Chronic Subthreshold Cortical Stimulation Research Articles

Qualitative Analysis of Decision to Pursue Electrical Brain Stimulation by Patients With Drug-Resistant Epilepsy and Their Caregivers.

To understand why patients with drug-resistant epilepsy (DRE) pursue invasive electrical brain stimulation (EBS). We interviewed patients with DRE (n = 20) and their caregivers about their experiences in pursuing EBS approximately 1 year post device implant. Inductive analysis was applied to identify key motivating factors. The cohort included participants aged from teens to 50s with deep brain stimulation, vagus nerve stimulation, responsive neurostimulation, and chronic subthreshold cortical stimulation. Patients' motivations included (1) improved quality of life (2) intolerability of antiseizure medications, (3) desperation, and (4) patient-family dynamics. Both patients and caregivers described a desire to alleviate burdens of the other. Patient apprehensions about EBS focused on invasiveness and the presence of electrodes in the brain. Previous experiences with invasive monitoring and the ability to see hardware in person during clinical visits influenced patients' comfort in proceeding with EBS. Despite realistic expectations for modest and delayed benefits, patients held out hope for an exceptionally positive outcome. Our findings describe the motivations and decision-making process for patients with DRE who pursue invasive EBS. Patients balance feelings of desperation, personal goals, frustration with medication side effects, fears about surgery, and potential pressure from concerned caregivers. These factors together with the sense that patients have exhausted therapeutic alternatives may explain the limited decisional ambivalence observed in this cohort. These themes highlight opportunities for epilepsy care teams to support patient decision-making processes.

Up to What Extent Does Dravet Syndrome Benefit From Neurostimulation Techniques?

BackgroundDravet syndrome (DS) is a refractory developmental and epileptic encephalopathy (EE) with a variety of comorbidities, including cognitive impairment, autism-like behavior, speech dysfunction, and ataxia, which can seriously affect the quality of life of patients and impose a great burden on society and their families. Currently, the pharmacological therapy is patient dependent and may work or not. Neuromodulation techniques, including vagus nerve stimulation (VNS), deep brain stimulation (DBS), transcranial magnetic stimulation (TMS), responsive neurostimulation (RNS), and chronic subthreshold cortical stimulation (CSCS), have become common adjuvant therapies for neurological diseases, but their efficacy in the treatment of DS is unknown.MethodsWe searched Web of Science, PubMed, and SpringerLink for all published cases related to the neuromodulation techniques of DS until January 15, 2022. The systematic review was supplemented with relevant articles from the references. The results reported by each study were summarized narratively.ResultsThe Web of science, PubMed and SpringerLink search yielded 258 items. A total of 16 studies published between 2016 and 2021 met the final inclusion criteria. Overall, 16 articles (109 cases) were included in this study, among which fifteen (107 patients) were involved VNS, and one (2 patients) was involved DBS. After VNS implantation, seizures were reduced to ≥50% in 60 cases (56%), seizure free were found in 8 cases (7.5%). Only two DS patients received DBS treatment, and the initial outcomes of DBS implantation were unsatisfactory. The seizures significantly improved over time for both DBS patients after the addition of antiepileptic drugs.ConclusionMore than half of the DS patients benefited from VNS, and VNS may be effective in the treatment of DS. However, it is important to note that VNS does not guarantee improvement of seizures, and there is a risk of infection and subsequent device failure. Although DBS is a safe and effective strategy for the treatment of refractory epilepsy, the role of DBS in DS needs further study, as the sample size was small. Thus far, there is no strong evidence for the role of DBS in DS.

A Review of Neurostimulation for Epilepsy in Pediatrics.

Neurostimulation for epilepsy refers to the application of electricity to affect the central nervous system, with the goal of reducing seizure frequency and severity. We review the available evidence for the use of neurostimulation to treat pediatric epilepsy, including vagus nerve stimulation (VNS), responsive neurostimulation (RNS), deep brain stimulation (DBS), chronic subthreshold cortical stimulation (CSCS), transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS). We consider possible mechanisms of action and safety concerns, and we propose a methodology for selecting between available options. In general, we find neurostimulation is safe and effective, although any high quality evidence applying neurostimulation to pediatrics is lacking. Further research is needed to understand neuromodulatory systems, and to identify biomarkers of response in order to establish optimal stimulation paradigms.

