Exploration of Changes in Health-Related Quality of Life after 3 Months of Vagus Nerve Stimulation

Vagus nerve stimulation for focal seizures

BACKGROUND

This is an updated version of the Cochrane Review published in 2015. Epilepsy is a chronic neurological disorder, characterised by recurring, unprovoked seizures. Vagus nerve stimulation (VNS) is a neuromodulatory treatment that is used as an adjunctive therapy for treating people with drug-resistant epilepsy. VNS consists of chronic, intermittent electrical stimulation of the vagus nerve, delivered by a programmable pulse generator.

OBJECTIVES

To evaluate the efficacy and tolerability of VNS when used as add-on treatment for people with drug-resistant focal epilepsy.

SEARCH METHODS

For this update, we searched the Cochrane Register of Studies (CRS), and MEDLINE Ovid on 3 March 2022. We imposed no language restrictions. CRS Web includes randomised or quasi-randomised controlled trials from the Specialised Registers of Cochrane Review Groups, including Epilepsy, CENTRAL, PubMed, Embase, ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform.

SELECTION CRITERIA

We considered parallel or cross-over, randomised, double-blind, controlled trials of VNS as add-on treatment, which compared high- and low-level stimulation (including three different stimulation paradigms: rapid, mild, and slow duty-cycle), and VNS stimulation versus no stimulation, or a different intervention. We considered adults or children with drug-resistant focal seizures who were either not eligible for surgery, or who had failed surgery.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methods, assessing the following outcomes: 1. 50% or greater reduction in seizure frequency 2. Treatment withdrawal (any reason) 3. Adverse effects 4. Quality of life (QoL) 5. Cognition 6. Mood

MAIN RESULTS

We did not identify any new studies for this update, therefore, the conclusions are unchanged. We included the five randomised controlled trials (RCT) from the last update, with a total of 439 participants. The baseline phase ranged from 4 to 12 weeks, and double-blind treatment phases from 12 to 20 weeks. We rated two studies at an overall low risk of bias, and three at an overall unclear risk of bias, due to lack of reported information about study design. Effective blinding of studies of VNS is difficult, due to the frequency of stimulation-related side effects, such as voice alteration. The risk ratio (RR) for 50% or greater reduction in seizure frequency was 1.73 (95% confidence interval (CI) 1.13 to 2.64; 4 RCTs, 373 participants; moderate-certainty evidence), showing that high frequency VNS was over one and a half times more effective than low frequency VNS. The RR for treatment withdrawal was 2.56 (95% CI 0.51 to 12.71; 4 RCTs, 375 participants; low-certainty evidence). Results for the top five reported adverse events were: hoarseness RR 2.17 (99% CI 1.49 to 3.17; 3 RCTs, 330 participants; moderate-certainty evidence); cough RR 1.09 (99% CI 0.74 to 1.62; 3 RCTs, 334 participants; moderate-certainty evidence); dyspnoea RR 2.45 (99% CI 1.07 to 5.60; 3 RCTs, 312 participants; low-certainty evidence); pain RR 1.01 (99% CI 0.60 to 1.68; 2 RCTs; 312 participants; moderate-certainty evidence); paraesthesia 0.78 (99% CI 0.39 to 1.53; 2 RCTs, 312 participants; moderate-certainty evidence). Results from two studies (312 participants) showed that a small number of favourable QOL effects were associated with VNS stimulation, but results were inconclusive between high- and low-level stimulation groups. One study (198 participants) found inconclusive results between high- and low-level stimulation for cognition on all measures used. One study (114 participants) found the majority of participants showed an improvement in mood on the Montgomery-Åsberg Depression Rating Scale compared to baseline, but results between high- and low-level stimulation were inconclusive. We found no important heterogeneity between studies for any of the outcomes.

AUTHORS' CONCLUSIONS

VNS for focal seizures appears to be an effective and well-tolerated treatment. Results of the overall efficacy analysis show that high-level stimulation reduced the frequency of seizures better than low-level stimulation. There were very few withdrawals, which suggests that VNS is well tolerated. Adverse effects associated with implantation and stimulation were primarily hoarseness, cough, dyspnoea, pain, paraesthesia, nausea, and headache, with hoarseness and dyspnoea more likely to occur with high-level stimulation than low-level stimulation. However, the evidence for these outcomes is limited, and of moderate to low certainty. Further high-quality research is needed to fully evaluate the efficacy and tolerability of VNS for drug-resistant focal seizures.

The potential of invasive and non-invasive vagus nerve stimulation to improve verbal memory performance in epilepsy patients

It has been demonstrated that acute vagus nerve stimulation (VNS) improves word recognition memory in epilepsy patients. Transcutaneous auricular vagus nerve stimulation (taVNS) has gained interest as a non-invasive alternative to improve cognition. In this prospective randomized cross-over study, we investigated the effect of both invasive VNS and taVNS on verbal memory performance in 15 patients with drug-resistant epilepsy. All patients conducted a word recognition memory paradigm in 3 conditions: VNS ON, VNS OFF and taVNS (3-period 3-treatment cross-over study design). For each condition, patients memorized 21 highlighted words from text paragraphs. Afterwards, the intervention was delivered for 30 s. Immediate recall and delayed recognition scores were obtained for each condition. This memory paradigm was repeated after 6 weeks of VNS therapy in 2 conditions: VNS ON and VNS OFF (2-period 2-treatment cross-over study design). Acute VNS and taVNS did not improve verbal memory performance. Immediate recall and delayed recognition scores were significantly improved after 6 weeks of VNS treatment irrespective of the acute intervention. We can conclude that the previously described positive effects of invasive VNS on verbal memory performance could not be replicated with invasive VNS and taVNS. An improved verbal memory performance was seen after 6 weeks of VNS treatment, suggesting that longer and more repetitive stimulation of the vagal pathway is required to modulate verbal memory performance.Clinical trial registration number: NCT05031208.

