What are the arguments for and against rational therapy for epilepsy?

Innovative drug discovery strategies in epilepsy: integrating next-generation syndrome-specific mouse models to address pharmacoresistance and epileptogenesis

INTRODUCTION

Although there are numerous treatment options already available for epilepsy, over 30% of patients remain resistant to these antiseizure medications (ASMs). Historically, ASM discovery has relied on the demonstration of efficacy through the use of 'traditional' acute in vivo seizure models (e.g. maximal electroshock, subcutaneous pentylenetetrazol, and kindling). However, advances in genetic sequencing technologies and remaining medical needs for people with treatment-resistant epilepsy or special patient populations have encouraged recent efforts to identify novel compounds in syndrome-specific models of epilepsy. Syndrome-specific models, including Scn1a variant models of Dravet syndrome and APP/PS1 mice associated with familial early-onset Alzheimer's disease, have already led to the discovery of two mechanistically novel treatments for developmental and epileptic encephalopathies (DEEs), namely cannabidiol and soticlestat, respectively.

AREAS COVERED

In this review, the authors discuss how it is likely that next-generation drug discovery efforts for epilepsy will more comprehensively integrate syndrome-specific epilepsy models into early drug discovery providing the reader with their expert perspectives.

EXPERT OPINION

The percentage of patients with pharmacoresistant epilepsy has remained unchanged despite over 30 marketed ASMs. Consequently, there is a high unmet need to reinvent and revise discovery strategies to more effectively address the remaining needs of patients with specific epilepsy syndromes, including drug-resistant epilepsy and DEEs.

Lamotrigine add-on therapy for drug-resistant focal epilepsy

BACKGROUND

This is an updated version of a Cochrane Review last updated in 2020. Epilepsy is a common neurological disorder, affecting 0.5% to 1% of the population. In nearly 30% of cases, epilepsy is resistant to currently available drugs. Pharmacological treatment remains the first choice to control epilepsy. Lamotrigine is a second-generation antiseizure medication. When used as an add-on (in combination with other antiseizure medications), lamotrigine can reduce seizures, but with some adverse effects.

OBJECTIVES

To evaluate the benefits and harms of add-on lamotrigine, compared with add-on placebo or no add-on treatment in people with drug-resistant focal epilepsy.

SEARCH METHODS

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

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that investigated add-on lamotrigine versus add-on placebo or no add-on treatment in people of any age with drug-resistant focal epilepsy. We used data from the first period of eligible cross-over trials.

DATA COLLECTION AND ANALYSIS

For this update, two review authors independently selected trials and extracted data. Our primary outcome was 50% or greater reduction in seizure frequency. Our secondary outcomes were treatment withdrawal, adverse effects, cognitive effects, and quality of life. Primary analyses were by intention-to-treat. We performed sensitivity best- and worse-case analyses to account for missing outcome data. We calculated pooled risk ratios (RRs) with 95% confidence intervals (95% Cls) for dichotomous outcomes.

MAIN RESULTS

We identified no new studies for this update, so the results and conclusions of the review are unchanged. We included five parallel-group studies in adults or children, eight cross-over studies in adults or children, and one parallel study with a responder-enriched design in infants. In total, these 14 studies enroled 1806 eligible participants (38 infants, 199 children, 1569 adults). Baseline phases ranged from four to 12 weeks and treatment phases ranged from eight to 36 weeks. We rated 11 studies (1243 participants) at low overall risk of bias and three (697 participants) at unclear overall risk of bias due to lack of information on study design. Four studies (563 participants) reported effective blinding. Lamotrigine compared with placebo probably increases the likelihood of achieving 50% or greater reduction in seizure frequency (RR 1.80, 95% CI 1.45 to 2.23; 12 trials, 1322 participants (adults and children); moderate-certainty evidence). There is probably little or no difference in risk of treatment withdrawal for any reason among people treated with lamotrigine versus people treated with placebo (RR 1.11, 95% CI 0.91 to 1.37; 14 trials; 1806 participants; moderate-certainty evidence). Lamotrigine compared with placebo is probably associated with a greater risk of ataxia (RR 3.34, 99% Cl 2.01 to 5.55; 12 trials; 1525 participants; moderate-certainty evidence), dizziness (RR 1.76, 99% Cl 1.28 to 2.43; 13 trials; 1768 participants; moderate-certainty evidence), nausea (RR 1.81, 99% CI 1.22 to 2.68; 12 studies, 1486 participants; moderate-certainty evidence), and diplopia (RR 3.79, 99% Cl 2.15 to 6.68; 3 trials, 944 participants; moderate-certainty evidence). There is probably little or no difference in the risk of fatigue between lamotrigine and placebo (RR 0.82, 99% CI 0.55 to 1.22; 12 studies, 1552 participants; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

Lamotrigine as an add-on treatment for drug-resistant focal seizures is probably effective for reducing seizure frequency. Certain adverse effects (ataxia, dizziness, diplopia, and nausea) are probably more likely to occur with lamotrigine compared with placebo. There is probably little or no difference in the number of people who withdraw from treatment with lamotrigine versus placebo. The trials were of relatively short duration and provided no long-term evidence. In addition, some trials had few participants. Further trials are needed to assess the long-term effects of lamotrigine and to compare lamotrigine with other add-on drugs.

Cannabidiol reveals a disruptive strategy for 21st century epilepsy drug discovery

