Tag: Deep Brain Stimulation

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Deep brain stimulation for obsessive-compulsive disorder: evolution of tractography-based targeting

J Neurosurg 144:293–304, 2026

This clinical study describes the development and prospective application of patient-specific tractography to refine anterior limb of the internal capsule (ALIC) deep brain stimulation (DBS) targeting for treatment-refractory obsessive-compulsive disorder (OCD). The authors generated a common responder connectivity map highlighting ALIC pathways to vmPFC/OFC, vlPFC, thalamus, STN, and midbrain, then used that map to guide implantation in a new cohort, achieving consistent and rapid Y-BOCS improvements.

The team also built a tractography-based stimulation model linking activation of specific unilateral ALIC pathways to symptom reduction, demonstrating selective prediction of obsessive–compulsive symptom improvement (but not mood or anxiety). Results suggest that tractography-guided “sweet spot” targeting at the ventral ALIC near the GPe can reduce trial-and-error programming and support precision ALIC DBS implementation.

Patient-specific tractography targeting: Using individualized diffusion MRI tractography to guide deep brain stimulation (DBS) lead placement in the anterior limb of the internal capsule (ALIC) for obsessive-compulsive disorder (OCD) enables more precise and consistent targeting of therapeutic white matter pathways.

Common responder map: A map of white matter connections shared by DBS responders was generated, highlighting key pathways to the ventromedial/orbitofrontal cortex (vmPFC/OFC), ventrolateral prefrontal cortex (vlPFC), and midbrain; targeting this “sweet spot” led to improved and predictable clinical outcomes.

Improved clinical efficacy: Tractography-based ALIC DBS resulted in an 80% response rate (≥35% Y-BOCS reduction) among prospective patients, with faster and more consistent OCD symptom improvement compared to prior methods.

Reduced trial-and-error programming: Targeting based on the common responder map minimized the need for multiple adjustments in stimulation parameters, streamlining clinical implementation.

Symptom specificity: Stimulation of the tractography-defined target selectively improved OCD symptoms (obsessions and compulsions) with less impact on mood or anxiety and minimal side effects such as hypomania.

Tractography-based predictive model: A quantitative model using patient-specific pathway activation predicted OCD symptom improvement (Y-BOCS reduction), with strongest predictive value for connections to vlPFC, vmPFC/OFC, thalamus, and midbrain, but not for depression or anxiety scores.

Updated common responder map validation: High-resolution 7T MRI data from additional responders confirmed the importance of connections to vlPFC, vmPFC/OFC, thalamus, and midbrain in therapeutic response.

Potential for clinical scalability: This precision targeting approach, if validated in larger cohorts, could enhance the predictability, effectiveness, and broader adoption of DBS for treatment-resistant OCD.

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Central thalamic deep brain stimulation for disorders of consciousness: an individual participant data meta-analysis

J Neurosurg 143:1217–1226, 2025

This individual participant data meta-analysis evaluates central thalamic deep brain stimulation (DBS) for chronic disorders of consciousness, pooling 49 patients from seven centers to assess neurological outcomes via the JFK Coma Recovery Scale–Revised. Results show modest mean CRS-R improvement, with age and shorter delay to implantation predicting better gains, but insufficient evidence that DBS alters the natural recovery trajectory.

The report details heterogeneity in targets, stimulation schedules, and methodological limitations—no randomized controls, selection bias, and variable reporting—highlighting the need for matched comparative studies, standardized outcome metrics, and refined targeting (CL vs CM-Pf/DTTm) to determine DBS efficacy and optimize patient selection.

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Multi-institutional recommendations on the use of 7T MRI in deep brain stimulation

J Neurosurg 143:1165–1175, 2025

This multi-institutional review presents consensus recommendations for integrating 7T ultrahigh-field MRI into deep brain stimulation (DBS) workflows, drawing on experience from over 1,000 procedures. It summarizes technical challenges—B1+ heterogeneity, susceptibility and gradient nonlinear distortions—and practical solutions for acquisition, distortion correction, and coregistration to ensure stereotactic accuracy.

The document details optimized sequences and target-specific imaging strategies (STN, GPi, thalamic nuclei, ANT, CM), advanced modalities (DTI/DiMANI, QSM, tractography), and multidisciplinary workflow considerations to improve patient-specific anatomical and connectivity-based DBS targeting and programming.

