Long-term follow-up of pallidal deep brain stimulation for craniocervical dystonia: is the globus pallidus internus the best target?

OBJECTIVE: Craniocervical dystonia (CCD) is a common type of segmental dystonia, which is a disabling disease that has been frequently misdiagnosed. Blepharospasm or cervical dystonia is the most usual symptom initially. Although deep brain stimulation (DBS) of the globus pallidus internus (GPi) has been widely used for treating CCD, its clinical outcome has been primarily evaluated in small-scale studies. This research examines the sustained clinical effectiveness of DBS of the GPi in individuals diagnosed with CCD. METHODS: The authors report 24 patients (14 women, 10 men) with refractory CCD who underwent DBS of the GPi between 2016 and 2023. The severity and disability of the dystonia were evaluated using the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS). The BFMDRS scores were collected preoperatively, 6 months postoperatively, and at the most recent follow-up visit. RESULTS: The mean age at onset was 52.0 ± 11.0 years (range 33-71 years) and the mean disease duration was 63.3 ± 73.3 months (range 7-360 months) (values for continuous variables are expressed as the mean ± SD). The mean follow-up period was 37.5 ± 23.5 months (range 6-84 months). The mean total BFMDRS motor scores at the 3 different time points were 13.3 ± 9.4 preoperatively, 5.0 ± 4.7 (55.3% improvement, p < 0.001) at 6 months, and 4.5 ± 3.6 (56.6% improvement, p < 0.001) at last follow-up. The outcomes were deemed poor in 6 individuals. CONCLUSIONS: Inferences drawn from the findings suggest that DBS of the GPi has long-lasting effectiveness and certain limitations in managing refractory CCD. The expected stability of the clinical outcome is not achieved. Patients with specific types of dystonia might consider targets other than GPi for a more precise therapy.

Subthalamic and pallidal oscillations and their couplings reflect dystonia severity and improvements by deep brain stimulation.

BACKGROUND: Deep brain stimulation (DBS) targeting the globus pallidus internus (GPi) and subthalamic nucleus (STN) is employed for the treatment of dystonia. Pallidal low-frequency oscillations have been proposed as a pathophysiological marker for dystonia. However, the role of subthalamic oscillations and STN-GPi coupling in relation to dystonia remains unclear. OBJECTIVE: We aimed to explore oscillatory activities within the STN-GPi circuit and their correlation with the severity of dystonia and efficacy achieved by DBS treatment. METHODS: Local field potentials were recorded simultaneously from the STN and GPi from 13 dystonia patients. Spectral power analysis was conducted for selected frequency bands from both nuclei, while power correlation and the weighted phase lag index were used to evaluate power and phase couplings between these two nuclei, respectively. These features were incorporated into generalized linear models to assess their associations with dystonia severity and DBS efficacy. RESULTS: The results revealed that pallidal theta power, subthalamic beta power and subthalamic-pallidal theta phase coupling and beta power coupling all correlated with clinical severity. The model incorporating all selected features predicts empirical clinical scores and DBS-induced improvements, whereas the model relying solely on pallidal theta power failed to demonstrate significant correlations. CONCLUSIONS: Beyond pallidal theta power, subthalamic beta power, STN-GPi couplings in theta and beta bands, play a crucial role in understanding the pathophysiological mechanism of dystonia and developing optimal strategies for DBS.

Asleep versus awake GPi DBS surgery for Parkinson's disease: A systematic review and meta-analysis.

