Review of treatment options for refractory epilepsy: new medications and vagal nerve stimulation

Basal Forebrain Impairment: Understanding the Mnemonic Function of the Septal Region Translates in Therapeutic Advances

The basal forebrain is one of the three major brain circuits involved in episodic memory formation together with the hippocampus and the diencephalon. The dysfunction of each of these regions is known to cause anterograde amnesia. While the hippocampal pyramidal neurons are known to encode episodic information and the diencephalic structures are known to provide idiothetic information, the contribution of the basal forebrain to memory formation has been exclusively associated with septo-hippocampal cholinergic signaling. Research data from the last decade broadened our understanding about the role of septal region in memory formation. Animal studies revealed that septal neurons process locomotor, rewarding and attentional stimuli. The integration of these signals results in a systems model for the mnemonic function of the medial septum that could guide new therapeutic strategies for basal forebrain impairment (BFI). BFI includes the disorders characterized with basal forebrain amnesia and neurodegenerative disorders that affect the basal forebrain. Here, we demonstrate how the updated model of septal mnemonic function can lead to innovative translational treatment approaches that include pharmacological, instrumental and behavioral techniques.

Movement Disorders Secondary to Novel Antiseizure Medications in Pediatric Populations: A Systematic Review and Meta-analysis of Risk

Novel antiseizure medications are thought to be safer than their conventional counterparts, though no dedicated analysis of movement disorder risk among pediatric populations using novel antiseizure medications has been completed. We report a systematic review with meta-analysis describing the relationship between novel antiseizure medications and movement disorders in pediatrics.MEDLINE, EMBASE, and the World Health Organization's International Clinical Trials Registry Platform were searched up to October 2020 for randomized controlled trials investigating novel antiseizure medications in pediatric populations. Antiseizure medications included lacosamide, perampanel, eslicarbazepine, rufinamide, fenfluramine, cannabidiol, and brivaracetam. Outcomes were pooled using random effects models; risk difference (RD) and 95% confidence intervals (CIs) were calculated.Twenty-three studies were selected from 1690 nonredundant manuscripts (n = 1912 total). There was a significantly increased risk of movement disorders associated with perampanel (RD 0.07, 95% CI 0.01-0.13; n = 133), though only 1 relevant trial was found. No increased risk of movement disorders was found with other antiseizure medications.Our findings indicate most novel antiseizure medications are safe to use in pediatric populations with respect to movement disorders. However, findings were limited by quality of adverse event reporting.

Hospital costs associated with vagus nerve stimulation and medical treatment in pediatric patients with refractory epilepsy

Objectives

Refractory epilepsy is a diagnosis of recurrent seizures that requires multiple resources for optimal chronic management. The disease negatively impacts the lives of affected patients and families and poses an economic burden to the health care system. This study compares hospital costs between pediatric patients treated with antiseizure medications (ASMs) only and ASMs plus vagus nerve stimulation (VNS).

Methods

Patients 0–17 years of age who were diagnosed with refractory epilepsy between January 1, 2011 and December 31, 2016, were identified from the Children's Hospital Association's Pediatric Health Information System (PHIS) database. Patients treated with ASMs only or ASMs plus VNS were included in the study and were followed 1 year prior and 2 years after meeting pre‐determined criteria for refractory epilepsy. The difference‐in‐difference (DID) approach along with the two‐part model was used to compare the changes in mean hospital costs captured in the PHIS database over time between the two cohorts.

Results

One thousand one hundred thirteen patients treated with ASMs plus VNS and 3471 patients treated with ASMs only were included. At a follow‐up time of 2 years, for the ASMs‐only cohort, the adjusted all‐cause and epilepsy‐related mean annual total costs increased by $14 715 (95% confidence interval [CI]: $12 375–$17 055) and $18 437 (95% CI: $15 978–$20 896), respectively. By comparison, the adjusted all‐cause and epilepsy‐related mean annual total costs of the ASMs plus VNS cohort increased by $12 838 (95% CI: $8171–$17 505) and $15 183 (95% CI: $10 253–$20 113), respectively. Compared to ASMs only, ASMs plus VNS generated a cost savings of $3254 for epilepsy‐related annual costs per year after the index date.

Significance

Compared to ASMs alone, ASMs plus VNS is a treatment modality associated with lower annual hospital costs over time. Our study shows that VNS is a cost‐beneficial treatment for a national cohort of pediatric patients with refractory epilepsy.

Comparison of healthcare resource utilization in pediatric patients with refractory epilepsy: Vagus nerve stimulation and medical treatment cohorts

OBJECTIVES

Refractory epilepsy imposes a substantial burden on affected patients, families, and healthcare system. In terms of treating seizures in children, vagus nerve stimulation (VNS) has been proved to be comparable to that of antiepileptic drugs (AEDs). This study compared healthcare resource utilization between pediatric patients treated with AEDs only and AEDs plus VNS.

METHODS

Pediatric patients diagnosed with refractory epilepsy between the 1st of January 2011 and the 31st of December 2016 were identified from the Pediatric Health Information System Database. Patients treated with AEDs only or AEDs plus VNS were included in the study and were followed up from one year before to two years after the date when defined criteria for refractory epilepsy were met. The difference-in-difference approach along with the hurdle model was used to compare the changes in healthcare resource utilization over time between patients treated with AEDs only and AEDs plus VNS.

RESULTS

The study included 1502 patients treated with AEDs plus VNS and 4541 patients treated with AEDs only. There was a difference in post-index all-cause and epilepsy-related inpatient visits compared to the pre-index period: inpatient hospitalizations were decreased in the AEDs plus VNS cohort, and increased in the AEDs only cohort. There was no significant difference in the pre-index to post-index change for all-cause and epilepsy-related emergency department visits between the two treatment cohorts. For outpatient encounters in the initial post-index period, patients treated with AEDs plus VNS had significantly higher increase in all-cause and epilepsy-related outpatient visits compared to the AEDs only cohort.