Over 30 antiseizure medicines (ASMs) have been uncovered in a diversity of preclinical seizure and epilepsy models, with several critical inflection points in the 20th century fundamentally transforming ASM discovery. This commentary aims to review the historical relevance of cannabidiol's (CBD; Epidiolex) approval for epilepsy in the context of other ASMs brought to market. Further, we highlight how CBD's approval may represent an inflection point for 21st century ASM discovery. CBD is one of the main phytocannabinoids of Cannabis sativa. Unlike its related phytocannabinoid, Δ9-tetrahydrocannabinol, CBD does not exert any euphorigenic, tolerance, or withdrawal effects at anticonvulsant doses. CBD also possess marked anti-inflammatory effects, offering the tantalizing potential of a new pharmacological approach in epilepsy. For decades, hints of the anticonvulsant profile of CBD had been suggested with a small handful of studies in rodent seizure models, yet difficulties in formulation, compounded by the social and regulatory pressures related to medical use of cannabis plant-derived agents constrained any clinical implementation. Nonetheless, CBD possesses a broad antiseizure profile in preclinical seizure and epilepsy models, but the transformative impact of CBD'-s approval came because of studies in a rodent model of the orphan disease Dravet syndrome (DS). DS is a pediatric developmental epileptic encephalopathy with high mortality, frequent spontaneous recurrent seizures, and marked resistance to conventional ASMs, such as phenytoin and carbamazepine. CBD was approved for DS by the US Food and Drug Administration in 2018 after convincing efficacy was established in randomized, placebo-controlled trials in children. Because of the clinical approval of CBD as a novel, cannabis plantderived ASM for DS, CBD has revealed a new strategy in ASM discovery to reignite 21st century therapeutic development for epilepsy. In this commentary, we review the major preclinical and clinical milestones of the late 20th century that made CBD, a compound historically subjected to regulatory restrictions, a key driver of a new discovery strategy for epilepsy in the 21st century.

Single-Target Versus Multi-Target Drugs Versus Combinations of Drugs With Multiple Targets: Preclinical and Clinical Evidence for the Treatment or Prevention of Epilepsy

Rationally designed multi-target drugs (also termed multimodal drugs, network therapeutics, or designed multiple ligands) have emerged as an attractive drug discovery paradigm in the last 10-20 years, as potential therapeutic solutions for diseases of complex etiology and diseases with significant drug-resistance problems. Such agents that modulate multiple targets simultaneously are developed with the aim of enhancing efficacy or improving safety relative to drugs that address only a single target or to combinations of single-target drugs. Although this strategy has been proposed for epilepsy therapy >25 years ago, to my knowledge, only one antiseizure medication (ASM), padsevonil, has been intentionally developed as a single molecular entity that could target two different mechanisms. This novel drug exhibited promising effects in numerous preclinical models of difficult-to-treat seizures. However, in a recent randomized placebo-controlled phase IIb add-on trial in treatment-resistant focal epilepsy patients, padsevonil did not separate from placebo in its primary endpoints. At about the same time, a novel ASM, cenobamate, exhibited efficacy in several randomized controlled trials in such patients that far surpassed the efficacy of any other of the newer ASMs. Yet, cenobamate was discovered purely by phenotype-based screening and its presumed dual mechanism of action was only described recently. In this review, I will survey the efficacy of single-target vs. multi-target drugs vs. combinations of drugs with multiple targets in the treatment and prevention of epilepsy. Most clinically approved ASMs already act at multiple targets, but it will be important to identify and validate new target combinations that are more effective in drug-resistant epilepsy and eventually may prevent the development or progression of epilepsy.

Understanding mechanisms of drug resistance in epilepsy and strategies for overcoming it

INTRODUCTION

The present evidence indicates that approximately 70% of patients with epilepsy can be successfully treated with antiepileptic drugs (AEDs). A significant proportion of patients are not under sufficient control, and pharmacoresistant epilepsy is clearly associated with poor quality of life and increased morbidity and mortality. There is a great need for newer therapeutic options able to reduce the percentage of drug-resistant patients.

AREAS COVERED

A number of hypotheses trying to explain the development of pharmacoresistance have been put forward. These include: target hypothesis (altered AED targets), transporter (overexpression of brain efflux transporters), pharmacokinetic (overexpression of peripheral efflux transporters in the intestine or kidneys), intrinsic severity (initial high seizure frequency), neural network (aberrant networks), and gene variant hypothesis (genetic polymorphisms).

EXPERT OPINION

A continuous search for newer AEDs or among non-AEDs (blockers of efflux transporters, interleukin antagonists, cyclooxygenase inhibitors, mTOR inhibitors, angiotensin II receptor antagonists) may provide efficacious drugs for the management of drug-resistant epilepsy. Also, combinations of AEDs exerting synergy in preclinical and clinical studies (for instance, lamotrigine + valproate, levetiracetam + valproate, topiramate + carbamazepine) might be of importance in this respect. Preclinically antagonistic combinations must be avoided (lamotrigine + carbamazepine, lamotrigine + oxcarbazepine).

Gabapentin add-on treatment for drug-resistant focal epilepsy

BACKGROUND

This is an updated version of the Cochrane Review previously published in 2018. Epilepsy is a common neurological disorder characterised by recurrent seizures. Most people with epilepsy have a good prognosis and their seizures are well controlled by a single antiepileptic drug, but up to 30% develop drug-resistant epilepsy, especially people with focal seizures. In this review, we summarised the evidence from randomised controlled trials (RCTs) of gabapentin, when used as an add-on treatment for drug-resistant focal epilepsy.

OBJECTIVES

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

SEARCH METHODS

For the latest update, we searched the Cochrane Register of Studies (CRS Web) and MEDLINE (Ovid) on 11 August 2020. CRS Web includes randomised or quasi-randomised, controlled trials from PubMed, Embase, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform (ICTRP), the Cochrane Central Register of Controlled Trials (CENTRAL), and the Specialised Registers of Cochrane Review Groups including Epilepsy. We imposed no language restrictions.

SELECTION CRITERIA

Randomised, placebo-controlled, double-blind, add-on trials of gabapentin in people with drug-resistant focal epilepsy. We also included trials using an active drug control group or comparing different doses of gabapentin.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion and extracted the relevant data. We assessed the following outcomes: seizure frequency, seizure freedom, treatment withdrawal (any reason) and adverse effects. Primary analyses were intention-to-treat. We also undertook sensitivity best-case and worst-case analyses. We estimated summary risk ratios (RR) for each outcome and evaluated dose-response in regression models.

