Short- and Long-Term Response of Vagus Nerve Stimulation Therapy in Drug-Resistant Epilepsy: A Systematic Review and Meta-Analysis

Long-term effects of vagus nerve stimulation therapy on cognitive functioning in patients with drug-resistant epilepsy

BACKGROUND

Despite the increasing use of vagus nerve stimulation (VNS) for drug-resistant epilepsy, its impact on cognitive functioning remains insufficiently investigated.

OBJECTIVE

We aimed to comprehensively assess changes in cognition after long-term VNS therapy in a prospective sample of adults with epilepsy.

METHODS

Between December 2019 and March 2023, patients scheduled for VNS implantation were invited for neuropsychological assessment, including tests of executive functions, working and short-term memory (recall of a verbal logical story and the Rey-Osterrieth complex figure (ROCF)), and social cognition. Participants were re-evaluated after a year of VNS therapy and the pre- and postoperative scores were compared by means of the Student's t or Wilcoxon's signed rank tests for paired samples. Patients available only after a longer follow-up (more than 24 months) were also re-examined and included in a secondary analysis.

RESULTS

The study included 28 PWE (16, 57.1% female, average age 33.7 ± 10.0 years). Twenty-two PWE followed-up at 14.5 ± 4.8 months had worse categorical verbal fluency than preoperatively (t = 2.613, p = 0.016). After including patients with long follow-up (n = 28, 21.6 ± 11.4 months), the group scored better on the delayed recall of the ROCF (17.09 ± 8.84 to 20.65 ± 8.32 points, t(22) =  - 2.618, p = 0.016) and the Happé strange stories test (5.0 ± 2.6 to 6.1 ± 2.1 points, t(14) =  - 3.281, p = 0.005). No significant changes were observed in other cognitive domains (p > 0.05).

CONCLUSION

We suggest improvements in a task of social cognition and short-term visual memory after longer use of VNS therapy. Such findings should be confirmed in larger trials after controlling for changes in ictal or interictal activity.

Effects of vagus nerve stimulation on cognitive function in patients with epilepsy: a systematic review and meta-analysis

Background

Previous studies showed that vagus nerve stimulation (VNS) can improve cognitive function in patients with epilepsy, but there is still great controversy about the effect of VNS on cognitive function in patients with epilepsy.

Objective

To investigate the effect of VNS on the cognitive function of epilepsy patients.

Methods

Clinical trials published in PubMed, The Cochrane Library, and Embase before September 20, 2022, were comprehensively searched. Primary outcomes were overall cognitive performance, executive function, attention, memory; Secondary outcomes were seizure frequency, mood, and quality of life (QOL). Random effects were used to calculate the pooled outcome.

Results

Twenty clinical trials were included. There was no significant improvement in overall cognitive performance in patients with epilepsy after VNS treatment (SMD = 0.07; 95% CI: -0.12 to 0.26; I2 = 0.00%) compared to pre-treatment. Compared to pre-treatment, there was no significant difference in executive function (SMD = -0.50; 95% CI: -1.50 to 0.50; p = 0.32), attention (SMD = -0.17; 95% CI: -0.43 to 0.09; p = 0.21) and memory (SMD = 0.64; 95% CI: -0.11 to 1.39; p = 0.09), but there were significant differences in seizure frequency, mood, and quality of life in patients with epilepsy after VNS.

Conclusion

This meta-analysis did not establish that VNS can significantly improve cognitive function in patients with epilepsy, but it shows that VNS can significantly improve the seizure frequency, mood and quality of life of patients with epilepsy.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier: CRD42023384059.

Complete Heart Block and Ventricular Asystole Caused by Vagus Nerve Stimulation Therapy

Left vagus nerve stimulation (VNS) is an advanced therapeutic option for refractory, drug-resistant epilepsy. A 45-year-old woman with a history of refractory catamenial focal epilepsy since age 16, treated with a five-drug antiepileptic regimen and VNS (implanted eight and one-half years prior), presented with dyspnea, chest discomfort, and lightheadedness. During observation, symptoms recurred and were associated with bradycardia (<20 bpm) and a complete atrioventricular node (AVN) block. Following admission, she continued to experience recurrent symptomatic AVN block and transient ventricular asystole, temporally correlated with her baseline seizure activity and resultant activation of her VNS. Deactivation of VNS resolved her bradyarrhythmia, and she experienced no recurrence over 14 months of follow-up. This case highlights a therapeutic dilemma in cases of refractory epilepsy, with limited therapeutic options if seizure activity requires VNS to be controlled.