Improvement of neurological function with chronic subthreshold cortical stimulation

Introduction: Chronic subthreshold cortical stimulation (CSCS) is a therapeutic option for focal drug-resistant epilepsy in patients with epileptogenic foci that are not amenable to surgical resection [1]. Here, we report on two patients who had seizure control and improvement of neurobehavioral and motor symptoms following CSCS implantation.

Trial stimulation and chronic subthreshold cortical stimulation to treat focal epilepsy

Trial stimulation and chronic subthreshold cortical stimulation to treat focal epilepsy

Chronic subthreshold cortical stimulation and stimulation-related EEG biomarkers for focal epilepsy.

Brain stimulation offers an alternative to focal resection for the treatment of focal drug-resistant epilepsy. Chronic subthreshold cortical stimulation is an individualized biomarker-informed open-loop continuous electrical stimulation approach targeting the seizure onset zone and surrounding areas. Before permanent implantation, trial stimulation is performed during invasive monitoring to assess stimulation efficacy as well as to optimize stimulation location and parameters by modifying interictal EEG biomarkers. We present clinical and neurophysiological results from a retrospective analysis of 21 patients, showing a median percent reduction in seizure frequency of 100% and responder rate of 89% with a median follow-up of 27 months. About 40% of patients were free of disabling seizures for a 12-month period or longer. We find that stimulation-induced decreases in delta (1–4 Hz) power and increases in alpha and beta (8–20 Hz) power during trial stimulation correlate with improved long-term clinical outcomes. These results suggest chronic subthreshold cortical stimulation may be an effective alternative approach to treating focal drug-resistant epilepsy and that short-term stimulation-related changes in spectral power may be a useful interictal biomarker and relate to long-term clinical outcome.

Responsive brain stimulation in epilepsy.

Stimulation devices are considered in patients with drug-resistant epilepsy and who are not surgical candidates. Responsive neurostimulation (RNS) is a cortically based stimulator activated by electrocorticography (ECoG) patterns. Stimulation is applied directly to the seizure focus. The vagal nerve stimulator AspireSR 106 is also a responsive device which, in addition to basal stimulation, is activated by tachycardia. Deep brain stimulation of the anterior nucleus of the thalamus is used in Europe for intractable epilepsy and yields similar response rates to RNS using duty cycle stimulation. Chronic subthreshold cortical stimulation is an experimental form of constant, low-level stimulation applied to a seizure focus. These modalities are discussed and compared in this review.

F05. Neurophysiological effects of chronic subthreshold cortical stimulation for focal epilepsy: Spike and spontaneous ECoG activity

