Shifts in epilepsy treatment: a 12-year review of surgical approaches and outcomes in lesional and nonlesional epilepsy

J Neurosurg 144:259–272, 2026

This study analyzes national inpatient trends from 2009–2020 comparing lesional and nonlesional epilepsy patients who underwent surgical or neuromodulation treatments. Using NIS data with propensity score matching, it reports demographic differences, socioeconomic disparities, and shifting utilization patterns across VNS, RNS, DBS, resection, radiosurgery, and LITT.

The findings reveal increasing adoption of RNS and LITT, declining VNS and radiosurgery, higher costs for most interventions, and shorter length of stay with LITT. Persistent racial and income-based inequities in access and differing outcomes by lesion status prompt calls for tailored care and further cost-effectiveness and long-term outcome studies.

Distinct Patient Profiles: Lesional epilepsy patients are older, more likely male, have higher comorbidity burdens, and higher income/Medicare coverage compared to nonlesional epilepsy patients, who are more prevalent in lower income quartiles and rely more on Medicaid or private insurance.

Surgical Treatment Trends: Use of responsive neurostimulation (RNS) and laser interstitial thermal therapy (LITT) increased significantly for both lesional and nonlesional epilepsy from 2009–2020, while vagus nerve stimulation (VNS) declined for nonlesional epilepsy; deep brain stimulation (DBS) and radiosurgery declined for both groups.

Resective Surgery Patterns: Resective surgery utilization increased significantly for nonlesional epilepsy, but not for lesional epilepsy, indicating a growing acceptance of surgery in nonlesional cases despite the absence of overt lesions.

Healthcare Disparities: White patients, and those in higher income quartiles, have higher probabilities of receiving advanced treatments (VNS, RNS, DBS, resective surgery, radiosurgery); Black patients have persistently lower access regardless of income, and Hispanic patients show variable, income-dependent access.

Outcomes by Modality: RNS and LITT are associated with shorter or unchanged length of stay (LOS) and higher likelihood of routine discharge, while DBS and resective surgery increase LOS and costs; all surgical interventions increase hospital charges.

LITT Advantages: LITT is linked to decreased LOS and improved routine discharge rates, especially for lesional epilepsy, but incurs higher total charges compared to other modalities.

Mortality Impact: None of the interventions (VNS, RNS, DBS, resective surgery, radiosurgery, LITT) significantly affected mortality in either lesional or nonlesional epilepsy groups.

Need for Tailored Approaches: Persistent demographic, socioeconomic, and clinical differences between lesional and nonlesional epilepsy patients highlight the importance of individualized treatment strategies and further research on long-term and cost-effectiveness outcomes.

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.

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.

Robotic Stereotaxy in Cranial Neurosurgery

Neurosurgery 83:642–650, 2018

Modern-day stereotactic techniques have evolved to tackle the neurosurgical challenge of accurately and reproducibly accessing specific brain targets. Neurosurgical advances have beenmadein synergywith sophisticated technological developments and engineering innovations such as automated robotic platforms. Robotic systems offer a unique combination of dexterity, durability, indefatigability, and precision.

OBJECTIVE: To perform a systematic review of robotic integration for cranial stereotactic guidance in neurosurgery. Specifically, we comprehensively analyze the strengths and weaknesses of a spectrum of robotic technologies, past and present, including details pertaining to each system’s kinematic specifications and targeting accuracy profiles.

METHODS: Eligible articles on human clinical applications of cranial robotic-guided stereotactic systems between 1985 and 2017 were extracted from several electronic databases, with a focus on stereotactic biopsy procedures, stereoelectroencephalography, and deep brain stimulation electrode insertion.

RESULTS: Cranial robotic stereotactic systems feature serial or parallel architectures with 4 to 7 degrees of freedom, and frame-based or frameless registration. Indications for robotic assistance are diversifying, and include stereotactic biopsy, deep brain stimulation and stereoelectroencephalography electrode placement, ventriculostomy, and ablation procedures. Complication rates are low, and mainly consist of hemorrhage. Newer systems benefit fromincreasing targeting accuracy, intraoperative imaging ability, improved safety profiles, and reduced operating times.

CONCLUSION: We highlight emerging future directions pertaining to the integration of robotic technologies into future neurosurgical procedures. Notably, a trend toward miniaturization, cost-effectiveness, frameless registration, and increasing safety and accuracy characterize successful stereotactic robotic technologies.