• 7T MRI Advantages: Ultrahigh-field 7T MRI provides superior spatial resolution, signal-to-noise ratio, and tissue contrast, enabling clearer visualization of deep brain structures critical for deep brain stimulation (DBS) targeting compared to 1.5T and 3T MRI.

• Improved DBS Targeting: 7T MRI enhances direct anatomical and connectivity-based targeting for DBS, supporting more precise, patient-specific electrode placement for Parkinson’s disease, essential tremor, and epilepsy.

• Key Technical Challenges: 7T MRI introduces unique challenges including B1+ transmit field inhomogeneity, increased image distortions (gradient nonlinearity and susceptibility), and chemical shift artifacts, all of which require specialized correction and protocol optimization.

• Distortion Correction and Coregistration: Accurate DBS planning with 7T MRI demands robust correction for gradient and susceptibility distortions, careful coregistration with stereotactic CT, and often manual or nonlinear registration adjustments for optimal anatomical alignment.

• Recommended Imaging Sequences: Specific 7T MRI sequences, such as T2-weighted, FGATIR, MP2RAGE, SWI, QSM, and advanced diffusion imaging (DTI/DiMANI), are recommended for visualizing common DBS targets (STN, GPi, thalamic nuclei), each offering distinct advantages for different structures.

• Connectivity and Tractography: Advanced diffusion MRI at 7T allows submillimetric tractography, enabling functional parcellation of DBS targets (e.g., STN, GPi, DRTT), which can improve patient outcomes by supporting symptom- and network-specific targeting.

• Clinical Impact: Implementation of 7T MRI in over 1000 DBS procedures across multiple centers has demonstrated that, with appropriate workflow and expertise, technical challenges can be managed and targeting accuracy and patient outcomes can be improved.

• Multidisciplinary Collaboration: Effective use of 7T MRI for DBS requires close collaboration between neurosurgeons, MR technicians, physicists, and neuroradiologists to optimize protocols and address the complexity of ultrahigh-field imaging

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Clinical Evaluation of the NaviNetics Stereotactic System Using Intraoperative Portable Surgical Imaging System in DBS Surgery

Operative Neurosurgery 29:93–101, 2025

Intraoperative O-arm imaging with the NaviNetics stereotactic head frame enables accurate, efficient deep brain stimulation (DBS) lead placement in both awake and asleep surgeries, streamlining workflow by eliminating patient transport for imaging and achieving submillimeter accuracy comparable to traditional CT-based methods.

• The study evaluates the NaviNetics stereotactic head frame system with intraoperative O-arm imaging for deep brain stimulation (DBS) surgery.

• Intraoperative O-arm imaging was used for both stereotactic registration and lead placement confirmation in awake and asleep DBS procedures.

• A total of 17 patients were included; 1 had both CT and O-arm, while 16 had only O-arm localization.

• Accuracy of O-arm imaging was comparable to traditional CT, with less than 0.1 mm difference and a mean radial error of 0.71 ± 0.33 mm for 32 leads.

• No surgical complications, lead repositioning, or infections were reported.

• The intraoperative O-arm workflow reduces patient transport, surgical time, and allows real-time confirmation of lead placement.

• Limitations include limited hemorrhage detection by O-arm and lack of direct comparison with stereotactic CT in larger samples.

• The study concludes O-arm imaging is safe, effective, and streamlines DBS surgery without compromising accuracy.

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The Rate and Risk Factors of Deep Brain Stimulation–Associated Complications

Operative Neurosurgery 28:519–527, 2025

The study investigates complications associated with deep brain stimulation (DBS) surgery, analyzing patient demographics, surgical techniques, and outcomes. It identifies factors influencing complications such as pneumocephalus, infection, and hemorrhage, aiming to improve patient selection and surgical strategies for better outcomes.

• Deep Brain Stimulation (DBS) is a recognized neurosurgical procedure for various neurological disorders, considered safe but not without complications. The study investigates these complications and their association with patient characteristics and surgical techniques.

• The study analyzed 481 patients who underwent DBS lead implantation between January 2012 and January 2020, with a total of 859 leads implanted.

• Common complications included pneumocephalus, edema, altered mental state, and infection. General anesthesia, hypertension, heart disease, and depression were linked to longer postoperative stays.

• High BMI was associated with increased rates of surgery-related infections and lead revision/explantation.

• Intraoperative mean arterial pressure and anesthesia type were significant predictors of postoperative pneumocephalus.

• The study found that certain comorbidities, such as hypertension, heart disease, and depression, were associated with longer hospital stays.

