A risk-benefit assessment of therapies for Lennox-Gastaut syndrome

Proposed anti-seizure medication combinations with rufinamide in the treatment of Lennox-Gastaut syndrome: Narrative review and expert opinion

Lennox-Gastaut syndrome (LGS) is a severe, chronic, complex form of early childhood-onset epilepsy characterized by multiple seizure types, generalized slow (≤2.5 Hz) spike-and-wave activity and other electroencephalography abnormalities, and cognitive impairment. A key treatment goal is early seizure control, and several anti-seizure medications (ASMs) are available. Due to the low success rate in achieving seizure control with monotherapy and an absence of efficacy data supporting any particular combination of ASMs for treating LGS, a rational approach to selection of appropriate polytherapy should be applied to maximize benefit to patients. Such "rational polytherapy" involves consideration of factors including safety (including boxed warnings), potential drug-drug interactions, and complementary mechanisms of action. Based on the authors' clinical experience, rufinamide offers a well-considered first adjunctive therapy for LGS, particularly in combination with clobazam and other newer agents for LGS, and may be particularly useful for reducing the frequency of tonic-atonic seizures associated with LGS.

Therapeutic and clinical foundations of cannabidiol therapy for difficult-to-treat seizures in children and adults with refractory epilepsies

Novel and effective antiseizure medications are needed to treat refractory and rare forms of epilepsy. Cannabinoids, which are obtained from the cannabis plant, have a long history of medical use, including for neurologic conditions. In 2018, the US Food and Drug Administration approved the first phytocannabinoid, cannabidiol (CBD, Epidiolex), which is now indicated for severe seizures associated with three rare forms of developmental and epileptic encephalopathy: Dravet syndrome, Lennox-Gastaut syndrome, and tuberous sclerosis complex. Compelling evidence supports the efficacy of CBD in experimental models and patients with epilepsy. In randomized clinical trials, highly-purified CBD has demonstrated efficacy with an acceptable safety profile in children and adults with difficult-to-treat seizures. Although the underlying antiseizure mechanisms of CBD in humans have not yet been elucidated, the identification of novel antiseizure targets of CBD preclinically indicates multimodal mechanisms that include non-cannabinoid pathways. In addition to antiseizure effects, CBD possesses strong anti-inflammatory and neuroprotective activities, which might contribute to protective effects in epilepsy and other conditions. This article provides a succinct overview of therapeutic approaches and clinical foundations of CBD, emphasizing the clinical utility of CBD for the treatment of seizures associated with refractory and rare epilepsies. CBD has shown to be a safe and effective antiseizure medicine, demonstrating a broad spectrum of efficacy across multiple seizure types, including those associated with severe epilepsies with childhood onset. Despite such promise, there are many perils with CBD that hampers its widespread use, including limited understanding of pharmacodynamics, limited exposure-response relationship, limited information for seizure freedom with continued use, complex pharmacokinetics with drug interactions, risk of adverse effects, and lack of expert therapeutic guidelines. These scientific issues need to be resolved by further investigations, which would decide the unique role of CBD in the management of refractory epilepsy.

Transcriptome meta-analysis of valproic acid exposure in human embryonic stem cells

Valproic acid (VPA) is a widely used antiepileptic drug not recommended in pregnancy because it is teratogenic. Many assays have assessed the impact of the VPA exposure on the transcriptome of human embryonic stem-cells (hESC), but the molecular perturbations that VPA exerts in neurodevelopment are not completely understood. This study aimed to perform a transcriptome meta-analysis of VPA-exposed hESC to elucidate the main biological mechanisms altered by VPA effects on the gene expression. Publicly available microarray and RNA-seq transcriptomes were selected in the Gene Expression Omnibus (GEO) repository. Samples were processed according to the standard pipelines for each technology in the Galaxy server and R. Meta-analysis was performed using the Fisher-P method. Overrepresented genes were obtained by evaluating ontologies, pathways, and phenotypes' databases. The meta-analysis performed in seven datasets resulted in 61 perturbed genes, 54 upregulated. Ontology and pathway enrichments suggested neurodevelopment and neuroinflammatory effects; phenotype overrepresentation included epilepsy-related genes, such as SCN1A and GABRB2. The NDNF gene upregulation was also identified; this gene is involved in neuron migration and survival during development. Sub-network analysis proposed TGFβ and BMP pathways activation. These results suggest VPA exerts effects in epilepsy-related genes even in embryonic cells. Neurodevelopmental genes, such as NDNF were upregulated and VPA might also disturb several development pathways. These mechanisms might help to explain the spectrum of VPA-induced congenital anomalies and the molecular effects on neurodevelopment.

Current Pharmacologic Strategies for Treatment of Intractable Epilepsy in Children

Epileptic encephalopathy (EE) is a devastating pediatric disease that features medically resistant seizures, which can contribute to global developmental delays. Despite technological advancements in genetics, the neurobiological mechanisms of EEs are not fully understood, leaving few therapeutic options for affected patients. In this review, we introduce the most common EEs in pediatrics (i.e., Ohtahara syndrome, Dravet syndrome, and Lennox-Gastaut syndrome) and their molecular mechanisms that cause excitation/inhibition imbalances. We then discuss some of the essential molecules that are frequently dysregulated in EEs. Specifically, we explore voltage-gated ion channels, synaptic transmission-related proteins, and ligand-gated ion channels in association with the pathophysiology of Ohtahara syndrome, Dravet syndrome, and Lennox-Gastaut syndrome. Finally, we review currently available antiepileptic drugs used to treat seizures in patients with EEs. Since these patients often fail to achieve seizure relief even with the combination therapy, further extensive research efforts to explore the involved molecular mechanisms will be required to develop new drugs for patients with intractable epilepsy.