CONCLUSIONS

Compared to those treated with AEDs only, pediatric patients with refractory epilepsy treated with AEDs plus VNS have fewer inpatient visits and more outpatient visits within a 2-year follow-up. Given the lower acuity of care in outpatient versus inpatient settings, this study can inform treatment choices for children with refractory epilepsy.

Analysis of pharmacotherapy regimen and costs in patients with drug-resistant epilepsy following vagus nerve stimulation therapy: a single-center study (Poland)

Approximately 30-40% of patients with drug-resistant epilepsy (DRE) who underwent vagus nerve stimulator (VNS) implantation achieve above 50% reduction in seizure frequency. VNS proves effective in reducing frequency of seizures in DRE patients, when combined with antiepileptic drugs (AEDs). This raises a question whether improvement of clinical parameters is achieved with VNS only or relies on combined therapy with AEDs. The aim of the study was the analysis of impact of VNS on clinical recovery of patients with DRE and the analysis of pharmacotherapy costs and drug regimen following VNS implantation in DRE patients. The study included all the patients who had VNS implanted at our department in the years 2014-2018. The patients would be followed up for 2 years after the VNS implantation date. The most commonly used drugs included levetiracetam, lacosamide, valproate, oxcarbazepine, and topiramate. Average cost of AEDs in year 1 following VNS implantation was between EUR 15.53 (CLB) and EUR 545.52 (TGB) and in year 2 between EUR 13.51 (NTZ) and EUR 779.44 (LAC). The greatest number of seizures affected the group of patients treated with three drugs. A statistically significant improvement in seizure frequency was observed in the group of patients treated with two and three drugs. With the rising costs of healthcare, the importance of economic efficiency is becoming increasingly relevant. VNS is a reasonable option for saving money in the healthcare system while ensuring measurable clinical and therapeutic outcomes over the long term.

Decreased electrodermal activity in patients with epilepsy

OBJECTIVE

Biofeedback therapy using electrodermal activity (EDA) is a new noninvasive therapy for intractable epilepsy. However, the characteristics of EDA in patients with epilepsy are little known; therefore, we assessed the EDA characteristics in patients with epilepsy.

METHODS

A cross-sectional observational study was conducted in 22 patients with epilepsy and 24 healthy individuals. We collected information on demographic characteristics, EDA, and state anxiety from both groups, and epilepsy diagnosis, seizure number per month, disease duration, and number of antiepileptic drugs (AED) from the epilepsy group. A wristband device was used to measure resting EDA from both wrists for 10 min under controlled temperature and humidity. We compared the EDA levels between the epilepsy group and the control group and examined correlations between EDA and epilepsy-associated factors in the epilepsy group.

RESULTS

A decreasing trend in EDA was observed during the first 1 min from the start of the measurement in 22 patients with epilepsy (with or without seizures) compared with healthy controls (P = 0.12). However, a significant decrease in EDA was found in 18 patients with epilepsy with seizures compared with healthy controls (-0.48 versus -0.26; P = 0.036). Furthermore, seizure frequency showed a significant inverse correlation with EDA in the epilepsy group (ρ = -0.50, P = 0.016). However, neither disease duration nor the number of drugs prescribed correlated with EDA in the epilepsy group .

SIGNIFICANCE

Marginally decreased EDA was observed in patients with epilepsy, and significantly decreased EDA was found in patients with a higher seizure frequency. The present findings shed light on the appropriateness of EDA-biofeedback therapy in epilepsy.

Economic and clinical evaluation of vagus nerve stimulation therapy

OBJECTIVES

The medical and social care of drug-resistant epilepsy (DRE) entails significant costs. Approximately 30 to 40 percent of patients with DRE who underwent vagus nerve stimulator (VNS) implantation achieve an above 50 percent reduction in seizure frequency. The study objective was to analyze the effect of VNS on clinical effects improvement and therapy cost reduction in patients with DRE over a 2-year follow-up period. The second purpose of the study was to compare average costs of VNS treatment of patients with DRE in selected countries, taking into account the purchasing power parity.

MATERIALS AND METHODS

The study included all the patients who had VNS implanted at our department between 2014 and 2018. Data on clinical events and medical costs were collected prospectively and obtained from medical documentation. We also reviewed relevant literature on costs of VNS therapy in patients with DRE from the last 18 years.

RESULTS

Resource utilization and epilepsy-related events were reduced during the follow-up period compared to the baseline. Average total cost was estimated at EUR 7703.59 in year 1 and at EUR 7108.38 in year 2 following VNS implantation. Average direct costs of VNS treatment of patients with DRE over the last 18 years varied between the countries and ranged from EUR 24 790.43 in the United States to EUR 64.84 in the United Kingdom.

CONCLUSION

Vagus nerve stimulator is a cost-effective therapy yielding measurable clinical and therapeutic outcomes over the long term. Moreover, the analysis contained in this review highlights the poor consensus of methodological approaches.

Galvanic Skin Response (GSR)/Electrodermal/Skin Conductance Biofeedback on Epilepsy: A Systematic Review and Meta-Analysis

Objectives: Dynamic changes in psychophysiological arousal are directly expressed in the sympathetic innervation of the skin. This activity can be measured as tonic and phasic fluctuations in electrodermal activity [Galvanic Skin Response (GSR)/skin conductance]. Biofeedback training can enable an individual to gain voluntary control over this autonomic response and its central correlates. Theoretically, control of psychophysiological arousal may be harnessed as a therapy for epilepsy, to mitigate pre-ictal states. Evidence is accumulating for the clinical efficacy of GSR biofeedback training in the management of drug resistant epilepsy. In this review, we analyse current evidence of efficacy with GSR biofeedback and evaluate the methodology of each study.

