Long-term outcomes after responsive neurostimulation for treatment of refractory epilepsy: a single-center experience of 100 cases.

OBJECTIVE: Despite antiepileptic drugs, more than 30% of people with epilepsy continue to have seizures. Patients with such drug-resistant epilepsy (DRE) may undergo invasive treatment such as resection, laser ablation of the epileptogenic focus, or vagus nerve stimulation, but many are not candidates for epilepsy surgery or fail to respond to such interventions. Responsive neurostimulation (RNS) provides a neuromodulatory option. In this study, the authors present a single-center experience with the use of RNS over the last 5 years to provide long-term control of seizures in patients with DRE with at least 1 year of follow-up. METHODS: The authors performed a retrospective analysis of a prospectively collected single-center database of consecutive DRE patients who underwent RNS system implantation from September 2015 to December 2020. Patients were followed-up postoperatively to evaluate seizure freedom and complications. RESULTS: One hundred patients underwent RNS placement. Seven patients developed infections: 2 responded to intravenous antibiotic therapy, 3 required partial removal and salvaging of the system, and 2 required complete removal of the RNS device. No postoperative tract hemorrhages, strokes, device migrations, or malfunctions were documented in this cohort. The average follow-up period was 26.3 months (range 1-5.2 years). In terms of seizure reduction, 8 patients had 0%-24% improvement, 14 had 25%-49% improvement, 29 experienced 50%-74% improvement, 30 had 75%-99% improvement, and 19 achieved seizure freedom. RNS showed significantly better outcomes over time: patients with more than 3 years of RNS therapy had 1.8 higher odds of achieving 75% or more seizure reduction (95% CI 1.07-3.09, p = 0.02). Also, patients who had undergone resective or ablative surgery prior to RNS implantation had 8.25 higher odds of experiencing 50% or more seizure reduction (95% CI 1.05-65.1, p = 0.04). CONCLUSIONS: Responsive neurostimulator implantation achieved 50% or more seizure reduction in approximately 80% of patients. Even in patients who did not achieve seizure freedom, significant improvement in seizure duration, severity, or postictal state was reported in more than 68% of cases. Infection (7%) was the most common complication. Patients with prior resective or ablative procedures and those who had been treated with RNS for more than 3 years achieved better outcomes.

Contemporary intraoperative visualization for GBM with use of exoscope, 5-ALA fluorescence-guided surgery and tractography.

Maximal safe resection is the primary goal of glioma surgery. By incorporating improved intraoperative visualization with the 3D exoscope combined with 5-ALA fluorescence, in addition to neuronavigation and diffusion tensor imaging (DTI) fiber tracking, the safety of resection of tumors in eloquent brain regions can be maximized. This video highlights some of the various intraoperative adjuncts used in brain tumor surgery for high-grade glioma. In this case, the authors highlight the resection of a left posterior temporal lobe high-grade glioma in a 33-year-old patient, who initially presented with seizures, word-finding difficulty, and right-sided weakness. They demonstrate the multiple surgical adjuncts used both before and during surgical resection, and how multiple adjuncts can be effectively orchestrated to make surgery in eloquent brain areas safer for patients. Patient consent was obtained for publication. The video can be found here: https://stream.cadmore.media/r10.3171/2021.10.FOCVID21174.

Responsive Neurostimulation of the Thalamus for the Treatment of Refractory Epilepsy.

Introduction: One-third of patients with epilepsy continue to have seizures despite antiepileptic medications. Some of these refractory patients may not be candidates for surgical resection primarily because the seizure onset zones (SOZs) involve both hemispheres or are located in eloquent areas. The NeuroPace Responsive Neurostimulation System (RNS) is a closed-loop device that uses programmable detection and stimulation to tailor therapy to a patient's individual neurophysiology. Here, we present our single-center experience with the use of RNS in thalamic nuclei to provide long-term seizure control in patients with refractory epilepsy. Methods: We performed a prospective single-center study of consecutive refractory epilepsy patients who underwent RNS system implantation in the anterior (ANT) and centromedian (CM) thalamic nuclei from September 2015 to December 2020. Patients were followed postoperatively to evaluate seizure freedom and complications. Results: Twenty-three patients underwent placement of 36 RNS thalamic leads (CM = 27 leads, ANT = 9 leads). Mean age at implant was 18.8 ± 11.2 years (range 7.8-62 years-old). Two patients (8.7%) developed infections: 1 improved with antibiotic treatments alone, and 1 required removal with eventual replacement of the system to recover the therapeutic benefit. Mean time from RNS implantation to last follow-up was 22.3 months. Based on overall reduction of seizure frequency, 2 patients (8.7%) had no- to <25% improvement, 6 patients (26.1%) had 25-49% improvement, 14 patients (60.9%) had 50-99% improvement, and 1 patient (4.3%) became seizure-free. All patients reported significant improvement in seizure duration and severity, and 17 patients (74%) reported improved post-ictal state. There was a trend for subjects with SOZs located in the temporal lobe to achieve better outcomes after thalamic RNS compared to those with extratemporal SOZs. Of note, seizure etiology was syndromic in 12 cases (52.2%), and 7 patients (30.4%) had undergone resection/disconnection surgery prior to thalamic RNS therapy. Conclusion: Thalamic RNS achieved ≥50% seizure control in ~65% of patients. Infections were the most common complication. This therapeutic modality may be particularly useful for patients affected by aggressive epilepsy syndromes since a young age, those whose seizure foci are located in the mesial temporal lobe, and those who have failed prior surgical interventions.

