Comprehensive long-term outcome of best drug treatment with or without add-on vagus nerve stimulation for epilepsy: A retrospective matched pairs case–control study

Efficacy and safety of VNS therapy or continued medication management for treatment of adults with drug-resistant epilepsy: systematic review and meta-analysis

Vagus nerve stimulation (VNS) Therapy® is an adjunctive neurostimulation treatment for people with drug-resistant epilepsy (DRE) who are unwilling to undergo resective surgery, have had unsuccessful surgery or are unsuitable for surgery. A systematic review and meta-analysis were conducted to determine the treatment effects of VNS Therapy as an adjunct to anti-seizure medications (ASMs) for the management of adults with DRE. A literature search was performed in August 2020 of the Medline®, Medline® Epub Ahead of Print, Embase, and the Cochrane library databases. Outcomes examined included reduction in seizure frequency, seizure freedom, ASM load, discontinuations, and serious adverse events (SAEs). Comparators included best medical practice, ASMs, low-stimulation or sham VNS Therapy. Four RCTs and six comparative observational studies were identified for inclusion. Against comparators, individuals treated with VNS had a significantly better odds of experiencing a ≥ 50% reduction in seizure frequency (OR: 2.27 [95% CI 1.47, 3.51]; p = 0.0002), a ≥ 75% reduction in seizure frequency (OR: 3.56 [95% CI 1.59, 7.98]; p = 0.002) and a reduced risk for increased ASM load (risk ratio: 0.36 [95% CI 0.21, 0.62]; p = 0.0002). There was no difference in the odds of discontinuation or the rate of SAEs between VNS versus comparators. This meta-analysis demonstrated the benefits of VNS Therapy in people with DRE, which included improvement in seizure frequency without an increase in the rate of SAEs or discontinuations, thereby supporting the consideration of VNS Therapy for people who are not responding to ASMs and those unsuitable or unwilling to undergo surgery.

Neuronal protective effect of Songling Xuemaikang capsules alone and in combination with carbamazepine on epilepsy in kainic acid-kindled rats

CONTEXT

Epilepsy is a common life-threatening neurological disorder that is often drug-resistant and associated with cognitive impairment. The traditional Chinese patent medicine Songling Xuemaikang capsules (SXC) is clinically used for epilepsy therapy and alleviation of cognitive impairment.

OBJECTIVE

This study investigates the neuronal protective effect of SXC combined with carbamazepine (CBZ) on epilepsy and cognitive impairment in kainic acid-kindled SD rats.

MATERIALS AND METHODS

Kainic acid-kindled rats were established by injection of 0.45 μg kainic acid and randomly divided into 5 groups (n = 14): saline (sham-operated), control, CBZ, SXC and CBZ + SXC combined group. Rats in the treatment groups received CBZ (50 mg/kg/d), SXC (600 mg/kg/d) or combined CBZ (50 mg/kg/d) + SXC (600 mg/kg/d) via intragastric injection for 60 days. Epileptic behaviours, cognitive impairment, neuronal apoptosis and expression of p-Akt, Akt and caspase-9 were measured, and the alleviation of cognitive damage and neuronal apoptosis was analyzed.

RESULTS

The combined administration of SXC and CBZ significantly decreased the frequency of seizures (1.2 ± 0.3) and the number of episodes (1.3 ± 0.5) above stage III (p < 0.05). Neuronal apoptosis was improved (p < 0.01), and cognitive damage was ameliorated (p < 0.05).The level of p-Akt was enhanced (p < 0.01) whereas the expression of caspase-9 was evidently inhibited (p < 0.01) in the combined group.

CONCLUSIONS

The present findings confirm that the combined use of SXC with CBZ can effectively control epileptic seizures, alleviate damage to hippocampal neurons and protect against cognitive impairment. The mechanism of action might be related to the upregulation of p-Akt and inhibition of caspase-9 expression.