BACKGROUND: Patients with Parkinson's Disease (PD) who receive either asleep image-guided subthalamic nucleus deep brain stimulation (DBS) or the traditional awake technique have comparable motor outcomes. However, there are fewer studies regarding which technique should be chosen for globus pallidus internus (GPi) DBS. This systematic review and meta-analysis aims to compare the accuracy of lead placement and motor outcomes of asleep versus awake GPi DBS PD population. METHODS: We systematically searched PubMed, Embase, and Cochrane for studies comparing asleep vs. awake GPi DBS lead placement in patients with PD. Outcomes were spatial accuracy of lead placement, measured by radial error between intended and actual location, motor improvement measured using (UPDRS III), and postoperative stimulation parameters. Statistical analysis was performed with Review Manager 5.1.7. and OpenMeta [Analyst]. RESULTS: Three studies met inclusion criteria with a total of 247 patients. Asleep DBS was used to treat 192 (77.7 %) patients. Follow-up ranged from 6 to 48 months. Radial error was not statistically different between groups (MD -0.49 mm; 95 % CI -1.0 to 0.02; I2 = 86 %; p = 0.06), with a tendency for higher target accuracy with the asleep technique. There was no significant difference between groups in change on motor function, as measured by UPDRS III, from pre- to postoperative (MD 8.30 %; 95 % CI -4.78 to 21.37; I2 = 67 %, p = 0.2). There was a significant difference in postoperative stimulation voltage, with the asleep group requiring less voltage than the awake group (MD -0.27 V; 95 % CI -0.46 to - 0.08; I2 = 0 %; p = 0.006). CONCLUSION: Our meta-analysis indicates that asleep image-guided GPi DBS presents a statistical tendency suggesting superior target accuracy when compared with the awake standard technique. Differences in change in motor function were not statistically significant between groups.

Pallidal versus subthalamic deep brain stimulation for Meige syndrome: A systematic review and meta-analysis.

Background: Globus pallidus internus (GPi) and subthalamic nucleus (STN) are two common deep brain stimulation (DBS) targets. This meta-analysis was to compared the efficacy and safety of these two DBS targets for the treatment of Meige syndrome (MS). Methods: A systematic search was performed using EMBASE, MEDLINE, the Cochrane Library, and ClinicalTrials.gov to identify DBS trials for MS. Review Manager 5.3 was used to perform meta-analysis and the mean difference (MD) was analyzed and calculated with a random effect model. Pearson's correlation coefficients and meta-regression analyses were utilized to identify relevant predictive markers. Results: Twenty trials involving 188 participants with GPi-DBS and 110 individuals with STN-DBS were eligible. Both groups showed improvement of the Burke-Fahn-Marsden Dystonia Rating Scale-Movement (BFMDRS-M) and Disability (BFMDRS-D) scores (BFMDRS-M: MD = 10.57 [7.74-13.41] for GPi-DBS, and MD = 8.59 [4.08-13.11] for STN-DBS; BFMDRS-D: MD = 5.96 [3.15-8.77] for GPi-DBS, and MD = 4.71 [1.38-8.04] for STN-DBS; all P < 0.001) from baseline to the final follow-up, while no notable disparity in improvement rates was observed between them. Stimulation-related complications occurrence was also similar between two groups (38.54 ± 24.07% vs. 43.17 ± 29.12%, P = 0.7594). Simultaneously, preoperative BFMDRS-M score and disease duration were positively connected with the relative changes in BFMDRS-M score at the final visit. Conclusion: Both GPi-DBS and STN-DBS are effective MS therapies, with no differences in efficacy or the frequency of stimulation-related problems. Higher preoperative scores and longer disease duration probably predict greater improvement.

Effect of Thalamic versus Pallidal Deep Brain Stimulation on Head Tremor in Dystonic and Essential Tremor Patients-A Retrospective Video-Blinded Study.

BACKGROUND: Head tremor is common in dystonia syndromes and difficult to treat. Deep brain stimulation (DBS) is a therapeutic option in medically-refractory cases. In most DBS-centers, the globus pallidus internus (GPi) is targeted in patients with predominant dystonia and the ventrointermediate nucleus of the thalamus (Vim) in predominant tremor. The aim of the study was to evaluate the effect of GPi- versus Vim-DBS in dystonic or essential head tremor. METHODS: All patients with dystonia or essential tremor (ET) (n = 381) who underwent DBS surgery at our institution between 1999 and 2020 were screened for head tremor in our database according to predefined selection criteria. Of the 33 patients meeting inclusion criteria tremor and dystonia severity were assessed at baseline, short- (mean 10 months) and long-term follow-up (41 months) by two blinded video-raters. RESULTS: Twenty-two patients with dystonic head tremor received either GPi- (n = 12) or Vim-stimulation (n = 10), according to the prevailing clinical phenotype. These two groups were compared with 11 patients with ET, treated with Vim-stimulation. The reduction in head tremor from baseline to short- and long-term follow-up was 60-70% and did not differ significantly between the three groups. CONCLUSIONS: GPi-DBS effectively and sustainably reduced head tremor in idiopathic dystonia. The effect was comparable to the effect of Vim-DBS on head tremor in dystonia patients with predominant limb tremor and to the effect of Vim-DBS on head tremor in ET.