Postoperative cognitive dysfunction after endovascular treatments for unruptured intracranial aneurysms: A pilot study.

OBJECTIVE: Post operative cognitive dysfunction (POCD) has been widely observed after major surgery, particularly in elderly patients with general anesthesia (GA). However, a specific unanswered question is whether different approaches to anesthetic managements are associated with different cognitive outcomes after endovascular treatments for unruptured intracranial aneurysms (UIAs). The purpose of this study is to assess the correlation of POCD with GA versus monitored anesthesia care (MAC). METHODS: We performed a pragmatic, prospective study to assess the association between different anesthetic approaches and POCD. We compared the pre- and post-procedural Montreal Cognitive Assessment (MoCA) scores in patients with normal cognition who underwent treatments of UIAs with various endovascular methods, using either GA or MAC. RESULTS: A total of 23 patients with UIAs were enrolled in the study. Seven (30.4%) and sixteen (69.6%) UIAs were treated without perioperative complications under GA or MAC, respectively. There was a significant decline in the post-procedural MoCA score under GA (mean difference = 1.14; 95% confidence interval = [0.42-1.87], P < 0.01). By contrast, there was no significant difference of MoCA score between pre- and post-procedure under MAC (mean difference = 0.19; 95% confidence interval = [-0.29-0.67], P = 0.59). CONCLUSIONS: Treating UIAs using MAC was associated with a decrease in POCD as compared to GA in patients undergoing endovascular treatments for UIAs with normal cognition. Larger randomized studies are needed to confirm these findings.

Dural arteriovenous fistulas without cortical venous drainage: presentation, treatment, and outcomes.

OBJECTIVE: Current evidence suggests that intracranial dural arteriovenous fistulas (dAVFs) without cortical venous drainage (CVD) have a benign clinical course. However, no large study has evaluated the safety and efficacy of current treatments and their impact over the natural history of dAVFs without CVD. METHODS: The authors conducted an analysis of the retrospectively collected multicenter Consortium for Dural Arteriovenous Fistula Outcomes Research (CONDOR) database. Patient demographics and presenting symptoms, angiographic features of the dAVFs, and treatment outcomes of patients with Borden type I dAVFs were reviewed. Clinical and radiological follow-up information was assessed to determine rates of new intracranial hemorrhage (ICH) or nonhemorrhagic neurological deficit (NHND), worsening of venous hyperdynamic symptoms (VHSs), angiographic recurrence, and progression or spontaneous regression of dAVFs over time. RESULTS: A total of 342 patients/Borden type I dAVFs were identified. The mean patient age was 58.1 ± 15.6 years, and 62% were women. The mean follow-up time was 37.7 ± 54.3 months. Of 230 (67.3%) treated dAVFs, 178 (77%) underwent mainly endovascular embolization, 11 (4.7%) radiosurgery alone, and 4 (1.7%) open surgery as the primary modality. After the first embolization, most dAVFs (47.2%) achieved only partial reduction in early venous filling. Multiple complementary interventions increased complete obliteration rates from 37.9% after first embolization to 46.7% after two or more embolizations, and 55.2% after combined radiosurgery and open surgery. Immediate postprocedural complications occurred in 35 dAVFs (15.2%) and 6 (2.6%) with permanent sequelae. Of 127 completely obliterated dAVFs by any therapeutic modality, 2 (1.6%) showed angiographic recurrence/recanalization at a mean of 34.2 months after treatment. Progression to Borden-Shucart type II or III was documented in 2.2% of patients and subsequent development of a new dAVF in 1.6%. Partial spontaneous regression was found in 22 (21.4%) of 103 nontreated dAVFs. Multivariate Cox regression analysis demonstrated that older age, NHND, or severe venous-hyperdynamic symptoms at presentation and infratentorial location were associated with worse prognosis. Kaplan-Meier curves showed no significant difference for stable/improved symptoms survival probability in treated versus nontreated dAVFs. However, estimated survival times showed better trends for treated dAVFs compared with nontreated dAVFs (288.1 months vs 151.1 months, log-rank p = 0.28). This difference was statistically significant for treated dAVFs with 100% occlusion (394 months, log-rank p < 0.001). CONCLUSIONS: Current therapeutic modalities for management of dAVFs without CVD may provide better symptom control when complete angiographic occlusion is achieved.

