Long-term results of vagus nerve stimulation in children and adolescents with drug-resistant epilepsy

A 3-year-old child with multi-drug resistant epilepsy responding to pharmacological and nonpharmacological treatments

Introduction: Despite the development of new antiseizure drugs (ASDs), around one third of epilepsy patients become refractory to treatment or experience adverse events due to ASDs. Therefore, discovery of new ASDs and new therapy options are crucial to improve the quality of life. Herein, we report a 3-year-old child with multi-drug resistant epilepsy caused by perinatal asphyxia whose seizures were reduced by 90% after the introduction of ketogenic diet, vagal nerve stimulation (VNS) AspireSR (SR-seizure response) and oral cannabidiol.Case presentation: A 9-month-old female infant had a history of multidrug resistant epilepsy due to perinatal asphyxia. At admission, she was experiencing up to 20-25 seizures per day lasting for 2-3 minutes. In addition to antiseizure drugs (ASDs), she was put on ketogenic diet (KD), vagal nerve stimulation (VNS) aspire seizure response (AspireSR) was inserted and oral cannabidiol (CBD) was started sequentially. Using pharmacological and nonph armacological therapies, her seizures have been reduced by 90%.Conclusion: The concurrent use of pharmacological and nonpharmacological therapies may be beneficial to improve seizures in infants with multi- Furthermore, our patient is the youngest child inserted VNS AspireSR in Turkey.

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

OBJECTIVES

To compare the short- and long-term efficacies as well as tolerability of vagus nerve stimulation (VNS) for the patients with drug-resistant epilepsy (DRE) in comparison with status at baseline.

MATERIALS AND METHODS

We conducted a specific and systematic search in online data bases for relevant literature published prior to December 2020. The literature retrieved, including randomized clinical trials (RCTs) and observational studies, were then reviewed, and analyzed. A fixed-effect model was used to evaluate the pooled odds ratio (OR) of responder rates and complications associated with RCTs. A random-effect model was used to generate overall responder rates and overall incidences of complication.

RESULTS

A total of 61 studies, featuring 5223 patients, were included in our study. The pooled ORs of responder rates, hoarseness/voice change, throat pain, coughing, dyspnea, paresthesia, muscle pain, and headache during the short-term phase were 2.195 (p = 0.001), 5.527 (p = 0.0001), 0.935 (p = 0.883), 1.119 (p = 0.655), 2.901 (p = 0.005), 1.775 (p = 0.061), 3.606 (p = 0.123), and 0.928 (p = 0.806), respectively. The overall responder rates in 3, 6, 12, 24, 36, 48, and 60 months postoperatively were 0.421, 0.455, 0.401, 0.451, 0.482, 0.502, and 0.508, respectively. The overall incidences of complication were 0.274 for hoarseness/voice change, 0.099 for throat pain, 0.133 for coughing, 0.099 for dyspnea, 0.102 for paresthesia, 0.062 for muscle pain, 0.101 for headache, 0.015 for dysphagia, 0.013 for neck pain, 0.040 for infection, 0.030 for lead fracture, 0.019 for vocal cord palsy, and 0.020 for device malfunction, respectively.

CONCLUSIONS

The estimating of efficacy and tolerability, using data from the existing literature, indicated VNS therapy is a safe and effective treatment option for patients with DRE.

Vagus Nerve Stimulation and Seizure Outcomes in Pediatric Refractory Epilepsy: Systematic Review and Meta-analysis

OBJECTIVE

We synthesized evidence for effectiveness of vagus nerve stimulation (VNS) as adjuvant therapy in pediatric drug-resistant epilepsy (DRE) by obtaining pooled estimates for seizure outcomes and analyzing their determinants.

METHODS

MEDLINE, EMBASE, and Cochrane databases were searched up to July 2019 for original research on VNS in pediatric (≤18 years of age) epilepsy. The primary outcome was 50% responder rate (50% RR), the proportion of patients with ≥50% seizure reduction, at the last reported follow-up. Other outcomes included a 50% RR and proportion of seizure-free patients at additional reported time points. A random-effects meta-analysis with restricted maximum likelihood estimation was performed to obtain pooled effect estimates. Meta-regression using multiple linear models was performed to obtain determinants of seizure outcomes and sources of heterogeneity.