Method: We searched published literature pertaining to interventional studies of GSR biofeedback for epilepsy, through MEDLINE and Cochrane databases (1950–2018). Using percentage seizure reduction as an indicator of therapeutic efficacy induced by GSR biofeedback, we used meta-analytic methods to summarize extant findings. We also compare and contrast study design with relevance to the interpretation of outcomes.

Results: Out of 21 articles retrieved for GSR/EDA/Skin conductance biofeedback, four studies were identified as interventional trials, involving 99 patients with drug-resistant epilepsy in total. Three of these studies included a control group and a positive therapeutic effect of biofeedback was reported in each of these. The difference in seizure frequency percentage (Biofeedback—Control) was between −54.4 and −74.0% with an overall weighted mean difference of −64.3% (95% CI: −85.4 to −43.2%). The response rates (proportion of patients manifesting >50% reduction in seizure frequency) varied from 45 to 66% across studies.

Significance: This timely evaluation highlights the potential value of GSR biofeedback therapy, and informs the optimal study design of larger scale studies that are now required to more definitively establish the utility of this non-invasive, non-pharmacological interventional approach for drug-resistant epilepsy.

Epileptic Seizures are Reduced by Autonomic Biofeedback Therapy Through Enhancement of Fronto-limbic Connectivity: A Controlled Trial and Neuroimaging Study

BACKGROUND

Thirty-percent of patients with epilepsy are drug-resistant, and might benefit from effective noninvasive therapeutic interventions. Evidence is accumulating on the efficacy of autonomic biofeedback therapy using galvanic skin response (GSR; an index of sympathetic arousal) in treating epileptic seizures. This study aimed to extend previous controlled clinical trials of autonomic biofeedback therapy with a larger homogeneous sample of patients with temporal lobe epilepsy. In addition, we used neuroimaging to characterize neural mechanisms of change in seizure frequency following the therapy.

METHODS

Forty patients with drug-resistant temporal lobe epilepsy (TLE) (age: 18 to 70years old), on stable doses of anti-epileptic medication, were recruited into a controlled and parallel-group trial from three screening centers in the UK. Patients were allocated to either an active intervention group, who received therapy with GSR biofeedback, or a control group, who received treatment as usual. Allocation to the group was informed, in part, by whether patients could travel to attend repeated therapy sessions (non-randomized). Measurement of outcomes was undertaken by an assessor blinded to the patients' group membership. Resting-state functional and structural MRI data were acquired before and after one month of therapy in the therapy group, and before and after a one-month interval in the control group. The percentage change of seizure frequency was the primary outcome measure. The analysis employed an intention-to-treat principle. The secondary outcome was the change in default mode network (DMN) and limbic network functional connectivity tested for effects of therapy. The trial was registered with the National Institute for Health Research (NIHR) portfolio (ID 15967).

FINDINGS

Data were acquired between May 2014 and October 2016. Twenty participants were assigned to each group. Two patients in the control group dropped out before the second scan, leaving 18 control participants. There was a significant difference in reduction of seizure frequency between the therapy and control groups (p<0.001: Mann Whitney U Test). The seizure frequency in the therapy group was significantly reduced (p<0.001: Wilcoxon Signed Rank Test) following GSR biofeedback, with a mean seizure reduction of 43% (SD=± 32.12, median=-37.26, 95% CI -58.02% to -27.96%). No significant seizure reduction was observed in the control group, with a mean increase in seizure frequency of 31% (SD=±88.27, median=0, 95% CI -12.83% to 74.96%). The effect size of group comparison was 1.14 (95% CI 0.44 to 1.82). 45% of patients in the therapy group showed a seizure reduction of >50%. Neuroimaging analysis revealed that post-therapy seizure reduction was linearly correlated with enhanced functional connectivity between right amygdala and both the orbitofrontal cortex (OFC) and frontal pole (FP).

INTERPRETATION

Our clinical study provides evidence for autonomic biofeedback therapy as an effective and potent behavioral intervention for patients with drug-resistant epilepsy. This approach is non-pharmacological, non-invasive and seemingly side-effect free.

Occipital nerve stimulation for chronic migraine: A randomized trial on subthreshold stimulation

Introduction

Occipital nerve stimulation (ONS) may provide pain relief in migraine patients. In this double-blinded trial we investigated the significance of paresthesia and possible placebo effects.

Methods

Patients already treated with ONS reporting stable treatment effect were included. “Effective stimulation,” “subthreshold stimulation” and “no stimulation” were compared. Patients cycled through all three treatment groups. Outcome was measured using the visual analog scale (VAS) for pain, McGill Pain Questionnaire and SF-36.

Results

Eight patients were included, mean preoperative VAS was 8.20 ± 1.22. A significant improvement in pain was observed in favor of suprathreshold stimulation compared to subthreshold stimulation (1.98 ± 1.56 vs 5.65 ± 2.11). Pain also significantly improved under subthreshold stimulation compared to no stimulation (5.65 ± 2.11 vs 8.45 ± 0.99). No changes in SF-36 were observed.

Conclusions

Paresthesia is not required to achieve pain reduction but suprathreshold stimulation yields better results, underlining the significance of stimulation parameter customization.

Pattern of adverse events of antiepileptic drugs: results of the aESCAPE study in Poland

INTRODUCTION

The Adverse Event Scale in Patients With Epilepsy (aESCAPE) European study (NCT00394927) explored and analyzed adverse events (AEs) and reasons for modifying treatment in patients treated with newer and older antiepileptic drugs (AEDs) used in monotherapy or polytherapy. The present analysis concerns the results of patients recruited in Poland.

MATERIAL AND METHODS

Multicentre, international, observational, cross-sectional study investigating AEs in patients with epilepsy (aged ≥ 4 years), on stable AED treatment with one or two AED(s) for ≥ 3 months, using standardized questionnaires completed by a physician during a single study visit.