Availability and Readability of Spinal Cord Injury Online Information Materials for Spanish Speaking Population in Neurosurgical Academic Programs: A Nationwide Study.

BACKGROUND: Recent publications have demonstrated that information has been transmitted inappropriately to the lay person in different pathologies. This limitation is also observed in Spanish language. We evaluate the availability and readability of online patient education material (PEM) on spinal cord injury (SCI) information for the Spanish-speaking population from academic neurosurgery residency programs in the United States. METHODS: This is a descriptive analysis of online SCI PEM from neurosurgical residency programs websites. We assess the availability of information in Spanish using a modification of a previously published classification. To assess accessibility, we calculated the time spent and the number of clicks to find the information in Spanish. We calculated the readability of the material using the "Indice Flesch-Szigriszt" (INFLESZ), which determines the difficulty of readability of health-related material in Spanish. RESULTS: A total of 116 accredited neurosurgery residency programs comprised our cohort. Ten (9%) programs had available "mirrored" information in Spanish from its original version in English, 9 (8.1%) used a translation software, 79 (71.2%) provide interpreter services, and 3 (2%) did not have written information or information about translation services. A mean of 72.9 seconds (SD +/- 71.2) were required to have access to the Spanish information or contact information for translation services. Twelve (57.1%) websites with written Spanish information had an INFLESZ score above 55.00, which translates as an appropriate readability level for the general population. CONCLUSIONS: More than half of the academic neurosurgery programs or affiliated hospital websites do not provide written informative material about SCI in Spanish. When available, the information is not always transmitted with a level of readability appropriate for the layperson. Most of the websites provide translation or interpreter services that are not directly related to SCI.

Insights into the pathogenesis of cerebral fusiform aneurysms: high-resolution MRI and computational analysis.

BACKGROUND: Intracranial fusiform aneurysms are complex and poorly characterized vascular lesions. High-resolution magnetic resonance imaging (HR-MRI) and computational morphological analysis may be used to characterize cerebral fusiform aneurysms. OBJECTIVE: To use advanced imaging and computational analysis to understand the unique pathophysiology, and determine possible underlying mechanisms of instability of cerebral fusiform aneurysms. METHODS: Patients with unruptured intracranial aneurysms prospectively underwent imaging with 3T HR-MRI at diagnosis. Aneurysmal wall enhancement was objectively quantified using signal intensity after normalization of the contrast ratio (CR) with the pituitary stalk. Enhancement between saccular and fusiform aneurysms was compared, as well as enhancement characteristics of fusiform aneurysms. The presence of microhemorrhages in fusiform aneurysms was determined with quantitative susceptibility mapping (QSM). Three distinct types of fusiform aneurysms were analyzed with computational fluid dynamics (CFD) and finite element analysis (FEA). RESULTS: A total of 130 patients with 160 aneurysms underwent HR-MRI. 136 aneurysms were saccular and 24 were fusiform. Fusiform aneurysms had a significantly higher CR and diameter than saccular aneurysms. Enhancing fusiform aneurysms exhibited more enhancement of reference vessels than non-enhancing fusiform aneurysms. Ten fusiform aneurysms underwent QSM analysis, and five aneurysms showed microhemorrhages. Microhemorrhage-positive aneurysms had a larger volume, diameter, and greater enhancement than aneurysms without microhemorrhage. Three types of fusiform aneurysms exhibited different CFD and FEA patterns. CONCLUSION: Fusiform aneurysms exhibited more contrast enhancement than saccular aneurysms. Enhancing fusiform aneurysms had larger volume and diameter, more enhancement of reference vessels, and more often exhibited microhemorrhage than non-enhancing aneurysms. CFD and FEA suggest that various pathophysiological processes determine the formation and growth of fusiform aneurysms.

