Machine learning for the localization of Subthalamic Nucleus during deep brain stimulation surgery: a systematic review and Meta-analysis.

INTRODUCTION: Delineating subthalamic nucleus (STN) boundaries using microelectrode recordings (MER) and trajectory history is a valuable resource for neurosurgeons, aiding in the accurate and efficient positioning of deep brain stimulation (DBS) electrodes within the STN. Here, we aimed to assess the application of artificial intelligence, specifically Hidden Markov Models (HMM), in the context of STN localization. METHODS: A comprehensive search strategy was employed, encompassing electronic databases, including PubMed, EuroPMC, and MEDLINE. This search strategy entailed a combination of controlled vocabulary (e.g., MeSH terms) and free-text keywords pertaining to "artificial intelligence," "machine learning," "deep learning," and "deep brain stimulation." Inclusion criteria were applied to studies reporting the utilization of HMM for predicting outcomes in DBS, based on structured patient-level health data, and published in the English language. RESULTS: This systematic review incorporated a total of 14 studies. Various machine learning compared wavelet feature to proposed features in diagnosing the STN, with the HMM yielding a diagnostic odds ratio (DOR) of 838.677 (95% CI: 203.309-3459.645). Similarly, the K-Nearest Neighbors (KNN) model produced parameter estimates, including a diagnostic odds ratio of 25.151 (95% CI: 12.270-51.555). Meanwhile, the support vector machine (SVM) model exhibited parameter estimates, with a DOR of 13.959 (95% CI: 10.436-18.671). CONCLUSIONS: MER data demonstrates significant variability in neural activity, with studies employing a wide range of methodologies. Machine learning plays a crucial role in aiding STN diagnosis, though its accuracy varies across different approaches.

Effect of deep brain stimulation on postoperative body mass index: A systematic review and meta-analysis.

BACKGROUND: Deep Brain Stimulation (DBS) is FDA-approved for several movement disorders; such as Parkinson's disease, dystonia, and neuropsychiatric disorders. There are various reports of Body mass index (BMI) changes following different DBS targets in various disorders. AIM: A comprehensive systematic review and meta-analysis were conducted to investigate the impact of DBS on patients' Body Mass Index (BMI) and provide an in-depth overview of its underlying mechanisms. MATERIALS AND METHODS: We conducted research according to PRISMA guidelines. Our study assessed comprehensively electronic databases, including Pubmed, Scopus, Embase, web of science, and the Cochrane Library, up to May 2024. The random-effect model analysis was performed by the Comprehensive Meta-analysis software (CMA) version 3.0. As well, Cochran's Q test was used to determine the statistical heterogeneity of included studies. RESULT: This systematic review ultimately included 49 studies, 46 of which entered the meta-analysis. The total number of patients was 1478, consisting of Parkinson's disease (PD), dystonia, and the obsessive compulsive disorder (OCD) patients. The most common DBS target was subthalamic nucleus, followed by globus pallidus internus (GPi). Our meta-analysis depicted the BMI of participants significantly mount after DBS electrode implantation (SMD = -0.542, 95%CI: -0.678 to -0.406, and P-value < 0.001). However, moderate to high heterogeneity was detected among the studies (I2 = 67.566%). Additionally, the Daily energy intake (DEI) of patients significantly decreased after DBS (SMD: 0.457, 95%CI; 0.205 to 0.709, and P-value < 0.001). CONCLUSION: STN and GPi DBS can lead to weight gain through distinct central pathways in various movement and neuropsychiatric disorders, posing a potential risk for obesity, insulin resistance, and metabolic syndrome.

The effect of subthalamic nucleus deep brain stimulation on speech performance: a prospective clinical and tractography study.

