Bilateral Deep Brain Stimulation is the Procedure to Beat for Advanced Parkinson Disease: A Meta-Analytic, Cost-Effective Threshold Analysis for Focused Ultrasound

Holographic Ultrasound Modulates Neural Activity in a 1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridine-Induced Mouse Model of Parkinson's Disease

Ultrasound (US) has emerged as a noninvasive neurostimulation method for motor control in Parkinson's disease (PD). Previous in vivo US neuromodulation studies for PD were single-target stimulation. However, the motor symptoms of PD are linked with neural circuit dysfunction, and multi-target stimulation is conducted in clinical treatment for PD. Thus, in the present study, we achieved multi-target US stimulation using holographic lens transducer based on the Rayleigh-Sommerfeld diffraction integral and time-reversal methods. We demonstrated that holographic US stimulation of the bilateral dorsal striatum (DS) could improve the motor function in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of PD. The holographic US wave (fundamental frequency: 3 MHz, pulse repetition frequency: 500 Hz, duty cycle: 20%, tone-burst duration: 0.4 ms, sonication duration: 1 s, interstimulus interval: 4 s, spatial-peak temporal-average intensity: 180 mw/cm2) was delivered to the bilateral DS 20 min per day for consecutive 10 d after the last injection of MPTP. Immunohistochemical c-Fos staining demonstrated that holographic US significantly increased the c-Fos-positive neurons in the bilateral DS compared with the sham group (P = 0.003). Moreover, our results suggested that holographic US stimulation of the bilateral DS ameliorated motor dysfunction (P < 0.05) and protected the dopaminergic (DA) neurons (P < 0.001). The neuroprotective effect of holographic US was associated with the prevention of axon degeneration and the reinforcement of postsynaptic densities [growth associated protein-43 (P < 0.001), phosphorylated Akt (P = 0.001), β3-tubulin (P < 0.001), phosphorylated CRMP2 (P = 0.037), postsynaptic density (P = 0.023)]. These data suggested that holographic US-induced acoustic radiation force has the potential to achieve multi-target neuromodulation and could serve as a reliable tool for the treatment of PD.

Role of Neurosurgical Interventions in the Treatment of Movement Disorders Like Parkinson's Disease, Dystonia, and Tourette Syndrome

This article provides an overview of neurosurgical therapies for movement disorders (MDs), including Tourette syndrome, dystonia, Parkinson's disease (PD), and others. It focuses on the benefits of these treatments and suggests directions for further research. A total of 10 years' worth of English-language PubMed articles were combed through, with an emphasis on studies conducted in North America. To manage MDs like Parkinson's disease and Tourette syndrome, the results suggest that non-invasive neuromodulation techniques, closed-loop deep brain stimulation (DBS), and other advanced therapies may become the treatment of choice in the future. Research on dystonia is being focused on improving treatment methods by investigating new areas of the brain that might be stimulated through neurosurgery and looking at gene therapy. Modern technological developments, such as non-invasive neuromodulation procedures and improved imaging, provide promising substitutes for traditional surgical approaches. This study highlights the need for continuous clinical trials for better outcomes, which is why research and development in this area must continue.

Magnetic resonance-guided focused ultrasound ventral intermediate thalamotomy for Tremor-Dominant Parkinson's disease: a systematic review and meta-analysis

INTRODUCTION

Tremor-dominant Parkinson's Disease (TDPD) has a slower neurological decline compared to other phenotypes of the disease, but significantly impacts daily activities and is often less responsive to standard medications. Magnetic Resonance-guided Focused Ultrasound (MRgFUS) lesioning of the Ventral Intermediate (VIM) nucleus of the thalamus may alleviate symptoms for these patients.

METHODS

A systematic review and meta-analysis of English-language studies from PubMed, Cochrane, and Embase were conducted, assessing the efficacy and safety of MRgFUS VIM thalamotomy in TDPD patients. Tremor scores were evaluated using the Clinical Scale Rating for Tremor and the Movement Disorders Society - Unified Parkinson's Disease Rating Scale (MDS-UPDRSIII). Neuropsychological outcomes were measured using the Parkinson Disease Questionnaire (PDQ) and the Montreal Cognitive Assessment. This analysis adhered to Cochrane and PRISMA guidelines.

RESULTS

Thirteen studies with 211 patients were included. MDS-UPDRSIII scores showed significant improvement at 1, 6, and 12 months post-MRgFUS, respectively: (MD -8.92 points, 95% CI: -15.44 to -2.40, p < 0.01; MD -7.39 points, 95% CI: -11.47 to -3.30, p < 0.01; MD -10.66 points, 95% CI: -16.89 to -4.43, p < 0.01). PDQ scores at baseline compared to 6 months post-treatment also indicated a significant improvement (SMD - 0.86, 95% CI: -1.21 to -0.50, p < 0.01). Neurological adverse events were generally mild and transient, with gait instability and sensory deficits being the most common.