MAIN RESULTS

We identified no new studies for this update, therefore, the results and conclusions are unchanged. In the previous update of this review, we combined data from six trials in meta-analyses of 1206 randomised participants. The overall risk ratio (RR) for reduction in seizure frequency of 50% or more compared to placebo was 1.89 (95% confidence interval (CI) 1.40 to 2.55; 6 studies, 1206 participants; moderate-certainty evidence). Dose regression analysis (for trials in adults) showed increasing efficacy with increasing dose, with 25.3% (95% CI 19.3 to 32.3) of people responding to gabapentin 1800 mg compared to 9.7% on placebo, a 15.5% increase in response rate (95% CI 8.5 to 22.5). The RR for treatment withdrawal compared to placebo was 1.05 (95% CI 0.74 to 1.49; 6 trials, 1206 participants; moderate-certainty evidence). Adverse effects were significantly associated with gabapentin compared to placebo. RRs were as follows: ataxia 2.01 (99% CI 0.98 to 4.11; 3 studies, 787 participants; low-certainty evidence), dizziness 2.43 (99% CI 1.44 to 4.12; 6 studies, 1206 participants; moderate-certainty evidence), fatigue 1.95 (99% CI 0.99 to 3.82; 5 studies, 1161 participants; low-certainty evidence) and somnolence 1.93 (99% CI 1.22 to 3.06; 6 studies, 1206 participants; moderate-certainty evidence). There was no evidence of a difference for the adverse effects of headache (RR 0.79, 99% CI 0.46 to 1.35; 6 studies, 1206 participants; moderate-certainty evidence) or nausea (RR 0.95, 99% CI 0.52 to 1.73; 4 trials, 1034 participants; moderate-certainty evidence). Overall, the studies were at low to unclear risk of bias due to information on each risk of bias domain not being available. We judged the overall certainty of the evidence (using the GRADE approach) as low to moderate due to potential attrition bias resulting from missing outcome data and imprecise results with wide CIs.

AUTHORS' CONCLUSIONS

Gabapentin has efficacy as an add-on treatment in people with drug-resistant focal epilepsy, and seems to be fairly well-tolerated. However, the trials reviewed were of relatively short duration and provide no evidence for the long-term efficacy of gabapentin beyond a three-month period. The results cannot be extrapolated to monotherapy or to people with other epilepsy types. Further trials are needed to assess the long-term effects of gabapentin, and to compare gabapentin with other add-on drugs.

Polygonogram with isobolographic synergy for three-drug combinations of phenobarbital with second-generation antiepileptic drugs in the tonic-clonic seizure model in mice

Background

Combination therapy consisting of two or more antiepileptic drugs (AEDs) is usually prescribed for patients with refractory epilepsy. The drug–drug interactions, which may occur among currently available AEDs, are the principal criterion taken by physicians when prescribing the AED combination to the patients. Unfortunately, the number of possible three-drug combinations tremendously increases along with the clinical approval of novel AEDs.

Aim

To isobolographically characterize three-drug interactions of phenobarbital (PB) with lamotrigine (LTG), oxcarbazepine (OXC), pregabalin (PGB) and topiramate (TPM), the maximal electroshock-induced (MES) seizure model was used in male albino Swiss mice.

Materials and method

The MES-induced seizures in mice were generated by alternating current delivered via auricular electrodes. To classify interactions for 6 various three-drug combinations of AEDs (i.e., PB + TPM + PGB, PB + OXC + TPM, PB + LTG + TPM, PB + OXC + PGB, PB + LTG + PGB and PB + LTG + OXC), the type I isobolographic analysis was used. Total brain concentrations of PB were measured by fluorescent polarization immunoassay technique.

Results

The three-drug mixtures of PB + TPM + PGB, PB + OXC + TPM, PB + LTG + TPM, PB + OXC + PGB, PB + LTG + PGB and PB + LTG + OXC protected the male albino Swiss mice from MES-induced seizures. All the observed interactions in this seizure model were supra-additive (synergistic) (p < 0.001), except for the combination of PB + LTG + OXC, which was additive. It was unable to show the impact of the studied second-generation AEDs on total brain content of PB in mice.

Conclusions

The synergistic interactions among PB and LTG, OXC, PGB and TPM in the mouse MES model are worthy of being transferred to clinical trials, especially for the patients with drug resistant epilepsy, who would benefit these treatment options.

Lamotrigine add-on therapy for drug-resistant focal epilepsy

BACKGROUND

This is an updated version of the Cochrane Review previously published in 2016. Epilepsy is a common neurological disorder, affecting 0.5% to 1% of the population. For nearly 30% of these people, their epilepsy is resistant to currently available drugs. Pharmacological treatment remains the first choice to control epilepsy. Lamotrigine is one of the newer antiepileptic drugs. Lamotrigine, in combination with other antiepileptic drugs (add-on), can reduce seizures, but with some adverse effects.

OBJECTIVES

To determine the effects of lamotrigine on (1) seizures, (2) adverse-effect profile, and (3) cognition and quality of life, compared to placebo, when used as an add-on treatment for people with drug-resistant focal epilepsy.

SEARCH METHODS

For the latest update of the review, we searched the following databases on 9 March 2020: Cochrane Register of Studies (CRS Web), MEDLINE (Ovid, 1946 to March 06, 2020). CRS Web includes randomized or quasi-randomized, controlled trials from PubMed, EMBASE, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform (ICTRP), the Cochrane Central Register of Controlled Trials (CENTRAL), and the Specialized Registers of Cochrane Review Groups including Epilepsy. No language restrictions were imposed.

SELECTION CRITERIA

Randomised placebo-controlled trials of people with drug-resistant focal epilepsy of any age, in which an adequate method of concealment of randomisation was used. The studies were double-, single- or unblinded, placebo-controlled. For cross-over studies, the first treatment period was treated as a parallel trial. Eligible participants were adults or children with drug-resistant focal epilepsy.

DATA COLLECTION AND ANALYSIS

For this update, two review authors independently assessed the trials for inclusion, and extracted data. Outcomes included 50% or greater reduction in seizure frequency, treatment withdrawal (any reason), adverse effects, effects on cognition and quality of life. Primary analyses were by intention-to-treat. Sensitivity best- and worse-case analyses were undertaken to account for missing outcome data. Pooled risk ratios (RRs) with 95% confidence intervals (95% Cls) were estimated for the primary outcomes of seizure frequency and treatment withdrawal. For adverse effects, we calculated pooled RRs and 99% Cls.