BACKGROUND: Speech changes significantly impact the quality of life for Parkinson's disease (PD) patients. Deep Brain Stimulation (DBS) of the Subthalamic Nucleus (STN) is a standard treatment for advanced PD, but its effects on speech remain unclear. This study aimed to investigate the relationship between STN-DBS and speech changes in PD patients using comprehensive clinical assessments and tractography. METHODS: Forty-seven PD patients underwent STN-DBS, with preoperative and 3-month postoperative assessments. Speech analyses included acoustic measurements, auditory-perceptual evaluations, and fluency-intelligibility tests. On the other hand, structures within the volume tissue activated (VTA) were identified using MRI and DTI. The clinical and demographic data and structures associated with VTA (Corticospinal tract, Internal capsule, Dentato-rubro-thalamic tract, Medial forebrain bundle, Medial lemniscus, Substantia nigra, Red nucleus) were compared with speech analyses. RESULTS: The majority of patients (36.2-55.4% good, 29.7-53.1% same) exhibited either improved or unchanged speech quality following STN-DBS. Only a small percentage (8.5-14.9%) experienced deterioration. Older patients and those with worsened motor symptoms postoperatively were more likely to experience negative speech changes (p < 0.05). Interestingly, stimulation of the right Substantia Nigra correlated with improved speech quality (p < 0.05). No significant relationship was found between other structures affected by VTA and speech changes. CONCLUSIONS: This study suggests that STN-DBS does not predominantly negatively impact speech in PD patients, with potential benefits observed, especially in younger patients. These findings underscore the importance of individualized treatment approaches and highlight the need for further long-term studies to optimize therapeutic outcomes and better understand the effects of STN-DBS on speech.

Analysis of diffusion changes in cerebral tissues of Parki̇nson's patients who underwent subthalamic nucleus deep brain stimulation: Correlation of improvements in motor and neuropsychiatric symptoms.

OBJECTIVE: Parkinson's disease (PD) as a neurodegenerative disorder characterized by a reduction in both the quantity and functionality of dopaminergic neurons. This succinctly highlights the central pathological feature of PD and its association with dopaminergic neuron degeneration, which underlies the motor and non-motor symptoms of the disease. This study aims to elucidate the nuances of apparent diffusion coefficient (ADC) changes in different cerebral regions by after the bilateral subthalamic nucleus (STN) deep brain stimulation (DBS) surgery of PD, as well as to investigate their potential interactions with the motor and neuropsychiatric spectrum. METHODS: Patients who underwent STN-DBS surgery for PD between 2017 and 2019 were included in this study. The results of diffusion magnetic resonance imaging (MRI), Unified Parkinson Disease Rating Scale (UPDRS) III scores, Beck and Hamilton depression tests were recorded before and at the 3rd month of postoperative stimulation. The data obtained were evaluated with the Wilcoxon signed rank test. Result of the statistical tests were within the 95 % confidence interval and p values were significant below 0.05. RESULTS: Our study was conducted with a total of 13 patients, 8 men and 5 women. As a result of measurements made in a total of 32 different regions, especially in the motor and neuropsychiatric areas of the brain, an increase in ADC values was found in all areas. ADC changes of eight localizations such as left corpus callosum, right corona radiata, left corona radiata, hippocampus, right insula, left superior cerebellar peduncle, left caudate nucleus and left putamen were statistically significant. UPDRS III scores improved by 57 % (p <0.05), and Beck and Hamilton depression scores by 25 % and 33 %, respectively (p> 0.05). CONCLUSIONS: This article implicate that bilateral STN-DBS surgery potentially exerts beneficial effects on both motor and neuropsychiatric symptomatology in individuals with PD. We believe that this therapeutic mechanism is hypothesized to involve modulation of diffusion alterations within distinct cerebral tissues.

The causal role of the subthalamic nucleus in the inhibitory network.