Noninvasive vagus nerve stimulation in Parkinson's disease: current status and future prospects

INTRODUCTION

Parkinson's disease (PD) is a common progressive neurodegenerative disorder with multifactorial etiology. While dopaminergic medication is the standard therapy in PD, it provides limited symptomatic treatment and non-pharmacological interventions are currently being trialed.

AREAS COVERED

Recent pathophysiological theories of Parkinson's suggest that aggregated α-synuclein form in the gut and spread to nuclei in the brainstem via autonomic connections. In this paper, we review the novel hypothesis that noninvasive vagus nerve stimulation (nVNS), targeting efferent and afferent vagal projections, is a promising therapeutic tool to improve gait and cognitive control and ameliorate non-motor symptoms in people with Parkinson's. We conducted an unstructured search of the literature for any studies employing nVNS in PD as well as for studies examining the efficacy of nVNS on improving cognitive function and where nVNS has been applied to co-occurring conditions in PD.

EXPERT OPINION

Evidence of nVNS as a novel therapeutic to improve gait in PD is preliminary, but early signs indicate the possibility that nVNS may be useful to target dopa-resistant gait characteristics in early PD. The evidence for nVNS as a therapeutic tool is, however, limited and further studies are needed in both brain health and disease.

Early Implantation as a Main Predictor of Response to Vagus Nerve Stimulation in Childhood-Onset Refractory Epilepsy

OBJECTIVE

We describe a multicenter experience with vagus nerve stimulator implantation in pediatric patients with drug-resistant epilepsy. Our goal was to assess vagus nerve stimulation efficacy and identify potential predictors of favorable outcome.

METHODS

This is a retrospective study. Inclusion criteria: ≤18 years at time of vagus nerve stimulator implantation, at least 1 year of follow-up. All patients were previously found to be unsuitable for an excisional procedure. Favorable clinical outcome and effective vagus nerve stimulation therapy were defined as seizure reduction >50%. Outcome data were reviewed at 1, 2, 3, and 5 years after vagus nerve stimulator implantation. Fisher exact test and multiple logistic regression analysis were employed.

RESULTS

Eighty-nine patients met inclusion criteria. Responder rate (seizure frequency reduction >50%) at 1-year follow-up was 25.8% (4.5% seizure-free). At last follow-up, 31.5% had a favorable outcome and 5.2% were seizure free. The only factor significantly predicting favorable outcome was time to vagus nerve stimulator implantation, with the best outcome achieved when vagus nerve stimulator implantation was performed within 3 years of seizure onset. Implantation between 3 and 5 years after epilepsy onset correlated with better long-term seizure freedom (13.3% at T5). Overall, 65.2% of patients evidenced improved quality of life at last follow-up. However, 12.4% had adverse events, but most were mild and disappeared after 3-4 months.

CONCLUSIONS

Early vagus nerve stimulator implantation within 5 years of seizure onset was the only predictor of favorable clinical outcome in pediatric patients. Improved quality of life and a low incidence of significant adverse events were observed.

Effect of Long-Term Treatment with Vagus Nerve Stimulation on Mood and Quality of Life in Korean Patients with Drug-Resistant Epilepsy

BACKGROUND AND PURPOSE

This study aimed to determine the long-term effects of vagus nerve stimulation (VNS) treatment on suicidality, mood-related symptoms, and quality of life (QOL) in patients with drug-resistant epilepsy (DRE). We also investigated the relationships among these main effects, clinical characteristics, and VNS parameters.

METHODS

Among 35 epilepsy patients who underwent VNS implantation consecutively in our epilepsy center, 25 patients were recruited to this study for assessing the effects of VNS on suicidality, mood-related symptoms, and QOL. The differences in these variables between before and after VNS treatment were analyzed statistically using paired t-tests. Multiple linear regression analyses were also performed to determine how the patients' demographic and clinical characteristics influenced the variables that showed statistically significant changes after long-term VNS treatment.

RESULTS

After VNS, our patients showed significant improvements not only in the mean seizure frequency but also in suicidality, depression, and QOL. The reduction in depression was associated with the improvement in QOL and more-severe depression at baseline. The reduction in suicidality was associated with higher suicidality at baseline, smaller changes in depression, and less-severe depression at baseline. Improved QOL was associated with lower suicidality at baseline.

CONCLUSIONS

This study found that VNS decreased the mean seizure frequency in patients with DRE, and also improved their depression, suicidality, and QOL. These results provide further evidence for therapeutic effect of VNS on psychological comorbidities of patients with DRE.

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.