Risk factors for postoperative urinary retention after deep brain stimulation surgery: the role of the subthalamic nucleus.

OBJECTIVE: Deep brain stimulation (DBS) is a common procedure in neurosurgery used for the treatment of Parkinson's disease (PD) and essential tremor (ET) among other disorders. Lower urinary tract dysfunction is a common complication in PD, and this study aimed to evaluate the risk factors of postoperative urinary retention (POUR) after DBS surgery in patients with PD compared with patients with ET. Understanding the risk factors associated with this complication may help in the development of strategies to minimize its occurrence and improve patient outcomes. METHODS: The study was a retrospective analysis of patients who underwent DBS surgery for PD and ET at the University of Florida between 2010 and 2021. The surgical technique used has been described in previous articles and included a two-stage procedure, with stage 1 involving burr hole placement, microelectrode recording, and electrode implantation and stage 2 involving the placement of an implantable pulse generator (IPG). Data were collected on patient characteristics and surgical details and analyzed using univariate and mixed-linear models. Post hoc propensity score matching was used to confirm the association between subthalamic nucleus (STN)-DBS and POUR. RESULTS: The study included 350 patients (153 with PD and 197 with ET) who underwent 1086 DBS surgeries (lead implantations, IPG placement, and IPG replacements). The POUR rates were 16.6% (79/477), 5.2% (19/363), and 0.4% (1/246) for stage 1, stage 2, and IPG replacement procedures, respectively. Optimal mixed-effects logistic modeling revealed history of urinary retention (OR 9.3, p = 0.004), male sex (OR 2.7, p = 0.011), having an electrode placed or connected for the first time (OR 2.2, p = 0.014), anesthesia time (OR 1.5 for each 30-minute increase, p < 0.0001), preoperative opioid use (OR 1.4 for each additional 10 morphine milligram equivalents, p = 0.032), and Charlson Comorbidity Index (OR 1.4 per comorbidity, p = 0.017) to be significant risk factors for POUR. Having an electrode in the STN was found to be protective of POUR (propensity score-matched analysis: OR 0.2, p = 0.010). CONCLUSIONS: Most risk factors found to increase the risk of POUR in DBS are not modifiable but are still important to consider in preoperative planning. Opioid use reduction and shorter anesthesia time may be modifiable risk factors to weigh against their alternative. Targeting the STN during DBS may result in decreased rates of POUR. This highlights the potential for STN-targeted DBS in reducing POUR risk in PD and ET patients.

Electrode position and cognitive outcome following deep brain stimulation surgery.