MAIN RESULTS

We did not identify any new studies for this update, therefore, the results and conclusions are unchanged. In previous updates of this review, the authors found five parallel add-on studies, eight cross-over studies in adults or children with drug-resistant focal epilepsy, and one parallel add-on study with a responder-enriched design in infants. In total, these 14 studies included 1806 eligible participants (38 infants, 199 children, 1569 adults). Baseline phases ranged from four to 12 weeks; treatment phases from eight to 36 weeks. Overall, 11 studies (1243 participants) were rated as having low risk of bias, and three (697 participants) had unclear risk of bias due to lack of reported information around study design. Effective blinding of studies was reported in four studies (563 participants). The overall risk ratio (RR) for 50% or greater reduction in seizure frequency was 1.80 (95% CI 1.45 to 2.23; 12 trials, 1322 participants (adults and children); moderate-certainty evidence) indicating that lamotrigine was significantly more effective than placebo in reducing seizure frequency. The overall RR for treatment withdrawal (for any reason) was 1.11 (95% CI 0.91 to 1.37; 14 trials; 1806 participants; moderate-certainty evidence). The adverse events significantly associated with lamotrigine were: ataxia, dizziness, diplopia (double vision), and nausea. The RR of these adverse effects were as follows: ataxia 3.34 (99% Cl 2.01 to 5.55; 12 trials; 1525 participants; high-certainty evidence); dizziness 2.00 (99% Cl 1.52 to 2.64;13 trials; 1768 participants; moderate-certainty evidence); diplopia 3.79 (99% Cl 2.15 to 6.68; 3 trials, 944 participants; high-certainty evidence); nausea 1.81 (99% Cl 1.22 to 2.68; 12 studies,1486 participants; moderate-certainty evidence). The limited data available precluded any conclusions about effects on cognition and quality of life. No important heterogeneity between studies was found for any of the outcomes. Overall, we assessed the evidence as high to moderate certainty, due to incomplete data for some outcomes.

AUTHORS' CONCLUSIONS

Lamotrigine as an add-on treatment for drug-resistant focal seizures appears to be effective in reducing seizure frequency, and seems to be fairly well-tolerated. However, the trials were of relatively short duration and provided no evidence for the long term. Further trials are needed to assess the long-term effects of lamotrigine, and to compare lamotrigine with other add-on drugs.

Loss of presenilin 2 age-dependently alters susceptibility to acute seizures and kindling acquisition

Patients with Alzheimer's disease (AD) experience seizures at higher rates than the general population of that age, suggesting an underexplored role of hyperexcitability in AD. Genetic variants in presenilin (PSEN) 1 and 2 genes lead to autosomal dominant early-onset AD (ADAD); patients with PSEN gene variants also report seizures. Pharmacological control of seizures in AD may be disease-modifying. Preclinical efficacy of FDA-approved antiseizure drugs (ASDs) is well defined in young adult rodents; however, the efficacy of ASDs in aged rodents with chronic seizures is less clear. The mechanism by which ADAD genes lead to AD remains unclear, and even less studied is the pathogenesis of epilepsy in AD. PSEN variants generally all result in a biochemical loss of function (De Strooper, 2007). We herein determined whether well-established models of acute and chronic seizure could be used to explore the relationship between AD genes and seizures through investigating whether loss of normal PSEN2 function age-dependently influenced susceptibility to seizures and/or corneal kindling acquisition. PSEN2 knockout (KO) and age-matched wild-type (WT) mice were screened from 2- to 10-months-old to establish age-dependent focal seizure threshold. Additionally, PSEN2 KO and WT mice aged 2- and 8-months-old underwent corneal kindling such that mice were aged 3- and 9-months old at the beginning of ASD efficacy testing. We then defined the dose-dependent efficacy of mechanistically distinct ASDs on kindled seizures of young versus aged mice to better understand the applicability of corneal kindling to real-world use for geriatric patients. PSEN2 KO mice demonstrated early-life reductions in seizure threshold. However, kindling acquisition was delayed in 2-month-old PSEN2 KO versus WT mice. Young male WT mice took 24.3 ± 1.3 (S.E.M.) stimulations to achieve kindling criterion, whereas age-matched PSEN2 KO male mice took 41.2 ± 1.1 stimulations (p < .0001). The rate of kindling acquisition of 8-month-old mice was no longer different from WT. This study demonstrates that loss of normal PSEN2 function is associated with age-dependent changes in the in vivo susceptibility to acute seizures and kindling. Loss of normal PSEN2 function may be an underexplored molecular contributor to seizures. The use of validated models of chronic seizures in aged rodents may uncover age-related changes in susceptibility to epileptogenesis and/or ASD efficacy in mice with AD-associated genotypes, which may benefit the management of seizures in AD.

Clinical opinion: Earlier employment of polytherapy in sequential pharmacotherapy of epilepsy

Modern pharmacotherapy for epilepsy consists of orderly, sequential drug trials, in which antiepileptic drugs (AEDs) are chosen under the concept of individual patient-oriented (or - tailored) pharmacotherapy. Although monotherapy has been established as the preferred mode of AEDs therapy in both newly diagnosed and drug resistant epilepsies, there are still lack of evidence to favor either monotherapy or polytherapy in epilepsy, which has generated continuing controversies on the preferred mode of pharmacotherapy. However, each mode of pharmacotherapy may have both advantages and disadvantages, which are different and variable related to individual case scenario. We conducted a brief comparative overview between monotherapy and polytherapy to provide clues for earlier employment of polytherapy in each steps of sequential drug trials. Previous claims about the advantages of monotherapy over polytherapy are not supported but gradually losing its ground by the introduction of a large number of drugs carrying pharmacological advantages for combination therapy. Current evidence stresses the importance of combining drugs having synergistic interactions for better outcome of polytherapy, which has not been considered in previous clinical investigations comparing monotherapy and polytherapy. It is likely that a significant improvement in the outcome of current AEDs therapy is feasible by earlier employment of polytherapy as well as identification of combination drug regimens carrying synergistic interactions. At present, lamotrigine(LTG) and valproate(VPA) combination regimen is the only well documented synergistic regimen, but there are a long-list of candidate regimens requiring future trials in appropriate designs.