Increased contrast enhancement of the parent vessel of unruptured intracranial aneurysms in 7T MR imaging.

BACKGROUND: Inflammation of the arterial wall may lead to aneurysm formation. The presence of aneurysm enhancement on high-resolution vessel wall imaging (HR-VWI) is a marker of wall inflammation and instability. We aim to determine if there is any association between increased contrast enhancement in the aneurysmal wall and its parent artery. METHODS: Patients with unruptured intracranial aneurysms (UIAs) prospectively underwent 7T HR-VWI. Regions of interest were selected manually and with a semi-automated protocol based on gradient algorithms of intensity patterns. Mean signal intensities in pre- and post-contrast T1-weighted sequences were adjusted to the enhancement of the pituitary stalk and then subtracted to objectively determine: circumferential aneurysmal wall enhancement (CAWE); parent vessel enhancement (PVE); and reference vessel enhancement (RVE). PVE was assessed over regions located 3- and 5 mm from the aneurysm's neck. RVE was assessed in arteries located in a different vascular territory. RESULTS: Twenty-five UIAs were analyzed. There was a significant moderate correlation between CAWE and 5 mm PVE (Pearson R=0.52, P=0.008), whereas no correlation was found between CAWE and RVE (Pearson R=0.20, P=0.33). A stronger correlation was found between CAWE and 3 mm PVE (Pearson R=0.78, P<0.001). Intra-class correlation analysis demonstrated good reliability between measurements obtained using semi-automated and manual segmentation (ICC coefficient=0.790, 95% CI 0.58 to 0.90). CONCLUSION: Parent arteries exhibit higher contrast enhancement in regions closer to the aneurysm's neck, especially in aneurysms≥7 mm. A localized inflammatory/vasculopathic process in the wall of the parent artery may lead to aneurysm formation and growth.

Ethmoidal dural arteriovenous fistulas: endovascular transvenous embolization technique.

Ethmoidal dural arteriovenous fistulas (dAVFs) are rare, accounting for 1­1.5% of all intracranial malformations. However, they may have angiographic features that increase the risk of rupture: cortical venous drainage, venous ectasia, venous stenosis and high arterial flow. If the dAVF has these angiographic features, treatment may be indicated regardless of the clinical presentation. In this neurosurgical endovascular video 1, we present two patients with high-flow ethmoidal dAVFs treated via transvenous endovascular approaches. The first case was successfully embolized without complications, whereas the second case was complicated with intraoperative rupture of a tortuous cortical draining vein. The transvenous endovascular approach may be a useful tool in treating these lesions; however, access and tortuosity of structures proximal to the fistula point have to be thoroughly assessed. We review the natural history and angio-architecture of these lesions. Important tips and bailout maneuvers for treatment of complex ethmoidal dAVFs in eloquent locations are also presented.

Recanalization of the Chronically Occluded Internal Carotid Artery: Review of the Literature.

INTRODUCTION: We reviewed the literature on interventions for patients with medically refractory chronically occluded internal carotid artery (COICA) to assess the risks and/or benefits after recanalization via an endovascular technique (ET) or hybrid surgery (HS, i.e., ET plus carotid endarterectomy). METHODS: A systematic search of the electronic databases was performed. Patients with COICA were classified into 4 different categories according to Hasan et al classification. RESULTS: Eighteen studies satisfied the inclusion criteria. Only 6 studies involved an HS procedure. We identified 389 patients with COICA who underwent ET or HS; 91% were males. The overall perioperative complication rate was 10.1% (95% confidence interval [CI]: 7.4%-13.1%). For types A and B, the successful recanalization rate was 95.4% (95% CI: 86.5%-100%), with a 13.7% (95% CI: 2.3%-27.4%) complication rate. For type C, the success rate for ET was 45.7% (95% CI: 17.8%-70.7%), with a complication rate of 46.0% (95% CI: 20.0%-71.4%) for ET and for the HS technique 87.6% (95% CI: 80.9%-94.4%), with a complication rate of 14.0% (95% CI: 7.0%-21.8%). For type D, the success rate of recanalization was 29.8% (95% CI: 7.8%-52.8%), with a 29.8% (95% CI: 6.1%-56.3%) complication rate. Successful recanalization resulted in a symmetrical perfusion between both cerebral hemispheres, resolution of penumbra, normalization of the mean transit time, and improvement in Montreal Cognitive Assessment (MoCA) score (ΔMoCA = 9.80 points; P = 0.004). CONCLUSIONS: Type A and B occlusions benefit from ET, especially in the presence of a large penumbra. Type C occlusions can benefit from HS. Unfortunately, we did not identify an intervention to help patients with type D occlusions. A phase 2b randomized controlled trial is needed to confirm these findings.