RESULTS

Out of 309 patients, 24.6% were treated exclusively with newer AED(s) in monotherapy or in combination, while 75.4% were treated with older AED(s) or a combination of older and newer AED(s). 60.8% were on monotherapy, and 39.9% on polytherapy. In general, 73.8% of patients reported ≥ 1 AE(s). There were no significant differences in the frequency of reported AEs in compared groups. The most common were disturbances in cognitive function (40.5%), psychological problems (36.2%), and sedation (32.7%). Some AEs were found to be more specific for particular types and treatment regimens. Changes in treatment or dose during the study visit occurred in 22.3% of the patients, mainly due to lack of efficacy (10.7%), AEs (5.2%) or absence of seizures (4.5%).

CONCLUSIONS

A detailed structured interview revealed high frequency of AEs in patients treated with AEDs. The main reasons for treatment modifications at the study visit were lack of efficacy, adverse events and absence of seizures.

Neurostimulation-past, present, and beyond

Neurostimulation as a treatment for epilepsy has been around for almost 20 years in the form of vagus nerve stimulation. Newer types of neurostimulation are being developed and stand on the brink of approval for use. The two newest therapies, not yet approved in the United States, are deep brain stimulation and the Responsive Neurostimulator System . In fact, in Europe, approval has already been given for deep brain stimulation and newer forms of vagus nerve stimulation. Efficacy is similar between these therapies, and side effects are moderate, so what will be the future? The challenge will be to learn how to use these therapies correctly and offer the right treatment for the right patient.

Interrater reliability of Engel, International League Against Epilepsy, and McHugh seizure outcome classifications following vagus nerve stimulator implantation

OBJECT

Interrater reliability as measured by the kappa (κ) statistic is a widely used and valuable tool to measure the robustness of a scoring system. Seizure frequency reduction is a central outcome measure following vagus nerve stimulation (VNS). A specific VNS scoring system has been proposed by McHugh, but its interrater reliability has not been tested. The authors assessed its interrater reliability and compared it with that of the Engel and International League Against Epilepsy (ILAE) systems.

METHODS

Using the Engel, ILAE, and McHugh scoring systems, 3 observers independently rated the medical records of children who had undergone vagus nerve stimulator implantation between January 2001 and April 2011 at the Southampton University Hospital. The interrater agreements were then calculated using the κ statistic.

RESULTS

Interrater reliability for the McHugh scale (κ0.693) was very good and was superior to those of the Engel (κ0.464) and ILAE (κ0.491) systems for assessing outcome in patients undergoing VNS.

CONCLUSIONS

The authors recommend considering the McHugh scoring system when assessing outcomes following VNS.

Hallucination in a seizure patient using levetiracetam: a case report

Levetiracetam, a relatively new antiepileptic drug (AED), is used mainly as adjuvant and less as monotherapy of seizure. Though rare, Levetiracetam is reported to induce hallucination. To highlight the potential of this adverse drug event, we report a seizure-case that had auditory hallucination with Levetiracetam. A 32-year lady had 7-year history of unresponsive spells which increased in the last year, also occurred while asleep and were diagnosed as “generalized seizure” with video-EEG. With gradual optimization of Levetiracetam to 2250 mg, she continuously heard distressing sound of saw cutting wooden blocks. After 3-day continuous auditory hallucination, Levetiracetam had to be changed to sodium valproate.

Tolerability of antiepileptic drugs: can we determine differences?

Patient tolerability of adverse effects is integral to successful treatment. Although standard antiepileptic drugs (AEDs) are well tolerated by many patients, the promise of newer AEDs has been the potential for diminished burden of problems with similar seizure control. This report reviews the prevalence of systemic and neurological adverse effects reported in clinical trials of AED monotherapy. A central finding in this report was the unidirectional higher prevalence of selected adverse effects from standard compared with newer AEDs. A system of questioning every patient at every visit to elicit information may be helpful when balancing benefit-to-risk ratio of individualized therapy during everyday practice.

Non-interventional surveillance study of adverse events in patients with epilepsy

OBJECTIVES

Compare adverse events (AEs) in patients with epilepsy taking different antiepileptic drugs (AEDs) using standardized physician-completed questionnaires.

MATERIALS AND METHODS

Multicenter, observational, cross-sectional study in epilepsy patients aged ≥4 , stable on 1-2 AED(s) for ≥3 months.

RESULTS

One thousand and nineteen patients were evaluated: 28.7% took newer, 71.3% older (or older + newer) AED(s); 56.9% monotherapy; 43.1% polytherapy. Overall, 68.3% reported ≥1 AE (61.3% newer; 71.1% older AEDs), most commonly: cognitive function disturbances, sedation, psychological problems. Patients taking newer AEDs were significantly less likely to report ≥1 AE (OR [95% CI]: 0.64 [0.46-0.89], P = 0.008). Treatment/dose changed at study visit: 22.8% (17.5% newer; 24.9% older AEDs) because of (newer/older); lack of efficacy (6.2%/7.8%); AEs (4.1/8.4%); absence of seizures (3.8/4.0%). Patients receiving levetiracetam or lamotrigine were significantly less likely to report AEs/modify treatment.

CONCLUSION

Patients taking newer AEDs were significantly less likely to report AEs, although the non-randomized study design does not allow the lower rate of AEs to be attributed with certainty to the use of newer AEDs. A standardized AE questionnaire appeared useful for monitoring AEs/optimizing AED therapy.

Vagus nerve stimulation: effectiveness and tolerability in patients with epileptic encephalopathies

PURPOSE

We discuss the effectiveness, tolerability, and safety of vagus nerve stimulation (VNS) as adjunctive therapy in 26 patients with refractory epileptic encephalopathies (EEs).