The neural network mediating successful response inhibition mainly includes right hemisphere activation of the pre-supplementary motor area, inferior frontal gyrus (IFG), subthalamic nucleus (STN), and caudate nucleus. However, the causal role of these regions in the inhibitory network is undefined. Five patients with Parkinson's disease were assessed prior to and after therapeutic thermal ablation of the right STN in two separate functional magnetic resonance imaging (fMRI) sessions while performing a stop-signal task. Initiation times were faster but motor inhibition with the left hand (contralateral to the lesion) was significantly impaired as evident in prolonged stop-signal reaction times. Reduced inhibition after right subthalamotomy was associated (during successful inhibition) with the recruitment of basal ganglia regions outside the established inhibitory network. They included the putamen and caudate together with the anterior cingulate cortex and IFG of the left hemisphere. Subsequent network connectivity analysis (with the seed over the nonlesioned left STN) revealed a new inhibitory network after right subthalamotomies. Our results highlight the causal role of the right STN in the neural network for motor inhibition and the possible basal ganglia mechanisms for compensation upon losing a key node of the inhibition network.

Letter to the Editor: Intraoperative microelectrode recording during asleep deep brain stimulation of subthalamic nucleus for Parkinson disease: a case series with systematic review of the literature.

This letter discusses the recent study by Izzo et al., which explored intraoperative microelectrode recording (MER) during asleep deep brain stimulation (DBS) of the subthalamic nucleus for Parkinson's disease. The study's integration of a systematic review positions its findings within the broader context of neurosurgical advances. Highlighting the practicality and patient comfort of the frameless technique under general anesthesia, it emphasizes the significance of MER in optimizing electrode placement, thereby potentially enhancing patient outcomes. The letter suggests future research directions, including randomized clinical trials, to assess the clinical benefits of this methodology further.

Deep brain stimulation of the subthalamic nucleus under general anesthesia versus local anesthesia in the treatment of Parkinson's disease: a meta-analysis of randomized clinical trials.

Deep brain stimulation (DBS) stands as the preferred treatment for Parkinson's disease (PD) patients manifesting refractory motor symptoms or when medication side effects outweigh the benefits. Though traditionally administered under local anesthesia coupled with sedation (LA + S), recent evidence hints at comparable outcomes under general anesthesia (GA). This systematic review and meta-analysis aimed to scrutinize post-surgical outcomes in randomized PD patients undergoing DBS surgery while GA versus LA + S. We searched PubMed, Cochrane, and Embase databases following PRISMA guidelines. We included randomized studies directly comparing DBS surgery under GA versus LA + S, delineating clinical outcomes. Safety outcomes assessed disparities in infection and hemorrhage risk. Mean differences (MD) and Risk Differences (RD) with 95% Confidence Intervals (CI) were utilized to evaluate outcomes, under a random-effects model. Heterogeneity was evaluated through I² statistics, and in studies exhibiting high heterogeneity, exclusion analysis was performed. Evaluated outcomes encompassed motor improvement, complications, behavioral and mood effects gauged by the Unified Parkinson's Disease Rating Scale (UPDRS), Parkinson's Disease Questionnaire 39 (PDQ39), and daily levodopa equivalent dose (LEDD). A total of 3 studies, encompassing 203 patients, were reviewed. At a 6-month follow-up, in patients undergoing GA during surgery, there was no statistically significant difference compared to the LA + S group in terms of UPDRS III ON (MD 0.19; 95% CI -2.21 to 2.59; p = 0.88; I²=0%), UPDRS III OFF (MD 0.58; 95% CI -4.30 to 5.45; p = 0.21; I²=0%), UPDRS IV ON ( (MD 0.98; 95% CI -0.95 to 2.92; p = 0.32; I²=23%), PDQ39 (MD -1.27; 95% CI -6.31 to 3.77; p = 0.62; I²=0%), and LEDD (MD -1.99; 95% CI -77.88 to 73.90; p = 0.96; I²=32%). There was no statistically significant difference between groups in terms of infection (RD 0.02; 95% CI -0.02 to 0.05; p = 0.377; I²=0%) or hemorrhage (RD 0.04; 95% CI -0.03 to 0.11; p = 0.215; I²=0%). Our findings suggest, based on short-term follow-up, that GA is not inferior to LA + S in terms of benefits for the selected outcomes. However, further studies are needed to determine whether there are significant long-term clinical differences between these groups.