Cannabidiol Therapy for Refractory Epilepsy and Seizure Disorders

Cannabis-derived cannabinoids have neuroactive properties. Recently, there has been emerging interest in the use of cannabidiol (CBD)-enriched products for treatment of drug-resistant epilepsy. In 2018, the FDA approved the use of CBD-rich Epidiolex for two severe forms of epilepsy in children (Lennox-Gastaut and Dravet syndromes). Experimental research supports the use of CBD in many CNS disorders, though the mechanisms underlying its anticonvulsant and neuroprotective effects remain unclear. CBD has been shown to reduce inflammation, protect against neuronal loss, normalize neurogenesis, and act as an antioxidant. These actions appear to be due to the multimodal mechanism of action of CBD in the brain. This chapter briefly describes the current information on cannabis pharmacology with an emphasis on the clinical utility of CBD in the treatment of refractory epilepsies and other related seizure conditions. Clinical trials are ongoing for other forms of epilepsy and refractory seizures associated with infantile spasms, tuberous sclerosis, and Rett syndrome. Overall, adjunct CBD has been found to be generally safe and effective for treatment-resistant seizures in children with severe early-onset epilepsy. Whether an add-on CBD is efficacious for the long-term treatment of various epilepsy and seizure types in adults being tested in various clinical trials.

GABAA receptor β3 subunit mutation D120N causes Lennox-Gastaut syndrome in knock-in mice

The Lennox-Gastaut syndrome is a devastating early-onset epileptic encephalopathy, associated with severe behavioural abnormalities. Its pathophysiology, however, is largely unknown. A de novo mutation (c.G358A, p.D120N) in the human GABA type-A receptor β3 subunit gene (GABRB3) has been identified in a patient with Lennox-Gastaut syndrome. To determine whether the mutation causes Lennox-Gastaut syndrome in vivo in mice and to elucidate its mechanistic effects, we generated the heterozygous Gabrb3^+/D120N knock-in mouse and found that it had frequent spontaneous atypical absence seizures, as well as less frequent tonic, myoclonic, atonic and generalized tonic-clonic seizures. Each of these seizure types had a unique and characteristic ictal EEG. In addition, knock-in mice displayed abnormal behaviours seen in patients with Lennox-Gastaut syndrome including impaired learning and memory, hyperactivity, impaired social interactions and increased anxiety. This Gabrb3 mutation did not alter GABA type-A receptor trafficking or expression in knock-in mice. However, cortical neurons in thalamocortical slices from knock-in mice had reduced miniature inhibitory post-synaptic current amplitude and prolonged spontaneous thalamocortical oscillations. Thus, the Gabrb3^+/D120N knock-in mouse recapitulated human Lennox-Gastaut syndrome seizure types and behavioural abnormalities and was caused by impaired inhibitory GABAergic signalling in the thalamocortical loop. In addition, treatment with antiepileptic drugs and cannabinoids ameliorated atypical absence seizures in knock-in mice. This congenic knock-in mouse demonstrates that a single-point mutation in a single gene can cause development of multiple types of seizures and multiple behavioural abnormalities. The knock-in mouse will be useful for further investigation of the mechanisms of Lennox-Gastaut syndrome development and for the development of new antiepileptic drugs and treatments.

Open-label, uncontrolled retrospective study of perampanel in adults with Lennox-Gastaut syndrome

PURPOSE

Perampanel (PER) was added to the anticonvulsant regimen of 71 patients with Lennox-Gastaut Syndrome (LGS) to evaluate its efficacy against seizures and its tolerability.

METHOD

We evaluated at 3-month intervals 62 with pure LGS and 9 with LGS-like epileptic encephalopathy (28 females, 43 males, mean age 40.1 ± 11.5 yrs, median 38, range 20-71) in whom PER was introduced by 2 mg steps at 2- to 4-week intervals up to 6 mg/day, with possible dose reduction or increases after that. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines were followed.

RESULTS

Mean PER exposure was 538.9 days ± 425 (median 429), with 44 patients (62 %) on PER at last follow-up. About 2/3 of patients were responders, including 35.2 % that had a ≥75 % decrease in their seizures. Among these 16.9 % had a ≥90 % decrease. No improvement was seen in 14 patients; 5 had a less than 50 % response, and 6 had seizure aggravation. Therefore, 25 (35.2 %) were considered non-responders. Half of the patients developed at least one side-effect. Significant negative changes in behavior were noted in 1/3 of the cases, including irritability (8.5 %) and aggressivity (7 %). Contrastingly, 4 patients reported positive behavioral and psychological well-being side-effects.

CONCLUSIONS

This retrospective, open-label study provides evidence that PER may significantly help in LGS. PER should be tried in LGS patients who are not satisfactorily controlled. Its use may be limited in some patients due to behavioral side-effects occurring, particularly at doses ≥ 6 mg/d.

Valproic Acid-Induced Coagulopathy

BACKGROUND

Valproic acid is one of the most commonly used antiseizure medications. Multiple hematologic abnormalities have been reported with the use of valproic acid, which may be particularly relevant in the perioperative surgical setting. The incidence of these abnormalities and prevalence of periprocedural hemorrhage vary significantly in the published literature. In this article we analyze the prevalence and possible etiology of coagulopathy and hemorrhage in patients receiving valproic acid.

METHODS

A literature search was completed using "VPA," "coagulopathy," and "surgery." The available published data from case reports to large case series were reviewed.

RESULTS

Thrombocytopenia was noted to be the most common laboratory abnormality associated with valproic acid. An association between valproic acid and acquired von Willebrand disease has also been suggested. There are case reports describing bleeding in the setting of hypofibrinogenemia and factor XIII deficiency. Perioperative hemorrhage was reported in pediatric studies of orthopedic procedures, but not in adult cohorts undergoing neurosurgical interventions.