Vessel wall imaging in intracranial aneurysms.

High-resolution vessel wall imaging (HR-VWI) is becoming a useful tool in the characterization and identification of unstable unruptured brain aneurysms. However, it has not been validated for clinical use. The current evidence on HR-VWI techniques for characterization of brain aneurysms is described in this review. Specific imaging approaches such as aneurysm wall contrast enhancement, MRI-quantitative susceptibility mapping, and 7T MRI are described in detail.

Methods and Devices for Posterior Ventriculoperitoneal Shunt Placement Surgery: 25 Years of Iterative Refinement.

BACKGROUND: The posterior ventriculoperitoneal shunt (VPS) placement procedure is technically efficient and cosmetically appealing. The main limitations of the posterior approach relate to the technical challenges associated with accurately placing the ventricular catheter. In this report, we describe methods and simple devices used for posterior VPS surgery that have evolved over a >25-year period to enhance catheter placement accuracy and reduce complication rates. OBJECTIVE: We describe the combination of methods and customized devices used at a single institution to perform posterior VPS surgery. Results are presented for the most recent 11-year epoch, along with a description of sources of technical errors and plans for further methodologic refinements. MATERIALS AND METHODS: The medical records and imaging studies of 468 patients undergoing posterior VPS, from 2007 to 2018 were reviewed. Ventricular catheter placement accuracy data were collected and complications were identified and recorded. RESULTS: Optimal ventricular catheter placement was achieved in 98.29%. Of the remaining 1.71%, one half (0.85%) required acute revision surgery. Four patients (0.85%) developed new neurologic deficits following surgery; 2 were related to intraparenchymal hemorrhages and 2 (0.43%) as a result of a misplaced catheter. The deficits resulting from poor catheter placement were transient. The complication rates due to causes other than catheter placement accuracy compared favorably with those reported previously in the literature. CONCLUSIONS: Using the methods and devices described in this series, posterior VPS operations can be performed safely with a high degree of ventricular catheter placement accuracy.

Cognitive and cerebral hemodynamic effects of endovascular recanalization of chronically occluded cervical internal carotid artery: single-center study and review of the literature.

OBJECTIVE: Revascularization of a symptomatic, medically refractory, cervical chronically occluded internal carotid artery (COICA) using endovascular techniques (ETs) has surfaced as a viable alternative to extracranial-intracranial bypass. The authors aimed to assess the safety, success, and neurocognitive outcomes of recanalization of COICA using ETs or hybrid treatment (ET plus carotid endarterectomy) and to identify candidate radiological markers that could predict success. METHODS: The authors performed a retrospective analysis of their prospectively collected institutional database and used their previously published COICA classification to assess the potential benefits of ETs or hybrid surgery to revascularize symptomatic patients with COICA. Subjects who had undergone CT perfusion (CTP) imaging and Montreal Cognitive Assessment (MoCA) testing, both pre- and postprocedure, were included. The authors then performed a review of the literature on patients with COICA to further evaluate the success and safety of these treatment alternatives. RESULTS: The single-center study revealed 28 subjects who had undergone revascularization of symptomatic COICA. Five subjects had CTP imaging and MoCA testing pre- and postrevascularization and thus were included in the study. All 5 patients had very large penumbra involving the entire hemisphere supplied by the ipsilateral COICA, which resolved postoperatively. Significant improvement in neurocognitive outcome was demonstrated by MoCA testing after treatment (preprocedure: 19.8 ± 2.4, postprocedure: 27 ± 1.6; p = 0.0038). Moreover, successful revascularization of COICA led to full restoration of cerebral hemodynamics in all cases. Review of the literature identified a total of 333 patients with COICA. Of these, 232 (70%) showed successful recanalization after ETs or hybrid surgery, with low major and minor complication rates (3.9% and 2.7%, respectively). CONCLUSIONS: ETs and hybrid surgery are safe and effective alternatives to revascularize patients with symptomatic COICA. CTP imaging could be used as a radiological marker to assess cerebral hemodynamics and predict the success of revascularization. Improvement in CTP parameters is associated with significant improvement in neurocognitive functions.