Impact of seizure frequency reduction on health-related quality of life among clinical trial subjects with refractory partial-onset seizures: A pooled analysis of phase III clinical trials of eslicarbazepine acetate

BACKGROUND

Subjects who received eslicarbazepine acetate (ESL) as adjunctive therapy experienced significantly greater seizure frequency reduction (SFR) than placebo in three phase III, randomized, double-blind trials. This analysis compared changes in health-related quality of life (HRQOL) between treatment responders and non-responders across the pooled, per-protocol population (N=842) using the validated Quality of Life in Epilepsy Inventory-31 (QOLIE-31).

METHODS

QOLIE-31 scores were calculated for Total Score (TS) and seven subscales; higher scores indicate better HRQOL. Mean changes from baseline were calculated. Analysis of covariance examined least square mean (LSM) differences in final scores between responders (≥50% and ≥75% SFR) and non-responders. Clinical significance was based on established minimal clinically important differences (MCIDs).

RESULTS

Mean changes were greater among responders for TS (5.2 versus 1.4 for ≥50% SFR; 7.5 versus 1.9 for ≥75% SFR) and all subscales. Additionally, the percentage of subjects with changes meeting or exceeding MCIDs was higher among responders for TS (48.4% versus 33.9% for ≥50% SFR; 56.9% versus 35.8% for ≥75% SFR) and all subscales. Responders had significantly higher final scores for TS (LSM difference=4.0 for ≥50% SFR; LSM difference=5.7 for ≥75% SFR) and all subscales except emotional well-being at ≥50% SFR. LSM differences exceeded MCIDs at ≥75% SFR for TS and five of seven subscales, and two subscales at ≥50% SFR. In a subgroup analysis with placebo removed, LSM differences were larger overall.

SIGNIFICANCE

In clinical trials of adjunctive ESL, higher levels of SFR were associated with greater improvements in HRQOL.

Vagal Nerve Stimulation for Drug-Resistant Epilepsy: Adverse Events and Outcome in a Series of Patients with Long-Term Follow-Up

BACKGROUND

Vagal nerve stimulation (VNS) is a palliative treatment option for drug-resistant epilepsy. The aim of this study was to describe the clinical and demographic features of selected patients scheduled for VNS and to evaluate the long-term efficacy of VNS in seizure control.

MATERIALS AND METHODS

Between 2006 and 2013, 32 consecutive epileptic patients (14 male and 18 female) were enrolled at our Institute for VNS implantation. In all cases resective surgery had previously been excluded by the use of a noninvasive presurgical study protocol. Mean age was 32 years (range 18-50), and mean epilepsy duration 23 years (range 11-39). All subjects were followed-up for at least 2 years (mean 6 years, range 2-9) after VNS implantation. Patients were considered responders when a reduction of seizures of more than 50 % was reported.

RESULTS

All patients had complex partial seizures, in 81 % of the patients with secondary generalization and in 56 % with drop attacks. Neurological examination revealed focal deficits in 19 % of the patients. Brain magnetic resonance imaging (MRI) was positive in 47 % of the patients. No surgical complications were observed in this series. Three patients were lost to follow-up. Twelve patients were classified as responders. Among the others, 1 patient experienced side effects (snoring and groaning during sleep) and the device was removed.

CONCLUSIONS

Our data confirm that VNS is a safe procedure and a valid palliative treatment option for drug-resistant epileptic patients not suitable for resective surgery.

Vagus nerve stimulation therapy: indications, programing, and outcomes

Vagus nerve stimulation (VNS) provides palliation of seizure reduction for patients with medically refractory epilepsy. VNS is indicated for symptomatic localization-related epilepsy with multiple and bilateral independent foci, symptomatic generalized epilepsy with diffuse epileptogenic abnormalities, refractory idiopathic generalized epilepsy, failed intracranial epilepsy surgery, and other several reasons of contraindications to epilepsy surgery. Programing of the parameters is a principal part in VNS. Output current and duty cycle should be adjusted to higher settings particularly when a patient does not respond to the initial setting, since the pivotal randomized trials performed in the United States demonstrated high stimulation made better responses in seizure frequency. These trials revealed that a ≥ 50% seizure reduction occurred in 36.8% of patients at 1 year, in 43.2% at 2 years, and in 42.7% at 3 years in 440 patients. Safety of VNS was also confirmed because side effects including hoarseness, throat discomfort, cough, paresthesia, and headache improved progressively during the period of 3 years. The largest retrospective study with 436 patients demonstrated the mean seizure reduction of 55.8% in nearly 5 years, and also found 75.5% at 10 years in 65 consecutive patients. The intermediate analysis report of the Japan VNS Registry showed that 60% of 164 cases got a ≥ 50% seizure reduction in 12 months. In addition to seizure reduction, VNS has positive effects in mood and improves energy level, memory difficulties, social aspects, and fear of seizures. VNS is an effective and safe option for patients who are not suitable candidates for intracranial epilepsy surgery.

Quality of Life and Memory after Vagus Nerve Stimulator Implantation for Epilepsy

Objective:

This prospective, case control study evaluates quality of life (QOL), depressive affect, and memory outcomes of epilepsy patients implanted with a vagus nerve stimulator (VNS).

Methods:

Three groups of patients with epilepsy underwent assessment on two occasions: 1) patients with a VNS were tested before and 12 months after implantation (n = 16); 2) patients who underwent cerebral resective surgery were tested pre- and post-operatively (n = 10); and 3) patients under medical management (n = 9). Group means were compared on the QOLIE-89, Geriatric Depression Scale, Wechsler Memory Scale - III, and the Memory Observation Questionnaire. Secondary analyses calculated the reliable change index, providing information on change beyond measurement error and chance.