CONCLUSIONS

VPA use can cause thrombocytopenia and other coagulation abnormalities. Rigorous, prospective trials are needed to better assess the association between valproic acid and clinically significant coagulopathy. Until such data are available, physicians need to be aware of the potential risk of bleeding in patients receiving valproic acid. A hemostatic evaluation should be considered in symptomatic patients, and may be considered for patients taking VPA who are scheduled for surgery. If an abnormality is detected, hematologists should be involved to make recommendation on perioperative hemostatic strategy.

Clobazam as Add-on Therapy in Children with Epileptic Encephalopathy

Rationale:

Clobazam has been used successfully in adults and children with partial epilepsy. The purpose of this study was to evaluate the safety and efficacy of clobazam as add-on therapy in children with epileptic encephalopathy.

Methods:

This was a retrospective study conducted at the pediatric epilepsy clinic of our university hospital. Children less than 18-years of age with epileptic encephalopathy were included in the study. Clobazam was introduced as add-on therapy, starting with 5 mg/Kg/day and increased in minimally effective doses, up to the maximum tolerated dose. Data were obtained from clinical files and follow-up visits.

Results:

Ninety-seven patients were included in the study (39 girls), aged between 1 and 17-years-old (mean = 9.9). Twenty-six patients had Lennox-Gastaut syndrome, seven had myoclonic astatic epilepsy, nine had West syndrome and, in 57 patients, the type of epileptic encephalopathy could not be determined. Clobazam dosage ranged from 5 to 60 mg/day (mean = 37.5 mg/day). Forty (41%) patients presented with adverse events, most of which were mild and transitory, and clobazam needed to be withdrawn in only 11 patients. Nine (9.2%) patients were seizure-free after clobazam adjunctive therapy. In 11 (11.3%) patients seizure improvement was >75%, in 16 (16.5%) it was >50%, in 17 (17.5%) improvement was <50% and in 44 (45.5%) there was no change in seizure frequency. Three patients were lost to follow-up. In 85% of the patients with seizure improvement, the results lasted for more than one year.

Conclusion:

Clobazam is safe and effective in the treatment of epileptic encephalopathies of childhood.

Spectrum of epilepsy - prevalence, impact, and treatment gap: an epidemiological study from Al-Quseir, Egypt

BACKGROUND

Epidemiology continues to be an important research tool in the study of epilepsy and related disorders, providing a better understanding of the frequency, causes, and natural history of the disorder.

OBJECTIVE

To estimate the prevalence of epilepsy in Al-Quseir, Red Sea Governorate, Egypt, and its magnitude of treatment gap.

METHODS

The study was part of a door-to-door study, including every door, to screen all inhabitants in Al-Quseir (33,818 inhabitants) by three specialists of neurology and 15 female social workers (for demographic data collection) using a standardized screening questionnaire. All suspected cases were subjected to detailed history, clinical examination, and electroencephalogram. Neuroimaging studies and estimation of serum drug level were done in select cases if needed.

RESULTS

The study revealed that the lifetime prevalence rate of epilepsy in Al-Quseir is 5.5/1,000, with the highest peak during early childhood, while that of active epilepsy is 3.3/1,000 population. The annual incidence rate is 48/100,000, and the age-specific incidence rate has a U-shaped pattern with two peaks of incidence in early infancy and elderly life. Localization-related epilepsy is the most frequently encountered type (58.8%). The treatment gap of epilepsy in Al-Quseir is 83.8%.

CONCLUSION

The lifetime prevalence of epilepsy in Al-Quseir city, Red Sea Governorate, was 5.5/1000.

Lennox-Gastaut syndrome. Management update

Lennox-Gastaut syndrome (LGS) is a severe pediatric epilepsy syndrome characterized by mixed seizures, cognitive decline, and generalized slow (<3 Hz) spike wave discharges on electroencephalography. Atonic seizures result in dangerous drop attacks with risks of injury and impairment of the quality of life. The seizures are frequently resistant to multiple antiepileptic (AED) drugs. Newer AEDs, such as rufinamide, are now available. When multiple AED trials fail, non-pharmacological treatments such as the ketogenic diet, vagus nerve stimulation, and epilepsy surgery, should be considered. The aim of this review is to present an updated outline of LGS and the available treatments. Although the prognosis for complete seizure control remains poor, the addition of newer therapies provides an improved hope for some of these patients and their families. Further long term randomized controlled trials are required to compare different therapeutic interventions in terms of efficacy and tolerability.

Comprehensive overview: efficacy, tolerability, and cost-effectiveness of clobazam in Lennox-Gastaut syndrome

Clobazam is the newest medication approved by the US Food and Drug Administration (FDA) for the treatment of Lennox–Gastaut syndrome (LGS) in patients at least 2 years of age, although the medication has been available in countries around the world to treat epilepsy and anxiety disorders for many years. Though classified as a benzodiazepine, the drug differs structurally from other drugs in the class as it possesses nitrogen atoms at the 1 and 5 positions within the heterocyclic ring rather than at the 1 and 4 positions. This difference and the classification of clobazam as a partial agonist are believed to be responsible for the decreased incidence of sedative effects compared to other benzodiazepines. Adverse events associated with clobazam use in clinical trials have generally been mild to moderate in nature. Data from an open-label extension trial have confirmed that clobazam is efficacious for the treatment of seizures associated with LGS, particularly atonic seizures (drop seizures), over the long term. Tolerance to the drug’s antiepileptic effects does not seem to be a common occurrence. The drug has proven to be a cost-effective option for therapy, particularly due to its ability to decrease the number of seizures that require medical treatment. Clobazam represents a welcome addition to the treatment options for LGS.