RESULTS

A total of 101 studies were included. The pooled prevalence estimates for a 50% RR and seizure freedom at last follow-up (mean 2.54 years) were 56.4% (95% confidence intervals [CIs] 52.4, 60.4) and 11.6% (95% CI 9.6, 13.9), respectively. Fewer antiseizure medications (ASMs) tried before VNS and later age at onset of seizures were associated with better seizure outcomes following VNS implantation. An effect of sex distribution of studies on long-term outcomes and a potential publication bias for short-term outcomes were also observed.

CONCLUSION

Pooled evidence supports possible effectiveness of VNS in pediatric DRE, although complete seizure freedom is less common. Early referral (fewer trials of ASMs) may be a modifiable factor for desirable seizure outcomes with VNS from a clinical perspective.

Preliminary analysis of the effect of vagus nerve stimulation in the treatment of children with intractable epilepsy

BACKGROUND

Implant vagus nerve stimulation is an adjunctive treatment for intractable epilepsy when patients are not suitable for resective surgery.

AIM

To identify the safety and efficacy of vagus nerve stimulation in children with intractable epilepsy and analyze the effects on different epilepsy syndromes.

METHODS

Eligible children with intractable epilepsy were admitted to the study. We collected data from preoperative assessments as the baseline. During the follow-up time, we recorded the process of seizures (frequency, duration, and seizure type), the changes of drugs or parameters, the complications, etc. The mean reduction rate of seizures, response rate, and McHugh scale were chosen as the outcomes.

RESULTS

A total of 213 patients were implanted with Tsinghua Pins vagus nerve stimulators, and the average age was 6.6 years. In the follow-up time of postoperative 3 mo, 6 mo, 12 mo, 18 mo, and 24 mo, the average reduction rate was 30.2%, 49.5%, 56.3%, 59.4%, and 63.2%, while the response rate was 21.8%, 62.5%, 57.1%, 69.2%, and 70.7%. In addition, implanted vagus nerve stimulation had different effects on epilepsy syndromes. The reduction rate of West syndrome increased from 36.4% (postoperative 6 m) to 74.3% (postoperative 24 m). The reduction rate of Lennox-Gastaut syndrome improved from 25.4% to 73.1% in 24 mo. The chi-square test of the five efficacy grades showed P < 0.05. The comparison between the 3-mo follow-up and the 6-mo follow-up showed P < 0.05, and the comparison between the 6-mo follow-up and the 24-mo follow-up showed P > 0.05.

CONCLUSION

Vagus nerve stimulation is safe and effective in children with intractable epilepsy, and the seizure reduction occurred in a time-dependent manner. Moreover, patients with West syndrome may get the most benefits.

Learnings from 30 years of reported efficacy and safety of vagus nerve stimulation (VNS) for epilepsy treatment: A critical review

Three decades after its introduction as an adjuvant therapeutic option in the management of selective drug-resistant epilepsy cases (DRE), vagus nerve stimulation (VNS) retains growing interest. An implantable device was first approved for epilepsy in Europe in 1994 and in the United States (US) in 1997. Subsequent modifications improved the safety and the efficacy of the system. The most recent application of vagal neurostimulation is represented by transcutaneous devices that are claimed to have strong therapeutic potential. In this review, we sought to analyze the most meaningful available data describing the indications, safety and efficacy of the different approaches of VNS in clinical practice. Therefore, we identified studies reporting VNS efficacy and/or safety in epilepsy and its comorbidities from January 1990 to February 2020 from various databases including PubMed, Scopus, Cochrane, US government databases and VNS manufacturer published resources. In general, VNS efficacy becomes optimal around the sixth month of treatment and a 50-100 % seizure frequency reduction is achieved in approximately 45-65 % of the patients. However, some clinically relevant differences have been reported with specific factors such as epilepsy etiology or type, patient age as well as the delay of VNS therapy onset. VNS efficacy on seizure frequency has been demonstrated in both children and adults, in lesional and non-lesional cases, in focal and generalized epilepsies, on both seizures and epilepsy comorbidities. Regarding the latter, VNS can lead to an improvement of about 25-35 % in depression scores, 35 % in anxiety scores and 25 % in mood assessment scores. If non-invasive devices are undeniably safer, their efficacy is limited due to the scarcity of large cohort studies and the disparity of methodological approaches (study design and stimulation parameters). Overall, we believe that there is a progress margin for improving the safety of implantable devices and, above all, the effectiveness of the various VNS approaches.