OBJECTIVE: Subthalamic nucleus (STN) and globus pallidus internus (GPI) deep brain stimulation (DBS) effectively treat motor symptoms in Parkinson's disease (PD) but may be associated with cognitive and psychiatric changes in some patients. Evaluation of changes in cognitive and psychiatric symptoms following DBS is complicated by changes in these symptoms that occur as part of the natural disease course. The aim of this study was to evaluate whether electrode position was associated with changes in neurocognitive symptoms in patients who underwent STN and GPI DBS. METHODS: A single-institution retrospective cohort study was conducted on patients with PD who underwent DBS from 2008 to 2019. Cognitive and psychiatric outcomes included Beck Depression Inventory II (BDI-II) score, presence of impulsive-compulsive behavior (ICB), Mini-Mental State Examination (MMSE) score, and overall cognitive status grade determined by comprehensive neuropsychology testing (normal, mild impairment, moderate impairment, and dementia). Pre- and postoperative comparisons were performed using a Wilcoxon signed-rank test or paired t-test. Patients with and without cognitive decline were compared using a Mann-Whitney U-test or unpaired t-test. A chi-square test was used for categorical comparisons. RESULTS: One hundred thirty patients were included (mean age 62.5 ± 7.9 years). At a mean postoperative follow-up from DBS of 13.0 ± 12.7 (range 6-66) months, there was an improvement in ICB (26.3% preoperatively vs 15.0% postoperatively, p = 0.017), but a decline in MMSE score (28.6 ± 1.6 vs 27.6 ± 2.0, p < 0.001) and overall cognitive status (normal: 66.2% vs 39.2%; mild: 12.3% vs 17.7%; moderate: 21.5% vs 33.1%; dementia: 0.0% vs 10.0%; p < 0.001). Patients undergoing STN DBS had a worse decline in overall cognitive status than patients who underwent GPI DBS (p = 0.006). Postoperative cognitive decline was associated with a more medial electrode position only for patients who underwent STN DBS. CONCLUSIONS: Cognitive change was observed in some patients with PD who underwent both GPI and STN DBS, likely due partly to underlying disease progression. Compared with GPI DBS, STN DBS was associated with a greater likelihood of cognitive decline. In STN but not GPI DBS, cognitive decline was associated with medialized electrode position, suggesting modulation of nonmotor STN divisions may contribute to cognitive changes following STN DBS.

Impacts of Deep Brain Stimulation of the Globus Pallidus Internus on Swallowing: A Retrospective, Cross-Sectional Study.

Deep brain stimulation (DBS) is a common treatment for motor symptoms of Parkinson disease (PD), a condition associated with increased risk of dysphagia. The effect of DBS on swallowing function has not been comprehensively evaluated using gold-standard imaging techniques, particularly for globus pallidus internus (GPi) DBS. The objective of this retrospective, cross-sectional study was to identify differences in swallowing safety and timing kinematics among PD subjects with and without GPi DBS. We investigated the effects of unilateral and bilateral GPi DBS as well as the relationship between swallowing safety and DBS stimulation parameters, using retrospective analysis of videofluoroscopy recordings (71 recordings from 36 subjects) from electronic medical records. Outcomes were analyzed by surgical status (pre-surgical, unilateral DBS, bilateral DBS). The primary outcome was percent of thin-liquid bolus trials rated as unsafe, with Penetration-Aspiration Scale scores of 3 or higher. Secondary analyses included swallowing timing measures, relationships between swallowing safety and DBS stimulation parameters, and Dynamic Imaging Grade of Swallowing Toxicity ratings. Most subjects swallowed all boluses safely (19/29 in the pre-surgical, 16/26 in the unilateral DBS, and 10/16 in the bilateral DBS conditions). Swallowing safety impairment did not differ among stimulation groups. There was no main effect of stimulation condition on timing metrics, though main effects were found for sex and bolus type. Stimulation parameters were not correlated with swallowing safety. Swallowing efficiency and overall impairment did not differ among conditions. These results provide evidence that GPi DBS does not affect pharyngeal swallowing function. Further, prospective, investigations are needed.

Chronic Pallidal Local Field Potentials Are Associated With Dystonic Symptoms in Children.

BACKGROUND: Novel deep brain stimulation devices can record local field potentials (LFPs), which represent the synchronous synaptic activity of neuronal populations. The clinical relevance of LFPs in patients with dystonia remains unclear. OBJECTIVES: We sought to determine whether chronic LFPs recorded from the globus pallidus internus (GPi) were associated with symptoms of dystonia in children. MATERIALS AND METHODS: Ten patients with heterogeneous forms of dystonia (genetic and acquired) were implanted with neurostimulators that recorded LFP spectral snapshots. Spectra were compared across parent-reported asymptomatic and symptomatic periods, with daily narrowband data superimposed in 24 one-hour bins. RESULTS: Spectral power increased during periods of registered dystonic symptoms: mean increase = 102%, CI: (76.7, 132). Circadian rhythms within the LFP narrowband time series correlated with dystonic symptoms: for delta/theta-waves, correlation = 0.33, CI: (0.18, 0.47) and for alpha waves, correlation = 0.27, CI: (0.14, 0.40). CONCLUSIONS: LFP spectra recorded in the GPi indicate a circadian pattern and are associated with the manifestation of dystonic symptoms.