• Older patients were less likely to require lead revision/explantation, while those with high BMI were at higher risk.

• Infection prevention techniques, like vancomycin powder, were effective, with infection rates at the lower end of the reported range.

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How Accurate Is Frameless Fiducial—Free Deep Brain Stimulation?

Operative Neurosurgery 27:431–439, 2024

Frameless deep brain stimulation (DBS) offers advantages in terms of patient comfort and reduced operative time. However, the need for bony fiducial markers for localization remains a drawback due to the time-consuming and uncomfortable procedure. An alternative localization method involves the direct tracking of an intraoperative 3-dimensional scanner. This study aims to assess the accuracy of the NexFrame frameless DBS system in conjunction with the O-Arm (Medtronic Inc.), both with and without fiducial markers.

METHODS: The locations of 100 DBS leads were determined, with 50 cases using fiducial-free localization and 50 involving fiducial markers. The coordinates were compared with the expected intraoperative targets. Absolute errors in the X, Y, and Z coordinates (ΔX, ΔY, and ΔZ) were calculated, along with the vector error (Euclidean) (vector error square root Δx 2 + Δy 2 + Δz 2 ).

RESULTS: The vector error averaged 1.61 ± 0.49 mm (right) and 1.52 ± 0.60 mm (left) for the group without fiducial bone markers and 1.66 ± 0.69 (right) and 1.44 ± 0.65 mm (left) for the other cohort (P = .76 right; P = .67 left). Absolute errors in the X, Y, and Z coordinates for the fiducial-free group were 0.88 ± 0.55, 0.79 ± 0.45, and 0.79 ± 0.57 mm (right) and 0.72 ± 0.37, 0.78 ± 0.56, and 0.77 ± 0.71 mm (left). For the group with fiducial markers, these errors were 0.87 ± 0.72, 0.92 ± 0.39, and 0.86 ± 0.50 mm (right) and 0.75 ± 0.33, 0.80 ± 0.51, and 0.73 ± 0.64 mm (left) with no statistically significant difference.

CONCLUSION: Our analysis of the accuracy of NexFrame DBS, both with and without fiducial markers, using an intraoperative navigable cone-beam computed tomography, demonstrates that both techniques provide sufficient and equivalent 3-dimensional accuracy.

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Topographical anatomy of the subthalamic region with special interest in the human medial forebrain bundle

J Neurosurg 141:570–580, 2024

The medial forebrain bundle (MFB) is a novel promising deep brain stimulation (DBS) target in severe affective disorders that courses through the subthalamic region according to tractography studies. Its potential therapeutic role arose in connection with the development of hypomania during stimulation of the subthalamic nucleus (STN) in Parkinson’s disease, offering an alternative explanation for the occurrence of this side effect. However, until now its course exclusively described by tractography had not yet been confirmed by any anatomical method. The aim of this study was to fill this gap as well as to provide a detailed description of the fiber tracts surrounding the STN to facilitate a better understanding of the background of side effects occurring during STN DBS.

METHODS Ten human cadaveric brains (20 hemispheres) and 100 healthy subjects (200 hemispheres) from the S500 Release of the Human Connectome Project were involved in this study. Nineteen hemispheres were dissected according to Klingler’s method. One additional hemisphere was prepared for histological examinations to validate the macroscopical results and stained with neurofibril silver impregnation according to Krutsay. The authors also aimed to reconstruct the MFB using tractography and correlated the results with their dissections and histological findings.

RESULTS The white matter connections coursing through the subthalamic region were successfully dissected. The ansa lenticularis, lenticular fasciculus, thalamic fasciculus, ipsi- and contralateral cerebellar fibers, and medial lemniscus were revealed as closely related fiber tracts to the STN. However, the existence of a distinct fiber bundle corresponding to the MFB described by tractography could not be identified. Using tractography, the authors showed that the depiction of the streamlines representing the MFB was also strongly dependent on the threshold parameters.

CONCLUSIONS According to this study’s findings, the streamlines of the MFB described by tractography arise from the limitations of the diffusion-weighted MRI fiber tracking method and actually correspond to subthalamic fiber bundles, especially the ansa lenticularis and lenticular fasciculus, which erroneously continue in the anterior limb of the internal capsule, toward the prefrontal cortex.