Antiepileptic Drug Therapy in Patients with Drug-Resistant Epilepsy

Antiepileptic drug (AED) therapy starts with an accurate diagnosis of epilepsy and is followed by sequential drug trials. Seizure freedom is largely achieved by the first two drug trials; thus, epilepsy that cannot be controlled after appropriately conducted trials of the first two drugs is defined as drug-resistant epilepsy (DRE). It is still unclear which mode of pharmacotherapy, among monotherapy and polytherapy, shows better outcomes in cases of DRE. However, in a recent large hospital cohort study over past two decades, combination therapy was associated with a progressive increase in seizure-free rate than monotherapy in DRE. The benefits of polytherapy in the management of DRE might be related to the recent introduction of many new AEDs with different and novel mechanisms of action and better pharmacokinetic and tolerability profiles. These new AEDs were introduced to the market after they have proven their superiority over placebos in randomized controlled trials (RCTs) on add-on therapy in patients with DRE. Therefore, polytherapy including these new AEDs in the regimen is the approved mode of treatment for cases of DRE; this has prompted physicians to try various combinations of polytherapy to optimize the clinical outcomes. In addition, the significant discrepancies in AED responder rates between RCTs and real-world practice may support the importance of judicious use of new drugs in polytherapy by experienced epileptologists. Most experts now agree to the concept of “rational polytherapy” consisting of mechanistic combinations of AEDs exerting synergistic interactions and to the importance of continuing trials of different rational polytherapy regimens to improve the outcome of the core population of epilepsy patients in the long term.

Gabapentin add-on treatment for drug-resistant focal epilepsy

BACKGROUND

This is an updated version of the Cochrane Review previously published in 2013.Most people with epilepsy have a good prognosis and their seizures are well controlled by a single antiepileptic drug, but up to 30% develop drug-resistant epilepsy, especially those with focal seizures. In this review, we summarised the evidence from randomised controlled trials (RCTs) of gabapentin, when used as an add-on treatment for drug-resistant focal epilepsy.

OBJECTIVES

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

SEARCH METHODS

For the latest update, we searched the Cochrane Register of Studies (CRS Web, 20 March 2018), which includes the Cochrane Epilepsy Group's Specialized Register and the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid, 1946 to 20 March 2018), ClinicalTrials.gov (20 March 2018) and the World Health Organization International Clinical Trials Registry Platform (ICTRP, 20 March 2018). We imposed no language restrictions.

SELECTION CRITERIA

Randomised, placebo-controlled, double-blind, add-on trials of gabapentin in people with drug-resistant focal epilepsy. We also included trials using an active drug control group or comparing different doses of gabapentin.

DATA COLLECTION AND ANALYSIS

For this update, two review authors independently selected trials for inclusion and extracted the relevant data. We assessed the following outcomes: seizure frequency, seizure freedom, treatment withdrawal (any reason) and adverse effects. Primary analyses were intention-to-treat. We also undertook sensitivity best-case and worst-case analyses. We estimated summary risk ratios (RR) for each outcome and evaluated dose-response in regression models.

MAIN RESULTS

We included 12 trials representing 2607 randomised participants. We combined data from six trials in meta-analyses of 1206 randomised participants. The overall RR for reduction in seizure frequency of 50% or more compared to placebo was 1.89 (95% confidence interval (CI) 1.40 to 2.55; 6 trials, 1206 participants; moderate-quality evidence). Dose regression analysis (for trials in adults) showed increasing efficacy with increasing dose, with 25.3% (19.3 to 32.3) of people responding to gabapentin 1800 mg compared to 9.7% on placebo, a 15.5% increase in response rate (8.5 to 22.5). The RR for treatment withdrawal compared to placebo was 1.05 (95% CI 0.74 to 1.49; 6 trials, 1206 participants; moderate-quality evidence). Adverse effects were significantly associated with gabapentin compared to placebo. RRs were as follows: ataxia 2.01 (99% CI 0.98 to 4.11; 3 studies, 787 participants; low-quality evidence), dizziness 2.43 (99% CI 1.44 to 4.12; 6 studies, 1206 participants; moderate-quality evidence), fatigue 1.95 (99% CI 0.99 to 3.82; 5 studies, 1161 participants; low-quality evidence) and somnolence 1.93 (99% CI 1.22 to 3.06; 6 studies, 1206 participants; moderate-quality evidence). There were no significant differences for the adverse effects of headache (RR 0.79, 99% CI 0.46 to 1.35; 6 studies, 1206 participants; moderate-quality evidence) or nausea (RR 0.95, 99% CI 0.52 to 1.73; 4 trials, 1034 participants; moderate-quality evidence). Overall, the studies were rated at low to unclear risk of bias due to information on each risk of bias domain not being available. We judged the overall quality of evidence (using the GRADE approach) as low to moderate due to potential attrition bias resulting from missing outcome data and imprecise results with wide confidence intervals.

AUTHORS' CONCLUSIONS

Gabapentin has efficacy as an add-on treatment in people with drug-resistant focal epilepsy. However, the trials reviewed were of relatively short duration and provide no evidence for the long-term efficacy of gabapentin beyond a three-month period. The results cannot be extrapolated to monotherapy or to people with other epilepsy types.

A viewpoint on rational and irrational fixed-drug combinations

INTRODUCTION

Considering that there are around 30% of patients with epilepsy resistant to monotherapy, the use of synergistic combinations of antiepileptic drugs is of particular importance. This review shows most beneficial as well as irrational combined treatments both from an experimental and clinical point of view. Areas covered: Preferably, experimental data derived from studies evaluating synergy, additivity, or antagonism by relevant methods, in terms of anticonvulsant or neurotoxic effects and pharmacokinetic data have been considered. Although there have been no randomized clinical trials on this issue, the clinical data have been analyzed from studies on considerable numbers of patients. Case-report studies have been not considered. Expert commentary: The experimental data provide a strong support that co-administration of lamotrigine with carbamazepine is negative, considering the anticonvulsant and neurotoxic effects. Clinical reports do not entirely support this conclusion. Other experimentally documented negative combinations comprise lamotrigine+ oxcarbazepine and oxcarbazepine+ phenytoin. From the experimental and clinical point of view, a combination of lamotrigine+ valproate may deserve recommendation. Other most positive experimental and clinical combinations include carbamazepine+valproate, phenytoin+phenobarbital, carbamazepine+gabapentin, carbamazepine+topiramate, levetiracetam+valproate, levetiracetam+carbamazepine. Certainly, experimental data have some limitations (non-epileptic animals, acute administration of antiepileptic drugs) so all experimental recommendations need a careful clinical evaluation.