Surgical Complications in Subthalamic Nucleus Deep Brain Stimulation for Parkinson's Disease: Experience in 800 Patients.

INTRODUCTION: We present our surgical complications resulting in neurological deficit or additional surgery during 25 years of DBS of the subthalamic nucleus (STN) for Parkinson's disease (PD). METHODS: We conducted a retrospective chart review of all PD patients that received STN DBS in our DBS center between 1998 and 2023. Outcomes were complications resulting in neurological deficit or additional surgery. Potential risk factors (number of microelectrode recording tracks, age, anesthesia method, hypertension, and sex) for symptomatic intracerebral hemorrhage (ICH) were analyzed. Furthermore, lead fixation techniques were compared. RESULTS: Eight hundred PD patients (507 men, 293 women) received unilateral (n = 11) or bilateral (n = 789) implantation of STN electrodes. Neurological deficit due to ICH, edema, delirium, or infarction was seen in 8.4% of the patients (7.4% transient, 1.0% permanent). Twenty-two patients (2.8%) had a symptomatic ICH following STN DBS, for which we did not find any risk factors, and five had permanent sequelae due to ICH (0.6%). Of all patients, 18.4% required additional surgery; the proportion was reduced from 27% in the first 300 cases to 13% in the last 500 cases (p < 0.001). The infection rate was 3.5%, which decreased from 5.3% in the first 300 cases to 2.2% in the last 500 cases. The use of a lead anchoring device led to significantly less lead migrations than miniplate fixation. CONCLUSION: STN DBS leads to permanent neurological deficit in a small number of patients (1.0%), but a substantial proportion needs some additional surgical procedure after the first DBS system implantation. The risk of revision surgery was reduced over time but remained significant. These findings need to be discussed with the patient in the preoperative informed consent process in addition to the expected health benefit.

Mapping of Capsular Side Effects by using Intraoperative Motor-Evoked Potentials during Asleep Deep Brain Stimulation Surgery of the Subthalamic Nucleus for Parkinson's Disease.

INTRODUCTION: The aim of this study was to present a novel technique for subthalamic nucleus (STN) deep brain stimulation (DBS) implantation under general anesthesia by using intraoperative motor-evoked potentials (MEPs) through direct lead stimulation and determining their correlation to the thresholds of postoperative stimulation-induced side effects. METHODS: This study included 22 consecutive patients with advanced Parkinson's disease who underwent surgery in our institution between January 2021 and September 2023. All patients underwent bilateral implantation in the STN (44 leads) under general anesthesia without microelectrode recordings (MERs) by using MEPs with electrostimulation directly through the DBS lead. No cortical stimulation was performed during this process. Intraoperative fluoroscopic guidance and immediate postoperative computed tomography were used to verify the electrode's position. The lowest MEP thresholds were recorded and were correlated to the postoperative stimulation-induced side-effect threshold. The predictive values of the MEPs were analyzed. Five DBS leads were repositioned intraoperatively due to the MEP results. RESULTS: A moderately strong positive correlation was found between the MEP threshold and the capsular side-effect threshold (RS = 0.425, 95% CI, 0.17-0.67, p = 0.004). The highest sensitivity and specificity for predicting a side-effect threshold of 5 mA were found to be at 2.4 mA MEP threshold (sensitivity 97%, specificity 87.5%, positive predictive value 97%, and negative predictive value 87.5%). We also found high sensitivity and specificity (100%) at 1.15 mA MEP threshold and 3 mA side-effect threshold. Out of the total 44 leads, 5 (11.3%) leads were repositioned intraoperatively due to MEP thresholds lower than 1 mA (4 leads) or higher than 5 mA (1 lead). The mean accuracy on postoperative CT was 1.05 mm, and there were no postoperative side-effects under 2.8 mA. CONCLUSION: Intraoperative MEPs with electrostimulation directly through the contacts of the DBS lead correlate with the stimulation-induced capsular side effects. The lead reposition based on intraoperative MEP may enlarge the therapeutic window of DBS stimulation.