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Robot-Assisted Minimally Invasive Asleep Single-Stage Deep Brain Stimulation Surgery

Operative Neurosurgery 26:363–371, 2024

Robotic assistance has garnered increased use in neurosurgery. Recently, this has expanded to include deep brain stimulation (DBS). Several studies have reported increased accuracy and improved efficiency with robotic assistance, but these are limited to individual robotic platforms with smaller sample sizes or are broader studies on robotics not specific to DBS. Our objectives are to report our technique for robot-assisted, minimally invasive, asleep, single-stage DBS surgery and to perform a meta-analysis comparing techniques from previous studies.

METHODS: We performed a single-center retrospective review of DBS procedures using a floor-mounted robot with a frameless transient fiducial array registration. We compiled accuracy data (radial entry error, radial target error, and 3dimensional target error) and efficiency data (operative time, setup time, and total procedure time). We then performed a meta-analysis of previous studies and compared these metrics.

RESULTS: We analyzed 315 electrodes implanted in 160 patients. The mean radial target error was 0.9 ± 0.5 mm, mean target 3-dimensional error was 1.3 ± 0.7 mm, and mean radial entry error was 1.1 ± 0.8 mm. The mean procedure time (including pulse generator placement) was 182.4 ± 47.8 minutes, and the mean setup time was 132.9 ± 32.0 minutes. The overall complication rate was 8.8% (2.5% hemorrhagic/ischemic, 2.5% infectious, and 0.6% revision). Our meta-analysis showed increased accuracy with floor-mounted over skull-mounted robotic platforms and with fiducial-based registrations over optical registrations.

CONCLUSION: Our technique for robot-assisted, minimally invasive, asleep, single-stage DBS surgery is safe, accurate, and efficient. Our data, combined with a meta-analysis of previous studies, demonstrate that robotic assistance can provide similar or increased accuracy and improved efficiency compared with traditional frame-based techniques. Our analysis also suggests that floor-mounted robots and fiducial-based registration methods may be more accurate.

 

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Use of differential stimulation of the nucleus accumbens and anterior limb of the internal capsule to improve outcomes of obsessive-compulsive disorder

J Neurosurg 139:1376–1385, 2023

Personalized stimulation is key to optimizing the outcomes of deep brain stimulation (DBS) for refractory obsessive-compulsive disorder (OCD). However, the contacts in a single conventional electrode cannot be programmed independently, which may affect the therapeutic efficacy of DBS for OCD. Therefore, a novel designed electrode and implantable pulse generator (IPG) that could achieve differential stimulation parameters for different contacts was implanted into the nucleus accumbens (NAc) and anterior limb of the internal capsule (ALIC) of a cohort of patients with OCD.

METHODS Thirteen consecutive patients underwent bilateral DBS of the NAc-ALIC between January 2016 and May 2021. Differential stimulation of the NAc-ALIC was applied at initial activation. Primary effectiveness was assessed on the basis of change in scores on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) from baseline to 6-month follow-up. Full-response was defined as a 35% decrease in Y-BOCS score. Secondary effectiveness measures were the Hamilton Anxiety Rating Scale (HAMA) and Hamilton Depression Rating Scale (HAMD). The local field potential of bilateral NAcALIC was recorded in 4 patients who were reimplanted with a sensing IPG after battery depletion of the previous IPG.

RESULTS The Y-BOCS, HAMA, and HAMD scores decreased remarkably during the first 6 months of DBS. Ten of 13 patients were categorized as responders (76.9%). Differential stimulation of the NAc-ALIC was favorable to optimization of the stimulation parameters by increasing the parameter configurations. Power spectral density analysis revealed pronounced delta-alpha frequency activity in the NAc-ALIC. Phase-amplitude coupling of the NAc-ALIC showed that strong coupling is present between the phase of delta-theta and broadband gamma amplitude.

CONCLUSIONS These preliminary findings indicate that differential stimulation of the NAc-ALIC can improve the efficacy of DBS for OCD.

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Altered brain network centrality in Parkinson’s disease patients after deep brain stimulation: a functional MRI study using a voxel-wise degree centrality approach

J Neurosurg 138:1712–1719, 2023

After deep brain stimulation (DBS), patients with Parkinson’s disease (PD) show improved motor symptoms and decreased verbal fluency, an effect that occurs before the initiation of DBS in the subthalamic nucleus. However, the underlying mechanism remains unclear. This study aimed to evaluate the effects of DBS on whole-brain degree centrality (DC) and seed-based functional connectivity (FC) in PD patients.