Long-term outcome in neurostimulation of epilepsy

For patients with pharmacoresistant focal epilepsy, neurostimulation offers nonpharmacological strategies to improve seizure control. Vagus nerve stimulation (VNS), deep brain stimulation of the anterior thalamic nuclei, and responsive neurostimulation (RNS) are approved therapies which have shown efficacy in randomized short-term trials. Controlled data from prospective studies are needed to confirm reports on stable or even increasing evidence from studies with longer follow-up and to confirm that neurostimulation may offer advantages also regarding cognitive tolerability and sudden unexpected death in epilepsy (SUDEP)-risk. Here, a review of long-term outcomes is given, highlighting both achievements in terms of efficacy and tolerability and limitations of conclusions thereon related to an uncontrolled data basis and decreasing cohort sizes. This article is part of the Special Issue? "Individualized Epilepsy Management: Medicines, Surgery and Beyond".

Rates and Predictors of Seizure Freedom With Vagus Nerve Stimulation for Intractable Epilepsy

Supplemental Digital Content is Available in the Text.

BACKGROUND:

Neuromodulation-based treatments have become increasingly important in epilepsy treatment. Most patients with epilepsy treated with neuromodulation do not achieve complete seizure freedom, and, therefore, previous studies of vagus nerve stimulation (VNS) therapy have focused instead on reduction of seizure frequency as a measure of treatment response.

OBJECTIVE:

To elucidate rates and predictors of seizure freedom with VNS.

METHODS:

We examined 5554 patients from the VNS therapy Patient Outcome Registry, and also performed a systematic review of the literature including 2869 patients across 78 studies.

RESULTS:

Registry data revealed a progressive increase over time in seizure freedom after VNS therapy. Overall, 49% of patients responded to VNS therapy 0 to 4 months after implantation (≥50% reduction seizure frequency), with 5.1% of patients becoming seizure-free, while 63% of patients were responders at 24 to 48 months, with 8.2% achieving seizure freedom. On multivariate analysis, seizure freedom was predicted by age of epilepsy onset >12 years (odds ratio [OR], 1.89; 95% confidence interval [CI], 1.38-2.58), and predominantly generalized seizure type (OR, 1.36; 95% CI, 1.01-1.82), while overall response to VNS was predicted by nonlesional epilepsy (OR, 1.38; 95% CI, 1.06-1.81). Systematic literature review results were consistent with the registry analysis: At 0 to 4 months, 40.0% of patients had responded to VNS, with 2.6% becoming seizure-free, while at last follow-up, 60.1% of individuals were responders, with 8.0% achieving seizure freedom.

CONCLUSION:

Response and seizure freedom rates increase over time with VNS therapy, although complete seizure freedom is achieved in a small percentage of patients.

ABBREVIATIONS:

AED, antiepileptic drug

VNS, vagus nerve stimulation

The role of vagus nerve stimulation in refractory epilepsy

ABSTRACT Vagus nerve stimulation is an adjunctive therapy used to treat patients with refractory epilepsy who are not candidates for resective surgery or had poor results after surgical procedures. Its mechanism of action is not yet fully comprehended but it possibly involves modulation of the locus coeruleus, thalamus and limbic circuit through noradrenergic and serotonergic projections. There is sufficient evidence to support its use in patients with focal epilepsy and other seizure types. However, it should be recognized that improvement is not immediate and increases over time. The majority of adverse events is stimulation-related, temporary and decreases after adjustment of settings. Future perspectives to improve efficacy and reduce side effects, such as different approaches to increase battery life, transcutaneous stimulation and identification of prognostic factors, should be further investigated.

Vagus Nerve Stimulation in children: A focus on intellectual disability

INTRODUCTION

Vagus Nerve Stimulation (VNS) can be an efficacious add-on treatment in patients with drug-resistant epilepsy, who are not eligible for surgery. Evidence of VNS efficacy in children with intellectual disability (ID) is scarce.