The Effect of Cranial Nerve Stimulation on Swallowing: A Systematic Review

This systematic review summarizes published studies on the effect of cranial nerve stimulation (CNS) on swallowing and determines the level of evidence of the included studies to guide the development of future research on new treatment strategies for oropharyngeal dysphagia (OD) using CNS. Studies published between January 1990 and October 2019 were found via a systematic comprehensive electronic database search using PubMed, Embase, and the Cochrane Library. Two independent reviewers screened all articles based on the title and abstract using strict inclusion criteria. They independently screened the full text of this initial set of articles. The level of evidence of the included studies was assessed independently by the two reviewers using the A-B-C rating scale. In total, 3267 articles were found in the databases. In the majority of these studies, CNS was used for treatment-resistant depression or intractable epilepsy. Finally, twenty-eight studies were included; seven studies on treatment of depression, thirteen on epilepsy, and eight on heterogeneous indications. Of these, eight studies reported the effects of CNS on swallowing and in 20 studies the swallowing outcome was described as an adverse reaction. A meta-analysis could not be carried out due to the poor methodological quality and heterogeneity of study designs of the included studies. These preliminary data suggest that specific well-indicated CNS might be effective in reducing OD symptoms in selective patient groups. But it is much too early for conclusive statements on this topic. In conclusion, the results of these studies are encouraging for future research on CNS for OD. However, randomized, double-blind, sham-controlled clinical trials with sufficiently large sample sizes are necessary.

Research progress of vagus nerve stimulation in the treatment of epilepsy

The International League Against Epilepsy (ILAE) defined drug-resistant epilepsy (DRE) that epilepsy seizure symptoms cannot be controlled with two well-tolerated and appropriately chosen antiepileptic drugs, whether they are given as monotherapy or in combination. According to the WHO reports, there is about 30%-40% of epilepsy patients belong to DRE. These patients need some treatments other than drugs, such as epilepsy surgery, and neuromodulation treatment. Traditional surgical approaches may be limited by the patient's clinical status, pathological tissue location, or overall prognosis. Thus, neuromodulation is an alternative choice to control their symptoms. Vagus nerve stimulation (VNS) is one of the neuromodulation methods clinically, which have been approved by the Food and Drug Administration (FDA). In this review, we systematically describe the clinical application, clinical effects, possible antiepileptic mechanisms, and future research directions of VNS for epilepsy.

Clinical outcomes of closed-loop vagal nerve stimulation in patients with refractory epilepsy

PURPOSE

The AspireSR® is a vagal nerve stimulation (VNS) device that operates as a closed-loop system, delivering an automatic stimulation in response to an ictal heart rate increase that serves as a predictor for an imminent seizure. Our purpose is to assess the outcome of the AspireSR® in a patient population managed in a pediatric neurology unit.

METHODS

The records of patients who underwent transplantation during 2015-2017 and are continuously followed in one pediatric-epilepsy clinic, were retrospectively analyzed. Collected information included demographics, use of antiepileptic drugs and seizure type, frequency and duration before and after VNS implantation.

RESULTS

46 patients ages 5-31 years (mean 15.7 ± 5.8), mean age at implantation 14 ± 5.8 years, were included. 29 patients (63%) were new insertions and 17 of the patients (37%) underwent a VNS replacement to the AspireSR® model. Mean follow-up was 13 ± 7.5 months (range 2-29 months). The total cohort responder rate (patients with ≥50% reduction in seizure frequency compared to the pre-implantation period) was 60.9%. (62% in the new insertion group; while 59% in the replacement group had additional benefit over their former VNS model, p = 0.981). Epilepsy etiology, age, age at implantation and type of seizures pre-implantation showed no correlation to response-rate. Five patients (10.9%) experienced complete seizure-freedom following implantation (4/5 in the "new insertion" group). Responses were reported at median follow up of 5 ± 1.3 months post-implantation. 67.4% experienced shorter seizure duration post-implantation.