METHODS The authors obtained resting-state functional MRI data of 28 PD patients before and after DBS surgery. All patients underwent MRI scans in the off-stimulation state. The DC method was used to evaluate the effects of DBS on whole-brain FC at the voxel level. Seed-based FC analysis was used to examine network function changes after DBS.

RESULTS After DBS surgery, PD patients showed significantly weaker DC values in the left middle temporal gyrus, left supramarginal gyrus, and left middle frontal gyrus, but significantly stronger DC values in the midbrain, left precuneus, and right precentral gyrus. FC analysis revealed decreased FC values within the default mode network (DMN).

CONCLUSIONS This study demonstrated that the DC of DMN-related brain regions decreased in PD patients after DBS surgery, whereas the DC of the motor cortex increased. These findings provide new evidence for the neural effects of DBS on voxel-based whole-brain networks in PD patients.

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Long-Term Outcomes of Bilateral Subthalamic Nucleus Deep Brain Stimulation for Patients With Parkinson’s Disease: 10 Years and Beyond

Neurosurgery 91:726–733, 2022

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) represents an effective treatment for severe Parkinson’s disease (PD), but little is known about the long-term benefit.

OBJECTIVE: To investigate the survival rate and long-term outcome of DBS.

METHODS: We investigated all 81 patients including 37 males and 44 females who underwent bilateral STN DBS from March 2005 to March 2008 at a single institution. The current survival status of the patients was investigated. Preoperative and postoperative follow-up assessments were analyzed.

RESULTS: The mean age at the time of surgery was 62 (range 27-82) years, and the median clinical follow-up duration was 145 months. Thirty-five patients (43%) died during the follow-up period. The mean duration from DBS surgery to death was 110.46 ± 40.8 (range 0-155) months. The cumulative survival rate is as follows: 98.8 ± 1.2% (1 year), 95.1 ± 2.4% (5 years), and 79.0 ± 4.5% (10 years). Of the 81 patients, 33 (40%) were ambulatory up to more than 11 years. The Unified Parkinson’s Disease Rating Scale (UPDRS) score was significantly improved until 5 years after surgery although it showed a tendency to increase again after 10 years. The patient group with both electrodes located within the STN showed a higher rate of survival and maintained ambulation.

CONCLUSION: STN DBS is a safe and effective treatment for patients with advanced PD. This study based on the long-term follow-up of large patient populations can be used to elucidate the long-term fate of patients who underwent bilateral STN DBS for PD.

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Tractography-Based Surgical Targeting for Thalamic Deep Brain Stimulation: A Comparison of Probabilistic vs Deterministic Fiber Tracking of the Dentato-Rubro-Thalamic Tract

Neurosurgery 90:419–425, 2022

The ventral intermediate (VIM) thalamic nucleus is the main target for the surgical treatment of refractory tremor. Initial targeting traditionally relies on atlas-based stereotactic targeting formulas, which only minimally account for individual anatomy. Al- ternative approaches have been proposed, including direct targeting of the dentato-rubro- thalamic tract (DRTT), which, in clinical settings, is generally reconstructed with deterministic tracking. Whether more advanced probabilistic techniques are feasible on clinical-grade magnetic resonance acquisitions and lead to enhanced reconstructions is poorly understood.

OBJECTIVE: To compare DRTT reconstructed with deterministic vs probabilistic tracking. METHODS: Thisisaretrospectivestudyof19patientswithessentialtremorwhounderwentdeep brain stimulation (DBS) with intraoperative neurophysiology and stimulation testing. We assessed the proximity of the DRTT to the DBS lead and to the active contact chosen based on clinical response.

RESULTS: In the commissural plane, the deterministic DRTT was anterior (P<104)and  < 104) to the DBS lead. By contrast, although the probabilistic DRTT was also anterior to the lead (P < 104), there was no difference in the mediolateral dimension (P = .5). Moreover, the 3- dimensional Euclidean distance from the active contact to the probabilistic DRTT was smaller vs the distance to the deterministic DRTT (3.32 ± 1.70 mm vs 5.01 ± 2.12 mm; P < 104).

CONCLUSION: DRTT reconstructed with probabilistic fiber tracking was superior in spatial proximity to the physiology-guided DBS lead and to the empirically chosen active contact. These data inform strategies for surgical targeting of the VIM.

