Deep Brain Stimulation: Technology at the Cutting Edge

Deep brain stimulation (DBS) surgery has been performed in over 75,000 people worldwide, and has been shown to be an effective treatment for Parkinson''s disease, tremor, dystonia, epilepsy, depression, Tourette''s syndrome, and obsessive compulsive disorder. We review current and emerging evidence for the role of DBS in the management of a range of neurological and psychiatric conditions, and discuss the technical and practical aspects of performing DBS surgery. In the future, evolution of DBS technology may depend on several key areas, including better scientific understanding of its underlying mechanism of action, advances in high-spatial resolution imaging and development of novel electrophysiological and neurotransmitter microsensor systems. Such developments could form the basis of an intelligent closed-loop DBS system with feedback-guided neuromodulation to optimize both electrode placement and therapeutic efficacy.     

Cognitive Effects of Subthalamic Nucleus Deep Brain Stimulation in Parkinson's Disease with GBA1 Pathogenic Variants

Genetic subtyping of patients with Parkinson's disease (PD) may assist in predicting the cognitive and motor outcomes of subthalamic deep brain stimulation (STN-DBS). Practical questions were recently raised with the emergence of new data regarding suboptimal cognitive outcomes after STN-DBS in individuals with PD associated with pathogenic variants in glucocerebrosidase gene (GBA1-PD). However, a variety of gaps and controversies remain. (1) Does STN-DBS truly accelerate cognitive deterioration in GBA1-PD? If so, what is the clinical significance of this acceleration? (2) How should the overall risk-to-benefit ratio of STN-DBS in GBA1-PD be established? (3) If STN-DBS has a negative effect on cognition in GBA1-PD, how can this effect be minimized? (4) Should PD patients be genetically tested before STN-DBS? (5) How should GBA1-PD patients considering STN-DBS be counseled? We aim to summarize the currently available relevant data and detail the gaps and controversies that exist pertaining to these questions. In the absence of evidence-based data, all authors strongly agree that clinicians should not categorically deny DBS to PD patients based solely on genotype (GBA1 status). We suggest that PD patients considering DBS may be offered genetic testing for GBA1, where available and feasible, so the potential risks and benefits of STN-DBS can be properly weighed by both the patient and clinician. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.     

Spectral Topography of the Subthalamic Nucleus to Inform Next-Generation Deep Brain Stimulation

Background

The landscape of neurophysiological symptoms and behavioral biomarkers in basal ganglia signals for movement disorders is expanding. The clinical translation of sensing-based deep brain stimulation (DBS) also requires a thorough understanding of the anatomical organization of spectral biomarkers within the subthalamic nucleus (STN).

Objectives

The aims were to systematically investigate the spectral topography, including a wide range of sub-bands in STN local field potentials (LFP) of Parkinson's disease (PD) patients, and to evaluate its predictive performance for clinical response to DBS.

Methods

STN-LFPs were recorded from 70 PD patients (130 hemispheres) awake and at rest using multicontact DBS electrodes. A comprehensive spatial characterization, including hot spot localization and focality estimation, was performed for multiple sub-bands (delta, theta, alpha, low-beta, high-beta, low-gamma, high-gamma, and fast-gamma (FG) as well as low- and fast high-frequency oscillations [HFO]) and compared to the clinical hot spot for rigidity response to DBS. A spectral biomarker map was established and used to predict the clinical response to DBS.

Results

The STN shows a heterogeneous topographic distribution of different spectral biomarkers, with the strongest segregation in the inferior-superior axis. Relative to the superiorly localized beta hot spot, HFOs (FG, slow HFO) were localized up to 2 mm more inferiorly. Beta oscillations are spatially more spread compared to other sub-bands. Both the spatial proximity of contacts to the beta hot spot and the distance to higher-frequency hot spots were predictive for the best rigidity response to DBS.

Conclusions

The spatial segregation and properties of spectral biomarkers within the DBS target structure can additionally be informative for the implementation of next-generation sensing-based DBS. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.     

Deep Brain Stimulation in China: Present and Future

Objective: We reviewed the clinical applications, academic communications, and specialized training required for deep brain stimulation (DBS) in China. Current problems and possible solutions also were discussed. Materials and Methods: We reviewed all literature on DBS by Chinese authors. The WANFANG and PUBMED (2000–2009) data bases were searched to collect publications on DBS by Chinese authors. To compare the Chinese academic publications on DBS with those by American authors, data from publications by American authors also were collected. Information on the DBS population as categorized by year, by province, and by indication was collected from the Medtronic Neuromodulation data base. Results: From 2000 to 2009, there were 187 publications on DBS in Chinese journals and 23 in English journals by Chinese authors. American peers contributed 569 articles during the same period. In total, 2082 patients received DBS treatment in China by the end of 2009. Conclusions: DBS has evolved significantly during the past decade in China. There are still several problems. The advent of Chinese homemade DBS hardware, multidisciplinary cooperation, and the establishment of guidelines and regulations for DBS will improve the application of this surgical treatment in China.     

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

Background and ObjectivesBilateral subthalamic nucleus deep brain stimulation (STN DBS) in Parkinson's disease (PD) can have detrimental effects on eye movement inhibitory control. To investigate this detrimental effect of bilateral STN DBS, we examined the effects of manipulating STN DBS amplitude on inhibitory control during the antisaccade task. The prosaccade error rate during the antisaccade task, that is, directional errors, was indicative of impaired inhibitory control. We hypothesized that as stimulation amplitude increased, the prosaccade error rate would increase.Materials and MethodsTen participants with bilateral STN DBS completed the antisaccade task on six different stimulation amplitudes (including zero amplitude) after a 12-hour overnight withdrawal from antiparkinsonian medication.ResultsWe found that the prosaccade error rate increased as stimulation amplitude increased (p < 0.01). Additionally, prosaccade error rate increased as the modeled volume of tissue activated (VTA) and STN overlap decreased, but this relationship depended on stimulation amplitude (p = 0.04).ConclusionsOur findings suggest that higher stimulation amplitude settings can be modulatory for inhibitory control. Some individual variability in the effect of stimulation amplitude can be explained by active contact location and VTA-STN overlap. Higher stimulation amplitudes are more deleterious if the active contacts fall outside of the STN resulting in a smaller VTA-STN overlap. This is clinically significant as it can inform clinical optimization of STN DBS parameters. Further studies are needed to determine stimulation amplitude effects on other aspects of cognition and whether inhibitory control deficits on the antisaccade task result in a meaningful impact on the quality of life.