Deep Brain Stimulation with Double Targeting of the VIM and PSA for the Treatment of Rare Tremor Syndromes.

INTRODUCTION: In tremor syndromes, pharmacological therapy is the primary treatment, but deep brain stimulation (DBS) is used when it is insufficient. We explore the use of DBS, focusing on the globus pallidus internus for dystonia and the ventral intermediate nucleus (VIM) for tremor conditions. We introduce the posterior subthalamic area (PSA) as a potential target, suggesting its efficacy in tremor reduction, particularly in rare tremor syndromes. We aim to evaluate the efficacy and safety of double targeting the VIM and PSA in rare tremor conditions, highlighting the limited existing data on this. METHODS: Between 2019 and 2023, 22 patients with rare tremor syndromes were treated with bilateral DBS of the VIM and PSA. This case series consisted of 7 isolated head tremor, 1 hepatic encephalopathic tremor due to Abernethy syndrome, 2 voice tremor, 4 dystonic tremor, and 8 Holmes tremor (2 multiple sclerosis, 2 cerebellar insult, and 4 posttraumatic) patients. Patients' preoperative and 12-month postoperative tremor scores were compared, and the optimum VIM and PSA stimulation areas were investigated. RESULTS: There was a significant reduction in the mean TRS score from 3.70 (±0.57) to 0.45 (±0.68) after 12 months of surgery. Specific outcomes for different indications were observed: for head tremor, 6 of 7 patients showed a reduction in TRS scores to 0 points; the vocal tremor patients demonstrated improvement; this change was not statistically significant, which is likely to be due to the low number of patients in this subgroup; the dystonic tremor patients showed either complete tremor abolition or a reduction in TRS scores; the Holmes tremor patients showed an 80% reduction in TRS scores; and the hepatic encephalopathy tremor and Abernethy syndrome patients showed a 75% improvement in TRS scores. The stimulation parameters converged on the VIM and dorsal PSA. Complications included the need for electrode repositioning, infections requiring electrode removal and re-implantation, dysarthria, and stimulation-induced ataxia, which was resolved by adjusting the stimulation parameters. DISCUSSION: The literature on DBS for rare tremors is limited. Double targeting of the VIM and PSA appears to produce promising improvements on the outcomes reported in the existing literature on VIM-only DBS. The proximity of the VIM and PSA allows for flexible electrode placement, contributing to the potential success of the dual-target approach. We also discuss the theoretical advantages of targeting the PSA based on the distribution of tremor circuits, emphasizing the need for further research and electrophysiological studies.

Staged Bilateral MRI-Guided Focused Ultrasound Subthalamotomy for Parkinson Disease.