CONCLUSION

This meta-analysis demonstrates significant improvements in tremor and neuropsychological outcomes following MRgFUS VIM thalamotomy in TDPD patients, with adverse events being typically mild and transient.

Cost Effectiveness of Deep Brain Stimulation for Parkinson's Disease: A Systematic Review

BACKGROUND AND OBJECTIVE

Deep brain stimulation (DBS) is an established treatment for Parkinson's disease (PD) in patients with advanced motor symptoms with an inadequate response to pharmacotherapies. Despite its effectiveness, the cost effectiveness of DBS remains a subject of debate. This systematic review aims to update and synthesize evidence on the cost effectiveness of DBS for PD.

METHODS

To identify full economic evaluations that compared the cost effectiveness of DBS with other best medical treatments, a comprehensive search was conducted of the PubMed, Embase, Scopus, and Tufts Cost-Effective Analysis registry databases. The selected papers were systematically reviewed, and the results were summarized. For the quality appraisal, we used the modified economic evaluations bias checklist. The review protocol was a priori registered with PROSPERO, CRD42022345508.

RESULTS

Sixteen identified cost-utility analyses that reported 19 comparisons on the use of DBS for PD were systematically reviewed. The studies were primarily conducted in high-income countries and employed Markov models. The costs considered were direct costs: surgical expenses, calibration, pulse generator replacement, and annual drug expenses. The majority of studies used country-specific thresholds. Fourteen comparisons from 12 studies reported on the cost effectiveness of DBS compared to best medical treatments. Eleven comparisons reported DBS as cost effective based on incremental cost-utility ratio results.

CONCLUSIONS

The cost effectiveness of DBS for PD varies by time horizon, costs considered, threshold utilized, and stage of PD progression. Standardizing approaches and comparing DBS with other treatments are needed for future research on effective PD management.

Modelling the Cost Effectiveness of Treatments for Parkinson's Disease: An Updated Methodological Review

OBJECTIVE

This article systematically reviewed the methodological quality of modelling approaches for economic evaluations of the treatment of motor symptoms in Parkinson's disease in studies published after 2010.

METHODS

A systematic literature search was undertaken using PubMed, EconLit, the Cochrane Database of Systematic Reviews, National Health Service Economic Evaluation Database and Health Technology Assessment databases of the UK National Health Service Centre for Review and Dissemination (March 2010 to July 2022). Quality was assessed using a checklist from the German Scientific Working Group.

RESULTS

A total of 20 studies were evaluated, with the majority based on Markov models (n = 18). Studies assessed the cost effectiveness of medical (n = 12) or surgical (n = 8) treatment, and included costs from a payer or healthcare provider's perspective (n = 17). Furthermore, all studies included quality-adjusted life-years as an effect measure. In the quality assessment of the literature, a mean score of 42.1 points (out of 56 points) on the checklist of the German Scientific Working Group was achieved. Seventeen studies concluded the intervention under study was (likely) cost effective. No intervention was classified as cost ineffective.

CONCLUSIONS

The quality of economic evaluation models in Parkinson's disease has improved in terms of calculating cost and transition parameters, as well as carrying out probabilistic sensitivity analyses, compared with the published literature of previous systematic reviews up to 2010. However, there is still potential for further development in terms of the integration of non-motor complications and treatment changes, the transparent presentation of parameter estimates, as well as conducting sensitivity analyses and validations to support the interpretation of results.

Identifying the Sources of Racial Disparity in the Treatment of Parkinson's Disease With Deep Brain Stimulation

BACKGROUND

Deep brain stimulation (DBS) is a highly efficacious treatment for appropriately selected patients with advanced, medically refractory Parkinson's disease (PD). It is severely underutilized in Black patients-constituting a major treatment gap. The source of this disparity is unknown, but its identification and correction are necessary to provide equitable care.

OBJECTIVE

To identify sources of racial disparity in DBS for PD.

METHODS

We predicted the demographics of potential DBS candidates by synthesizing published data on PD and race. We retrospectively examined the clinical course of a cohort including all patients with PD evaluated for DBS at our center from 2016 to 2020, testing whether the rate of DBS use and time from evaluation to surgery differed by race. We also tested whether the geographic distribution of patient catchment was biased relative to racial demographics.

RESULTS

Far fewer Black patients were evaluated for DBS than would be expected, given regional demographics. There was no significant difference in the rate at which Black patients evaluated in our clinic were treated with DBS, compared with White patients. Fewer patients were recruited from portions of the surrounding area with larger Black populations.

CONCLUSION

The known underuse of DBS in Black patients with PD was replicated in this sample from a center in a racially diverse metropolitan area, but was not attributable to the presurgical workup. Future work should examine the transition from medical management to surgical evaluation where drivers of disparity are potentially situated. Surgical practices should increase outreach to physicians managing PD in underserved areas.