Stimulation sites in the subthalamic nucleus and clinical improvement in Parkinson’s disease

stimulation-sites-in-the-subthalamic-nucleus-and-clinical-improvement-in-parkinsons-disease

J Neurosurg 125:1068–1079, 2016

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is widely used in patients with Parkinson’s disease (PD). However, which target area of this region results in the highest antiparkinsonian efficacy is still a matter of debate. The aim of this study was to develop a more accurate methodology to locate the electrodes and the contacts used for chronic stimulation (active contacts) in the subthalamic region, and to determine the position at which stimulation conveys the greatest clinical benefit.

Methods The study group comprised 40 patients with PD in whom bilateral DBS electrodes had been implanted in the STN. Based on the Morel atlas, the authors created an adaptable 3D atlas that takes into account individual anatomical variability and divides the STN into functional territories. The locations of the electrodes and active contacts were obtained from an accurate volumetric assessment of the artifact using preoperative and postoperative MR images. Active contacts were positioned in the 3D atlas using stereotactic coordinates and a new volumetric method based on an ellipsoid representation created from all voxels that belong to a set of contacts. The antiparkinsonian benefit of the stimulation was evaluated by the reduction in the Unified Parkinson´s Disease Rating Scale Part III (UPDRS-III) score and in the levodopa equivalent daily dose (LEDD) at 6 months. A homogeneous group classification for contact position and the respective clinical improvement was applied using a hierarchical clustering method.

Results Subthalamic stimulation induced a significant reduction of 58.0% ± 16.5% in the UPDRS-III score (p < 0.001) and 64.9% ± 21.0% in the LEDD (p < 0.001). The greatest reductions in the total and contralateral UPDRS-III scores (64% and 76%, respectively) and in the LEDD (73%) were obtained when the active contacts were placed approximately 12 mm lateral to the midline, with no influence of the position being observed in the anteroposterior and dorsoventral axes. In contrast, contacts located about 10 mm from the midline only reduced the global and contralateral UPDRS-III scores by 47% and 41%, respectively, and the LEDD by 33%. Using the ellipsoid method of location, active contacts with the highest benefit were positioned in the rostral and most lateral portion of the STN and at the interface between this subthalamic region, the zona incerta, and the thalamic fasciculus. Contacts placed in the most medial regions of the motor STN area provided the lowest clinical efficacy.

Conclusions The authors report an accurate new methodology to assess the position of electrodes and contacts used for chronic subthalamic stimulation. Using this approach, the highest antiparkinsonian benefit is achieved when active contacts are located within the rostral and the most lateral parts of the motor region of the STN and at the interface of this region and adjacent areas (zona incerta and thalamic fasciculus).

A single thalamic target for deep brain stimulation to treat hemi-body pain syndrome

A single thalamic target

Acta Neurochir (2015) 157:1519–1523

Patients experiencing hemi-body pain represent a difficult problem when using the thalamus as a DBS target given its anatomical topology.
Methods A 50-year-old HIV positive male underwent a right unilateral thalamic DBS to treat his severe left hemi-body central post-stroke pain following years of unsuccessful medication therapy.
Results The final active contact of the electrode corresponded to stimulation of the nucleus ventrocaudalis parvocellularis internis, which has provided prolonged pain relief.
Conclusion To our knowledge this was the first time this pattern of pain was treated by a single thalamic DBS electrode, suggesting stimulation in this region may be a feasible target for achieving relief from chronic severe hemi-body pain.

Bilateral stereotactic anterior capsulotomy for obsessive-compulsive disorder: long-term follow-up

DBS-OCD

J Neurol Neurosurg Psychiatry 2013;84:1208–1213

Psychosurgery, such as anterior capsulotomy, is a therapeutic option for treatment-resistant obsessive-compulsive disorder (OCD). In this paper, we present a prospective, long-term follow-up study aimed at evaluating both the efficacy and the safety of anterior capsulotomy for the treatment of severe, refractory OCD.

Methods Twenty-four patients were surgically treated in our centre between 1997 and 2009, 19 of whom were included in this study. Patients were assessed at 3, 6, 12, and 24 months and last follow-up (mean of 7 years) was carried out by phone. OCD symptom severity was evaluated using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). A patient with an improvement rate of over 35% in the Y-BOCS score was considered a responder, while a patient with a 25% improvement was considered a partial responder.

Results With a mean improvement of 31% in the Y-BOCS score at long-term follow-up, 36.8% of the patients responded fully to the procedure and 10.5% were considered partial responders, for an overall response rate of 47.3% of patients. At the end of the study, 3/19 patients had recovered (Y-BOCS score <8) and 3/19 were in remission (Y-BOCS score <16). No cases of mortality were reported and the overall adverse event rate was 57.9%. Only 2 patients had permanent surgical complications.