Importance: Unilateral magnetic resonance imaging (MRI)-guided focused ultrasound subthalamotomy (FUS-STN) improves cardinal motor features among patients with asymmetrical Parkinson disease (PD). The feasibility of bilateral FUS-STN is as yet unexplored. Objective: To assess the safety and effectiveness of staged bilateral FUS-STN to treat PD. Design, Setting, and Participants: This prospective, open-label, case series study was conducted between June 18, 2019, and November 7, 2023, at HM-CINAC, Puerta del Sur University Hospital, Madrid, Spain, and included 6 patients with PD who had been treated with unilateral FUS-STN contralateral to their most affected body side and whose parkinsonism on the untreated side had progressed and was not optimally controlled with medication. Intervention: Staged bilateral FUS-STN. Main Outcomes and Measures: Primary outcomes were assessed 6 months after the second treatment and included safety (incidence and severity of adverse events after second treatment) and effectiveness in terms of motor change (measured with the Movement Disorders Society Unified Parkinson's Disease Rating Scale part III [MDS-UPDRS III]) in the off-medication state (ie, after at least 12 hours of antiparkinsonian drug withdrawal) compared with baseline (ie, prior to the first side ablation). Secondary outcomes included motor change in patients in the on-medication state (ie, after usual antiparkinsonian medication intake), motor complications (measured with the MDS-UPDRS IV), daily living activities (measured with the MDS-UPDRS I-II), quality of life (measured with the 39-item Parkinson's Disease Questionnaire), change in dopaminergic treatment, patient's global impression of change (measured with the Global Impression of Change [PGI-C] scale), and long-term (24-month) follow-up. Results: Of 45 patients previously treated with unilateral FUS-STN, 7 were lost to follow-up, and 4 were excluded due to adverse events. Of the remaining 34 patients, 6 (median age at first FUS-STN, 52.6 years [IQR, 49.0-57.3 years]; 3 women [50%]) experienced progression of parkinsonism on the untreated body side and were included. At the time of the first FUS-STN, patients' median duration of disease was 5.7 years (IQR, 4.7-7.3 years). The median time between procedures was 3.2 years (IQR, 1.9-3.5 years). After the second FUS-STN, 4 patients presented with contralateral choreic dyskinesia, which resolved by 3 months. Four patients developed speech disturbances, which gradually improved but remained in a mild form for 2 patients at 6 months; 1 patient experienced mild imbalance and dysphagia during the first week after treatment, which subsided by 3 months. No behavioral or cognitive disturbances were found on neuropsychological testing. For patients in the off-medication state, MDS-UPDRS III scores improved by 52.6% between baseline and 6 months after the second FUS-STN (from 37.5 [IQR, 34.2-40.0] to 20.5 [IQR, 8.7-24.0]; median difference, 23.0 [95% CI, 7.0-33.7]; P = .03). The second treated side improved by 64.3% (MDS-UPDRS III score, 17.0 [IQR, 16.0-19.5] prior to the second treatment vs 5.5 [IQR, 3.0-10.2]; median difference, 9.5 [95% CI, 3.2-17.7]; P = .02). After the second procedure, all self-reported PGI-C scores were positive. Conclusions: Findings of this pilot study suggest that staged bilateral FUS-STN was safe and effective for the treatment of PD, although mild but persistent speech-related adverse events were observed among a small number of patients.

Delayed-onset seizures after subthalamic nucleus deep brain stimulation surgery for Parkinson's disease.

BACKGROUND: Delayed-onset seizures after deep brain stimulation (DBS) surgery were seldom reported. This study summarized the clinical characteristics of delayed-onset seizures after subthalamic nucleus (STN) DBS surgery for Parkinson's disease (PD) and analyzed risk factors. METHODS: A single-center retrospective study containing consecutive STN-DBS PD patients from 2006 to 2021 was performed. Seizures occurred during the DBS surgery or within one month after DBS surgery were identified based on routine clinical records. Patients with postoperative magnetic resonance imaging (MRI) were included to further analyze the risk factors for postoperative seizures with univariate and multivariate statistical methods. RESULTS: 341 consecutive PD patients treated with bilateral STN-DBS surgery wereidentified, and five patients experienced seizures after DBS surgery with an incidence of 1.47 %. All seizures of the five cases were characterized as delayed onset with average 12 days post-operatively. All seizures presented as generalized tonic-clonic seizures and didn't recur after the first onset. In those seizures cases, peri-electrode edema was found in both hemispheres without hemorrhage and infarction. The average diameter of peri-electrode edema of patients with seizures was larger than those without seizures (3.15 ± 1.00 cm vs 1.57 ± 1.02 cm, p = 0.005). Multivariate risk factor analysis indicated that seizures were only associated with the diameter of peri-electrode edema (OR 4.144, 95 % CI 1.269-13.530, p = 0.019). CONCLUSIONS: Delayed-onset seizures after STN-DBS surgery in PD patients were uncommon with an incidence of 1.47 % in this study. The seizures were transient and self-limiting, with no developing into chronic epilepsy. Peri-electrode edema was a risk factor for delayed-onset seizures after DBS surgery. Patients with an average peri-electrode edema diameter > 2.70 cm had a higher risk to develop seizures.

Deep Brain Stimulation Modulates the Visual Pathway to Improve Freezing of Gait in Parkinson's Disease Patients.