Association of clinical outcomes and connectivity in awake versus asleep deep brain stimulation for Parkinson disease

OBJECTIVE

Deep brain stimulation (DBS) for Parkinson disease (PD) is traditionally performed with awake intraoperative testing and/or microelectrode recording. Recently, however, the procedure has been increasingly performed under general anesthesia with image-based verification. The authors sought to compare structural and functional networks engaged by awake and asleep PD-DBS of the subthalamic nucleus (STN) and correlate them with clinical outcomes.

METHODS

Levodopa equivalent daily dose (LEDD), pre- and postoperative motor scores on the Movement Disorders Society-Unified Parkinson's Disease Rating Scale part III (MDS-UPDRS III), and total electrical energy delivered (TEED) at 6 months were retroactively assessed in patients with PD who received implants of bilateral DBS leads. In subset analysis, implanted electrodes were reconstructed using the Lead-DBS toolbox. Volumes of tissue activated (VTAs) were used as seed points in group volumetric and connectivity analysis.

RESULTS

The clinical courses of 122 patients (52 asleep, 70 awake) were reviewed. Operating room and procedure times were significantly shorter in asleep cases. LEDD reduction, MDS-UPDRS III score improvement, and TEED at the 6-month follow-up did not differ between groups. In subset analysis (n = 40), proximity of active contact, VTA overlap, and desired network fiber counts with motor STN correlated with lower DBS energy requirement and improved motor scores. Discriminative structural fiber tracts involving supplementary motor area, thalamus, and brainstem were associated with optimal clinical improvement. Areas of highest structural and functional connectivity with VTAs did not significantly differ between the two groups.

CONCLUSIONS

Compared to awake STN DBS, asleep procedures can achieve similarly optimal targeting-based on clinical outcomes, electrode placement, and connectivity estimates-in more efficient procedures and shorter operating room times.

Comparative efficacy of surgical approaches to disease modification in Parkinson disease

Parkinson's disease (PD) may optimally be treated with a disease-modifying therapy to slow progression. We compare data underlying surgical approaches proposed to impart disease modification in PD: (1) cell transplantation therapy with stem cell-derived dopaminergic neurons to replace damaged cells; (2) clinical trials of growth factors to promote survival of existing dopaminergic neurons; (3) subthalamic nucleus deep brain stimulation early in the course of PD; and (4) abdominal vagotomy to lower risk of potential disease spread from gut to brain. Though targeted to engage potential mechanisms of PD these surgical approaches remain experimental, indicating the difficulty in translating therapeutic concepts into clinical practice. The choice of outcome measures to assess disease modification separate from the symptomatic benefit will be critical to evaluate the effect of the disease-modifying intervention on long-term disease burden, including imaging studies and clinical rating scales, i.e., Unified Parkinson Disease Rating Scale. Therapeutic interventions will require long follow-up times (i.e., 5-10 years) to analyze disease modification compared to symptomatic treatments. The promise of invasive, surgical treatments to achieve disease modification through mechanistic approaches has been constrained by the reality of translating these concepts into effective clinical trials.

Can responsive deep brain stimulation be a cost-effective treatment for severe obesity?

OBJECTIVE

A first-in-human responsive deep brain stimulation (rDBS) trial (NCT03868670) for obesity is under way, which is based on promising preclinical evidence. Given the upfront costs of rDBS, it is prudent to examine the success threshold for cost-effectiveness compared with laparoscopic Roux-en-Y gastric bypass (LRYGB).

METHODS

Efficacy and safety data on LRYGB and safety data on rDBS were collected for established indications through a literature search. The success threshold was defined as minimum BMI reduction. Treatment costs were calculated via Medicare national reimbursement data.

RESULTS

LRYGB had a mean BMI reduction of 13.75 kg/m² . Based on adverse events, LRYGB was a less-preferred health state (overall adverse event utility of 0.96 [0.02]) than rDBS (0.98 [0.01]), but LRYGB ($14,366 [$6,410]) had a significantly lower treatment cost than rDBS ($29,951 [$4,490]; p < 0.0001). Therefore, for rDBS to be cost-effective compared with LRYGB, the multiple models yielded a success threshold range of 13.7 to 15.2 kg/m² .

CONCLUSIONS

This study established a preliminary efficacy success threshold for rDBS to be cost-effective for severe obesity, and results from randomized controlled trials are needed. This analysis allows for interpretation of the economic impact of advancing rDBS for obesity in light of ongoing trial results and suggests an attainable threshold is needed for cost-effectiveness.