OBJECTIVES

The purpose of this study was to review all available VNS data in the pediatric population (≤18 years old) and focus on the subpopulation with ID since appropriate treatment of these children is often challenging and complex.

METHODS

Cochrane, EMBASE, PubMed and MEDLINE were used to collect all research associated to VNS and ID (or synonyms) leading to a total of 37 studies. Seven studies showed the results of patients with ID and those without separately; thereby only these studies were included in the VNS meta-analysis.

RESULTS

Our meta-analysis showed that VNS was less effective in pediatric epilepsy patients with ID compared to those without ID (Mantel-Haenszel meta-analysis; p = 0.028, OR 0.18 (CI 95% 0.039-0.84)). However, there were no prospective controlled studies. Numerous studies reported quality of life (QoL) improvements in this subpopulation. The most common adverse events were transient and well tolerated. Side effects on cognition and behavior were not reported.

DISCUSSION

These results might be a reason to consider VNS early on in the treatment of this subgroup. The significantly greater amount of retrospective studies, differences in follow-up (FU), lack of control data, heterogeneous series and limited number of patients could have biased the outcome measurements. Hence, current data do not exclude VNS for children with drug-resistant epilepsy and ID but should be interpreted with caution.

The prognosis of refractory epilepsy patients rejected from epilepsy surgery

OBJECTIVE

Up to one-third of individuals diagnosed as having epilepsy continue to have seizures despite appropriate anti-epileptic drug treatment. These patients are often referred for presurgical evaluation, and many are rejected from focal resective surgery due to medical reasons or, alternatively, they choose not to undergo it. We compared the outcomes and characteristics of the non-operated patients who continued on medical therapy alone with those who underwent vagus nerve stimulator (VNS) implantation in addition to medical therapy.

METHODS

The medical records of consecutive adult patients referred for presurgical evaluation for suitability for epilepsy surgery in the Tel-Aviv Sourasky Medical Center between 2007 and 2011 and were rejected from or decided against surgery were reviewed. Updated information on seizure frequency was supplemented by telephone interviews between April and July, 2013.

RESULTS

Fifty-two patients who continued solely on medical therapy and 35 patients who additionally underwent VNS implantation were included in the study. Forty-seven of the former and 33 of the latter agreed to be interviewed. There was a significant improvement in the seizure frequency between the time of the presurgical evaluation and the time of the interview in both groups. Eight medically treated patients (17%) and 2 patients who also underwent VNS implantation (6%) reported being seizure-free during the preceding 3 months.

CONCLUSIONS

A considerable minority of patients with refractory epilepsy who were rejected or chose not to undergo epilepsy surgery may improve over time and even become seizure-free following adjustment of anti-epileptic drugs with or without concomitant VNS.

Preliminary experience with a new system for vagus nerve stimulation for the treatment of refractory focal onset seizures

Vagus nerve stimulation (VNS) is an accepted therapy for the treatment of drug-resistant epilepsy. A new VNS system ("FitNeS"; manufactured by BioControl Medical (B.C.M.) Ltd., Yehud, Israel) was implanted in 5 patients with refractory focal epilepsy. The system is composed of a programmable pulse generator and a cuff electrode that is able to provide unidirectional stimulation, both of which are implanted in the left chest and in the neck, respectively. FitNeS is based on the CardioFit vagus nerve stimulation system, which is intended for the treatment of heart failure and which is currently in a randomized controlled phase III clinical trial. Long-term stimulation in the 5 patients resulted in a 50% seizure reduction in 2 patients, 25% in 2 patients, and no effect in one patient, with few reports concerning side effects. There were no complaints of hoarseness at levels of stimulation below 2mA nor were there any reports of dysphagia or cough. The lack of perceived stimulation effects might finally allow for the design of a truly blinded randomized controlled study to evaluate the efficacy of VNS compared to placebo.