Unraveling the complexities of programming neural adaptive deep brain stimulation in Parkinson's disease.

Over the past three decades, deep brain stimulation (DBS) for Parkinson's disease (PD) has been applied in a continuous open loop fashion, unresponsive to changes in a given patient's state or symptoms over the course of a day. Advances in recent neurostimulator technology enable the possibility for closed loop adaptive DBS (aDBS) for PD as a treatment option in the near future in which stimulation adjusts in a demand-based manner. Although aDBS offers great clinical potential for treatment of motor symptoms, it also brings with it the need for better understanding how to implement it in order to maximize its benefits. In this perspective, we outline considerations for programing several key parameters for aDBS based on our experience across several aDBS-capable research neurostimulators. At its core, aDBS hinges on successful identification of relevant biomarkers that can be measured reliably in real-time working in cohesion with a control policy that governs stimulation adaption. However, auxiliary parameters such as the window in which stimulation is allowed to adapt, as well as the rate it changes, can be just as impactful on performance and vary depending on the control policy and patient. A standardize protocol for programming aDBS will be crucial to ensuring its effective application in clinical practice.

Estimulación cerebral profunda combinada del núcleo subtalámico y el globo pálido interno en la enfermedad de Parkinson / Combined subthalamic nucleus and globus pallidus internus deep brain stimulation in Parkinson’s disease

Introducción: La estimulación cerebral profunda (ECP) del núcleo subtalámico (NST) y el globo pálido interno (GPi) son los principales abordajes quirúrgicos en la enfermedad de Parkinson avanzada. La estimulación suele aplicarse de forma bilateral en la misma estructura cerebral. Sin embargo, cuando diferentes síntomas motores se presentan concomitantemente en el mismo paciente, la modulación simultánea de diferentes estructuras cerebrales puede ser una alternativa eficaz. Caso clínico: Presentamos un paciente con enfermedad de Parkinson avanzada en el que se realizó ECP combinada en NST y el GPi. La ECP del NST izquierdo controló de manera óptima la sintomatología del hemicuerpo derecho, mientras que las discinesias problemáticas que presentaba en el hemicuerpo izquierdo se redujeron con éxito mediante la estimulación del GPi derecho. Discusión. La estimulación combinada del NST/GPi puede considerarse un enfoque neuroquirúrgico adecuado cuando surge una sintomatología motora desafiante en pacientes con enfermedad de Parkinson avanzada.(AU)

Introduction: Subthalamic nucleus (STN) and globus pallidus internus (GPi) deep brain stimulation (DBS) are the main surgical approaches for advanced Parkinson’s disease. Stimulation is usually applied bilaterally in the same brain structure. However, when various motor symptoms concomitantly present in the same patient, simultaneous modulation of different brain structures may be a suitable alternative. Case report: We present a patient with advanced Parkinson’s disease with a combined DBS neurosurgery. Left STN DBS optimally controlled the off right hemibody symptomatology while left side troublesome dyskinesias were successfully relieved by right GPi stimulation. Discussion: Combined STN/GPi stimulation can be considered a suitable approach when challenging motor symptomatology arises in advanced Parkinson’s disease patients.(AU)

Case report: Short-term efficacy and changes in 18F-FDG-PET with acute multi-target stimulation in spinocerebellar ataxia type 3 (SCA3/MJD).