Focused ultrasound: growth potential and future directions in neurosurgery

Over the past two decades, vast improvements in focused ultrasound (FUS) technology have made the therapy an exciting addition to the neurosurgical armamentarium. In this time period, FUS has gained US Food and Drug Administration (FDA) approval for the treatment of two neurological disorders, and ongoing efforts seek to expand the lesion profile that is amenable to ultrasonic intervention. In the following review, we highlight future applications for FUS therapy and compare its potential role against established technologies, including deep brain stimulation and stereotactic radiosurgery. Particular attention is paid to tissue ablation, blood-brain-barrier opening, and gene therapy. We also address technical and infrastructural challenges involved with FUS use and summarize the hurdles that must be overcome before FUS becomes widely accepted in the neurosurgical community.

Utility of routine surface electrophysiology to screen for functional tremor prior to surgical treatment of essential tremor

Background

Patients with functional tremor may be clinically misdiagnosed as “medication-refractory” essential tremor (ET) and referred for surgical treatment. Electrophysiology can screen for functional tremor and avoid inappropriate surgery.

Objective

To report the utility of surface electrophysiology (SEMG) to screen for functional tremor in patients referred for ET surgery.

Methods

Retrospective review of consecutive ET patients referred to the Mayo Clinic DBS clinic over 1.5 years. Included subjects had a clinical diagnosis of medication-refractory ET and completed presurgical workup including routine SEMG tremor study.

Results

Of 87 subjects, 9 (10%) were clinically suspected of functional tremor by the DBS neurologist. Electrophysiology confirmed functional tremor features in 7/9 and ET in the other 2/9; and newly identified 5 additional cases of functional tremor. There were 12 total confirmed cases of functional tremor: isolated in 1, and mixed functional tremor and ET in 11. Of 11 mixed patients, 6 with mild functional overlay were approved for surgery. The remaining 5 patients with moderate-severe functional overlay and the single patient with isolated functional tremor were referred to the functional tremor motor retraining program. Of these, 1 patient with mixed tremor had residual disabling organic ET after program completion and was later approved for surgery. Thus, 5/87 patients (6%) avoided unnecessary surgery.

Conclusions

Functional tremor may frequently overlay “medication-refractory” ET amongst patients referred for surgery, affecting 1 of 7 patients in our quaternary referral DBS center. Electrophysiology studies are useful to routinely screen patients and prevent unnecessary surgery.

Personalized Medicine in Parkinson's Disease: New Options for Advanced Treatments

Parkinson’s disease (PD) presents varying motor and non-motor features in each patient owing to their different backgrounds, such as age, gender, genetics, and environmental factors. Furthermore, in the advanced stages, troublesome symptoms vary between patients due to motor and non-motor complications. The treatment of PD has made great progress over recent decades and has directly contributed to an improvement in patients’ quality of life, especially through the progression of advanced treatment. Deep brain stimulation, radiofrequency, MR–guided focused ultrasound, gamma knife, levodopa-carbidopa intestinal gel, and apomorphine are now used in the clinical setting for this disease. With multiple treatment options currently available for all stages of PD, we here discuss the most recent options for advanced treatment, including cell therapy in advanced PD, from the perspective of personalized medicine.

Deep Brain Stimulation Compared With Contingency Management for the Treatment of Cocaine Use Disorders: A Threshold and Cost-Effectiveness Analysis

OBJECTIVES

Cocaine is the second most frequently used illicit drug worldwide (after cannabis), and cocaine use disorder (CUD) related deaths increased globally by 80% from 1990 to 2013. There is yet to be a regulatory-approved treatment. Emerging preclinical evidence indicates that deep brain stimulation (DBS) of the nucleus accumbens may be a therapeutic option. Prior to expanding the costly investigation of DBS for treatment of CUD, it is important to ensure societal cost-effectiveness.

AIMS

We conducted a threshold and cost-effectiveness analysis to determine the success rate at which DBS would be equivalent to contingency management (CM), recently identified as the most efficacious therapy for treatments of CUDs.

MATERIALS AND METHODS

Quality of life, efficacy, and safety parameters for CM were obtained from previous literature. Costs were calculated from a societal perspective. Our model predicted the utility benefit based on quality-adjusted-life-years (QALYs) and incremental-cost-effectiveness-ratio resulting from two treatments on a one-, two-, and five-year timeline.

RESULTS

On a one-year timeline, DBS would need to impart a success rate (i.e., cocaine free) of 70% for it to yield the same utility benefit (0.492 QALYs per year) as CM. At no success rate would DBS be more cost-effective (incremental-cost-effectiveness-ratio <$50,000) than CM during the first year. Nevertheless, as DBS costs are front-loaded, DBS would need to achieve success rates of 74% and 51% for its cost-effectiveness to exceed that of CM over a two- and five-year period, respectively.

CONCLUSIONS

We find DBS would not be cost-effective in the short-term (one year) but may be cost-effective in longer timelines. Since DBS holds promise to potentially be a cost-effective treatment for CUDs, future randomized controlled trials should be performed to assess its efficacy.