CONCLUSION

Our results suggest that the AspireSR® device provides an early and meaningful benefit to drug-resistant epilepsy patients, which is relevant for both patients with new insertions and those with replacements of former VNS devices.

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

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.

An interictal EEG can predict the outcome of vagus nerve stimulation therapy for children with intractable epilepsy

PURPOSE

This study aimed to evaluate the long-term efficacy of vagus nerve stimulation (VNS) in children and adolescents with intractable epilepsy and identify predictive factors for responsiveness to VNS.

METHODS

Medical records of pediatric patients who underwent VNS implantation at two Korean tertiary centers were reviewed. At 0.5, 1, 3, and 5 years post-VNS implantation, the frequency of the most disabling seizures in each patient was assessed. Responders were defined as showing an overall 50 % reduction from baseline seizure frequency during follow-up. The clinical characteristics of responders and non-responders were compared.

RESULTS

Among 58 patients, approximately half (29/58) were responders. The mean age at implantation was 10.9 years (range, 2.7-20.9) and the mean follow-up duration after VNS implantation was 8.4 years (range, 1-15.5). At 0.5, 1, 3, and 5 years after implantation, 43.1, 50.0, 56.9, and 58.1 % of patients exhibited ≥50 % seizure frequency reduction disabling seizures. The patients with focal or multifocal epileptiform discharges were more likely to be responders than those with generalized epileptiform activities by video or conventional EEG at the time of VNS implantation (Pearson's and χ ² test, p = 0.001). No other clinical variables were found to be associated with seizure outcomes. Wound infections caused VNS removal in two cases. All other adverse events, including cough and hoarseness, were tolerable.

CONCLUSION

VNS is a well-tolerated and effective adjuvant therapy in pediatric patients with intractable epilepsy. Notably, patients with focal epileptiform discharges alone rather than those with generalized epileptiform discharges maybe better candidates for VNS.

Neuromodulation Therapy with Vagus Nerve Stimulation for Intractable Epilepsy: A 2-Year Efficacy Analysis Study in Patients under 12 Years of Age

To study the efficacy of vagus nerve stimulation (VNS) therapy as an adjunctive treatment for intractable epilepsy in patients under 12 years of age, we analyzed 2-year postimplant data of 35 consecutive patients. Of the 35 patients, 18 (51.4%) at 6 months, 18 (51.4%) at 12 months, and 21 (60.1%) at 24 months showed ≥50% reduction in seizure frequency (responders). Although incremental seizure freedom was noted, no patient remained seizure-free throughout the 3 study periods. Partial response (≥50% seizure reduction in 2 or less study periods) was seen in 8 (22.9%) patients. Twelve patients (34.3%) were nonresponders. Out of 29 patients with primary generalized epilepsy, 20 (68.9%) and, out of 6 patients with focal epilepsy, 3 (50%) had ≥50% seizure control in at least one study period. No major complications or side effects requiring discontinuation of VNS therapy were encountered. We conclude that (1) patients with intractable primary generalized epilepsy respond better to VNS therapy, (2) cumulative effect of neuromodulation with improving responder rate to seizure freedom with continuation of VNS therapy is noted, and (3) VNS therapy is safe and is well tolerated in children receiving implant under 12 years of age.

Automatic Vagus Nerve Stimulation Triggered by Ictal Tachycardia: Clinical Outcomes and Device Performance--The U.S. E-37 Trial

Objectives

The Automatic Stimulation Mode (AutoStim) feature of the Model 106 Vagus Nerve Stimulation (VNS) Therapy System stimulates the left vagus nerve on detecting tachycardia. This study evaluates performance, safety of the AutoStim feature during a 3‐5‐day Epilepsy Monitoring Unit (EMU) stay and long‐ term clinical outcomes of the device stimulating in all modes.