Conceptualizing lennox-gastaut syndrome as a secondary network epilepsy

Lennox–Gastaut Syndrome (LGS) is a category of severe, disabling epilepsy, characterized by frequent, treatment-resistant seizures, and cognitive impairment. Electroencephalography (EEG) shows characteristic generalized epileptic activity that is similar in those with lesional, genetic, or unknown causes, suggesting a common underlying mechanism. The condition typically begins in young children, leaving many severely disabled with recurring seizures throughout their adult life. Scalp EEG of the tonic seizures of LGS is characterized by a diffuse high-voltage slow transient evolving into generalized low-voltage fast activity, likely reflecting sustained fast neuronal firing over a wide cortical area. The typical interictal discharges (runs of slow spike-and-wave and bursts of generalized paroxysmal fast activity) also have a “generalized” electrical field, suggesting widespread cortical involvement. Recent brain mapping studies have begun to reveal which cortical and subcortical regions are active during these “generalized” discharges. In this critical review, we examine findings from neuroimaging studies of LGS and place these in the context of the electrical and clinical features of the syndrome. We suggest that LGS can be conceptualized as “secondary network epilepsy,” where the epileptic activity is expressed through large-scale brain networks, particularly the attention and default-mode networks. Cortical lesions, when present, appear to chronically interact with these networks to produce network instability rather than triggering each individual epileptic discharge. LGS can be considered as “secondary” network epilepsy because the epileptic manifestations of the disorder reflect the networks being driven, rather than the specific initiating process. In this review, we begin with a summation of the clinical manifestations of LGS and what this has revealed about the underlying etiology of the condition. We then undertake a systematic review of the functional neuroimaging literature in LGS, which leads us to conclude that LGS can best be conceptualized as “secondary network epilepsy.”

Combination of corpus callosotomy and vagus nerve stimulation in the treatment of refractory epilepsy

BACKGROUND

Palliative techniques such as partial corpus callosotomy (CC) and vagus nerve stimulation (VNS) may be effective for adequate control of seizures in pharmacoresistant patients who are not candidates for resective surgery.

OBJECTIVE

The objective of this study was to analyze the efficacy of the combination of these two techniques in patients where the first surgery had not achieved adequate control.

MATERIALS AND METHODS

This is a retrospective review of 6 patients with refractory epilepsy in which both types of surgery were performed, CC and VNS. We analyzed variables such as age, sex, age at onset of epilepsy, seizure types, electroencephalogram and magnetic resonance imaging results, and number of pre- and postoperative seizures.

RESULTS

Three patients first underwent VNS and then CC, and 3 patients were treated in reverse order. All patients had some improvement after the first surgery, but they continued to experience persistent falls, so a second palliative technique was used. The mean improvement after both surgeries was 89% (90% in patients first receiving CC and 87% in patients who first underwent VNS).

CONCLUSIONS

In adequately studied patients who are not optimal candidates for resective surgery, palliative surgery is a choice. The combination of VNS and CC shows good results in our series, although the right order to perform both procedures has not been defined. These results should be confirmed in a larger group of patients.

lennox-Gastaut syndrome: an updateon treatment

Lennox-Gastaut syndrome (LGS) is a severe epileptic encephalopathy. Few current treatment options are effective in improving seizure control. This paper reviews the available treatments of LGS and discusses a new option in Canada, rufinamide. It is a wide spectrum anticonvulsant, approved in a number of countries for the treatment of LGS. In a randomized controlled trial in the LGS population, adjunctive rufinamide therapy has been shown to offer significantly greater reduction in total seizure frequency and tonic-atonic seizure frequency in comparison to placebo. Efficacy has been assessed over three years and appears to be sustained. Most adverse events were cognitive (e.g. somnolence) or gastrointestinal in nature and in many cases transient or mild. based on the efficacy and safety data on rufinamide obtained to date, this medication will provide additional benefits to patients with LGS in Canada and is an important consideration for our patients in the adjunctive treatment setting.

Clobazam : in patients with Lennox-Gastaut syndrome

Clobazam, as with other benzodiazepines, has a long history of use in the treatment of epilepsy. More recently, it was approved in the USA as adjunctive therapy for the treatment of seizures associated with Lennox-Gastaut syndrome in patients aged ≥2 years. In the pivotal, placebo-controlled CONTAIN trial in paediatric and adult patients with Lennox-Gastaut syndrome (n = 217 evaluable), adjunctive therapy with clobazam 5-40 mg/day for 12 weeks significantly reduced mean weekly drop seizure rates from baseline compared with adjunctive placebo (primary endpoint), with a significant dosage-dependent improvement in these rates. Results from a dosage-ranging, double-blind, multi-centre, phase II trial add further support for the efficacy of clobazam in paediatric and adult patients with Lennox-Gastaut syndrome (n = 61 evaluable). Improvements in mean weekly drop seizure rates with adjunctive clobazam treatment in these short-term trials was maintained in an ongoing, open-label extension study, with a 91.6 % reduction in mean weekly drop seizure rates from baseline (at randomization in the initial trials) to 24 months in the overall population. Treatment with adjunctive clobazam was generally well tolerated in these clinical trials and after at least 2 years of treatment in an open-label extension study. Most adverse events were mild or moderate and similar to those typically observed with other benzodiazepines.

Vagus nerve stimulation vs. corpus callosotomy in the treatment of Lennox-Gastaut syndrome: a meta-analysis

PURPOSE

Lennox-Gastaut syndrome (LGS) is an epileptogenic disorder that arises in childhood and is typically characterized by multiple seizure types, slow spike-and-wave complexes on EEG and cognitive impairment. If medical treatment fails, patients can proceed to one of two palliative surgeries, vagus nerve stimulation (VNS) or corpus callosotomy (CC). Their relative seizure control rates in LGS have not been well studied. The purpose of this paper is to compare seizure reduction rates between VNS and CC in LGS using meta-analyses of published data.