Results:

Mean ratings of QOL, depression, and memory complaints and objective memory scores remained stable or improved in all the groups. The QOL improved more after cerebral resective surgery than VNS or medication controls, but the VNS and medication control groups did not differ. In the VNS group, QOL was not related to seizure reduction. The percentage of cases showing real change in memory was equivalent across groups, except in one of eight indices (i.e., verbal recognition memory).

Conclusions:

This first case controlled design found that vagus nerve stimulation as an adjunctive therapy for seizure control did not change QOL, depressive affect, or objective memory scores over one-year more so than medical management alone. We point out the need for larger case control, non-industry funded investigations.

Selection of antiepileptic drugs in older people

OPINION STATEMENT

Elderly people are one of the fastest-growing populations in the United States, and the incidence of epilepsy in older people is much higher than in other population subgroups. This age group is the most vulnerable because of the increased incidence of multiple medical comorbidities, including stroke. The diagnosis of epilepsy is extremely challenging and often delayed in this age group because of an atypical presentation. Seizures are manifest through extremely vague complaints, such as episodes of altered mental status or memory lapses. Once the diagnosis is established by careful history taking and diagnostic testing, anticonvulsants are the mainstay of treatment. The choice of anticonvulsants in elderly patients requires careful evaluation of medical comorbidities, which vary on an individual basis. This subgroup also is more susceptible to adverse effects because of the physiologic changes in the body due to older age, which affect the pharmacokinetics of most anticonvulsants. The ideal drug in this age group should have linear pharmacokinetics, fewer adverse effects, minimal or no drug-drug interactions, no enzyme induction/inhibition, a long half-life, and minimal protein binding, and should be cost-effective. As such, there is no ideal drug for this patient population, although both older- and newer-generation anticonvulsants are used for long-term treatment. Most newer anticonvulsants have the advantage of a favorable pharmacokinetic profile, minimal or no drug-drug interactions, and fewer adverse events, as well as being well tolerated. The older anticonvulsants still are widely used, because the newer anticonvulsants are much more expensive.

Efficacy of vagus nerve stimulation as a treatment for medically intractable epilepsy in brain tumor patients. A case-controlled study using the VNS therapy Patient Outcome Registry

PURPOSE

Vagus nerve stimulation (VNS) therapy is a procedure to control seizure frequency in patients with medically intractable epilepsy. However, there is no data on efficacy in the subset of these patients with brain tumors. The purpose of this study is to evaluate the efficacy of VNS therapy in patients with brain tumor-associated medically intractable epilepsy.

METHODS

Data from the VNS therapy Patient Outcome Registry, maintained by the manufacturer of the device, Cyberonics Inc. (Houston, TX, USA), was queried to characterize the response of patients in whom a brain tumor was listed as the etiology of epilepsy. A case-control analysis was implemented and patient outcome was measured by Engel classification, median seizure response and responder rate (≥50% seizure reduction) using t-tests and chi-squared tests.

RESULTS

In 107 patients with an epilepsy etiology related to a brain tumor, seizure reduction was 45% at 3 months and 79% at 24 months with a responder rate of 48% at 3 months and 79% at 24 months. There was no statistical difference in seizure reduction compared with 326 case-control patients from the registry without brain tumors. There was no significant difference in anti-epileptic drug (AED) usage from baseline to 24 months post implant in either group.

CONCLUSIONS

VNS therapy is equally effective in patients who suffer seizures secondary to brain tumors as in patients without history of a brain tumor. VNS therapy is a viable treatment option for patients with brain tumor associated medically intractable epilepsy, assuming cytoreductive and other adjuvant therapies have been fully explored.

Efficacy of vagus nerve stimulation in brain tumor-associated intractable epilepsy and the importance of tumor stability

OBJECT

Vagus nerve stimulation (VNS) is a viable option for patients with medically intractable epilepsy. However, there are no studies examining its effect on individuals with brain tumor-associated intractable epilepsy. This study aims to evaluate the efficacy of VNS in patients with brain tumor-associated medically intractable epilepsy.

METHODS

Epilepsy surgery databases at 2 separate epilepsy centers were reviewed to identify patients in whom a VNS device was placed for tumor-related intractable epilepsy between January 1999 and December 2011. Preoperative and postoperative seizure frequency and type as well as antiepileptic drug (AED) regimens and degree of tumor progression were evaluated. Statistical analysis was performed using odds ratios and t-tests to examine efficacy.

RESULTS

Sixteen patients were included in the study. Eight patients (50%) had an improved outcome (Engel Class I, II, or III) with an average follow-up of 39.6 months. The mean reduction in seizure frequency was 41.7% (p = 0.002). There was no significant change in AED regimens. Seizure frequency decreased by 10.9% in patients with progressing tumors and by 65.6% in patients with stable tumors (p = 0.008).

CONCLUSIONS

Vagus nerve stimulation therapy in individuals with brain tumor-associated medically intractable epilepsy was shown to be comparably effective in regard to seizure reduction and response rates to the general population of VNS therapy patients. Outcomes were better in patients with stable as opposed to progressing tumors. The authors' findings support the recommendation of VNS therapy in patients with brain tumor-associated intractable epilepsy, especially in cases in which imminent tumor progression is not expected. Vagus nerve stimulation may not be indicated in more malignant tumors.