Vagus nerve stimulation for treating developmental and epileptic encephalopathy in young children

Objective

To investigate the clinical variables that might predict the outcome of developmental and epileptic encephalopathy (DEE) after vagus nerve stimulation (VNS) therapy and identify the risk factors for poor long-term outcome.

Patients and methods

We retrospectively studied 32 consecutive children with drug-resistant DEE who had undergone VNS surgery from April 2019 to July 2021, which were not suitable for corpus callosotomy. In spite of combining valproic acid, levetiracetam, lamotrigine, topiramate, etc. (standard anti-seizure medicine available in China) it has not been possible to effectively reduce seizures in the population we investigate (Cannabidiol and brivaracetam were not available in China). A responder was defined as a frequency reduction decrease > 50%. Seizure freedom was defined as freedom from seizures for at least 6 months. Sex, electroencephalograph (EEG) group, neurodevelopment, time lag, gene mutation, magnetic resonance imaging (MRI), and epilepsy syndrome were analyzed with Fisher's exact test, The age at onset and age at VNS therapy were analyzed with Kruskal-Wallis test, statistical significance was defined as p < 0.05. And used the effect size to correction.

Results

Among the 32 patients, the median age at VNS implantation was 4.7 years (range: 1-12 years). At the most recent follow-up, five children (15.6%) were seizure-free and 22 (68.8%) were responders. Univariate analysis demonstrated that the responders were significantly associated with mild development delay/intellectual disability (p = 0.044; phi coefficient = 0.357) and a multifocal EEG pattern (p = 0.022; phi coefficient = -0.405). Kaplan-Meier survival analyses demonstrated that a multifocal EEG pattern (p = 0.049) and DEE without epileptic spasm (ES) (p = 0.012) were statistically significant (p = 0.030). Multivariate analysis demonstrated that DEE with ES had significant predictive value for poor long-term outcome (p = 0.014, hazard ratio = 5.433, confidence interval = 1.402-21.058).

Conclusions

Our study suggested that VNS was a generally effective adjunct treatment for DEE. Although the predictive factors for VNS efficacy remain unclear, it should be emphasized that patients with ES are not suitable candidates for epilepsy surgery. Further investigations are needed to validate the present results.

Effect of vagus nerve stimulation against generalized seizure and status epilepticus recurrence

Objective

Vagus nerve stimulation (VNS) is a palliative surgery for drug-resistant epilepsy. The two objectives of this study were to (1) determine the seizure type most responsive to VNS and (2) investigate the preventive effect on status epilepticus (SE) recurrence.

Methods

We retrospectively reviewed 136 patients with drug-resistant epilepsy who underwent VNS implantation. We examined seizure outcomes at 6, 12, and 24 months following implantation of VNS as well as at the last visit to the Juntendo Epilepsy Center. Univariate analysis and multivariate logistic regression models were used to estimate the prognostic factors.

Results

125 patients were followed up for at least 1 year after VNS implantation. The percentage of patients with at least a 50% reduction in seizure frequency compared with prior to VNS implantation increased over time at 6, 12, and 24 months after VNS implantation: 28, 41, and 52%, respectively. Regarding overall seizure outcomes, 70 (56%) patients responded to VNS. Of the 40 patients with a history of SE prior to VNS implantation, 27 (67%) showed no recurrence of SE. The duration of epilepsy, history of SE prior to VNS implantation and seizure type were correlated with seizure outcomes after VNS implantation in univariate analysis (p = 0.05, p < 0.01, and p = 0.03, respectively). In multivariate logistic regression analysis, generalized seizure was associated with VNS response [odds ratio (OR): 4.18, 95% CI: 1.13-15.5, p = 0.03]. A history of SE prior to VNS implantation was associated with VNS non-responders [(OR): 0.221, 95% CI: 0.097-0.503, p < 0.01]. The duration of epilepsy, focal to bilateral tonic-clonic seizure and epileptic spasms were not significantly associated with VNS responders (p = 0.07, p = 0.71, and p = 0.11, respectively).

Conclusion

Following 125 patients with drug-resistant epilepsy for an average of 69 months, 56% showed at least 50% reduction in seizure frequency after VNS implantation. This study suggests that generalized seizure is the most responsive to VNS, and that VNS may reduce the risk of recurrence of SE. VNS was shown to be effective against generalized seizure and also may potentially influence the risk of further events of SE, two marker of disease treatment that can lead to improved quality of life.