MATERIAL AND METHODS

Twenty-six patients (17 male and 9 female) with electroclinical features compatible with Lennox-Gastaut syndrome (LGS) in 20 patients, Dravet syndrome (DS) in 3 patients, and epilepsy with myoclonic-astatic seizures (EMAS) in 3 patients implanted with the NCP system were analyzed.

RESULTS

In our series of patients with LGS, 17 cases showed a significant improvement in seizure control, with a reduction in seizure frequency of at least 50%. Seven of them previously had epileptic spasms. Three patients with EMAS and two patients with DS showed a significant improvement in seizure control, with a reduction in seizure frequency of at least 50%. A good clinical response was evident early and efficacy progressively improved with the duration of treatment up to 36 months. In patients who had a reduction in seizure frequency of at least 50%, quality of life (QOL) and neuropsychological performance improved. VNS was well-tolerated in all patients.

CONCLUSION

VNS is an effective and well-tolerated treatment for patients with epileptic encephalopathies EEs, improving QOL and neuropsychological performance.

Retigabine: has the orphan found a home?

Randomized, Multicenter, Dose-Ranging Trial of Retigabine for Partial-Onset Seizures. Porter RJ, Partiot A, Sachdeo R, Nohria V, Alves WM; 205 Study Group. Neurology 2007;68(15):1197–1204. OBJECTIVE: To evaluate the efficacy and safety of retigabine 600, 900, and 1,200 mg/day administered three times daily as adjunctive therapy in patients with partial-onset seizures. METHODS: A multicenter, randomized, double-blind, placebo-controlled trial was performed. After an 8-week baseline phase, patients were randomized to a 16-week double-blind treatment period (8-week forced titration and 8-week maintenance) followed by either tapering or entry into an open-label extension study. Primary efficacy was the percentage change from baseline in monthly seizure frequency and compared across treatment arms. Secondary efficacy comparisons included the proportion of patients experiencing 50% reduction in seizure frequency (responder rate), emergence of new seizure types, and physician assessment of global clinical improvement. Safety/tolerability assessments included adverse events (AEs), physical and neurologic examinations, and clinical laboratory evaluations. Efficacy analyses were performed on the intent-to-treat population. RESULTS: Of the 399 randomized patients, 279 (69.9%) completed the double-blind treatment period. The median percent change in monthly total partial seizure frequency from baseline was −23% for 600 mg/day, −29% for 900 mg/day, and −35% for 1,200 mg/day vs −13% for placebo ( p < 0.001 for overall difference across all treatment arms). Responder rates for retigabine were 23% for 600 mg/day, 32% for 900 mg/day ( p = 0.021), and 33% for 1,200 mg/day ( p = 0.016), vs 16% for placebo. The most common treatment-emergent AEs were somnolence, dizziness, confusion, speech disorder, vertigo, tremor, amnesia, abnormal thinking, abnormal gait, paresthesia, and diplopia. CONCLUSION: Adjunctive therapy with retigabine is well tolerated and reduces the frequency of partial-onset seizures in a dose-dependent manner.

Choosing among antiepileptic drugs

Selecting an antiepileptic drug (AED) for treatment of seizures is daunting because there are now 20 from which to choose. Following simple principles allows a systematic approach to drug selection. Efficacy studies provide limited information. For initial monotherapy of partial seizures, high-level evidence exists for the efficacy of lamotrigine, carbamazepine, oxcarbazepine, and topiramate. For initial monotherapy of generalized seizures, high-level evidence is available for valproate, lamotrigine, topiramate, and oxcarbazepine. For initial monotherapy of absence seizures, high-level evidence exists for valproate, lamotrigine, and ethosaximide. All second-generation AEDs have efficacy as adjunctive therapy for partial seizures. AEDs are often useful for comorbid conditions or have properties that should be avoided in some groups. Thus, AEDs should usually be selected on the basis of comorbid conditions, including depression, migraine, chronic pain, obesity, and nephrolithiasis, or patient characteristics, especially for women of childbearing potential and older adults.

Management of epilepsy in drug-resistant patients

Epilepsy affects > 2 million people in the United States, making it one of the most common neurobiological conditions. Typically, epilepsy is treated with one of several available antiepileptic drugs and patients are able to experience freedom from seizures with minimal side effects. However, there are some patients who do not respond to treatment and require the use of multiple drug combinations or surgical intervention. Although there are few studies supporting its use, multi-drug regimens have been known to be helpful for patients, although clinicians should monitor patients for adverse side effects. Vagus nerve stimulation is the only US Food and Drug Administration-approved surgical neurostimulation therapy for epilepsy, and patients' conditions often progress for many years before epilepsy surgery options are considered. Lastly, due to the chronic nature of epilepsy, clinicians should be aware of the presence of comorbid psychiatric conditions as well. This supplement is Part One in the "Case in Point: Evidence-Based Insights for Epilepsy Management" series. In this Expert Review Supplement, Andrew J. Cole, MD, FRCPC, outlines a case of a patient with drug resistant epilepsy, and Brien J. Smith, MD, outlines the best practices for the case patient including discussion on defining drug resistance in patients as well as the benefits and risks of available and emerging drug and surgical treatments.

Long-term vagus nerve stimulation in the treatment of Lennox-Gastaut syndrome

The long-term effects of vagus nerve stimulation (VNS) on seizure frequency were studied in 30 patients with Lennox-Gastaut syndrome. Median observation time was 52 months (17-123). The effect parameters investigated were total number of seizures and different seizure types. The median reduction in number of seizures was 60.6%. The effects of VNS varied considerably between seizure types. Best effects were observed with atonic seizures (80.8% median reduction, number of responders: 8/12), followed closely by tonic seizures (73.3% median reduction, number of responders: 8/13). Least effects were with generalized tonic-clonic seizures (median reduction 57.4%, number of responders: 11/20). Additional positive effects included milder or shorter ictal or postictal phase in 16 patients. Improved alertness was reported in 76.7%. Adverse effects, of which drooling and voice alteration were most frequent, were reported in 20 patients. There was a statistically significant reduction in the median number of antiepileptic drugs used. The discontinuation rate was 16.7%.