OBJECTIVE: To investigate the involvement of the visual cortex in improving freezing of gait (FoG) after subthalamic nucleus (STN) deep brain stimulation (DBS) in Parkinson's disease (PD) patients using whole-brain seed-based functional connectivity. METHODS: A total of 66 PD patients with FoG who underwent bilateral STN-DBS were included in our study. Patients were divided into a FoG responder group and an FoG nonresponder group according to whether FoG improved 1 year after DBS. We compared the differences in clinical characteristics, brain structural imaging, and seed-based functional connectivity between the 2 groups. The locations of active contacts were further analyzed. RESULTS: All PD patients benefited from STN-DBS. No significant differences in the baseline characteristics or brain structures were found between the 2 groups. Seed-based functional connectivity analysis revealed that better connectivity in bilateral primary visual areas was associated with better clinical improvement in FoG (P < 0.05 familywise error corrected). Further analysis revealed that this disparity was associated with the location of the active contacts within the rostral region of the sensorimotor subregion in the FoG responder group, in contrast to the findings in the FoG nonresponder group. CONCLUSIONS: This study suggested that DBS in the rostral region of the STN sensorimotor subregion may alleviate FoG by strengthening functional connectivity in primary visual areas, which has significant implications for guiding surgical strategies for FoG in the future.

Clinical evaluation of a stereotactic system for single-stage deep brain stimulation surgery under general anesthesia: technical note.

OBJECTIVE: Conventional frame-based stereotactic systems have circumferential base frames, often necessitating deep brain stimulation (DBS) surgery in two stages: intracranial electrode insertion followed by surgical re-preparation and pulse generator implantation. Some patients do not tolerate awake surgery, underscoring the need for a safe alternative for asleep DBS surgery. A frame-based stereotactic system with a skull-mounted "key" in lieu of a circumferential base frame received US FDA clearance. The authors describe the system's application for single-stage, asleep DBS surgery in 8 patients at their institution and review its workflow and technical considerations. METHODS: Eight patients underwent DBS lead insertion and IPG implantation in a single surgical preparation under general anesthesia using the system. Postoperative CT imaging confirmed lead placement. RESULTS: Eight patients underwent implantation of 15 total leads targeting the ventral intermediate nucleus (4 patients), globus pallidus internus (GPi; 3 patients), and subthalamic nucleus (STN; 1 patient). Intraoperative microelectrode recording was conducted for GPi and STN targets. Postoperative CT imaging revealed a mean ± SD radial error of 1.24 ± 0.45 mm (n = 15 leads), without surgical complications. CONCLUSIONS: The stereotactic system facilitated safe and effective asleep, single-stage DBS surgery, maintaining traditional lead accuracy standards.

Magnetic Resonance-Guided Focused Ultrasound for Treatment of Essential Tremor: Ventral Intermediate Nucleus Ablation Alone or Additional Posterior Subthalamic Area Lesioning?

BACKGROUND: Magnetic resonance-guided focused ultrasound (MRgFUS) for treatment of essential tremor (ET) traditionally targets the ventral intermediate (Vim) nucleus. Recent strategies include a secondary lesion to the posterior subthalamic area (PSA). OBJECTIVE: The aim was to compare lesion characteristics, tremor improvement, and adverse events (AE) between patients in whom satisfactory tremor suppression was achieved with lesioning of the Vim alone and patients who required additional lesioning of the PSA. METHODS: Retrospective analysis of data collected from ET patients treated with MRgFUS at St Vincent's Hospital Sydney was performed. Clinical Rating Scale for Tremor (CRST), hand tremor score (HTS), and Quality of Life in Essential Tremor Questionnaire (QUEST) were collected pre- and posttreatment in addition to the prevalence of AEs. The lesion coordinates and overlap with the dentatorubrothalamic tract (DRTT) were evaluated using magnetic resonance imaging. RESULTS: Twenty-one patients were treated in Vim only, and 14 were treated with dual Vim-PSA lesions. Clinical data were available for 29 of the 35 patients (19 single target and 10 dual target). At follow-up (mean: 18.80 months) HTS, CRST, and QUEST in single-target patients improved by 57.97% (P < 0.001), 36.71% (P < 0.001), and 58.26% (P < 0.001), whereas dual-target patients improved by 68.34% (P < 0.001), 35.37% (P < 0.003), and 46.97% (P < 0.005), respectively. The Vim lesion of dual-target patients was further anterior relative to the posterior commissure (PC) (7.84 mm), compared with single-target patients (6.92 mm), with less DRTT involvement (14.85% vs. 23.21%). Dual-target patients exhibited a greater proportion of patients with acute motor AEs (100% vs. 58%); however, motor AE prevalence was similar in both groups at long-term follow-up (33% vs. 38%). CONCLUSION: Posterior placement of lesions targeting the Vim may confer greater tremor suppression. The addition of a PSA lesion, in patients with inadequate tremor control despite Vim lesioning, had a trend toward better long-term tremor suppression; however, this approach was associated with greater prevalence of gait disturbance in the short term.