Focal Cortex Stimulation With a Novel Implantable Device and Antiseizure Outcomes in 2 Prospective Multicenter Single-Arm Trials

Importance

For the large population of people with drug-refractory epilepsy, alternative treatment approaches are needed. Clinical trial outcomes of a novel stimulation device, which is newly available in Europe for the treatment of patients with a predominant seizure focus, are reported for the first time.

Objective

To perform a pooled analysis of the results of 2 prospective, multicenter, single-arm trials, A Pilot Study to Assess the Feasibility of Neurostimulation With the EASEE System to Treat Medically Refractory Focal Epilepsy (EASEE II) and A Pilot Study to Assess the Feasibility of Patient-Controlled Neurostimulation With the EASEE System to Treat Medically Refractory Focal Epilepsy (PIMIDES I), assessing the safety and efficacy of epicranial focal cortex stimulation (FCS) with a novel implantable device (EASEE [Precisis]) as adjunctive treatment for adult patients with drug-refractory focal epilepsy.

Design, Setting, and Participants

This study was a pooled analysis of 2 nonrandomized uncontrolled trials, EASEE II and PIMIDES I, which began on January 15, 2019, and January 14, 2020, respectively, and ended on July 28, 2021. EASEE II and PIMIDES I were the first in-human, prospective, single-arm trials with an 8-month evaluation period. Patients were recruited at 7 European epilepsy centers. Consecutive participants with drug-refractory focal epilepsy were enrolled. Study data were analyzed from September 29, 2021, to February 2, 2022.

Interventions

After a 1-month prospective baseline period, patients were implanted with the neurostimulation device. After a 1-month postimplantation recovery period, unblinded FCS was activated using both high-frequency and direct current (DC)-like components performed via electrode arrays placed epicranially above the individual epileptic focus region.

Main Outcomes and Measures

Efficacy was prospectively assessed by the responder rate in the sixth month of stimulation compared with baseline; safety and additional end points were assessed after device implantation and during the stimulation period.

Results

Of the 34 adult patients enrolled at 6 German and 1 Belgian investigational site, 33 (mean [SD] age, 34.6 [13.5] years; 18 male patients [54.5%]) received the neurostimulation device implant. A total of 32 patients underwent combined high-frequency direct current-like stimulation at least until the 8-month postimplant follow-up visit. After 6 months of stimulation, 17 of 32 patients (53.1%) were responders to treatment with at least a 50% reduction in seizure frequency compared with baseline, corresponding to a significant median seizure reduction by 52% (95% CI, 0.37%-0.76%; P < .001). No device- or procedure-related serious adverse events were reported (0; 95% CI, 0%-10.58%). There were no significant alterations in cognition, mood, or overall quality of life.

Conclusions and Relevance

Results of this pooled analysis of 2 nonrandomized uncontrolled trials suggest that FCS with a novel neurostimulation device was associated with an effective reduction in seizure frequency in patients with drug-refractory focal epilepsy and may offer a promising treatment option for patients with a predominant epileptic focus.

Trial Registration

German Clinical Trials Register: DRKS00015918 and DRKS00017833, respectively, and jointly under PROSPERO: CRD42021266440.

Safety and efficacy of rapid withdrawal of antiseizure medications during long-term video-electroencephalogram monitoring in children with drug-resistant epilepsy: A retrospective study

OBJECTIVE

Performing long-term video-electroencephalographic monitoring (LTVEM) to obtain the ictal electroencephalogram (EEG) is important for presurgical evaluation. This study aimed at investigating the safety and efficacy of our protocol developed at Peking University First Hospital (PUFH) for rapid withdrawal of antiseizure medications (ASMs) during LTVEM to induce seizures in children with drug-resistant epilepsy (DRE) exhibiting nondaily seizures.

METHODS

Children with DRE who followed the PUFH protocol for rapid withdrawal of ASMs during LTVEM between 2018 and 2021 were enrolled. The occurrence of seizures, number of ASMs withdrawn, seizure onset time after ASM tapering initiation, changes in interictal epileptiform discharge (IED), and adverse events were evaluated during LTVEM.

RESULTS

Among 80 children evaluated in this study, seizures were induced successfully in 72 (90%) children. Furthermore, no change in IED sites was observed in these 72 children following the initiation of ASM tapering while 2 children exhibited secondary bilateral tonic-clonic seizures. The median time from ASM tapering initiation to the onset of the first seizure was found to be 3 days (2-4), while the median number of ASMs withdrawn was 2 (1-2). Finally, 66 children (91.7%) had habitual seizures while 6 children had nonhabitual seizure semiology.