Efficacy and tolerability of pregabalin in partial epilepsy

Pregabalin, the most recently approved antiepileptic drug, is a structural analog of GABA with a favorable pharmacokinetic profile. Pregabalin binds to the alpha2-delta subunit of a neuronal voltage-gated calcium channel and is believed to exert its anticonvulsant effect by modulating the release of specific neurotransmitters from hyperexcited presynaptic neurons. Animal models of epilepsy have suggested that this drug will be efficacious against partial-onset and generalized tonic-clonic seizures. Four pivotal, add-on clinical trials conducted in patients with partial-onset seizures demonstrated that pregabalin at daily doses of 150-600 mg is efficacious and associated with dose-dependent adverse events. Meta-analyses of efficacy and tolerability indicated that pregabalin is an efficacious and relatively well-tolerated antiepileptic drug.

Efficacy and Safety of Oral Lacosamide as Adjunctive Therapy in Adults with Partial-Onset Seizures

PURPOSE

To evaluate the efficacy and safety of lacosamide when added to 1 or 2 antiepileptic drugs (AEDs) in adults with uncontrolled partial-onset seizures, and assess plasma concentrations of concomitant AEDs to determine any potential for drug interactions.

METHODS

During this multicenter, double-blind, placebo-controlled trial, patients were randomized to placebo or lacosamide 200, 400, or 600 mg/day after an 8-week baseline period. Lacosamide was titrated in weekly increments of 100 mg/day over 6 weeks and maintained for 12 weeks. Results were analyzed on an intention-to-treat basis.

RESULTS

Four hundred eighteen patients were randomized and received trial medication; 312 completed the trial. The median percent reduction in seizure frequency per 28 days was 10%, 26%, 39%, and 40% in the placebo, lacosamide 200, 400, and 600 mg/day treatment groups, respectively. The median percent reduction in seizure frequency over placebo was significant for lacosamide 400 mg/day (p=0.0023) and 600 mg/day (p=0.0084). The 50% responder rates were 22%, 33%, 41%, and 38% for placebo, lacosamide 200, 400, and 600 mg/day, respectively. The 50% responder rate over placebo was significant for lacosamide 400 mg/day (p=0.0038) and 600 mg/day (p=0.0141). Adverse events that appeared dose-related included dizziness, nausea, fatigue, ataxia, vision abnormal, diplopia, and nystagmus. Lacosamide did not affect mean plasma concentrations of concomitantly administered AEDs.

CONCLUSIONS

In this trial, adjunctive lacosamide significantly reduced seizure frequency in patients with uncontrolled partial-onset seizures. Along with favorable pharmacokinetic and tolerability profiles, these results support further development of lacosamide as an AED.

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.

Guidelines--are they useful?

Antiepileptic drug (AED) guidelines are developed to improve medical decision making, to provide guidance and recommendation for patient management, to develop standards to judge or assess clinical practice, and to keep the cost-benefit ratio at an acceptable level. These guidelines are derived from evidence-based medicine (EBM), a four-tiered grading system that is used to analyze clinical trials and published experiments independent of clinical bias and experience. Although guidelines may not answer all questions it is critical that clinicians using them consider the available evidence, as well as the quality of the evidence, when incorporating the information in their decision making.

Novel anticonvulsant drugs

Principles of complex mechanisms of action of anticonvulsants including latest reports concerning new antiepileptic drugs (AED) are considered. Different aspects of new anticonvulsant drugs (2nd generation) from preclinical and clinical testing, pharmacokinetics, and mono or combination therapy in children and adults are summarized. In the following condensed synopsis pharmacological and clinical characteristics of gabapentin (GBP), lamotrigine (LTG), levetiracetam (LEV), oxcarbazepine (OXC), pregabalin (PGB) and tiagabine (TGB) as well as topiramate (TPM) and zonisamide (ZNS) are discussed. In addition to the mechanisms of action, pharmacokinetics, interactions, indications and dosages as well as side effects are considered. Important data concerning the effect and tolerability of anticonvulsant drugs can be obtained from controlled studies. In comparison to drugs of the first generation (phenobarbital [PB], primidon [PRD], phenytoin [PHT], carbamazepine [CBZ] and valproic acid [VPA]) the potential for interactions and side effects due to enzyme induction or inhibition is reduced by most of the anticonvulsant drugs of the second generation. New anticonvulsant drugs increase the spectrum of treatment and represent further steps with regard to the optimization of an individual therapy of the epilepsies.

Comparison of the efficacy and tolerability of new antiepileptic drugs: what can we learn from long-term studies?

OBJECTIVE

A review of long-term open-label studies was performed with the aim of detecting differences in efficacy and/or tolerability of new antiepileptic drugs (AEDs).

METHODS

From more than 500 open studies conducted to evaluate the efficacy and tolerability of gabapentin (GBP), lamotrigine (LTG), levetiracetam (LEV), oxcarbazepine (OXC), pregabalin (PGB), tiagabine (TGB), topiramate (TPM) or zonisamide (ZNS), we selected all studies that reported or allowed us to calculate the number of patients who achieved seizure freedom for 6 months and/or the number of patients withdrawing for adverse effects and/or the number or percentage of patients continuing treatment after 1 year.