Conclusions Anterior capsulotomy is an effective and safe technique for the treatment of severe refractory OCD in patients who have no other alternative to improve their symptoms.

Memory Enhancement and Deep-Brain Stimulation of the Entorhinal Area

N Eng J Med, Vol 366(6), 9 February 2012, p 502–509. DOI: 10.1056/NEJMcibr1113400

The medial temporal structures, including the hippocampus and the entorhinal cortex, are critical for the ability to transform daily experience into lasting memories. We tested the hypothesis that deep-brain stimulation of the hippocampus or entorhinal cortex alters memory performance.

METHODS: We implanted intracranial depth electrodes in seven subjects to identify seizure-onset zones for subsequent epilepsy surgery. The subjects completed a spatial learning task during which they learned destinations within virtual environments. During half the learning trials, focal electrical stimulation was given below the threshold that elicits an afterdischarge (i.e., a neuronal discharge that occurs after termination of the stimulus).

RESULTS: Entorhinal stimulation applied while the subjects learned locations of landmarks enhanced their subsequent memory of these locations: the subjects reached these landmarks more quickly and by shorter routes, as compared with locations learned without stimulation. Entorhinal stimulation also resulted in a resetting of the phase of the theta rhythm, as shown on the hippocampal electroencephalogram. Direct hippocampal stimulation was not effective. In this small series, no adverse events associated with the procedure were observed.

CONCLUSIONS: Stimulation of the entorhinal region enhanced memory of spatial information when applied during learning.

Is MRI a reliable tool to locate the electrode after deep brain stimulation surgery? Comparison study of CT and MRI for the localization of electrodes after DBS

Acta Neurochir (2010) 152:2029–2036. DOI 10.1007/s00701-010-0779-2

MRI has been utilized to localize the electrode after deep brain stimulation, but its accuracy has been questioned due to image distortion. Under the hypothesis that MRI is not adequate for evaluation of electrode position after deep brain stimulation, this study is aimed at validating the accuracy of MRI in electrode localization in comparison with CT scan. Methods Sixty one patients who had undergone STN DBS were enrolled for the analysis. Using mutual information technique, CT and MRI taken at 6 months after the operation were fused. The x and y coordinates of the centers of electrodes shown of CT and MRI were compared in the fused images to calculate average difference at five different levels. The difference of the tips of the electrodes, designated as the z coordinate, was also calculated. Results The average of the distance between the centers of the electrodes in the five levels estimated in the fused image of brain CT and MRI taken at least 6 months after STN DBS was 1.33 mm (0.1–5.8 mm). The average discrepancy of x coordinates for all five levels between MRI and CT was 0.56±0.54 mm (0–5.7 mm), the discrepancy of y coordinates was 1.06±0.59 mm (0–3.5 mm), and for the z coordinate, it was 0.98±0.52 mm (0–3.1 mm) (all p values <0.001). Notably, the average discrepancy of x coordinates at 3.5 mm below AC–PC level, i.e., at the STN level between MRI and CT, was 0.59±0.42 mm (0–2.4 mm); the discrepancy of y coordinates was 0.81±0.47 mm (0–2.9 mm) (p values<0.001). Conclusions The results suggest that there was significant discrepancy between the centers of electrodes estimated by CT and MRI after STN DBS surgery.

Implantation of Deep Brain Stimulator Electrodes Using Interventional MRI

Philip A. Starr, MD, Alastair J.Martin, PhD, Paul S. Larson, MD

Neurosurgery Clinics of North America

Volume 20, Issue 2, Pages 207-217 (April 2009)

The authors describe a method for placement of deep brain stimulator electrodes using interventional MRI in conjunction with a skull-mounted aiming device (Medtronic Nexframe). This approach adapts the procedure to a standard-configuration 1.5-T diagnostic MRI scanner in a radiology suite. Preoperative imaging, device implantation, and postimplantation MRI are integrated into a single procedure performed under general anesthesia, providing real-time, high-resolution magnetic resonance confirmation of electrode position. The method is conceptually simpler than the current standard technique for deep brain stimulator placement, as it eliminates the stereotactic frame, the subsequent requirement for registration of the brain in stereotactic space, physiologic testing, and the need for patient cooperation. With further technical refinement, the interventional MRI method should improve the accuracy, safety, and speed of deep brain stimulator electrode placement.