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Direct targeting of the ventral intermediate nucleus of the thalamus in deep brain stimulation for essential tremor

J Neurosurg 136:662–671, 2022

The ventral intermediate nucleus of the thalamus (VIM) is an effective target for deep brain stimulation (DBS) to control symptoms related to essential tremor. The VIM is typically targeted using indirect methods, although studies have reported visualization of the VIM on proton density–weighted MRI. This study compares the outcomes between patients who underwent VIM DBS with direct and indirect targeting.

METHODS Between August 2013 and December 2019, 230 patients underwent VIM DBS at the senior author’s institution. Of these patients, 92 had direct targeting (direct visualization on proton density 3-T MRI). The remaining 138 patients had indirect targeting (relative to the third ventricle and anterior commissure–posterior commissure line).

RESULTS Coordinates of electrodes placed with direct targeting were significantly more lateral (p < 0.001) and anterior (p < 0.001) than those placed with indirect targeting. The optimal stimulation amplitude for devices measured in voltage was lower for those who underwent direct targeting than for those who underwent indirect targeting (p < 0.001). Patients undergoing direct targeting had a greater improvement only in their Quality of Life in Essential Tremor Questionnaire hobby score versus those undergoing indirect targeting (p = 0.04). The direct targeting group had substantially more symptomatic hemorrhages than the indirect targeting group (p = 0.04). All patients who experienced a postoperative hemorrhage after DBS recovered without intervention.

CONCLUSIONS Patients who underwent direct VIM targeting for DBS treatment of essential tremor had similar clinical outcomes to those who underwent indirect targeting. Direct VIM targeting is safe and effective.

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Perioperative complications of deep brain stimulation among patients with advanced age

J Neurosurg 135:1421–1428, 2021

Deep brain stimulation (DBS) is an elective procedure that can dramatically enhance quality of life. Because DBS is not considered lifesaving, it is important that providers produce consistently good outcomes, and one factor they usually consider is patient age. While older age may be a relative contraindication for some elective surgeries, the progressive nature of movement disorders treated with DBS may suggest that older patients stand to benefit substantially from surgery. To better understand the risks of treating patients of advanced age with DBS, this study compares perioperative complication rates in patients ≥ 75 to those < 75 years old.

METHODS Patients undergoing DBS surgery for various indications by a single surgeon (May 2013–July 2019) were stratified into elderly (age ≥ 75 years) and younger (age < 75 years) cohorts. The risks of common perioperative complications and various outcome measures were compared between the two age groups using risk ratios (RRs) and 95% confidence intervals (CIs).

RESULTS A total of 861 patients were available for analysis: 179 (21%) were ≥ 75 years old and 682 (79%) were < 75 years old (p < 0.001). Patients ≥ 75 years old, compared with those < 75 years old, did not have significantly different RRs (95% CIs) of seizure (RR 0.4, 95% CI 0.1–3.3), cerebrovascular accident (RR 1.9, 95% CI 0.4–10.3), readmission within 90 days of discharge (RR 1.22, 95% CI 0.8–1.8), explantation due to infection (RR 2.5, 95% CI 0.4–15.1), or surgical revision (for lead, RR 2.5, 95% CI 0.4–15.1; for internal pulse generator, RR 3.8, 95% CI 0.2–61.7). Although the risk of postoperative intracranial bleeding was higher in the elderly group (6.1%) than in the younger group (3.1%), this difference was not statistically significant (p = 0.06). However, patients ≥ 75 years old did have significantly increased risk of altered mental status (RR 2.5, 95% CI 1.6–4.0), experiencing more than a 1-night stay (RR 1.7, 95% CI 1.4–2.0), and urinary retention (RR 2.3, 95% CI 1.2–4.2; p = 0.009).

CONCLUSIONS Although elderly patients had higher risks of certain outcome measures than younger patients, this study showed that elderly patients undergoing DBS for movement disorders did not have an increased risk of more serious complications, such as intracranial hemorrhage, infection, or readmission. Advanced age alone should not be considered a contraindication for DBS.

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Fields of Forel Brain Stimulation Improves Levodopa-Unresponsive Gait and Balance Disorders in Parkinson’s Disease

Neurosurgery 89:450–459, 2021

Gait and balance disturbance are challenging symptoms in advanced Parkinson’s disease (PD). Anatomic and clinical data suggest that the fields of Forel may be a potential surgical target to treat these symptoms.

OBJECTIVE: To test whether bilateral stimulation centered at the fields of Forel improves levodopa unresponsive freezing of gait (FOG), balance problems, postural instability, and falls in PD.