RESULTS

No studies were found in which this information was available for OXC, PGB, TGB or ZNS. The number of patients who achieved seizure freedom for 6 months was reported in four studies each for GBP and TPM, five studies for LTG, and eight studies for LEV. The best efficacy profile using this end point was found for LEV, followed by TPM, LTG, and GBP. Twenty-two studies reported the number of patients withdrawing due to adverse effects. LEV was the best-tolerated AED, a little ahead of LTG, and significantly better than GBP or TPM . TPM was by far the least well-tolerated drug. Information concerning patients continuing treatment after 1 year was reported in two GBP studies, two TPM studies, six LEV studies and five LTG studies. GBP had a very low retention rate (between 20% and 25% of patients continued the drug), while TPM and LTG had a retention rate of 40-60% and LEV had a retention rate of 60-75%.

CONCLUSION

One limitation of these rankings is that their statistical value is limited because of the indirect nature of the comparisons. Anyhow, this review covers the main studies published thus far on this subject and provides full updated information on the current literature about these drugs.

Brain calcifications induce neurological dysfunction that can be reversed by a bone drug

Perivascular calcifications within the brain form in response to a variety of insults. While considered by many to be benign, these calcium phosphate deposits or "brain stones" can become large and are associated with neurological symptoms that range from seizures to parkinsonian symptoms. Here we hypothesize that the high concentrations of calcium in these deposits produce reversible, toxic effects on neurons that can be overcome with "bone" drugs that chelate solid phase calcium phosphates. We present preliminary findings that suggest a direct association between progressive neurological symptoms and brain calcification and the symptomatic improvement of seizures, headaches, and parkinsonian symptoms in patients treated with the bisphosphonate drug disodium etidronate, normally used to treat bone diseases. Future, longitudinal epidemiological studies and randomized trials will be needed to determine the true relationship between brain stones and neurological disorders as well as the utility of bisphosphonates in their prevention and treatment.

Efficacy and safety of levetiracetam (up to 2000 mg/day) in Taiwanese patients with refractory partial seizures: a multicenter, randomized, double-blind, placebo-controlled study

PURPOSE

To assess the efficacy and safety of adjunctive levetiracetam (LEV) therapy in controlling partial-onset seizures refractory to other antiepileptic drugs (AEDs) in a multicenter study in Taiwanese adults.

METHODS

Ninety-four patients aged 16-60 years with refractory partial seizures were randomized to receive LEV (n = 47) or placebo (47) for 14 weeks and composed the intention-to-treat (ITT) population. After the first 2 weeks, LEV patients had their dosage increased from 500 mg twice daily to 1,000 mg twice daily. A 12-week maintenance phase followed, after which patients switched to long-term, open-label LEV therapy or entered a 4-week phase of medication discontinuation.

RESULTS

All patients from the ITT population, except one LEV-treated patient with missing seizure-count data, were included in the primary efficacy analysis. The least square mean of logarithmically transformed weekly partial-seizure frequency was significantly lower in the LEV than in the placebo group (0.813 vs. 1.085; p = 0.001). LEV reduced log-transformed weekly partial-seizure frequency by 23.8% (95% confidence interval, 10.4-35.2%) relative to placebo. Significantly more LEV than placebo patients (43.5% vs. 10.6%) experienced a response of a >or=50% decrease from baseline in weekly frequency of partial seizures [odds ratio, 6.5 (95% CI, 2.2-19.3); p < 0.001]. Adverse events were reported in 34 (72.3%) of 47 LEV-treated patients and 32 (68.1%) of 47 placebo patients. The three most common adverse events in the LEV and placebo groups were somnolence (40.4% and 14.9%), dizziness (14.9% and 8.5%), and headache (10.6% and 8.5%), respectively. Only four patients (three LEV-treated patients and one placebo patient) were withdrawn from the study because of adverse events.

CONCLUSIONS

Adjunctive LEV therapy, <or=1,000 mg twice daily, was significantly more effective than placebo and was generally well tolerated in Taiwanese adults with treatment-resistant partial-onset seizures.

Vagus nerve stimulation use and effect in epilepsy: what have we learned?

Vagus nerve stimulation (VNS) for epilepsy has been available in the United States for 8 years. Pivotal randomized, blinded clinical trials leading to FDA approval in patients age 12 and older with refractory partial seizures have not been performed for other age groups or epilepsy syndromes. This practical review takes stock of the current information about VNS use and efficacy in various types of epilepsy. We review the evidence for commonly used stimulation parameters, end of battery life, predictors of response including duration of epilepsy, seizure type/epilepsy syndrome, bihemispheric seizures, age at implant, and prior cranial surgery. We review adverse events and VNS effects on respiratory patterns, cardiac function, and mood and behavior. With the recent U.S. approval of VNS for treatment-resistant depression, we anticipate that lessons learned from treating patients with epilepsy will be useful to physicians using VNS to treat patients with depression and possibly other conditions.

Management of Focal-Onset Seizures

Focal-onset seizures are manifestations of abnormal epileptic firing of brain cells in a localised area or areas of the brain. The diagnosis of focal-onset seizures initially entails an EEG, a detailed history from the patient and eyewitnesses, as well as computer tomographic or, preferably, magnetic resonance imaging scans. Video EEG to record ictal events may be necessary to establish the correct diagnosis. Focal seizures are classified according to the International Classification of Epileptic Seizures and International Classification of Epilepsies and Epilepsy Syndromes. It is important to try to decide how the seizure event fits into this system in order to successfully evaluate and optimise treatment, as well as to give detailed information to the patient about their seizures and prognosis. Once the decision to treat the seizures has been made, the physician must choose which medication is the most appropriate to begin with. Carbamazepine, phenytoin or valproic acid (sodium valproate) are often rated as first-line drugs, but factors such as adverse-effect profiles, age, possibility of pregnancy, and concomitant diseases and medication also need to be considered. Most of the newer antiepileptic drugs (AEDs) appear to have good efficacy and better tolerability than the older agents, but evidence to support their superiority is scarce and has led to conflicting advice in several guidelines. Among the newer AEDs, lamotrigine, gabapentin, topiramate and oxcarbazepine have obtained monotherapy indication in many countries. The higher costs of the newer AEDs may inhibit their wider use, especially in poorer countries.

