptoms, the notion of simultaneous timing of their initiation is questioned, and an individualized therapy evaluation is derived, with a focus on quality of life and participation.

Advanced therapies in Parkinson's disease: an individualized approach to their indication

Device aided therapies (DAT) comprising the intrajejunal administration of levodopa/carbidopa intestinal gel (LCIG) and levodopa/carbidopa/entacapone intestinal gel (LECIG), the continuous subcutaneous application of foslevodopa/foscarbidopa or apomorphine infusion (CSAI) and deep brain stimulation (DBS) are used to treat Parkinson's disease with insufficient symptom alleviation under intensified pharmacotherapy. These DAT significantly differ in their efficacy profiles, indication, invasiveness, contraindications, and potential side effects. Usually, the evaluation of all these procedures is conducted simultaneously at the same point in time. However, as disease progression and symptom burden is extremely heterogeneous, clinical experience shows that patients reach the individual milestones for a certain therapy at different points in their disease course. Therefore, advocating for an individualized therapy evaluation for each DAT, requiring an ongoing evaluation. This necessitates that, during each consultation, the current symptomatology should be analyzed, and the potential suitability for a DAT be assessed. This work represents a critical interdisciplinary appraisal of these therapies in terms of their individual profiles and compares these DAT regarding contraindications, periprocedural considerations as well as their efficacy regarding motor- and non-motor deficits, supporting a personalized approach.

Deep brain stimulation for Tourette's syndrome

This is a protocol for a Cochrane Review (intervention). The objectives are as follows: To assess the efficacy and harm of deep brain stimulation for motor symptoms, with psychiatric and behavioural comorbidities, either individually or in combination, in adults and adolescents with Tourette's syndrome compared to placebo, sham intervention, or the best available behavioural and pharmacological treatment.

High frequency electrical stimulation reduces α-synuclein levels and α-synuclein-mediated autophagy dysfunction

Accumulation of α-synuclein (α-Syn) has been implicated in proteasome and autophagy dysfunction in Parkinson's disease (PD). High frequency electrical stimulation (HFS) mimicking clinical parameters used for deep brain stimulation (DBS) in vitro or DBS in vivo in preclinical models of PD have been found to reduce levels of α-Syn and, in certain cases, provide possible neuroprotection. However, the mechanisms by which this reduction in α-Syn improves cellular dysfunction associated with α-Syn accumulation remains elusive. Using HFS parameters that recapitulate DBS in vitro, we found that HFS led to a reduction of mutant α-Syn and thereby limited proteasome and autophagy impairments due to α-Syn. Additionally, we observed that HFS modulates via the ATP6V0C subunit of V-ATPase and mitigates α-Syn mediated autophagic dysfunction. This study highlights a role for autophagy in reduction of α-Syn due to HFS which may prove to be a viable approach to decrease pathological protein accumulation in neurodegeneration.

Neuroscience fundamentals relevant to neuromodulation: Neurobiology of deep brain stimulation in Parkinson's disease

Deep Brain Stimulation (DBS) has become a pivotal therapeutic approach for Parkinson's Disease (PD) and various neuropsychiatric conditions, impacting over 200,000 patients. Despite its widespread application, the intricate mechanisms behind DBS remain a subject of ongoing investigation. This article provides an overview of the current knowledge surrounding the local, circuit, and neurobiochemical effects of DBS, focusing on the subthalamic nucleus (STN) as a key target in PD management. The local effects of DBS, once thought to mimic a reversible lesion, now reveal a more nuanced interplay with myelinated axons, neurotransmitter release, and the surrounding microenvironment. Circuit effects illuminate the modulation of oscillatory activities within the basal ganglia and emphasize communication between the STN and the primary motor cortex. Neurobiochemical effects, encompassing changes in dopamine levels and epigenetic modifications, add further complexity to the DBS landscape. Finally, within the context of understanding the mechanisms of DBS in PD, the article highlights the controversial question of whether DBS exerts disease-modifying effects in PD. While preclinical evidence suggests neuroprotective potential, clinical trials such as EARLYSTIM face challenges in assessing long-term disease modification due to enrollment timing and methodology limitations. The discussion underscores the need for robust biomarkers and large-scale prospective trials to conclusively determine DBS's potential as a disease-modifying therapy in PD.

Unilateral focused ultrasound subthalamotomy in early Parkinson's disease: a pilot study

BACKGROUND

Unilateral focused ultrasound subthalamotomy (FUS-STN) improves motor features of Parkinson's disease (PD) in moderately advanced patients. The less invasive nature of FUS makes its early application in PD feasible. We aim to assess the safety and efficacy of unilateral FUS-STN in patients with PD of less than 5 years from diagnosis (early PD).

METHODS

Prospective, open-label study. Eligible patients with early PD had highly asymmetrical cardinal features. The primary outcome was safety, defined as treatment-related adverse events at 6 months. Secondary outcomes included efficacy, assessed as motor improvement in the Movement Disorders Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS), motor fluctuations, non-motor symptoms, daily living activities, quality of life, medication and patients' impression of change.