Seizure treatment in transplant patients

OPINION STATEMENT

Solid organ transplantation is frequently complicated by a spectrum of seizure types, including single partial-onset or generalized tonic-clonic seizures, acute repetitive seizures or status epilepticus, and sometimes the evolution of symptomatic epilepsy. There is currently no specific evidence involving the transplant patient population to guide the selection, administration, or duration of antiepileptic drug (AED) therapy, so familiarity with clinical AED pharmacology and application of sound judgment are necessary for successful patient outcomes. An initial detailed search for symptomatic seizure etiologies, including metabolic, infectious, cerebrovascular, and calcineurin inhibitor treatment-related neurotoxic complications such as posterior reversible encephalopathy syndrome (PRES), is imperative, as underlying central nervous system disorders may impose additional serious risks to cerebral or general health if not promptly detected and appropriately treated. The mainstay for post-transplant seizure management is AED therapy directed toward the suspected seizure type. Unfavorable drug interactions could place the transplanted organ at risk, so choosing an AED with limited interaction potential is also crucial. When the transplanted organ is dysfunctional or vulnerable to rejection, AEDs without substantial hepatic metabolism are favored in post-liver transplant patients, whereas after renal transplantation, AEDs with predominantly renal elimination may require dosage adjustment to prevent adverse effects. Levetiracetam, gabapentin, pregabalin, and lacosamide are drugs of choice for treatment of partial-onset seizures in post-transplant patients given their efficacy spectrum, generally excellent tolerability, and lack of drug interaction potential. Levetiracetam is the drug of choice for primary generalized seizures in post-transplant patients. When intravenous drugs are necessary for acute seizure management, benzodiazepines and fosphenytoin are the traditional and best evidence-based options, although intravenous levetiracetam, valproate, and lacosamide are emerging options. Availability of several newer AEDs has greatly expanded the therapeutic armamentarium for safe and efficacious treatment of post-transplant seizures, but future prospective clinical trials and pharmacokinetic studies within this specific patient population are needed.

Vagus nerve stimulation and the postictal state

Vagus nerve stimulation (VNS) is an established neurostimulation therapy used to treat refractory epilepsy. The effect of acute or chronic VNS on the postictal state as a separate entity is seldom reported in clinical or experimental studies. Apart from its antiseizure effects, VNS has several other beneficial effects. These effects may be of particular benefit for patients with postictal neuropsychiatric symptoms. The hypothesized mechanisms underlying the initiation and sustainment of the postictal phase, to some extent, overlap with mechanisms involved in the seizure-suppressing effects of VNS as well as other neurological and psychotropic effects of VNS. Both the clinical symptoms and the basic research hypotheses of the postictal state show similarities with clinical effects induced by VNS and its underlying mechanisms of action.

The Art of Managing Conversions between Antiepileptic Drugs: Maximizing Patient Tolerability and Quality of Life

Conversion between anti-epilectic drugs (AEDs) is frequently necessary in epilepsy care, exposing patients to a risk of incurring adverse effects and reduced quality of life. Little practical guidance is available to practitioners to guide conversions between AED monotherapies, or in adding a new adjunctive AED into a polytherapy regimen. This article reviews the impact of adverse effects of AEDs on quality of life in epilepsy patients, then reviews several important patient-related factors such as age, gender, medical and psychiatric co-morbidities, and co-medications that must be considered when selecting AEDs and ensuring tolerable and safe AED conversions. Practical strategies for transitional polytherapy AED conversion are then considered in different commonly encountered clinical scenarios in newly diagnosed and refractory epilepsy care, including inadequate seizure control, intolerable adverse effects, or idiosyncratic safety hazards. Successful conversion between AEDs requires regular monitoring for patient-reported adverse effects and appropriately reactive adjustment of AED therapy to maximize patient quality of life.

Dramatic first words spoken in 2 children after vagus nerve stimulation

Vagus nerve stimulation has become an accepted adjunctive treatment for refractory epilepsy with more recent FDA approval in the treatment of depression. Many "positive" effects have been noted in patients with epilepsy namely increased alertness, improved cognition, behavior and mood. These changes appear to be independent of seizure reduction and antiepileptic drug decrease. We present two children (aged 8 and 9 years) who were non-verbal and spoke their first words shortly after vagus nerve stimulators were implanted. The mechanism is unclear although vagus nerve stimulation has been clearly shown to induce neuronal, chemical and perfusion changes in both subcortical and cortical regions of the brain. There is likely a combined effect on primary speech areas as well subcortical and mamillothalamic tracts, and possibly even stimulation and changes at the local vocal cord level contributing to this phenomenon. Our observation has important implications in encephalopathic patients both with and without epilepsy.