SIGNIFICANCE

The PUFH protocol can be used for the rapid withdrawal of ASMs during LTVEM in children with DRE. Using this protocol, ictal EEG patterns can be obtained in a relatively short time for most patients with fewer adverse effects during LTVEM, which may provide meaningful electro-clinical information for presurgical evaluation.

Laryngology Outcomes Following Implantable Vagus Nerve Stimulation

Importance

Vagus nerve stimulation (VNS) devices have gained widespread acceptance for treatment of resistant epilepsy and depression. The increasing number of procedures has resulted in an increasing number of iatrogenic injuries to the vagus nerve, which can have a significant effect on vocalization and quality of life.

Objective

To determine the relative frequency of laryngeal adverse effects reported to the US Food and Drug Administration (FDA) after VNS implantation and to analyze associated VNS device problems.

Design, Setting, and Participants

This retrospective cross-sectional analysis queried the FDA Manufacturer and User Facility Device Experience database of adverse events in the US between 1996 and 2020.

Main Outcomes and Measures

The primary outcome was the percent of adverse events reported to the FDA that included patients who received VNS with laryngeal adverse effects and the associated proportion of device problems after VNS surgery.

Results

A total of 12 725 iatrogenic vagus nerve issues were documented after VNS implantation, with apnea (n = 395; 3.1%) being the most common patient problem. Overall, 187 reports of laryngeal adverse effects associated with VNS devices were identified and represented the eighth most common iatrogenic vagus nerve problem reported to the FDA. Laryngeal adverse effects included 78 reports of voice alteration and 57 reports of paresis/paralysis. The VNS device problems frequently associated with laryngeal adverse effects were high impedance (n = 15, 8.02%), incorrect frequency delivery (n = 10, 5.35%), and battery problems (n = 11, 5.88%). The number of laryngeal adverse effect reports per year peaked in 2012 with 43 cases.

Conclusions and Relevance

This cross-sectional study found that although the literature demonstrates that vocal changes occur with nearly all VNS devices, the FDA receives adverse event reports of voice changes. Our results emphasize a potential need to improve patient counseling prior to VNS surgery to better set patient expectations regarding vocal changes and to prevent unnecessary patient concern. In addition, reports of vocal fold paresis/paralysis potentially suggest that patients may benefit from preoperative laryngeal assessment to differentiate preexisting vocal fold paralysis from that caused by VNS surgery.

Vagus Nerve Stimulation for Drug Resistant Epilepsy: Clinical Outcome, Adverse Events, and Potential Prognostic Factors in a Single Center Experience

OBJECTIVE

Vagus nerve stimulation (VNS) has been used for adjunctive treatment in drug resistant epilepsy (DRE) for decades. Nevertheless, information is lacking on possible potential prognostic factors. Our study presents the efficacy and safety of VNS with a focus on prognostic factors in 45 patients with DRE.

METHODS

We retrospectively evaluated the clinical outcome of 45 consecutive patients with DRE undergoing VNS implantation in The First Affiliated Hospital of Anhui Medical University between November 2016 and August 2021. Medical records were aggregated across all patient visits. Cox proportional hazards regression was used to estimate the prognostic factors.

RESULTS

Significant decrease in seizure frequency was observed after intermittent stimulation of the vagus nerve. According to the modified McHugh classification, 11 patients (24.4%) were Class I, 11 patients (24.4%) were Class II, four patients (8.9%) were Class III, 10 patients (22.2%) were Class IV, and nine patients (20.0%) were Class V. Notably, 22 patients (48.9%) were responders and four patients (8.9%) were seizure-free at the final follow-up. No significant prognostic factors were found in this cohort. Furthermore, 37 patients reported improved quality of life. Of the patients, 22 (48.9%) experienced adverse events after surgery; hoarseness, discomfort at the surgical site, and coughing were the most common.

CONCLUSION

The results confirmed the efficacy and safety of VNS. No prognostic factors were identified.

Parents' opinions about epilepsy surgery in children with epilepsy

OBJECTIVE

This survey aimed to investigate the opinions of the parents of children with epilepsy with regard to the application of epilepsy surgery for their children.

METHODS

We surveyed all the parents of children with epilepsy referred to our neurology clinic (Shiraz University of Medical Sciences) in April-July 2022. We collected their opinions about epilepsy surgery based on a predesigned questionnaire. The inclusion criteria included parents of all children with epilepsy (1 to 16 years of age, with at least one-year history of epilepsy, and with at least one drug used in the past 12 months).