METHODS

A systematic search of Pubmed, Ovidsp, and Cochrane was performed to find articles that met the following criteria: (1) prospective or retrospective study, (2) at least one patient diagnosed with Lennox-Gastaut syndrome, and (3) well-defined measure of seizure frequency reduction. Seizure reduction rates were divided into seizure subtypes, as well as total seizures, and categorized as 100%, >75%, and >50%. Patient groups were compared using chi-square tests for categorical variables and t-test for continuous measures. Pooled proportions with 95% confidence interval (95% CI) of seizure outcomes were estimated for total seizures and seizure subtypes using random effects methods.

RESULTS

17 VNS and 9 CC studies met the criteria for inclusion. CC had a significantly better outcome than VNS for >50% atonic seizure reduction (80.0% [67.0-90.0%] vs. 54.1% [32.1-75.4%], p<0.05) and for >75% atonic seizure reduction (70.0% [48.05-87.0%] vs. 26.3% [5.8-54.7%], p<0.05). All other seizure types, as well as total number of seizures, showed no statistically significant difference between VNS and CC.

CONCLUSIONS

CC may be more beneficial for LGS patients whose predominant disabling seizure type is atonic. For all other seizure types, VNS offers comparable rates to CC.

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.

Management of seizures in Lennox-Gastaut syndrome

Lennox-Gastaut syndrome is an epilepsy syndrome that begins in childhood (between 1 and 8 years of age), worsens during latency and persists frequently into adulthood, is refractory to antiepileptic medications, and results in cognitive decline and behavioral problems in affected individuals. Seizure types consist primarily of axial tonic, atonic, and atypical absence; nocturnal tonic seizures are the most common seizure pattern in this population, but often are not one of the initial seizure patterns. Some patients also have myoclonic seizures; this seizure pattern is less frequent than the three preceding types. Although there are some cases that are cryptogenic, most are symptomatic, arising during prenatal and perinatal periods from intrauterine infections, and vascular insults to the brain. Examples of causes of Lennox-Gastaut syndrome include migrational abnormalities of the brain, late effects of CNS infections, certain genetic disorders such as tuberous sclerosis, and inherited metabolic disorders. The difficulty early in the course of Lennox-Gastaut syndrome is distinguishing this diagnosis from severe myoclonic epilepsy of infancy (Dravet syndrome) or from myoclonic-astatic epilepsy (Doose syndrome), as the seizure patterns in these three syndromes may overlap at the onset. EEG is a helpful diagnostic tool in the diagnosis of Lennox-Gastaut syndrome, usually demonstrating high voltage, bifrontal 1.5-2.5 Hz spike and wave complexes interictally, and attenuation with paroxysmal fast activity (10-13 Hz) during the ictal phase. Treatment options for Lennox-Gastaut syndrome have been less than optimal. In recent years, several drugs have been tested and approved for the treatment of this syndrome; these include felbamate, lamotrigine, topiramate, and rufinamide. The long-term outcome does not appear to be any better with the newer antiepileptic drugs than when using earlier prescribed antiepileptic drugs or polytherapy. Treatment options other than antiepileptic drugs include a ketogenic diet, vagus nerve stimulation, and corpus callosotomy. Long-term outcome of these patients relative to seizure control and cognition is poor. Most develop moderate intellectual disability within a few years of onset of the syndrome. Many develop behavioral problems with inattention, hyperactivity, and aggression.

Clobazam as an adjunctive therapy in treating seizures associated with Lennox-Gastaut syndrome

Lennox-Gastaut syndrome (LGS) is a devastating childhood epilepsy syndrome characterized by the occurrence of multiple types of seizures and cognitive decline. Most children suffer from frequent seizures that are refractory to current medical management. Recent clinical trials have suggested that addition of clobazam may improve the clinical outcome for some LGS patients. Although clobazam has been available for over five decades, it has only recently been approved by the US Food and Drug Administration for this indication. As a 1,5-benzodiazepine, clobazam is structurally related to the widely used 1,4-benzodiazepines, which include diazepam. Clobazam has been shown to modulate GABAergic neurotransmission by positive allosteric modulation of GABA(A) receptors, and to increase expression of transporters for both GABA and glutamate. The active metabolite n-desmethylclobazam (norclobazam) also modulates GABA(A) receptors, and the relative importance of these two compounds in the clinical effectiveness of clobazam remains an open question. Clinical trials involving clobazam as an addon therapy in a variety of pediatric epilepsy populations have found a significant improvement in seizure control. In patients with LGS, clobazam may have greatest efficacy for drop seizures. Longstanding clinical experience suggests that clobazam is a safe and well tolerated antiepileptic drug with infrequent and mild adverse effects. These results suggest that adjunctive treatment with clobazam may be a reasonable option for LGS patients, particularly those who are treatment-resistant.

Treating Lennox-Gastaut syndrome in epileptic pediatric patients with third-generation rufinamide

Lennox-Gastaut syndrome (LGS) is a rare but debilitating pediatric epileptic encephalopathy characterized by multiple intractable seizure types. Treatment of LGS is challenging because of the small number of antiepileptic drugs (AEDs) which are effective for this syndrome, as well as the need for polytherapy in the majority of patients. This review focuses on the treatment of LGS with rufinamide, a recently approved third-generation AED with reported efficacy as adjunctive therapy for LGS. All relevant papers identified through a PubMed search on the treatment of LGS with rufinamide were reviewed. To date, the literature suggests improvements in seizure frequency for pediatric patients with LGS on rufinamide. Rufinamide appears to be especially effective for atonic or drop attack seizures. Rufinamide also displays a favorable adverse event profile compared with the older anticonvulsants, as well as a minimal number of drug interactions, making it a promising option for the adjunctive treatment of seizures associated with LGS.