METHODS: A total of 13 patients with levodopa-unresponsive gait disturbance (Hoehn and Yahr stage ≥3) were included. Patients were evaluated before (on-medication condition) and 1 yr after surgery (on-medication-on-stimulation condition). Motor symptoms and quality of life were assessed with the Unified Parkinson’s Disease Rating scale (UPDRS III) and Quality of Life scale (PDQ-39). Clinical and instrumented analyses assessed gait, balance, postural instability, and falls.

RESULTS: Surgery improved balance by 43% (95% confidence interval [CI]: 21.2-36.4 to 35.2-47.1; P = .0012), reduced FOG by 35% (95% CI: 15.1-20.3 to 8.1-15.3; P = .0021), and the monthly number of falls by 82.2% (95% CI: 2.2-6.9 to −0.2-1.7; P = .0039). Anticipatory postural adjustments, velocity to turn, and postural sway measurements also improved 1 yr after deep brain stimulation (DBS). UPDRS III motor scores were reduced by 27.2% postoperatively (95% CI: 42.6-54.3 to 30.2-40.5; P < .0001). Quality of life improved 27.5% (95% CI: 34.6-48.8 to 22.4-37.9; P = .0100).

CONCLUSION: Our results suggest that DBS of the fields of Forel improved motor symptoms in PD, as well as the FOG, falls, balance, postural instability, and quality of life.

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A Novel Framework for Network-Targeted Neuropsychiatric Deep Brain Stimulation

Neurosurgery 89:E116–E121, 2021

Deep brain stimulation (DBS) has emerged as a promising therapy for neuropsychiatric illnesses, including depression and obsessive-compulsive disorder, but has shown inconsistent results in prior clinical trials. We propose a shift away from the empirical paradigm for developing new DBS applications, traditionally based on testing brain targets with conventional stimulation paradigms. Instead, we propose a multimodal approach centered on an individualized intracranial investigation adapted from the epilepsy monitoring experience, which integrates comprehensive behavioral assessment, such as the Research Domain Criteria proposed by the National Institutes of Mental Health. In this paradigm-shifting approach, we combine readouts obtained from neurophysiology, behavioral assessments, and self-report during broad exploration of stimulation parameters and behavioral tasks to inform the selection of ideal DBS parameters. Such an approach not only provides a foundational understanding of dysfunctional circuits underlying symptom domains in neuropsychiatric conditions but also aims to identify generalizable principles that can ultimately enable individualization and optimization of therapy without intracranial monitoring.

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Neurostimulation for treatment-resistant posttraumatic stress disorder

J Neurosurg 134:1715–1723, 2021

Posttraumatic stress disorder (PTSD) is a widespread and often devastating psychiatric condition. Core symptoms include intrusive and distressing thoughts, heightened reactivity, mood changes, cognitive impairments, and consequent avoidance of trauma-related stimuli. Symptoms of PTSD are often refractory to standard treatments, and neuromodulatory techniques have therefore drawn significant interest among the most treatment-resistant patients.

Transcranial magnetic stimulation has demonstrated minimal efficacy, and deep brain stimulation trials are currently ongoing.

PTSD is a disorder of neural circuitry; the current understanding includes involvement of the amygdala (basolateral and central nuclei), the prefrontal cortex (ventral medial and dorsolateral regions), and the hippocampus. Neuroimaging and optogenetic studies have improved the understanding of large-scale neural networks and the effects of microcircuitry manipulation, respectively.

This review discusses the current PTSD literature and ongoing neurostimulation trials, and it highlights the current understanding of neuronal circuit dysfunction in PTSD. The authors emphasize the anatomical correlations of PTSD’s hallmark symptoms, offer another potential deep brain stimulation target for PTSD, and note the need for continued research to identify useful biomarkers for the development of closed-loop therapies. Although there is hope that neuromodulation will become a viable treatment modality for PTSD, this concept remains theoretical, and further research should involve institutional review board–approved controlled prospective clinical studies.

 

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Electrocorticography During Deep Brain Stimulation Surgery

Neurosurgery 88:E420–E426, 2021

Intraoperative research during deep brain stimulation (DBS) surgery has enabled major advances in understanding movement disorders pathophysiology and potential mechanisms for therapeutic benefit. In particular, over the last decade, recording electrocorticography (ECoG) from the cortical surface, simultaneously with subcortical recordings, has become an important research tool for assessing basal gangliathalamocortical circuit physiology.