RESULTS

In total, 472 people participated in the study; 277 participants (58.7%) were willing to have epilepsy surgery for their child; the most common reason was to be able to discontinue the drugs. Sex (male), age (younger), and education (college) of the parents had significant associations with the parental willingness to have surgery for their children. The patient's drug regimen (polytherapy) and history of ictal injury (in the child) also had significant associations with the parental willingness to have surgery for the children.

CONCLUSION

Most parents of children with epilepsy are willing to have epilepsy surgery for their children if their physician presents epilepsy surgery to them as an established, safe, and effective treatment option. Patient and parental-related factors should be considered when designing educational materials and programs for preoperative counseling for the parents of children with drug-resistant seizures.

Long-term follow-up of vagus nerve stimulation in drug-resistant KCNT1-related epilepsy: a case presentation

Background

The KCNT1 gene encodes a Na+-activated K+ channel. Gain-of-function mutations of KCNT1 lead to autosomal dominant sleep-related hypermotor epilepsy, early-onset epileptic encephalopathy, focal epilepsy and other epileptic encephalopathies. In this paper, we report a boy carrying a KCNT1 gene mutation, who presented with drug-resistant focal-onset seizures. He had decreased seizure frequency and improvement of background changes in electroencephalography (EEG) after vagus nerve stimulation (VNS).

Case presentation

The case was a nonverbal 9-year-old male who presented with drug-resistant focal-onset seizures since age 3 and had underwent VNS therapy for 2 years. He had hypermotor symptoms, automatism and bilateral asymmetric tonic seizures with cognitive decline and aphasis from age 3. The patient had a variety of seizure types that only occurred at night. The most common seizure type was automatisms, and ictal video EEG showed high-amplitude delta waves, followed by a fast rhythmic sharp activity in the mesial frontal and bitemporal regions. The patient was diagnosed with KCNT1-related epilepsy, epileptic encephalopathy and cognitive disorder. He was refractory to multiple anti-seizure medicines (ASM) and ketogenic diet. After VNS treatment at age 7, the frequency of seizures was reduced significantly and EEG was improved in background slowing.

Conclusions

Children with KCNT1-related epilepsy usually have early onset of disease, are nonverbal, and are refractory to ASM. This boy with drug-resistant KCNT1-related epilepsy showed significantly reduced seizure frequency after VNS. This report may provide reference for management of cases of KCNT1-related epilepsy.

Governance of the clinical pathway and management of the patient suffering from epilepsy and drug-resistant epilepsy

Epilepsy is a diffuse chronic neurological disease affecting around 50 million people worldwide. The diagnostic criteria by the International League against Epilepsy must be fulfilled to diagnose the disease, which is characterized by brief and transient episodes of abnormal neuronal activity involving one or both hemispheres, depending on the epilepsy type. The diagnosis of epilepsy should be properly and timely made because patients suffering from the disease are affected not only by seizure recurrence but also by epilepsy-related psychiatric and/or cognitive comorbidities that may have a huge impact with severe professional and social implications. It is of vital importance to define a specific governance model that has to be virtuously applied into the different phases of the clinical pathway of the patients with epilepsy in order to guarantee them the best model of care possible.

Effects of Stable Vagus Nerve Stimulation Efficacy on Autistic Behaviors in Ten Pediatric Patients With Drug Resistant Epilepsy: An Observational Study

Vagus nerve stimulation (VNS) is a safe and effective therapy for pediatric patients with drug-resistant epilepsy (DRE). However, in children with DRE, the effects of VNS on autistic behaviors remain controversial. We retrospectively collected data from 10 children with DRE who underwent VNS implantation and regular parameter regulation in three pediatric epilepsy centers, and completed the behavioral assessments, including the autistic behavior checklist and the child behavior checklist, at follow-ups 1 (mean 2.16 years) and 2 (mean 2.98 years). The 10 children maintained stable seizure control between the two follow-ups. Their autistic behaviors, especially in language, social and self-help, were reduced at follow-up 2 compared to follow-up 1 (p = 0.01, p = 0.01, respectively). Moreover, these improvements were not associated with their seizure control, whether it was positive or negative. These results suggested that the VNS had a positive effect on autistic behaviors, which provided a preliminary clinical basis that VNS may benefit to younger children with DRE comorbidity autism spectrum disorder (ASD).