Role of clobazam in the treatment of epilepsies

The antiepileptic effect of clobazam was first described in 1973. The main advantages of clobazam as an antiepileptic drug are its fast-onset of action and effect against a wide variety of seizures. Despite sometimes losing its effectiveness after a previous period in which it has been effective, clobazam may keep its antiepileptic effect when used intermittently. Tolerance is much more common with benzodiazepines than the other antiepileptic drugs. Although tolerance to clobazam does occur, sustained responders have been identified, and many patients maintain their controlled seizures for several months. Clobazam is a safe drug, and its efficacy is probably equivalent to that of the new antiepileptic drugs. Therefore, it should be considered as add-on medication in the treatment of epilepsy. Clobazam is rapidly and completely absorbed and can be used intermittently, especially for catamenial epilepsy and in patients with clusters of seizures, but only during periods of seizure exacerbation.

Medical management of Lennox-Gastaut syndrome

Lennox-Gastaut syndrome occurs in 3% of children with epilepsy and is characterized by multiple seizure types, slow spike-and-wave discharges and a poor prognosis for seizure control and cognitive development. Although randomized controlled trials of adjunctive felbamate, lamotrigine, topiramate and rufinamide have demonstrated a > or =50% reduction in seizure frequency, very few children achieve complete seizure control and a Cochrane review of the treatment of Lennox-Gastaut syndrome concluded that the optimum treatment was uncertain and that no drug has been shown to be highly efficacious. Valproate, lamotrigine and topiramate were considered recently by expert panels in the US and Europe to be the first-line drugs. The ketogenic diet may be more effective than antiepileptic drugs and should be considered early in treatment. An improvement in the management of Lennox-Gastaut syndrome requires a better understanding of the pathophysiology of this disorder and the development of animal models in which to test new compounds.

Supporting the recommended paediatric dosing regimen for rufinamide in Lennox-Gastaut syndrome using clinical trial simulation

Rufinamide was approved for the treatment of seizures associated with Lennox-Gastaut syndrome (LGS) as adjunctive therapy in patients aged 4 years and older. Rufinamide pharmacokinetics (PK) has been established on pooled data from several clinical studies in epilepsy, including one in LGS patients. Demographic covariates and drug-drug interactions with several antiepileptic drugs have been explored using population PK modelling. Two types of drug-drug interactions models were developed and compared. The PK analysis demonstrated that the coadministration of valproate decreases rufinamide clearance, requiring potential dose adjustment. To explore rufinamide exposure under different dosing regimens in LGS patients, clinical trial simulations were performed. The objective of the simulations was to select the doses giving an exposure shown to be safe and efficacious in larger populations. The concentrations simulated in a subgroup of patients with body weight less than 30 kg presented a larger inter-individual variability than in other patients. Additional simulations demonstrated that this increased variability was due partly to greater valproate concentrations in some of the children treated with rufinamide. Simulations of the rufinamide exposure under different maximum daily dose in presence and in absence of valproate co-administration were used to establish the dosing recommendation. The simulations support the proposal of a lower maximum daily rufinamide dose for patients under 30 kg receiving both drugs: the dose of 600 mg/day was proposed as a maximum daily dose in children also receiving valproate concomitantly, whereas in absence of valproate, the maximum daily dose is 1000 mg/day.

Approach to pediatric epilepsy surgery: State of the art, Part II: Approach to specific epilepsy syndromes and etiologies

The second of this 2-part review depicts the specific approach to the common causes of pediatric refractory epilepsy amenable to surgery. These include tumors, malformations due to abnormal cortical development, vascular abnormalities and certain epileptic syndromes. Seizure freedom rates are high (usually 60-80%) following tailored focal resection, lesionectomy, and hemispherectomy. However, in patients in whom the epileptogenic zone overlaps with unresectable eloquent cortex, and in certain epileptic syndromes, seizure freedom may not be achievable. In such cases, palliative procedures such as callosotomy, multiple subpial transections and vagus nerve stimulation can achieve reduction in seizure severity but rarely seizure freedom. Integration of the new imaging techniques and the concepts of neuronal plasticity, the epileptogenic lesion, the ictal onset, symptomatogenic, irritative, and epileptogenic zones is an expanding and dynamic process that will allow us, in the future, to better decide on the surgical approach of choice and its timing.

Update on the management of Lennox-Gastaut syndrome with a focus on rufinamide

OBJECTIVE

This review summarizes the treatment of Lennox-Gastaut syndrome, an intractable epileptic encephalopathy of early childhood. In particular, the review focuses on rufinamide, a recently released anticonvulsant medication with reported effectiveness in this epilepsy syndrome.

METHODS

A systematic literature search (PubMed) was performed to review the existing literature pertaining to the treatment of Lennox-Gastaut syndrome as well as studies involving rufinamide as an anticonvulsant medication.

RESULTS

The published literature to date documents a beneficial effect of rufinamide on children over 4 years old with Lennox-Gastaut syndrome. Studies indicate a significant decrease in tonic and atonic seizure frequency as well as total seizure frequency compared to placebo-treated children. Rufinamide appears to be well tolerated and a safe medication, somnolence and vomiting being the most common side effects.

CONCLUSIONS

Rufinamide is a promising adjunctive therapy for Lennox-Gastaut syndrome, an intractable childhood epilepsy. To ensure its optimal effectiveness, clinicians must be familiar with the medication's clinical response profile and potential for adverse effects.