Oxidative stress in patients with refractory temporal lobe epilepsy and mesial temporal sclerosis: Possible association with major depressive disorder?

OBJECTIVE

The objective was to evaluate the genetic and biochemical profiles associated with oxidative stress (OS) in patients with temporal lobe epilepsy with mesial temporal sclerosis (TLE-MTS) and a healthy control group, and also to verify the possible existence of association between OS markers and psychiatric disorders (PD) in group with TLE-MTS.

METHODS

Forty-six patients with refractory TLE-MTS and 112 healthy controls were included. Psychiatric evaluation occurred through Diagnostical and Statistical Manual of Mental Disorders (DSM-5) criteria. A peripheral blood sample was collected for analysis of glutathione S-transferase (GST) T1/M1 polymorphisms and serum levels of malondialdehyde (MDA) and antioxidant capacity equivalent to the trolox (TEAC), serum markers of OS. Student's t-test, Fisher's exact test, Chi-square test, and Analysis of Variance (ANOVA) were used, with a significance level of P<0.05.

RESULTS

The PD were observed in 27 patients of the group with TLE-MTS (58.6%); major depressive disorder (MDD) was the most frequent. Serum levels of MDA (P<0.0001) and TEAC (P<0.0001) were higher in group with TLE-MTS. When patients with MDD were compared with patients without PD, significant differences were observed between MDA (P=0.002) and TEAC (P=0.003) serum levels. Patients with TLE-MTS and MDD presented higher levels when compared with patients with TLE-MTS without PD and with another PD except MDD.

CONCLUSIONS

The present study observed significantly higher serum levels of MDA and of TEAC in patients with refractory TLE-MTS in comparison with the control group. The MDD was observed as an important issue associated with higher OS levels in refractory TLE-MTS. Further studies are needed to investigate the association of OS, TLE-MTS, and PD.

Combination therapy of levetiracetam and gabapentin against nonconvulsive seizures induced by penetrating traumatic brain injury

BACKGROUND

Posttraumatic seizures are a medical problem affecting patients with traumatic brain injury. Yet effective treatment is lacking owing to the limitations of antiepileptic drugs (AEDs) applicable to these patients.

METHODS

In this study, we evaluated the dose-response efficacy of levetiracetam (12.5-100.0 mg/kg) and gabapentin (1.25-25.0 mg/kg) administered either individually or in pairs at fixed-dose ratios as a combination in mitigating posttraumatic nonconvulsive seizures induced by severe penetrating ballistic-like brain injury (PBBI) in rats. Seizures were detected by continuous electroencephalogram (EEG) monitoring for 72 hours postinjury. Animals were treated twice per day for 3 days by intravenous injections.

RESULTS

Both levetiracetam (25-100 mg/kg) and gabapentin (6.25-25 mg/kg) significantly reduced PBBI-induced seizure frequency by 44% to 73% and 61% to 69%, and seizure duration by 45% to 64% and 70% to 78%, respectively. However, the two drugs manifested different dose-response profiles. Levetiracetam attenuated seizure activity in a dose-dependent fashion, whereas the beneficial effects of gabapentin plateaued across the three highest doses tested. Combined administration of levetiracetam and gabapentin mirrored the more classic dose-response profile of levetiracetam monotherapy. However, no additional benefit was derived from the addition of gabapentin. Furthermore, isobolographic analysis of the combination dose-response profile of levetiracetam and gabapentin failed to reach the expected level of additivity, suggesting an unlikelihood of favorable interactions between these two drugs against spontaneously occurring posttraumatic seizure activities at the particular set of dose ratios tested.

CONCLUSION

This study was the first attempt to apply isobolographic approach to studying AED combination therapy in the context of spontaneously occurring posttraumatic seizures. Despite the failure to achieve additivity from levetiracetam and gabapentin combination, it is important to recognize the objectivity of the isobolographic approach in the evaluation of AED combination therapy against seizures directly associated with brain injuries.

Anti-Epileptic Drug Combination Efficacy in an In Vitro Seizure Model - Phenytoin and Valproate, Lamotrigine and Valproate

In this study, we investigated the relative efficacy of different classes of commonly used anti-epileptic drugs (AEDs) with different mechanisms of action, individually and in combination, to suppress epileptiform discharges in an in vitro model. Extracellular field potential were recorded in 450 μm thick transverse hippocampal slices prepared from juvenile Wistar rats, in which “epileptiform discharges” (ED’s) were produced with a high-K⁺ (8.5 mM) bicarbonate-buffered saline solution. Single and dual recordings in stratum pyramidale of CA1 and CA3 regions were performed with 3–5 MΩ glass microelectrodes. All drugs—lamotrigine (LTG), phenytoin (PHT) and valproate (VPA)—were applied to the slice by superfusion at a rate of 2 ml/min at 32°C. Effects upon frequency of ED’s were assessed for LTG, PHT and VPA applied at different concentrations, in isolation and in combination. We demonstrated that high-K⁺ induced ED frequency was reversibly reduced by LTG, PHT and VPA, at concentrations corresponding to human therapeutic blood plasma concentrations. With a protocol using several applications of drugs to the same slice, PHT and VPA in combination displayed additivity of effect with 50μM PHT and 350μM VPA reducing SLD frequency by 44% and 24% individually (n = 19), and together reducing SLD frequency by 66% (n = 19). 20μM LTG reduced SLD frequency by 32% and 350μM VPA by 16% (n = 18). However, in combination there was a supra-linear suppression of ED’s of 64% (n = 18). In another independent set of experiments, similar results of drug combination responses were also found. In conclusion, a combination of conventional AEDs with different mechanisms of action, PHT and VPA, displayed linear additivity of effect on epileptiform activity. More intriguingly, a combination of LTG and VPA considered particularly efficacious clinically showed a supra-additive suppression of ED’s. This approach may be useful as an in vitro platform for assessing drug combination efficacy.