RESULTS

Twelve patients with PD (median age 52.0 (IQR 49.8-55.3) years, median time from diagnosis 3.0 (2.1-3.9) years) underwent unilateral FUS-STN. Within 2 weeks after treatment, five patients developed dyskinesia on the treated side, all resolved after levodopa dose adjustment. One patient developed mild contralateral motor weakness which fully resolved in 4 weeks. One patient developed dystonic foot and another hand and foot dystonia. The latter impaired gait and became functionally disabling initially. Both cases were well controlled with botulinum toxin injections. The off-medication motor MDS-UPDRS score for the treated side improved at 12 months by 68.7% (from 14.5 to 4.0, p=0.002), and the total motor MDS-UPDRS improved by 49.0% (from 26.5 to 13.0, p=0.002). Eleven patients (92%) reported global improvement 12 months after treatment.

CONCLUSION

Unilateral FUS-STN may be safe and effective to treat motor manifestations in patients with early PD. A larger confirmatory trial is warranted.

TRIAL REGISTRATION NUMBER

NCT04692116.

Connectivity Profile for Subthalamic Nucleus Deep Brain Stimulation in Early Stage Parkinson Disease

OBJECTIVE

This study was undertaken to describe relationships between electrode localization and motor outcomes from the subthalamic nucleus (STN) deep brain stimulation (DBS) in early stage Parkinson disease (PD) pilot clinical trial.

METHODS

To determine anatomical and network correlates associated with motor outcomes for subjects randomized to early DBS (n = 14), voxelwise sweet spot mapping and structural connectivity analyses were carried out using outcomes of motor progression (Unified Parkinson Disease Rating Scale Part III [UPDRS-III] 7-day OFF scores [∆baseline➔24 months, MedOFF/StimOFF]) and symptomatic motor improvement (UPDRS-III ON scores [%∆baseline➔24 months, MedON/StimON]).

RESULTS

Sweet spot mapping revealed a location associated with slower motor progression in the dorsolateral STN (anterior/posterior commissure coordinates: 11.07 ± 0.82mm lateral, 1.83 ± 0.61mm posterior, 3.53 ± 0.38mm inferior to the midcommissural point; Montreal Neurological Institute coordinates: +11.25, -13.56, -7.44mm). Modulating fiber tracts from supplementary motor area (SMA) and primary motor cortex (M1) to the STN correlated with slower motor progression across STN DBS subjects, whereas fiber tracts originating from pre-SMA and cerebellum were negatively associated with motor progression. Robustness of the fiber tract model was demonstrated in leave-one-patient-out (R = 0.56, p = 0.02), 5-fold (R = 0.50, p = 0.03), and 10-fold (R = 0.53, p = 0.03) cross-validation paradigms. The sweet spot and fiber tracts associated with motor progression revealed strong similarities to symptomatic motor improvement sweet spot and connectivity in this early stage PD cohort.

INTERPRETATION

These results suggest that stimulating the dorsolateral region of the STN receiving input from M1 and SMA (but not pre-SMA) is associated with slower motor progression across subjects receiving STN DBS in early stage PD. This finding is hypothesis-generating and must be prospectively tested in a larger study. ANN NEUROL 2023;94:271-284.

Long-term neuropsychological outcomes of deep brain stimulation in early-stage Parkinson's disease

INTRODUCTION

The pilot trial of deep brain stimulation (DBS) in early-stage Parkinson's disease (PD) randomized 30 patients (medication duration 0.5-4 years; without dyskinesia or motor fluctuations) to receive optimal drug therapy alone (early ODT) or subthalamic nucleus (STN) DBS plus ODT (early DBS + ODT). This study reports long-term neuropsychological outcomes from the early DBS pilot trial.

METHODS

This is an extension of an earlier study that examined two-year neuropsychological outcomes in the pilot trial. The primary analysis was conducted on the five-year cohort (n = 28), and a secondary analysis was conducted on the 11-year cohort (n = 12). Linear mixed effects models for each analysis compared overall trend in outcomes for randomization groups. All subjects who completed the 11-year assessment were also pooled to evaluate long-term change from baseline.

RESULTS

There were no significant differences between groups in either the five- or 11-year analyses. Across all PD patients who completed the 11-year visit, there was significant decline in Stroop Color and Color-Word and Purdue Pegboard from baseline to 11 years.

CONCLUSIONS

Previous significant differences between the groups in phonemic verbal fluency and cognitive processing speed showing more decline for early DBS + ODT subjects one year after baseline diminished as PD progressed. No cognitive domains were worse for early DBS + ODT subjects compared to standard of care subjects. There were shared declines across all subjects on cognitive processing speed and motor control, likely reflecting disease progression. More study is needed to understand the long-term neuropsychological outcomes associated with early DBS in PD.