Treatment of Lennox-Gastaut syndrome: overview and recent findings

Lennox-Gastaut syndrome (LGS) is a rare, age-related syndrome, characterized by multiple seizure types, a specific electro-encephalographic pattern, and mental regression. However, published data on the etiology, evolution, and therapeutic approach of LGS are contradictory, partly because the precise definition of LGS used in the literature varies. In the most recent classification, LGS belongs to the epileptic encephalopathies and is highly refractory to all antiepileptic drugs. Numerous treatments, medical and non-medical, have been proposed and results mostly from open studies or case series have been published. Sometimes, patients with LGS are included in a more global group of patients with refractory epilepsy. Only 6 randomized double-blind controlled trials of medical treatments, which included patients with LGS, have been published. Overall, treatment is rarely effective and the final prognosis remains poor in spite of new therapeutic strategies. Co-morbidities need specific treatment. This paper summarizes the definition, diagnosis and therapeutic approach to LGS, including not only recognized antiepileptic drugs, but also "off label" medications, immune therapy, diet, surgery and some perspectives for the future.

Stress, the hippocampus, and epilepsy

Stress is among the most frequently self-reported precipitants of seizures in patients with epilepsy. This review considers how important stress mediators like corticotropin-releasing hormone, corticosteroids, and neurosteroids could contribute to this phenomenon. Cellular effects of stress mediators in the rodent hippocampus are highlighted. Overall, corticosterone--with other stress hormones--rapidly enhances CA1/CA3 hippocampal activity shortly after stress. At the same time, corticosterone starts gene-mediated events, which enhance calcium influx several hours later. This later effect serves to normalize activity but also imposes a risk for neuronal injury if and when neurons are concurrently strongly depolarized, for example, during epileptic activity. In the dentate gyrus, stress-induced elevations in corticosteroid level are less effective in changing membrane properties such as calcium influx; here, enhanced inhibitory tone mediated through neurosteroid effects on gamma-aminobutyric acid (GABA) receptors might dominate. Under conditions of repetitive stress (e.g., caused from experiencing repetitive and unpredictable seizures) and/or early life stress, hormonal influences on the inhibitory tone, however, are diminished; instead, enhanced calcium influx and increased excitation become more important. In agreement, perinatal stress and elevated steroid levels accelerate epileptogenesis and lower seizure threshold in various animal models for epilepsy. It will be interesting to examine how curtailing the effects of stress in adults, for example, by brief treatment with antiglucocorticoids, may be beneficial to the treatment of epilepsy.

Intractable epilepsy: management and therapeutic alternatives

More than half of patients with newly diagnosed epilepsy achieve complete seizure control without major side-effects. Patients who continue to have seizures after initial medical therapy should have an early and detailed assessment to confirm the diagnosis, to determine the underlying cause and epilepsy syndrome, and to choose an adequate treatment strategy. The risks and potential benefits of surgical procedures or experimental therapy have to be weighed against the chance of improvement and the potential side-effects of additional medical therapy. Surgery for temporal lobe epilepsy, the most common cause of focal epilepsy, can control seizures and improve quality of life in appropriately selected patients. However, around 20-30% of patients do not respond to medical or surgical treatment. The management of chronic intractable epilepsy requires comprehensive care to address the adverse events of medical treatment, quality of life issues, and comorbid disorders. Much research focuses on the experimental treatment options that offer hope of seizure reduction or cure.

Lennox gastaut syndrome, review of the literature and a case report

Background

Lennox-Gastaut syndrome (LGS) is a severe form of childhood epilepsy that is defined by generalized multiple type seizures, slowness of intellectual growth, and a specific EEG disturbance. Children affected might previously have infantile spasms or underlying brain disorder but etiology can be idiopathic. In South Africa, the incidence of secondary epilepsy is higher than what is found in developed countries resulting in higher incidence of the disease. LGS seizures are often treatment resistant and the long term prognosis is poor.

Report

A twenty six year old female, presented with anterior open bite, macroglossia, supragingival as well as subgingival calculus. The gingiva was red, swollen and friable and there was generalized bleeding and localized suppuration. The patient had gingival recession. After periodontal therapy a remarkable improvement in oral health status was noted.

Conclusion

The clinical findings in LGS included facial deformities, periodontitis and gingival swellings. Interdisciplinary treatment of these patients is fundamental and oral attention is of outstanding importance. Non-surgical periodontal therapy was effective in controlling periodontal disease in the reported case, but prevention of periodontal and dental diseases is preferable for this high-risk group of patients.

Comparison of corpus callosotomy and vagus nerve stimulation in children with Lennox-Gastaut syndrome

PURPOSE

To compare the efficacy of corpus callosotomy and vagus nerve stimulation (VNS) for long-term adjunctive therapy in children with Lennox-Gastaut syndrome (LGS).

METHOD

Fourteen patients underwent a total corpus callosotomy and 10 patients received VNS implantation. The patients were monitored for more than 12 months after treatment, and seizure rates and complications were retrospectively evaluated.

RESULTS

Seizure types among the 24 patients included atonic or tonic seizures with head-drops in 17 patients, generalized tonic seizures in two patients, atypical absence seizures in one patient, generalized tonic-clonic seizures in one patient, and myoclonic seizures in three patients. Of the 14 patients who underwent a corpus callosotomy, nine (64.3%) had a greater than 50% reduction in seizure frequency and five (35.7%) had a greater than 75% reduction. Of the 10 patients who underwent VNS implantation, seven (70.0%) had a greater than 50% reduction in seizure frequency and two (20.0%) had a greater than 75% reduction. There was no significant difference between the two procedures in terms of final efficacy. Complications of corpus callosotomy included aphasia in one patient, ataxia in another, and paresis in a third. Among patients receiving VNS, one patient experienced dyspnea while sleeping and one patient suffered from drooling. These complications were transient and tolerable, and were controlled by simple adjustments of VNS treatment parameters.