Objective: Spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph disease (MJD), is a rare neurodegenerative disease for which there is no specific treatment. Very few cases have been treated with single-target deep brain stimulation (DBS), and the results were not satisfactory. We applied multi-target DBS to an SCA3/MJD patient and performed positron emission computed tomography (PET) before and after DBS to explore the short-term clinical therapeutic effect. Materials and methods: A 26-year-old right-hand-dominant female with a family history of SCA3/MJD suffered from cerebellar ataxia and dystonia. Genetic testing indicated an expanded CAG trinucleotide repeat in the ATXN3 gene and a diagnosis of SCA3/MJD. Conservative treatment had no obvious effect; therefore, leads were implanted in the bilateral dentate nucleus (DN) and the globus pallidus internus (GPi) and connected to an external stimulation device. The treatment effect was evaluated in a double-blind, randomized protocol in five phases (over a total of 15 days): no stimulation, GPi, DN, or sham stimulation, and combined GPi and DN stimulation. 18F-fluoro-2-deoxy-d-glucose and dopamine transporter PET, Scale for the Assessment and Rating of Ataxia, Fahn-Tolosa-Marin Clinical Rating Scale for Tremor (FTM), Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS), and SF-36 quality of life scores were compared before and after DBS. Results: The Total Scale for the Assessment and Rating of Ataxia scores improved by ~42% (from 24 to 14). The BFMDRS movement scores improved by ~30% (from 40.5 to 28.5). The BFMDRS disability scores improved by ~12.5% (from 16 to 14). Daily living activities were not noticeably improved. Compared with the findings in pre-DBS imaging, 18F-fluoro-2-deoxy-d-glucose uptake increased in the cerebellum, while according to dopamine transporter imaging, there were no significant differences in the bilateral caudate nucleus and putamen. Conclusion: Multi-target acute stimulation (DN DBS and GPi DBS) in SCA3/MJD can mildly improve cerebellar ataxia and dystonia and increase cerebellar metabolism.

Deep Brain Stimulation Before Anterior Cervical Discectomy and Fusion for a Patient With Cervical Dystonia and Cervical Myelopathy: A Case Report.

Cervical dystonia with concurrent cervical myelopathy is a challenging pathology that requires thoughtful management. A 46-year-old female was referred to our center with this presentation. We elected to perform bilateral globus pallidus internus deep brain stimulation (DBS-GPi) prior to C5 to C7 anterior cervical discectomy and fusion (ACDF) to avoid the potential for dystonic movements to negatively impact cervical fusion. The patient was followed up at three months post C5 to C7 ACDF and nine months post DBS-GPi with complete control of tremor and no radiographic evidence of hardware loosening or malalignment. Though this strategy was successful in treating both our patient's cervical myelopathy and cervical dystonia, larger studies need to be conducted to optimize the treatment of patients presenting with these concurrent pathologies.

Weight and survival after deep brain stimulation for Parkinson's disease.

BACKGROUND: Weight loss in Parkinson's disease (PD) is common and associated with increased mortality. The clinical significance of weight changes following deep brain stimulation (DBS) of the subthalamic nucleus (STN) and globus pallidus internus (GPi) is unclear. OBJECTIVES: To address (1) whether PD patients exhibit progressive weight loss, (2) whether staged DBS surgery is associated with weight changes, and (3) whether survival after DBS correlates with post-DBS weight. METHODS: This is a single-center, longitudinal, retrospective cohort study of 1625 PD patients. We examined trends in weight over time and the relationship between weight and years survival after DBS using regression and mixed model analyses. RESULTS: There was a decline in body weight predating motor symptom onset (n = 756, 0.70 ± 0.03% decrease per year, p < 0.001). Weight decline accelerated in the decade preceding death (n = 456, 2.18 ± 0.31% decrease per year, p < 0.001). DBS patients showed a weight increase of 2.0 ± 0.33% at 1 year following the first DBS lead implant (n = 455) and 2.68 ± 1.1% at 3 years if a contralateral DBS lead was placed (n = 249). The bilateral STN DBS group gained the most weight after surgery during 6 years of follow up (vs bilateral GPi, 3.03 ± 0.45% vs 1.89 ± 0.31%, p < 0.01). An analysis of the DBS cohort with date of death available (n = 72) revealed that post-DBS weight (0-12 months after the first or 0-36 months after the second surgery) was positively associated with survival (R2 = 0.14, p < 0.001). DISCUSSION: Though PD is associated with significant weight loss, DBS patients gained weight following surgery. Higher post-operative weight was associated with increased survival. These results should be replicated in other cohorts.

The Effects of Deep Brain Stimulation on Mood and Quality of Life in Parkinson's Disease: A Systematic Review and Meta-Analysis.