Materials and Methods

The E‐37 protocol (NCT01846741) was a prospective, unblinded, U.S. multisite study of the AspireSR^® in subjects with drug‐resistant partial onset seizures and history of ictal tachycardia. VNS Normal and Magnet Modes stimulation were present at all times except during the EMU stay. Outpatient visits at 3, 6, and 12 months tracked seizure frequency, severity, quality of life, and adverse events.

Results

Twenty implanted subjects (ages 21–69) experienced 89 seizures in the EMU. 28/38 (73.7%) of complex partial and secondarily generalized seizures exhibited ≥20% increase in heart rate change. 31/89 (34.8%) of seizures were treated by Automatic Stimulation on detection; 19/31 (61.3%) seizures ended during the stimulation with a median time from stimulation onset to seizure end of 35 sec. Mean duty cycle at six‐months increased from 11% to 16%. At 12 months, quality of life and seizure severity scores improved, and responder rate was 50%. Common adverse events were dysphonia (n = 7), convulsion (n = 6), and oropharyngeal pain (n = 3).

Conclusions

The Model 106 performed as intended in the study population, was well tolerated and associated with clinical improvement from baseline. The study design did not allow determination of which factors were responsible for improvements.

Implantation of a new Vagus Nerve Stimulation (VNS) Therapy® generator, AspireSR®: considerations and recommendations during implantation and replacement surgery--comparison to a traditional system

INTRODUCTION

The most widely used neuro-stimulation treatment for drug-resistant epilepsy is Vagus Nerve Stimulation (VNS) Therapy®. Ictal tachycardia can be an indicator of a seizure and, if monitored, can be used to trigger an additional on-demand stimulation, which may positively influence seizure severity or duration. A new VNS Therapy generator model, AspireSR®, was introduced and approved for CE Mark in February 2014. In enhancement of former models, the AspireSR has incorporated a cardiac-based seizure-detection (CBSD) algorithm that can detect ictal tachycardia and automatically trigger a defined auto-stimulation. To evaluate differences in preoperative, intraoperative and postoperative handling, we compared the AspireSR to a conventional generator model (Demipulse®).

METHOD

Between February and September 2014, seven patients with drug-resistant epilepsy and ictal tachycardia were implanted with an AspireSR. Between November 2013 and September 2014, seven patients were implanted with a Demipulse and served as control group. Operation time, skin incision length and position, and complications were recorded. Handling of the new device was critically evaluated.

RESULTS

The intraoperative handling was comparable and did not lead to a significant increase in operation time. In our 14 operations, we had no significant short-term complications. Due to its larger size, patients with the AspireSR had significantly larger skin incisions. For optimal heart rate detection, the AspireSR had to be placed significantly more medial in the décolleté area than the Demipulse. The preoperative testing is a unique addition to the implantation procedure of the AspireSR, which may provide minor difficulties, and for which we provide several recommendations and tips. The price of the device is higher than for all other models.

CONCLUSIONS

The new AspireSR generator offers a unique technical improvement over the previous Demipulse. Whether the highly interesting CBSD feature will provide an additional benefit for the patients, and will rectify the additional costs, respectively, cannot be answered in the short-term. The preoperative handling is straightforward, provided that certain recommendations are taken into consideration. The intraoperative handling is equivalent to former models-except for the placement of the generator, which might cause cosmetic issues and has to be discussed with the patient carefully. We recommend the consideration of the AspireSR in patients with documented ictal tachycardia to provide a substantial number of patients for later seizure outcome analysis.