Minimizing AED adverse effects: improving quality of life in the interictal state in epilepsy care

The goals of epilepsy therapy are to achieve seizure freedom while minimizing adverse effects of treatment. However, producing seizure-freedom is often overemphasized, at the expense of inducing adverse effects of treatment. All antiepileptic drugs (AEDs) have the potential to cause dose-related, "neurotoxic" adverse effects (i.e., drowsiness, fatigue, dizziness, blurry vision, and incoordination). Such adverse effects are common, especially when initiating AED therapy and with polytherapy. Dose-related adverse effects may be obviated in most patients by dose reduction of monotherapy, reduction or elimination of polytherapy, or substituting for a better tolerated AED. Additionally, all older and several newer AEDs have idiosyncratic adverse effects which usually require withdrawal in an affected patient, including serious rash (i.e., Stevens-Johnson Syndrome, toxic epidermal necrolysis), hematologic dyscrasias, hepatotoxicity, teratogenesis in women of child bearing potential, bone density loss, neuropathy, and severe gingival hyperplasia. Unfortunately, occurrence of idiosyncratic AED adverse effects cannot be predicted or, in most cases, prevented in susceptible patients. This article reviews a practical approach for the definition and identification of adverse effects of epilepsy therapies, and reviews the literature demonstrating that adverse effects result in detrimental quality of life in epilepsy patients. Strategies for minimizing AED adverse effects by reduction or elimination of AED polytherapy, appropriately employing drug-sparing therapies, and optimally administering AEDs are outlined, including tenets of AED selection, titration, therapeutic AED laboratory monitoring, and avoidance of chronic idiosyncratic adverse effects.

Epilepsy treatment as a predeterminant of psychosocial ill health

Epilepsy is a chronic disorder with complex effects on social, vocational, physical, and psychological well-being. Patient-oriented research has demonstrated that recurrent seizures have a strong adverse effect on health-related quality of life, but also that seizure rate in persons with pharmacoresistant epilepsy has only a modest correlation with quality of life. Although treatment side effects have received limited attention in epilepsy research, available evidence indicates that adverse medication effects may explain more variance in quality of life than any other clinical variable in persons with pharmacoresistant epilepsy. Furthermore, systematic screening for adverse effects has been shown to be associated with significant reduction in subjective toxicity and improvement in quality of life. There has been only limited research on the relative contribution of specific adverse effects to impaired health-related quality of life. The relative importance of reduction of medication burden after resective epilepsy surgery or vagal nerve stimulation has similarly received sparse attention. Existing deficiencies in the available published research present challenges and opportunities to perform further investigations to define and improve best clinical practices in epilepsy care.

Quality of life and seizure outcome after vagus nerve stimulation in children with intractable epilepsy

This study examined the effect of vagus nerve stimulation on quality of life in children with epilepsy using a validated quality-of-life scale and an empirical technique that accounts for measurement error in assessing individual change (the reliable change index). Participants were 34 children with severe intractable epilepsy who underwent vagus nerve stimulation and 19 children with intractable epilepsy who received medical management. Parent-completed epilepsy-specific and global ratings at baseline and after 1 year indicated that most children had no changes in quality of life following vagus nerve stimulation (52%-77%), similar to the comparison group. There was a trend for decreases to be less common in the vagus nerve stimulation group (14% vs 37%, P < .07), but there was no relation between improved quality of life and seizure control. The results raise questions about the mechanisms that underlie changes in quality of life after vagus nerve stimulation in this group of children.

Vagal nerve stimulation: exploring its efficacy and success for an improved prognosis and quality of life in cerebral palsy patients

Cerebral palsy (CP) continues to pose a cause for major socioeconomic concern and medical challenge worldwide. It is associated with a multi-faceted symptomatology warranting a multi-dimensional management-approach. Recent recognition of neurocognitive impairment and its hopefully possible treatment has opened up a new dimension in its management to the neurologists. Vagal nerve stimulation (VNS) technique is presently emerging as an effective alternative anti-epileptic therapeutic measure in intractable epilepsy. VNS has recently been shown to possess a suppressive effect also on interictal epileptiform discharges (IEDs) that are now being widely accepted as established associates of neurocognitive impairment. In this paper, the author proposes VNS technique implantation in CP patients on account of its dual therapeutic effectiveness, i.e. anti-epileptic and IED-suppression. These two effects are likely to control seizures that are quite often drug-resistant and also improve neurocognition in CP patients, thus hoping for a better overall prognostic outcome and an improved quality of life of the CP patients by VNS.

Outcome measurement after vagal nerve stimulation therapy: proposal of a new classification

PURPOSE

Vagal nerve stimulation (VNS) is an adjunctive palliative therapy for refractory epilepsy. Effects of treatment are varied and some, such as the use of an external magnet for seizure termination, are unique to VNS. No accepted standard exists for outcome measurement after VNS treatment. We present a novel classification for outcome, which includes assessment of both seizure frequency and severity in VNS-treated patients.

METHODS

We devised a classification system modeled on the Engel classification for surgically treated patients, but tailored for use in VNS therapy, which incorporates five classes of outcome. We retrospectively reviewed VNS-treated patients in our centre, and used the data to illustrate our system and compare it with the Engel model.

RESULTS

With this system, 48 patients (mean age, 30 years) were followed up over a median of 18 months. Seventy-eight percent had partial epilepsy. Sixteen and a half percent experienced class I outcome (>80% seizure-frequency reduction). Twenty percent had class II improvement (50-79% seizure-frequency reduction). One-third had no improvement (class V). The remaining patients comprised class III (seizure-frequency reduction <50%) or class IV (magnet benefit alone) outcomes. Class I-III outcomes were further subdivided according to effects on ictal or postictal severity.