Deep brain stimulation (DBS) is extensively used to treat motor and non-motor symptoms in Parkinson's disease (PD). The aim of this study was to investigate the difference between subthalamic (STN) and globus pallidus internus (GPi) DBS on mood and quality of life with reference to minimal clinically important differences (MCID). A systematic literature search for articles published until November 2022 yielded 14 studies meeting the eligibility criteria, with a total of 1,088 patients undergoing STN (n=571) or GPi (n=517) stimulation. Baseline patient and clinical characteristics were comparable between the two groups. Results showed that GPi stimulation demonstrated a greater reduction in the Beck depression inventory (mean difference (MD)=1.68) than STN stimulation (MD=0.84). Hospital anxiety and depression scale showed a 2.69- and 3.48-point decrease by the GPi group in the depression and anxiety categories, respectively. The summary index (SI) of the PD questionnaire depicted a greater improvement in the GPi group from baseline (mean=41.01, 95% CI 34.89, 47.13) to follow-up (mean=30.85, 95% CI 22.08, 39.63) when compared to the STN group (baseline mean=42.43, 95% CI 34.50, 50.37; follow-up mean=34.21, 95% CI 25.43, 42.99). The emotions category also demonstrated a similar trend. However, STN stimulation showed greater reductions in motor symptoms and medication than GPi stimulation. This meta-analysis demonstrated that GPi stimulation seems to offer an advantage over STN stimulation in improving mood and quality of life in PD, but those effects must be further validated by larger studies.

Bilateral globus pallidus internus (GPi) deep brain stimulation for cervical dystonia: Effects on motor and non-motor symptoms within 5 years follow.

BACKGROUND: Cervical Dystonia ("CD") is a movement disorder characterised by sustained muscle contractions in the neck, causing involuntary posturing. Deep brain stimulation ("DBS") of the globus pallidal internus (GPi) is advanced treatment for pharmaco-refractory patients. As CD is a rare disease, cohort studies are often limited to patients of heterogenous disease profile, small sample size or short follow-up. This study firstly aimed to measure the efficacy of GPi-DBS on motor and non-motor symptoms of CD. A secondary aim was to evaluate if clinical factors - such as age, disease duration and baseline disease severity - influence variability of motor outcomes. METHODS: 37 idiopathic CD patients were recruited from movement disorders clinics at The Walton NHS Foundation Trust, Liverpool, UK. Patients were assessed pre-operatively, and 1 year, 3 years and 5 years post-operatively with the following clinical scales: Toronto Western Spasmodic Torticollis Rating Scale ("TWSTRS"), Hospital Anxiety and Depression Scale and EuroQuol-5D. RESULTS: GPI-DBS significantly improved overall TWSTRS scores by 57% from baseline to 5Y FU (p < 0.001). It also significantly improved TWSTRS severity, disability, and pain sub-scores by 72%, 59% and 46% respectively. We did not find a significant improvement in mood or quality of life scores at 5 years. Similarly, clinical factors at baseline did not correlate with variability in motor outcome. CONCLUSION: We concluded that GPi-DBS is an effective treatment for motor symptoms and pain in CD. There was limited effect on mood and QoL, and no clinical predictive factors of outcome were identified.

Intraoperative electrophysiological monitoring determines the final electrode position for pallidal stimulation in dystonia patients.