Vagus nerve stimulation magnet activation for seizures: a critical review

Some patients receiving VNS Therapy report benefit from manually activating the generator with a handheld magnet at the time of a seizure. A review of 20 studies comprising 859 subjects identified patients who reported on-demand magnet mode stimulation to be beneficial. Benefit was reported in a weighted average of 45% of patients (range 0-89%) using the magnet, with seizure cessation claimed in a weighted average of 28% (range 15-67%). In addition to seizure termination, patients sometimes reported decreased intensity or duration of seizures or the post-ictal period. One study reported an isolated instance of worsening with magnet stimulation (Arch Pediatr Adolesc Med, 157, 2003 and 560). All of the reviewed studies assessed adjunctive magnet use. No studies were designed to provide Level I evidence of efficacy of magnet-induced stimulation. Retrospective analysis of one pivotal randomized trial of VNS therapy showed significantly more seizures terminated or improved in the active stimulation group vs the control group. Prospective, controlled studies would be required to isolate the effect and benefit of magnet mode stimulation and to document that the magnet-induced stimulation is the proximate cause of seizure reduction. Manual application of the magnet to initiate stimulation is not always practical because many patients are immobilized or unaware of their seizures, asleep or not in reach of the magnet. Algorithms based on changes in heart rate at or near the onset of the seizure provide a methodology for automated responsive stimulation. Because literature indicates additional benefits from on-demand magnet mode stimulation, a potential role exists for automatic activation of stimulation.

Evidence-based guideline update: vagus nerve stimulation for the treatment of epilepsy: report of the guideline development subcommittee of the american academy of neurology

OBJECTIVE

To evaluate the evidence since the 1999 assessment regarding efficacy and safety of vagus nerve stimulation (VNS) for epilepsy, currently approved as adjunctive therapy for partial-onset seizures in patients >12 years.

METHODS

We reviewed the literature and identified relevant published studies. We classified these studies according to the American Academy of Neurology evidence-based methodology.

RESULTS

VNS is associated with a >50% seizure reduction in 55% (95% confidence interval [CI] 50%-59%) of 470 children with partial or generalized epilepsy (13 Class III studies). VNS is associated with a >50% seizure reduction in 55% (95% CI 46%-64%) of 113 patients with Lennox-Gastaut syndrome (LGS) (4 Class III studies). VNS is associated with an increase in ≥50% seizure frequency reduction rates of ~7% from 1 to 5 years postim-plantation (2 Class III studies). VNS is associated with a significant improvement in standard mood scales in 31 adults with epilepsy (2 Class III studies). Infection risk at the VNS implantation site in children is increased relative to that in adults (odds ratio 3.4, 95% CI 1.0-11.2). VNS is possibly effective for seizures (both partial and generalized) in children, for LGS-associated seizures, and for mood problems in adults with epilepsy. VNS may have improved efficacy over time.

RECOMMENDATIONS

VNS may be considered for seizures in children, for LGS-associated seizures, and for improving mood in adults with epilepsy (Level C). VNS may be considered to have improved efficacy over time (Level C). Children should be carefully monitored for site infection after VNS implantation. Neurology® 2013;81:1-7.

Vagal nerve stimulation in children under 12 years old with medically intractable epilepsy

OBJECTIVE

This study aims to assess the efficacy and safety of vagal nerve stimulation (VNS) in children less than 12 years old operated on at the University Hospital Wales.

METHOD

Retrospective review of patients undergoing VNS insertion, over a 3-year period, was undertaken. All children had a minimum follow-up period of 2 years. Sixteen patients were identified via the paediatric epilepsy surgery database. A case note review and telephone evaluation was conducted. Seizure frequency using the McHugh classification was the primary outcome measure, with anti-epileptic drug (AED) use as a secondary outcome measure.

RESULTS

There were 10 males and 6 females. The mean time with epilepsy prior to surgery was 5.7 years and the mean age at the time of surgery was 7.6 years. Overall, nine (56 %) children experienced a reduction in their seizure frequency of 50 % or more. Of these, four (25 %) had a reduction of more than 80 %. Seven children (44 %) had no reduction in their seizure frequency, although two of these patients reported benefit regarding seizure control and post-ictal recovery. The VNS system was removed in two patients due to infection and no benefit, respectively. Half of the cohort (50 %) reduced the number of anti-epileptic drugs post-surgery, and there was an overall mean reduction of AED of 0.5.

CONCLUSION

This study suggests that VNS is a safe and effective adjuvant therapy in children under 12 years old, with over half reporting significant benefit. Further studies are needed to enable preoperative selection of patients in order to maximise the potential benefit.