CONCLUSIONS

We propose a new classification, which can be used for all epilepsies and which reflects outcome measures beyond seizure-frequency reduction alone. Use of this system would allow greater comparison between future studies of VNS therapy.

Non-invasive measurement of vagus activity in the brainstem - a methodological progress towards earlier diagnosis of dementias?

In Alzheimer's disease (AD), mild functional disturbances should precede gross structural damage and even more clinical symptoms, possibly by decades. Moreover, alterations in the brainstem are supposed to occur earlier as cortical affections. Based on these considerations, we developed a new method aiming at the measurement of vagal brainstem functioning by means of evoked potentials after electrical stimulation of the cutaneous representation of the vagus nerve in the external auditory channel. In the current study, a first sample of patients with Alzheimer's disease (n = 7) and mild cognitive impairment (n = 3) were investigated (6m, 4f, range from 57 to 78 y, mean age 68.6 years). Vagus somatosensory evoked potentials (VSEP) were characterized by significantly longer latencies as compared to healthy age- and gender-matched controls (p < 0.05). Future large scale studies - also including preclinical stages of AD - have to assess the value of this non-invasive, fast and cheap method in the early diagnosis of neurodegenerative disorders.

Increase in 20–50Hz (gamma frequencies) power spectrum and synchronization after chronic vagal nerve stimulation

OBJECTIVE

Though vagus nerve stimulation (VNS) is an important option in pharmaco-resistant epilepsy, its mechanism of action remains unclear. The observation that VNS desynchronised the EEG activity in animals suggested that this mechanism could be involved in VNS antiepileptic effects in humans. Indeed VNS decreases spiking bursts, whereas its effects on the EEG background remain uncertain. The objective of the present study is to investigate how VNS affects local and inter regional syncronization in different frequencies in pharmaco-resistant partial epilepsy.

METHODS

Digital recordings acquired in 11 epileptic subjects 1 year and 1 week before VNS surgery were compared with that obtained 1 month and 1 year after VNS activation. Power spectrum and synchronization were then analyzed and compared with an epileptic group of 10 patients treated with AEDs only.

RESULTS

VNS decreases the synchronization of theta frequencies (P < 0.01), whereas it increases gamma power spectrum and synchronization (< 0.001 and 0.01, respectively).

CONCLUSIONS

The reduction of theta frequencies and the increase in power spectrum and synchronization of gamma bands can be related to VNS anticonvulsant mechanism. In addition, gamma modulation could also play a seizure-independent role in improving attentional performances.

SIGNIFICANCE

These results suggest that some antiepileptic mechanisms affected by VNS can be modulated by or be the reflection of EEG changes.

A retrospective analysis of the effects of magnet-activated stimulation in conjunction with vagus nerve stimulation therapy

Vagus nerve stimulation (VNS) therapy offers two methods to help control seizures, automatic stimulation delivered at programmed intervals and on-demand stimulation initiated with a magnet. This study retrospectively analyzes magnet use during the E03 and E04 clinical trials of VNS therapy. Magnet activation that aborted, decreased, terminated, or diminished a seizure was classified as an improvement; for purposes of evaluation, the patient was considered to have received a benefit. When patients in the E03 trial used magnets to activate stimulation, patients with active magnets were more likely to report seizure improvement than patients with inactive magnets (P=0.0479, Fisher's test). In the E04 trial, 22% of patients using the magnet reported seizure termination and 31% reported seizure diminution. Unrelated to seizure reduction with programmed VNS therapy, approximately half of the patients who used the magnet in this study received some benefit. Additional studies can provide a better understanding of this unique mode of delivering antiseizure therapy.

Epilepsy and cognition

Patients with epilepsy are more prone to cognitive and behavioral deficits. Epilepsy per se may induce or exacerbate an underlying cognitive impairment, a variety of factors contribute to such deficits, i.e., underlying neuropathology, seizure type, age of onset, psychosocial problems, and treatment side effects. Epilepsy treatment may offset the cognitive and behavioral impairments by stopping or decreasing the seizures, but it may also induce untoward effects on cognition and behavior. The neurocognitive burden of epilepsy may even start through in utero exposure to medications. Epilepsy surgery can also induce certain cognitive deficits, although in most cases this can be minimized. Clinicians should consider cognitive side effect profiles of antiepileptic medications, particularly in extreme age groups. While no effective treatments are available for cognitive and behavioral impairments in epilepsy, comprehensive pretreatment evaluation and meticulous selection of antiepileptic drugs or surgical approach may minimize such untoward effects.

The impact of epilepsy on subjective health status

Epilepsy is a chronic disorder that has complex effects on many aspects of personal health. Recent advances in the methods to reliably and validly assess subjective health status have allowed major advances in our understanding of these diverse effects, and have also provided evidence to guide treatment and future research. Studies that have included measures of quality of life, patient preferences, and disability in epilepsy have shown that the magnitude of the adverse effects of recurrent seizures on many aspects of subjective health status is as large as that seen with diabetes mellitus and active cardiovascular disease. Studies of patient-oriented, comprehensive outcomes after epilepsy surgery indicate positive treatment effects in broad areas of function and well-being. Although few trials of epilepsy drugs have included health outcome instruments, available studies suggest that greater than 50% seizure reduction is associated with improved quality of life. Adverse medication effects and depression appear to have a strong association with subjective health status in epilepsy, independent of seizure frequency.