Fit for purpose application of currently existing animal models in the discovery of novel epilepsy therapies

Animal seizure and epilepsy models continue to play an important role in the early discovery of new therapies for the symptomatic treatment of epilepsy. Since 1937, with the discovery of phenytoin, almost all anti-seizure drugs (ASDs) have been identified by their effects in animal models, and millions of patients world-wide have benefited from the successful translation of animal data into the clinic. However, several unmet clinical needs remain, including resistance to ASDs in about 30% of patients with epilepsy, adverse effects of ASDs that can reduce quality of life, and the lack of treatments that can prevent development of epilepsy in patients at risk following brain injury. The aim of this review is to critically discuss the translational value of currently used animal models of seizures and epilepsy, particularly what animal models can tell us about epilepsy therapies in patients and which limitations exist. Principles of translational medicine will be used for this discussion. An essential requirement for translational medicine to improve success in drug development is the availability of animal models with high predictive validity for a therapeutic drug response. For this requirement, the model, by definition, does not need to be a perfect replication of the clinical condition, but it is important that the validation provided for a given model is fit for purpose. The present review should guide researchers in both academia and industry what can and cannot be expected from animal models in preclinical development of epilepsy therapies, which models are best suited for which purpose, and for which aspects suitable models are as yet not available. Overall further development is needed to improve and validate animal models for the diverse areas in epilepsy research where suitable fit for purpose models are urgently needed in the search for more effective treatments.

Lamotrigine add-on for drug-resistant partial epilepsy

BACKGROUND

This is an updated version of the Cochrane review published in The Cochrane Library 2010, Issue 1.Epilepsy is a common neurological disorder, affecting almost 0.5% to 1% of the population. For nearly 30% of these people, their epilepsy is refractory to currently available drugs. Pharmacological treatment remains the first choice to control epilepsy. Lamotrigine is one of the newer antiepileptic drugs and is the topic of this review. Lamotrigine in combination with other antiepileptic drugs (add-on) can reduce seizures, but with some adverse effects. The aim of this systematic review was to overview the current evidence for the efficacy and tolerability of lamotrigine when used as an adjunctive treatment for people with refractory partial epilepsy.

OBJECTIVES

To determine the effects of lamotrigine on (1) seizures, (2) adverse effect profile, and (3) cognition and quality of life, compared to placebo controls, when used as an add-on treatment for people with refractory partial epilepsy.

SEARCH METHODS

For the previous version of the review, the authors searched the Cochrane Epilepsy Group Specialized Register (January 2010), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library 2010, Issue 1), MEDLINE (1950 to January 2010), and reference lists of articles.For this update, we searched the Cochrane Epilepsy Group Specialized Register (28 May 2015), CENTRAL (The Cochrane Library 2015, Issue 4), MEDLINE (Ovid, 1946 to May 2015), and reference lists of articles. We also contacted the manufacturers of lamotrigine (GlaxoSmithKline). No language restrictions were imposed.

SELECTION CRITERIA

Randomised placebo-controlled trials of people with drug-resistant partial epilepsy of any age, in which an adequate method of concealment of randomisation was used. The studies were double-, single- or unblinded. For cross-over studies, the first treatment period was treated as a parallel trial. Eligible participants were adults or children with drug-resistant partial epilepsy.

DATA COLLECTION AND ANALYSIS

For this update, two review authors independently assessed the trials for inclusion, and extracted data. Outcomes included 50% or greater reduction in seizure frequency, treatment withdrawal (any reason), adverse effects, effects on cognition and quality of life. Primary analyses were by intention-to-treat. Sensitivity best and worse case analyses were undertaken to account for missing outcome data. Pooled Risk Ratios (RR) with 95% confidence intervals (95% Cl) were estimated for the primary outcomes of seizure frequency and treatment withdrawal. For adverse effects, pooled RRs and 99% Cls were calculated.

MAIN RESULTS

We did not identify any new studies for this update, therefore, the results are unchanged.For the previous version of the review, the authors found five parallel add-on studies and eight cross-over studies in adults or children with refractory focal epilepsy, and one parallel add-on study with a responder-enriched design in infants. In total, these 14 studies included 1958 participants (38 infants, 199 children, and 1721 adults). Baseline phases ranged from 4 to 12 weeks; treatment phases from 8 to 36 weeks. Overall, eleven studies (n = 1243 participants) were rated as having a low risk of bias, and three (n = 715 participants) had un unclear risk of bias due to lack of reported information around study design. Effective blinding of studies was reported in three studies (n = 504 participants). The overall risk ratio (RR) for 50% or greater reduction in seizure frequency was 1.80 (95% CI 1.45 to 2.23; 12 RCTs) for twelve studies (n = 1322 participants, adults and children) indicating that lamotrigine was significantly more effective than placebo in reducing seizure frequency. The overall RR for treatment withdrawal (for any reason) was 1.11 (95% CI 0.90 to 1.36; 14 RCTs) for fourteen studies (n = 1958 participants). The adverse events significantly associated with lamotrigine were: ataxia, dizziness, diplopia, and nausea. The RR of these adverse effects were as follows: ataxia 3.34 (99% Cl 2.01 to 5.55; 12 RCTs; n = 1524); dizziness 2.00 (99% Cl 1.51 to 2.64;13 RCTs; n = 1767); diplopia 3.79 (99% Cl 2.15 to 6.68; 3 RCTs; n = 943); nausea 1.81 (99% Cl 1.22 to 2.68; 12 RCTs; n = 1486). The limited data available precluded any conclusions about effects on cognition and quality of life. No important heterogeneity between studies was found for any of the outcomes. Overall, we assessed the evidence as high to moderate quality, due to incomplete data for some outcomes.

AUTHORS' CONCLUSIONS

Lamotrigine as an add-on treatment for partial seizures appears to be effective in reducing seizure frequency, and seems to be fairly well tolerated. However, the trials were of relatively short duration and provided no evidence for the long-term. Further trials are needed to assess the long-term effects of lamotrigine, and to compare it with other add-on drugs.Since we did not find any new studies, our conclusions remain unchanged.

Synergism of perampanel and zonisamide in the rat amygdala kindling model of temporal lobe epilepsy

OBJECTIVE

Anticonvulsive monotherapy fails to be effective in one third of patients with epilepsy resulting in the need for polytherapy regimens. However, with the still limited knowledge, drug choices for polytherapy remain empirical. Here we report experimental data from a chronic epilepsy model for the combination of perampanel and zonisamide, which can render guidance for clinical studies and individual drug choices.