Evidence-based guideline update: vagus nerve stimulation for the treatment of epilepsy: report of the Guideline Development Subcommittee of the American Academy of Neurology

OBJECTIVE

To evaluate the evidence since the 1999 assessment regarding efficacy and safety of vagus nerve stimulation (VNS) for epilepsy, currently approved as adjunctive therapy for partial-onset seizures in patients >12 years.

METHODS

We reviewed the literature and identified relevant published studies. We classified these studies according to the American Academy of Neurology evidence-based methodology.

RESULTS

VNS is associated with a >50% seizure reduction in 55% (95% confidence interval [CI] 50%-59%) of 470 children with partial or generalized epilepsy (13 Class III studies). VNS is associated with a >50% seizure reduction in 55% (95% CI 46%-64%) of 113 patients with Lennox-Gastaut syndrome (LGS) (4 Class III studies). VNS is associated with an increase in ≥ 50% seizure frequency reduction rates of ≈ 7% from 1 to 5 years postimplantation (2 Class III studies). VNS is associated with a significant improvement in standard mood scales in 31 adults with epilepsy (2 Class III studies). Infection risk at the VNS implantation site in children is increased relative to that in adults (odds ratio 3.4, 95% CI 1.0-11.2). VNS is possibly effective for seizures (both partial and generalized) in children, for LGS-associated seizures, and for mood problems in adults with epilepsy. VNS may have improved efficacy over time.

RECOMMENDATIONS

VNS may be considered for seizures in children, for LGS-associated seizures, and for improving mood in adults with epilepsy (Level C). VNS may be considered to have improved efficacy over time (Level C). Children should be carefully monitored for site infection after VNS implantation.

Long-term results of vagal nerve stimulation for adults with medication-resistant epilepsy who have been on unchanged antiepileptic medication

PURPOSE

Several studies suggest that vagal nerve stimulation (VNS) is an effective treatment for medication-resistant epileptic patients, although patients' medication was usually modified during the assessment period. The purpose of this prospective study was to evaluate the long-term effects of VNS, at 18 months of follow-up, on epileptic patients who have been on unchanged antiepileptic medication.

METHODS

Forty-three patients underwent a complete epilepsy preoperative evaluation protocol, and were selected for VNS implantation. After surgery, patients were evaluated on a monthly basis, increasing stimulation 0.25mA at each visit, up to 2.5mA. Medication was unchanged for at least 18 months since the stimulation was started. The outcome was analysed in relation to patients' clinical features, stimulation parameters, epilepsy type, magnetic resonance imaging (MRI) results, and history of prior brain surgery.

RESULTS

Of the 43 operated patients, 63% had a similar or greater than 50% reduction in their seizure frequency. Differences in the responder rate according to stimulation intensity, age at onset of epilepsy, duration of epilepsy before surgery, previous epilepsy surgery and seizure type, did not reach statistical significance. Most side effects were well tolerated.

CONCLUSIONS

62.8% of our series of 43 medication-resistant epileptic patients experienced a significant long-term seizure reduction after VNS, even in a situation of on unchanged medical therapy. Patient characteristics predictive of VNS responsiveness remain subject to investigation. Controlled studies with larger sample sizes, on VNS for patients with medication-resistant epilepsy on unchanged medication, are necessary to confirm VNS efficacy for drug-resistant epilepsy, and to identify predictive factors.

Nanobionics: the impact of nanotechnology on implantable medical bionic devices

The nexus of any bionic device can be found at the electrode-cellular interface. Overall efficiency is determined by our ability to transfer electronic information across that interface. The nanostructure imparted to electrodes plays a critical role in controlling the cascade of events that determines the composition and structure of that interface. With commonly used conductors: metals, carbon and organic conducting polymers, a number of approaches that promote control over structure in the nanodomain have emerged in recent years with subsequent studies revealing a critical dependency between nanostructure and cellular behaviour. As we continue to develop our understanding of how to create and characterise electromaterials in the nanodomain, this is expected to have a profound effect on the development of next generation bionic devices. In this review, we focus on advances in fabricating nanostructured electrodes that present new opportunities in the field of medical bionics. We also briefly evaluate the interactions of living cells with the nanostructured electromaterials, in addition to highlighting emerging tools used for nanofabrication and nanocharacterisation of the electrode-cellular interface.