Ojemann, Steven

Abstract Objective This study was undertaken to evaluate the safety and effectiveness of responsive thalamic stimulation as adjunctive therapy for drug‐resistant idiopathic generalized epilepsy (IGE) with generalized tonic–clonic seizures (GTCSs). Methods NAUTILUS is a prospective, multicenter, single‐blind, randomized sham‐controlled pivotal trial. Patients were ≥12 years of age with drug‐resistant IGE and ≥2 GTCSs over a 3‐month baseline. Bilateral depth leads were targeted to the centromedian thalamus. One month later, patients were randomized to Active (responsive stimulation, n = 44) or Sham (no stimulation, n = 43). The effectiveness evaluation period (EEP) began 3 months postimplant through 1 year. After a second GTCS in the EEP, patients transitioned to open‐label active stimulation. The primary safety endpoint was the serious adverse device‐related event (SADE) rate at 84 days postimplant. The primary effectiveness endpoint was time‐to‐second‐GTCS during the EEP. Additional endpoints included median percent change in days with any generalized seizure, GTCS frequency, and responder rate (RR). Results Eighty‐seven patients were implanted across 23 US centers. The SADE rate was significantly below the performance goal (6.9%, p < .0001), with no adverse effects on cognition, mood, or sleep. The prespecified primary effectiveness endpoint was not significant. However, a post hoc mixed‐effects model considering all EEP days demonstrated greater GTCS reduction in the originally randomized Active group (61%) compared to patients originally randomized to Sham (49%, p = .030). Eighteen‐month outcomes included 76.8% median GTCS reduction, 62.5% RR, 40% GTCS‐free at that timepoint, and 77.8% median reduction in days with any generalized seizure. More than 90% of patients and 86% of physicians reported improvement on Global Impression of Change scales. Significance NAUTILUS is the first randomized controlled neuromodulation trial in IGE. Responsive thalamic stimulation provided a clinically meaningful and durable reduction in seizures with an acceptable safety profile, offering a much‐needed option for drug‐resistant IGE.

Abstract Objectives Pivotal trials have established the effectiveness of the Responsive Neurostimulation System (RNS® System) in treating focal epilepsy. In clinical trials, depth leads were primarily used to treat mesial temporal seizure onsets while cortical strip leads were used to treat neocortical seizure onsets. Here, we systematically analyze the safety and efficacy of stereoelectroencephalography (sEEG)‐guided depth leads to provide responsive stimulation to neocortical gray matter. Methods Patients were stratified as strong responders (>median cohort seizure reduction %), weak responders (>0% and ≤median cohort seizure reduction %), and anti‐responders (≤0%) based on percent seizure reduction at 1 year post‐implant (1‐Y). Pre‐operative T1‐weighted magnetic resonance imaging and post‐operative computed tomography images were merged, and the Euclidean distance between the sEEG epileptic focus (sEEG‐EF) and the nearest RNS System depth lead contacts was calculated. Results A total of 87 depth leads were implanted in 55 patients across neocortical brain regions. The median reduction in clinical seizures improved from 66.7% at 1‐Y to 77.5% at long‐term follow‐up (LTFU: 2.35 ± 0.95 years), with 10 patients (18.2%) achieving complete seizure freedom. Seven patients (12.7%) experienced six serious adverse events. At 1‐Y, shorter Euclidean distance between the sEEG‐EF and RNS System depth leads predicted improved seizure outcome in strong responders ( β = −0.84, p = 0.008) but not in weak responders ( β = 0.21, p = 0.9) or anti‐responders ( β = −20.34, p = 0.11). At LTFU, there was no significant relationship between Euclidean distance and seizure reduction in strong responders ( β = 0.77, p = 0.18), weak responders ( β = 2.05, p = 0.54), or anti‐responders ( β = 0.24, p = 0.99). Exploratory analyses at 1‐Y showed nominal associations between older age ( ρ = 0.32), longer epilepsy duration ( ρ = 0.27), and non‐mesial temporal sEEG‐EFs and greater seizure reduction; however, none survived Bonferroni correction (adjusted α = 0.0027; all post‐correction p > 0.0027), and no associations were observed at LTFU. Significance In this series, neocortical depth leads for RNS therapy had favorable safety and efficacy and proximity to the sEEG‐EF drove initial outcomes for strong responders to RNS therapy. Plain Language Summary In this multi‐center study, patients with difficult‐to‐treat seizures received brain‐responsive stimulation using a device called responsive neurostimulation (RNS), which delivers small electrical pulses to reduce seizures. We focused on patients treated with electrodes placed in the brain's outer regions (the neocortex) and guided by a mapping procedure called sEEG. On average, patients had their seizures cut by two‐thirds after one year and by more than three‐quarters with longer follow‐up, with about one in five becoming seizure‐free. The treatment was safe, and closer electrode placement to the seizure source helped explain early—but not long‐term—improvements.

BACKGROUND AND OBJECTIVES: Stereotactic procedures are used to manage a diverse set of patients across a variety of clinical contexts. The stereotactic devices and software used in these procedures vary between surgeons, but the fundamental principles that constitute safe and accurate execution do not. The aim of this work is to describe these principles to equip readers with a generalizable knowledge base to execute and understand stereotactic procedures. METHODS: A combination of a review of the literature and empirical experience from several experienced surgeons led to the creation of this work. Thus, this work is descriptive and qualitative by nature, and the literature is used to support instead of generate the ideas of this framework. RESULTS: The principles detailed in this work are categorized based on 5 clinical domains: imaging, registration, mechanical accuracy, target planning and adjustment, and trajectory planning and adjustment. Illustrations and tables are used throughout to convey the concepts in an efficient manner. CONCLUSION: Stereotactic procedures are complex, requiring a thorough understanding of each step of the workflow. The concepts described in this work enable functional neurosurgeons with the fundamental knowledge necessary to provide optimal patient care.

BACKGROUND AND OBJECTIVES: Identifying and characterizing sources of targeting error in stereotactic procedures is essential to maximizing accuracy, potentially improving surgical outcomes. We aim to describe a generic framework which characterizes sources of stereotactic inaccuracy. METHODS: We assembled a list of stereotactic systems: ROSA, Neuromate, Mazor Renaissance, ExcelsiusGPS, Cirq, STarFix (FHC), Nexframe, ClearPoint, CRW, and Leksell. We searched the literature for qualitative and quantitative work identifying and quantifying potential sources of inaccuracy and describing each system's implementation using Standards for Reporting Qualitative Research guidelines. Our literature search spanned 1969 to 2024, and various studies were included, with formats ranging from phantom studies to systematic reviews. Keyword searches were conducted, and the details about each system were used to create a framework for identifying and describing the unique targeting error profile of each system. RESULTS: We describe and illustrate the details of various sources of stereotactic inaccuracies and generate a framework to unify these sources into a single framework. This framework entails 5 domains: imaging, registration, mechanical accuracy, target planning and adjustment, and trajectory planning and adjustment. This framework was applied to 10 stereotactic systems. CONCLUSION: This framework provides a rubric to analyze the sources of error for any stereotactic system. Illustrations allow the reader to understand sources of error conceptually so that they may apply them to their practice.