OBJECTIVE: To provide confirmation of the safety of performing ECoG duringDBS surgery, using data fromcenters involved in 2 BRAIN (Brain Research through Advancing Innovative Neurotechnologies) Initiative-funded basic human neuroscience projects. METHODS: Datawere collected separately at 4 centers. The primary endpoint was complication rate, defined as any intraoperative event, infection, or postoperative magnetic resonance imaging abnormality requiring clinical follow-up. Complication rates for explanatory variables were compared using point biserial correlations and Fisher exact tests.

RESULTS: A total of 367 DBS surgeries involving ECoG were reviewed. No cortical hemorrhages were observed. Seven complications occurred: 4 intraparenchymal hemorrhages and 3 infections (complication rate of 1.91%; CI=0.77%-3.89%). The placement of 2 separate ECoG research electrodes through a single burr hole (84 cases) did not result in a significantly different rate of complications, compared to placement of a single electrode (3.6% vs 1.5%; P = .4). Research data were obtained successfully in 350 surgeries (95.4%).

CONCLUSION: Combined with the single report previously available, which described no ECoG-related complications in a single-center cohort of 200 cases, these findings suggest that research ECOG during DBS surgery did not significantly alter complication rates.

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Congress of Neurological Surgeons Systematic Review and Evidence-Based Guidelines for Deep Brain Stimulations for Obsessive-Compulsive Disorder: Update of the 2014 Guidelines

 Neurosurgery 88:710–712, 2021

In 2020, the Guidelines Task Force conducted another systematic review of the relevant literature on deep brain stimulation (DBS) for obsessive-compulsive disorder (OCD) to update the original 2014 guidelines to ensure timeliness and accuracy for clinical practice.

OBJECTIVE: To conduct a systematic review of the literature and update the evidencebased guidelines on DBS for OCD.

METHODS: The Guidelines Task Force conducted another systematic review of the relevant literature, using the same search terms and strategies as used to search PubMed and Embase for relevant literature. The updated search included studies published between 1966 and December 2019. The same inclusion/exclusion criteria as the original guideline were also applied. Abstracts were reviewed and relevant full-text articles were retrieved and graded. Of 864 articles, 10 were retrieved for full-text review and analysis. Recommendations were updated according to new evidence yielded by this update.

RESULTS: Seven studies were included in the original guideline, reporting the use of bilateral DBS as more effective in improving OCD symptoms than sham treatment. An additional 10 studies were included in this update: 1 class II and 9 class III.

CONCLUSION: Based on the data published in the literature, the following recommendations can be made: (1) It is recommended that clinicians utilize bilateral subthalamic nucleus DBS over best medical management for the treatment of patients with medically refractory OCD (level I). (2) Cliniciansmay use bilateral nucleus accumbens or bed nucleus of stria terminalis DBS for the treatment of patientswithmedically refractory OCD (level II). There is insufficient evidence to make a recommendation for the identification of themost effective target. The full guidelines can be accessed at https://www.cns.org/guidelines/browse-guidelinesdetail/ deep-brain-stimulation-obsessive-compulsive-disord.

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Deep brain stimulation for aggressiveness: long-term follow-up and tractography study of the stimulated brain areas

J Neurosurg 134:366–375, 2021

Initial studies applying deep brain stimulation (DBS) of the posteromedial hypothalamus (PMH) to patients with pathological aggressiveness have yielded encouraging results. However, the anatomical structures involved in its therapeutic effect have not been precisely identified. The authors’ objective was to describe the long-term outcome in their 7-patient series, and the tractography analysis of the volumes of tissue activated in 2 of the responders.

METHODS This was a retrospective study of 7 subjects with pathological aggressiveness. The findings on MRI with diffusion tensor imaging (DTI) in 2 of the responders were analyzed. The authors generated volumes of tissue activated according to the parameters used, and selected those volumes as regions of interest to delineate the tracts affected by stimulation.

RESULTS The series consisted of 5 men and 2 women. Of the 7 patients, 5 significantly improved with stimulation. The PMH, ventral tegmental area, dorsal longitudinal fasciculus, and medial forebrain bundle seem to be involved in the stimulation field.

CONCLUSIONS In this series, 5 of 7 medication-resistant patients with severe aggressiveness who were treated with bilateral PMH DBS showed a significant long-lasting improvement. The PMH, ventral tegmental area, dorsal longitudinal fasciculus, and medial forebrain bundle seem to be in the stimulation field and might be responsible for the therapeutic effect of DBS.

 

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