The effects of vagus nerve stimulation therapy on patients with intractable seizures and either Landau-Kleffner syndrome or autism

Acquired and developmental comorbid conditions, including language and behavioral disorders, are often associated with epilepsy. Although the relationship between these disorders is not fully understood, their close association may indicate that they share common features, suggesting that these conditions may respond to the same therapies. Not only has vagus nerve stimulation (VNS) therapy been proven to reduce the frequency of pharmacoresistant seizures in epilepsy patients, but preliminary studies also indicate that VNS therapy may improve neurocognitive performance. On the basis of these findings, we hypothesized that VNS therapy would improve the quality of life of patients with either Landau-Kleffner syndrome (LKS) or autism, independent of its effects on seizures. Data were retrospectively queried from the VNS therapy patient outcome registry (Cyberonics, Inc; Houston, TX, USA). A constant cohort of 6 LKS patients and 59 autistic patients were identified. Among the LKS patients, 3 patients at 6 months experienced at least a 50% reduction in seizure frequency as compared with baseline. Physicians reported quality-of-life improvements in all areas assessed for at least 3 of the 6 children. More than half of the patients with autism (58%) experienced at least a 50% reduction in seizure frequency at 12 months. Improvements in all areas of quality of life monitored were reported for most patients, particularly for alertness (76% at 12 months). Although these preliminary findings are encouraging, a prospective study using standardized measurement tools specific to these disorders and a longer-term follow-up are necessary to better gauge the efficacy of VNS therapy among these patient populations.

Long-term outcome of vagus nerve stimulation for refractory partial epilepsy

We assessed 1- and 2-year outcomes of specific seizure types, quality of life, depression, and anxiety among patients treated with vagus nerve stimulation (VNS) for refractory partial epilepsy. Patients completed a seizure questionnaire, the Quality of Life in Epilepsy-89 (QOLIE-89) questionnaire, the Beck Anxiety Inventory (BAI), and the Beck Depression Inventory (BDI) at baseline and 1 year, and 2 years after activation of VNS. VNS was associated with >or=50% reduction in total seizure frequency in 54% of patients at 1 year and 61% of patients 2 years post-VNS activation compared with baseline. No statistically significant changes from baseline to 12 or 24 months were found in mean quality of life, depression, or anxiety measures in the overall study population. Patients with at least 50% reduction in seizures had significant improvement in anxiety at 12 and 24 months compared with patients who did not have the same degree of seizure reduction.

Neurostimulation therapy for epilepsy: current modalities and future directions

Neurostimulation is a recent development in the treatment of epilepsy. Vagus nerve stimulation (VNS), the only approved neurostimulation therapy for epilepsy to date, has proved to be a viable adjunctive treatment option. The exact mechanism of action of VNS is not fully understood. In 2 randomized double-blind trials, seizure frequency declined approximately 30% after 3 months of treatment. Long-term follow-up studies suggest that response improves over time, with approximately 35% of patients experiencing a 50% reduction and 20% experiencing a 75% reduction in seizure frequency after 18 months of treatment. Unfortunately, the number of patients rendered medication-free and seizure-free with VNS is low. Vagus nerve stimulation is best viewed as an option for patients who are not surgical candidates or who hesitate to take the risk of surgery yet continue to have seizures despite maximal medical therapy. Stimulation of other regions of the central nervous system for treating epilepsy, including the anterior and centromedian nuclei of the thalamus, the hippocampus, the subthalamic nucleus, and the cerebral neocortex, is currently under investigation. We review the history, proposed mechanisms of action, clinical trials, adverse effects, and future direction of VNS and other modalities of neurostimulation therapy for epilepsy.

Vagus-nerve stimulation for the treatment of epilepsy

Vagus-nerve stimulation (VNS) is now an accepted treatment for patients with refractory epilepsy. There have been many studies suggesting that VNS affects the brain in such areas as the thalamus and other limbic structures. In addition, there is some evidence that norepinephrine is important in the prophylactic antiseizure effects of VNS. The efficacy of VNS has been established for partial seizure types, even in refractory patients who did not respond to surgical treatment for epilepsy. There are also data, from open-label studies, that suggest efficacy in other seizure types. Therefore, VNS seems to be a broad-spectrum treatment for epilepsy. Improvement is not immediate but increases over 18-24 months of treatment. Most studies report subjective improvements in various quality-of-life measurements during treatment with VNS--objective trials have confirmed this observation. Side-effects are mainly stimulation related and reversible and they tend to decrease over time. They are generally mild to moderate and seldom necessitate the removal of the device. No idiosyncratic side-effects have been reported in 12 years of experience, and VNS does not interact with antiepileptic drugs. Most adverse events are predictable and related to the specific stimulation regimen. VNS does not have cognitive and systemic side-effects and can, therefore, be a valuable treatment approach even for patients who have poor tolerance of antiepileptic drugs.

Vagus nerve stimulation: where are we?

Now nearly 5 years post-approval, vagus nerve stimulation has emerged as a major non-pharmacological treatment for epilepsy. The place of vagus nerve stimulation among antiepileptic drugs and other surgical therapies is still evolving. This review evaluates the role of vagus nerve stimulation in light of recently published research of its mechanism(s) of action, long-term efficacy, safety and tolerability, and application to other disorders besides epilepsy.