Biphasic actions of topiramate on monoamine exocytosis associated with both soluble N-ethylmaleimide-sensitive factor attachment protein receptors and Ca(2+)-induced Ca(2+)-releasing systems

To explore the pharmacological mechanisms of topiramate (TPM), we determined the effects of TPM on monoamine (dopamine and serotonin) exocytosis associated with N-ethylmaleimide-sensitive factor attachment protein receptors and Ca(2+)-induced Ca(2+)-releasing systems, including inositol-triphosphate receptor and ryanodine receptor in freely moving rat pre-frontal cortex using in vivo microdialysis. During resting stage, Ca(2+) output from endoplasmic reticulum Ca(2+) store via inositol-triphosphate receptor regulates syntaxin-associated monoamine exocytosis mechanism, whereas during neuronal hyperexcitable stage, Ca(2+) output via ryanodine receptor regulates synaptobrevin-associated monoamine exocytosis mechanism. Basal monoamine releases were increased and decreased by therapeutically relevant and supratherapeutic concentration of TPM, respectively. The therapeutic-relevant concentration of TPM increased Ca(2+)-evoked release concentration-dependently; however, its stimulatory effect was attenuated in the supratherapeutic range. The K(+)-evoked releases were reduced by TPM concentration-dependently (from therapeutic to supratherapeutic ranges). The therapeutic-relevant concentration of TPM-induced elevation of basal release was reduced by cleavage with syntaxin and inhibition of inositol-triphosphate receptor predominantly, by cleavage with SNAP-25 and synaptobrevin weakly, but not by ryanodine receptor inhibitor. The therapeutic-relevant concentration of TPM-induced elevation of Ca(2+)-evoked release was reduced by cleavage with syntaxin and inositol-triphosphate receptor inhibitor selectively. The therapeutic-relevant concentration of TPM-induced reduction of K(+)-evoked monoamine release was abolished by cleavage with synaptobrevin, but was not affected by cleavage with SNAP-25 or synaptobrevin. The stimulatory effect of ryanodine receptor agonist on K(+)-evoked monoamine release was reduced by TPM, whereas that of inositol-triphosphate receptor agonist was not affected by TPM. Therefore, these results indicate that the combination of the effects of TPM on exocytosis mechanisms associated with SNARE and Ca(2+)-induced Ca(2+)-releasing systems, enhancement of inositol-triphosphate receptor/syntaxin and inhibition of ryanodine receptor/synaptobrevin in pre-frontal cortex, may be involved in clinical actions of TPM.

Effects of zonisamide on neurotransmitter exocytosis associated with ryanodine receptors

To clarify the antiepileptic and neuroprotective actions of zonisamide (ZNS), we determined acute effects of ZNS on exocytosis of GABA and glutamate associated with ryanodine-receptor (Ryr) in rat hippocampus using microdialysis. ZNS increased basal GABA release concentration-dependently without affecting basal glutamate release; however, K(+)-evoked glutamate and GABA releases were reduced by ZNS concentration-dependently. Inhibition of Ryr reduced K(+)-evoked GABA and glutamate releases without affecting their basal releases. Ryanodine affected GABA and glutamate releases biphasic concentration-dependently: lower concentration of ryanodine increased both basal and K(+)-evoked releases of GABA and glutamate, whereas higher concentration reduced them. The therapeutically relevant concentration of ZNS inhibited ryanodine-induced GABA and glutamate releases, and abolished the inflection point in concentration-response curve for ryanodine on neurotransmitter exocytosis. These data suggest that ZNS elevates seizure threshold via enhancement of GABAergic transmission during resting stage. ZNS inhibits propagation of epileptic hyperexcitability and Ryr-associated neuronal damage during neuronal hyperexcitable stage. These demonstrations indicate that the indirect inhibition of Ryr activities by ZNS during neuronal hyperexcitability appear to be involved in the mechanisms of action of antiepileptic and neuroprotective actions of ZNS.

An audit of lamotrigine, levetiracetam and topiramate usage for epilepsy in a district general hospital

The aim of this audit was to ascertain outcomes for people who had taken or who were still taking three "new generation" broad-spectrum antiepileptic drugs (AEDs), namely lamotrigine, levetiracetam and topiramate. Thirteen percent of people became seizure free and approximately, one-third had a reduction of greater than 50% in their seizures. Two-thirds of people were still taking their audit AED. In addition, approximately one-third of people with a learning disability derived substantial benefit, although the rate of seizure freedom was lower. All three AEDs were most successful at treating primary generalised epilepsy and least successful with symptomatic generalised epilepsy. With some reservations the data suggests that levetiracetam and topiramate are the most efficacious AEDs, but topiramate is the least well tolerated. These results mean consideration of a "general prescribing policy" is important when using and choosing these AEDs. We conclude that lamotrigine, levetiracetam and topiramate are useful additions to the armamentarium of AEDs.

Zonisamide: a review of its use in the management of partial seizures in epilepsy

Zonisamide (Zonegran, Excegran) is a new-generation, broad-spectrum antiepileptic drug (AED) currently approved as adjunctive therapy for the treatment of medically refractory partial seizures in adults in the US and as adjunctive therapy or monotherapy in the control of partial and generalised seizures in adults and children in Japan and Korea. Either as adjunctive therapy or monotherapy, zonisamide effectively reduces the frequency of partial seizures, with or without secondary generalisation to tonic-clonic seizures, in adults and children with epilepsy. The drug is generally well tolerated and, additionally, has a favourable pharmacokinetic profile permitting once- or twice-daily administration. Direct head-to-head comparisons with other AEDs would be beneficial in fully defining the place of zonisamide in therapy. In the meantime, adjunctive therapy or monotherapy with zonisamide is a convenient, useful option for the management of partial seizures, including those refractory to other AEDs.