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.

Overlapping stimulation of subthalamic nucleus and dentato-rubro-thalamic tract in Parkinson's disease after deep brain stimulation.

BACKGROUND: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) reduces tremor, rigidity, and akinesia. According to the literature, the dentato-rubro-thalamic tract (DRTt) is verified target for DBS in essential tremor; however, its role in the treatment of Parkinson's disease is only vaguely described. The aim of our study was to identify the relationship between symptom alleviation in PD patients and the distance of the DBS electrode electric field (EF) to the DRTt. METHODS: A single-center retrospective analysis of patients (N = 30) with idiopathic Parkinson's disease (PD) who underwent DBS between November 2018 and January 2020 was performed. DRTt and STN were visualized using diffusion-weighted imaging (DWI) and tractography protocol of magnetic resonance (MR). The EF was calculated and compared with STN and course of DRTt. Evaluation of patients before and after surgery was performed with use of UPDRS-III scale. The association between distance from EF to DRTt and clinical outcomes was examined. To confirm the anatomical variation between DRTt and STN observed in tractography, white matter dissection was performed with the Klingler technique on ten human brains. RESULTS: Patients with EF overlapping STN and DRTt benefited from significant motor symptoms improvement. Anatomical findings confirmed the presence of population differences in variability of the DRTt course and were consistent with the DRTt visualized by MR. CONCLUSIONS: DRTt proximity to STN, the main target in PD DBS surgery, confirmed by DWI with tractography protocol of MR combined with proper predefined stimulation parameters may improve efficacy of DBS-STN.

The Use of Image Guided Programming to Improve Deep Brain Stimulation Workflows with Directional Leads in Parkinson's Disease.

BACKGROUND: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a preferred treatment for parkinsonian patients with severe motor fluctuations. Proper targeting of the STN sensorimotor segment appears to be a crucial factor for success of the procedure. The recent introduction of directional leads theoretically increases stimulation specificity in this challenging area but also requires more precise stimulation parameters. OBJECTIVE: We investigated whether commercially available software for image guided programming (IGP) could maximize the benefits of DBS by informing the clinical standard care (CSC) and improving programming workflows. METHODS: We prospectively analyzed 32 consecutive parkinsonian patients implanted with bilateral directional leads in the STN. Double blind stimulation parameters determined by CSC and IGP were assessed and compared at three months post-surgery. IGP was used to adjust stimulation parameters if further clinical refinement was required. Overall clinical efficacy was evaluated one-year post-surgery. RESULTS: We observed 78% concordance between the two electrode levels selected by the blinded IGP prediction and CSC assessments. In 64% of cases requiring refinement, IGP improved clinical efficacy or reduced mild side effects, predominantly by facilitating the use of directional stimulation (93% of refinements). CONCLUSIONS: The use of image guided programming saves time and assists clinical refinement, which may be beneficial to the clinical standard care for STN-DBS and further improve the outcomes of DBS for PD patients.