Background: Bilateral deep brain stimulation (DBS) of the globus pallidus internus (GPi) is an effective treatment for refractory dystonia. Neuroradiological target and stimulation electrode trajectory planning with intraoperative microelectrode recordings (MER) and stimulation are used. With improving neuroradiological techniques, the need for MER is in dispute mainly because of the suspected risk of hemorrhage and the impact on clinical post DBS outcome. Objective: The aim of the study is to compare the preplanned GPi electrode trajectories with final trajectories selected for electrode implantation after electrophysiological monitoring and to discuss the factors potentially responsible for differences between preplanned and final trajectories. Finally, the potential association between the final trajectory selected for electrode implantation and clinical outcome will be analyzed. Methods: Forty patients underwent bilateral GPi DBS (right-sided implants first) for refractory dystonia. The relationship between preplanned and final trajectories (MicroDrive system) was correlated with patient (gender, age, dystonia type and duration) and surgery characteristics (anesthesia type, postoperative pneumocephalus) and clinical outcome measured using CGI (Clinical Global Impression parameter). The correlation between the preplanned and final trajectories together with CGI was compared between patients 1-20 and 21-40 for the learning curve effect. Results: The trajectory selected for definitive electrode implantation matched the preplanned trajectory in 72.5% and 70% on the right and left side respectively; 55% had bilateral definitive electrodes implanted along the preplanned trajectories. Statistical analysis did not confirm any of the studied factors as predictor of the difference between the preplanned and final trajectories. Also no association between CGI and final trajectory selected for electrode implantation in the right/left hemisphere has been proven. The percentages of final electrodes implanted along the preplanned trajectory (the correlation between anatomical planning and intraoperative electrophysiology results) did not differ between patients 1-20 and 21-40. Similarly, there were no statistically significant differences in CGI (clinical outcome) between patients 1-20 and 21-40. Conclusion: The final trajectory selected after electrophysiological study differed from the preplanned trajectory in a significant percentage of patients. No predictor of this difference was identified. The anatomo-electrophysiological difference was not predictive of the clinical outcome (as measured using CGI parameter).

Globus pallidus internus versus subthalamic nucleus deep brain stimulation for isolated dystonia: A 3-year follow-up.

BACKGROUND AND PURPOSE: Bilateral deep brain stimulation (DBS) surgery targeting the globus pallidus internus (GPi) or the subthalamic nucleus (STN) is widely used in medication-refractory dystonia. However, evidence regarding target selection considering various symptoms remains limited. This study aimed to compare the effectiveness of these two targets in patients with isolated dystonia. METHODS: This retrospective study evaluated 71 consecutive patients (GPi-DBS group, n = 32; STN-DBS group, n = 39) with isolated dystonia. Burke-Fahn-Marsden Dystonia Rating Scale scores and quality of life were evaluated preoperatively and at 1, 6, 12, and 36 months postoperatively. Cognition and mental status were assessed preoperatively and at 36 months postoperatively. RESULTS: Targeting the STN (STN-DBS) yielded effects within 1 month (65% vs. 44%; p = 0.0076) and was superior at 1 year (70% vs. 51%; p = 0.0112) and 3 years (74% vs. 59%; p = 0.0138). For individual symptoms, STN-DBS was preferable for eye involvement (81% vs. 56%; p = 0.0255), whereas targeting the GPi (GPi-DBS) was better for axis symptoms, especially for the trunk (82% vs. 94%; p = 0.015). STN-DBS was also favorable for generalized dystonia at 36-month follow-up (p = 0.04) and required less electrical energy (p < 0.0001). Disability, quality of life, and depression and anxiety measures were also improved. Neither target influenced cognition. CONCLUSIONS: We demonstrated that the GPi and STN are safe and effective targets for isolated dystonia. The STN has the benefits of fast action and low battery consumption, and is superior for ocular dystonia and generalized dystonia, while the GPi is better for trunk involvement. These findings may offer guidance for future DBS target selection for different types of dystonia.

Differential remodeling of subthalamic projections to basal ganglia output nuclei and locomotor deficits in 6-OHDA-induced hemiparkinsonian mice.

The subthalamic nucleus (STN) controls basal ganglia outputs via the substantia nigra pars reticulata (SNr) and the globus pallidus internus (GPi). However, the synaptic properties of these projections and their roles in motor control remain unclear. We show that the STN-SNr and STN-GPi projections differ markedly in magnitude and activity-dependent plasticity despite the existence of collateral STN neurons projecting to both the SNr and GPi. Stimulation of either STN projection reduces locomotion; in contrast, inhibition of either the STN-SNr projection or collateral STN neurons facilitates locomotion. In 6-OHDA-hemiparkinsonian mice, the STN-SNr projection is dramatically attenuated, but the STN-GPi projection is robustly enhanced; apomorphine inhibition of the STN-GPi projection through D2 receptors is significantly augmented and improves locomotion. Optogenetic inhibition of either the STN-SNr or STN-GPi projection improves parkinsonian bradykinesia. These results suggest that the STN-GPi and STN-SNr projections are differentially involved in motor control in physiological and parkinsonian conditions.