Neurostimulation is a treatment option for drug-resistant focal epilepsy. Chronic subthreshold cortical stimulation (CSCS) is a novel, promising technique that directly targets the seizure onset zone (SOZ) with continuous electrical stimulation. Prior retrospective analyses have shown reduced seizure frequencies and improved quality of life. Here, we investigate underlying neurophysiological changes induced by CSCS in order to gain an insight into the mechanism underlying the clinical effect of chronic electrical stimulation in focal epilepsy. We examined intracranial EEG data from seven patients with drug-resistant focal epilepsy and SOZs located in eloquent cortex who underwent continuous stimulation during their hospitalization. Subdural grid electrodes were implanted, and after the SOZ was localized to eloquent cortex, 2 Hz electrical stimulation was applied to contacts targeting the SOZ. Ninety minutes of intracranial EEG from a 4 × 4 electrode grid was analyzed before and during stimulation. Electrophysiological parameters were estimated for both pre-stimulation and stimulation data. Power spectrum and coherence of background activity was analysed together with spiking activity characteristics including spike rate, spike amplitude, and spike duration. Cortical stimulation resulted in a marked reduction of the amplitudes of background activity across all channel types for frequencies 5–40 Hz, particularly over SOZ electrodes. During cortical stimulation there was increased coherence between all electrodes and a decrease in spike rate, greatest over SOZ (p < 0.001). Spike-rate coherence was greatest within and between SOZ for pre-stimulation recordings and showed a significant decrease with cortical stimulation for electrodes near SOZ (p < 0.001). No such effect was seen for the other electrodes. Analysis of spike amplitudes showed that cortical stimulation resulted in a clear reduction of spikes over SOZ electrodes (p < 0.001) and only minor reductions for other electrodes (p < 0.001). Moreover, stimulation onset resulted in minor changes in the distribution of spike durations over all electrodes (p < 0.001). Spike-rate and power of background activity showed a significant correlation (p < 0.01). These results show changes in cortical electrophysiology during CSCS over the SOZ where reduction in interictal spikes is correlated with an attenuation of background activity. This suggests a possible causal relationship between background activity and interictal spikes and with seizure frequency rate. With an improved understanding of chronic electrical stimulation better stimulation paradigms might be developed for improved suppression of seizure frequency.

216 Chronic Subthreshold Cortical Stimulation for Adult Drug Resistant Focal Epilepsy

Abstract INTRODUCTION Epilepsy surgery, while high successful for lesional epilepsy, can be associated with significant morbidity. The objective was to evaluate the safety profile of chronic subthreshold cortical stimulation in patients with seizure foci not amenable to surgical resection. METHODS Patients underwent intracranial electroencephalography monitoring. Those with seizure foci that were deemed unsafe for resection were offered trial of continuous subthreshold cortical stimulation via intracranial monitoring electrodes. After successful trial, trial electrodes were replaced with permanent stimulation. Patients with permanent implantation prior to February, 2016, reported their seizure severity and life satisfaction before and after stimulation. RESULTS &gt;Eight patients from 2014 to 2016 were included in this study. Age ranged (19-56 years). Intracranial pathologies included: cortical dysplasia (n = 3), encephalomalacia (n = 3), cortical tubers (n = 1), and linear migrational anomaly (n = 1). The duration of intracranial monitoring ranged (3-20 days). All patients experienced were discharged to home (median length of stay: 10 days). No postoperative surgical complications have developed to date (median length of follow-up: 187 days). Patients (n = 4) reported a improvement in seizure severity (worst = 10) from mean 7.5 (SE 0.29) to 1.25 (SE 0.75) and life satisfaction (best = 10) from mean 4.25 (SE 1.03) to 7 (SE 1.1), mean follow-up 8.8 months CONCLUSION Our institutional experience shows that chronic cortical stimulation can be safely and effectively performed in appropriately selected patients without postoperative complications. Future investigation will hopefully provide further insight to recently published results into the efficacy of this novel and promising intervention.

Chronic subthreshold cortical stimulation: a therapeutic and potentially restorative therapy for focal epilepsy

ABSTRACTIntroduction: Approximately one third of patients with focal epilepsy continue to have ongoing seizures despite adequate trials of anti-seizure medications. Surgery to remove the epileptogenic zone remains the most efficacious treatment option for focal drug-resistant epilepsy. However, when cortical areas are eloquent or there are multiple epileptogenic zones, surgical resection is not an ideal approach. Cortical stimulation provides an attractive alternative.Area covered: Here, the authors describe Chronic Subthreshold Cortical Stimulation (CSCS), which uses continuous intracranial electrical stimulation applied near the epileptogenic zone to lower seizure probability. The authors review literature related to CSCS. One challenge is finding the most efficacious set of stimulation parameters for each patient.Expert commentary: Data supporting CSCS are limited but promising for the treatment of patients with focal drug resistant epilepsy who are not surgical candidates. Additional electrophysiological biomarkers to estimate cortical excitability are needed.

Chronic Subthreshold Cortical Stimulation to Treat Focal Epilepsy

Chronic Subthreshold Cortical Stimulation to Treat Focal Epilepsy