METHODS

The anticonvulsant effects of the combination of perampanel and zonisamide were evaluated in a rat amygdala kindling model. Furthermore, the potential for motor impairment was evaluated. The type of interaction was quantitatively assessed based on isobolographic analysis.

RESULTS

When administered alone, zonisamide dose-dependently increased the afterdischarge threshold in fully kindled rats. Moreover, data confirmed efficacy of perampanel to inhibit seizure initiation and progression with an impact on propagation of activity from the focus. Pronounced threshold increases were observed following administration of a constant zonisamide dosage combined with different doses of perampanel. Isobolographic analysis of drug responses, which is based on individual drug dose-effect data, revealed a synergistic interaction substantiating the high efficacy of the combination. Furthermore, rotarod data indicated that the combination has a favorable tolerability profile when zonisamide is coadministered with low doses of perampanel. Plasma concentration analysis argued against a pharmacokinetic interaction as a basis for the synergism.

SIGNIFICANCE

The findings clearly indicate a pronounced synergistic anticonvulsant effect for the combination of the noncompetitive α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist perampanel with zonisamide, which modulates voltage-sensitive sodium channels and T-type calcium currents. Consequently, polytherapy using these two antiepileptic drugs might be efficacious for clinical management of partial-onset seizures. The findings indicate that the impact of dose ratios on tolerability needs be taken into account. With regard to conclusions about the extent of the synergism and its implications further antiepileptic drug combinations need to be evaluated allowing direct comparison.

The anticonvulsant action of the galanin receptor agonist NAX-5055 involves modulation of both excitatory- and inhibitory neurotransmission

The endogenous neuropeptide galanin is ubiquitously expressed throughout the mammalian brain. Through the galanin receptors GalR1-3, galanin has been demonstrated to modulate both glutamatergic and GABAergic neurotransmission, and this appears to be important in epilepsy and seizure activity. Accordingly, galanin analogues are likely to provide a new approach to seizure management. However, since peptides are generally poor candidates for therapeutic agents due to their poor metabolic stability and low brain bioavailability, a search for alternative strategies for the development of galanin-based anti-convulsant drugs was prompted. Based on this, a rationally designed GalR1 preferring galanin analogue, NAX-5055, was synthesized. This compound demonstrates anti-convulsant actions in several animal models of epilepsy. However, the alterations at the cellular level leading to this anti-convulsant action of NAX-5055 are not known. Here we investigate the action of NAX-5055 at the cellular level by determining its effects on excitatory and inhibitory neurotransmission, i.e. vesicular release of glutamate and GABA, respectively, in cerebellar, neocortical and hippocampal preparations. In addition, its effects on cell viability and neurotransmitter transporter capacity were examined to evaluate potential cell toxicity mediated by NAX-5055. It was found that vesicular release of glutamate was reduced concentration-dependently by NAX-5055 in the range from 0.1 to 1000 nM. Moreover, exposure to 1 μM NAX-5055 led to a reduction in the extracellular level of glutamate and an elevation of the extracellular level of GABA. Altogether these findings may at least partly explain the anti-convulsant effect of NAX-5055 observed in vivo.

Evaluating an etiologically relevant platform for therapy development for temporal lobe epilepsy: effects of carbamazepine and valproic acid on acute seizures and chronic behavioral comorbidities in the Theiler's murine encephalomyelitis virus mouse model

Central nervous system infections can underlie the development of epilepsy, and Theiler's murine encephalomyelitis virus (TMEV) infection in C57BL/6J mice provides a novel model of infection-induced epilepsy. Approximately 50-65% of infected mice develop acute, handling-induced seizures during the infection. Brains display acute neuropathology, and a high number of mice develop spontaneous, recurrent seizures and behavioral comorbidities weeks later. This study characterized the utility of this model for drug testing by assessing whether antiseizure drug treatment during the acute infection period attenuates handling-induced seizures, and whether such treatment modifies associated comorbidities. Male C57BL/6J mice infected with TMEV received twice-daily valproic acid (VPA; 200 mg/kg), carbamazepine (CBZ; 20 mg/kg), or vehicle during the infection (days 0-7). Mice were assessed twice daily during the infection period for handling-induced seizures. Relative to vehicle-treated mice, more CBZ-treated mice presented with acute seizures; VPA conferred no change. In mice displaying seizures, VPA, but not CBZ, reduced seizure burden. Animals were then randomly assigned to acute and long-term follow-up. VPA was associated with significant elevations in acute (day 8) glial fibrillary acidic protein (astrocytes) immunoreactivity, but did not affect NeuN (neurons) immunoreactivity. Additionally, VPA-treated mice showed improved motor performance 15 days postinfection (DPI). At 36 DPI, CBZ-treated mice traveled significantly less distance through the center of an open field, indicative of anxiety-like behavior. CBZ-treated mice also presented with significant astrogliosis 36 DPI. Neither CBZ nor VPA prevented long-term reductions in NeuN immunoreactivity. The TMEV model thus provides an etiologically relevant platform to evaluate potential treatments for acute seizures and disease modification.

Cardiac functions of voltage-gated Ca(2+) channels: role of the pharmacoresistant type (E-/R-Type) in cardiac modulation and putative implication in sudden unexpected death in epilepsy (SUDEP)

Voltage-gated Ca(2+) channels (VGCCs) are ubiquitous in excitable cells. These channels play key roles in many physiological events like cardiac regulation/pacemaker activity due to intracellular Ca(2+) transients. In the myocardium, the Cav1 subfamily (L-type: Cav1.2 and Cav1.3) is the main contributor to excitation-contraction coupling and/or pacemaking, whereas the Cav3 subfamily (T-type: Cav3.1 and Cav3.2) is important in rhythmically firing of the cardiac nodal cells. No established cardiac function has been attributed to the Cav2 family (E-/R-type: Cav2.3) despite accumulating evidence of cardiac dysregulation observed upon deletion of the Cav2.3 gene, the only member of this family so far detected in cardiomyocytes. In this review, we summarize the pathophysiological changes observed after ablation of the E-/R-type VGCC and propose a cardiac mechanism of action for this channel. Also, considering the role played by this channel in epilepsy and its reported sensitivity to antiepileptic drugs, a putative involvement of this channel in the cardiac mechanism of sudden unexpected death in epilepsy is also discussed.