CONCLUSION

The efficacy and safety of corpus callosotomy and VNS were comparable in children with LGS.

Ethosuximide: from bench to bedside

Ethosuximide, 2-ethyl-2-methylsuccinimide, has been used extensively for "petit mal" seizures and it is a valuable agent in studies of absence epilepsy. In the treatment of epilepsy, ethosuximide has a narrow therapeutic profile. It is the drug of choice in the monotherapy or combination therapy of children with generalized absence (petit mal) epilepsy. Commonly observed side effects of ethosuximide are dose dependent and involve the gastrointestinal tract and central nervous system. Ethosuximide has been associated with a wide variety of idiosyncratic reactions and with hematopoietic adverse effects. Typical absence seizures are generated as a result of complex interactions between the thalamus and the cerebral cortex. This thalamocortical circuitry is under the control of several specific inhibitory and excitatory systems arising from the forebrain and brainstem. Corticothalamic rhythms are believed to be involved in the generation of spike-and-wave discharges that are the characteristic electroencephalographic signs of absence seizures. The spontaneous pacemaker oscillatory activity of thalamocortical circuitry involves low threshold T-type Ca2+ currents in the thalamus, and ethosuximide is presumed to reduce these low threshold T-type Ca2+ currents in thalamic neurons. Ethosuximide also decreases the persistent Na+ and Ca2+ -activated K+ currents in thalamic and layer V cortical pyramidal neurons. In addition, there is evidence that in a genetic absence epilepsy rat model ethosuximide reduces cortical gamma-aminobutyric acid (GABA) levels. Also, elevated glutamate levels in the primary motor cortex of rats with absence epilepsy (but not in normal animals) are reduced by ethosuximide.

Levetiracetam and felbamate interact both pharmacodynamically and pharmacokinetically: an isobolographic analysis in the mouse maximal electroshock model

PURPOSE

Polytherapy with two or more antiepileptic drugs (AEDs) is generally required for approximately 30% of patients with epilepsy, who do not respond satisfactorily to monotherapy. The potential usefulness of AED combinations, producing synergistic anticonvulsant efficacy and minimal adverse effects, is therefore of significant importance. The present study sought to ascertain the potential usefulness of levetiracetam (LEV) and felbamate (FBM) in combination in the mouse maximal electroshock (MES)-induced seizure model.

METHODS

The anticonvulsant interaction profile between LEV and FBM in the mouse MES-induced seizure model was determined using type II isobolographic analysis. Acute adverse effects (motor performance) were ascertained by use of the chimney test. LEV and FBM brain concentrations were measured by HPLC in order to determine any pharmacokinetic contribution to the observed antiseizure effect.

RESULTS

LEV in combination with FBM, at the fixed ratios of 1:2, 1:1, 2:1, and 4:1, were supraadditive, whereas at the fixed ratio of 1:4, additivity was observed in the mouse MES model. Furthermore, none of the investigated combinations altered motor performance in the chimney test. Brain FBM concentrations were unaffected by concomitant LEV administration. In contrast, FBM significantly increased LEV brain concentrations.

CONCLUSIONS

LEV in combination with FBM was associated with pharmacodynamic supraadditivity in the MES test. However, this anticonvulsant supraadditivity was associated with a concurrent increase in brain LEV concentrations indicating a pharmacokinetic contribution to the observed pharmacodynamic interaction between LEV and FBM.

Role of rufinamide in the management of Lennox-Gastaut syndrome (childhood epileptic encephalopathy)

Rufinamide, a triazole derivative that is structurally distinct from currently marketed antiepileptic drugs (AEDs), is in development for the adjunctive treatment of Lennox-Gastaut syndrome (LGS) in children and adults. Rufinamide is well absorbed after oral administration, demonstrates low protein binding, and is metabolized by enzymatic hydrolysis without involvement of cytochrome P450 enzymes, conferring a low drug interaction potential. In a randomized, double-blind trial involving 138 adult and pediatric patients with LGS, compared with placebo, rufinamide 45 mg/kg/day resulted in significantly superior reductions in drop attacks (median change -42.5% vs +1.4% with placebo) and total seizures (-32.1% vs -11.7% with placebo), accompanied by significantly higher responder rates. These results are comparable with findings reported for other AEDs in randomized, controlled clinical trials in patients with LGS. Rufinamide produced statistically significant seizure reduction which was maintained during long-term therapy and accompanied by good tolerability. The most frequently reported adverse events from a pooled safety database evaluating short- and long-term therapy were headache (22.9% and 29.5%), dizziness (15.5% and 22.5%) and fatigue (13.6% and 17.7%). Rufinamide therefore presents a favorable efficacy and tolerability profile and is a promising candidate for the adjunctive therapy of LGS.

Valproate as a mainstay of therapy for pediatric epilepsy

This article reviews relevant pharmacologic and clinical information gathered for valproate since it was introduced into clinical practice 37 years ago and the application of this information for the treatment of childhood epilepsy. Valproate is available for oral and parenteral use. Oral forms are almost completely bioavailable but the rate of absorption varies between formulations. The Chrono tablet formulation has not been adapted for children aged <6 years, in whom the oral solution or syrup, requiring two or three daily administrations, has been used until recently. A new formulation specifically adapted for children, Chronosphere, administrated once or twice daily, is a modified-release formulation of valproate that minimizes fluctuations in serum drug concentrations during a dosage interval. Plasma protein binding is 80-94% and tends to decrease with increasing drug concentration. Valproate elimination is markedly decreased in newborns compared with older children and adults. Elimination by glucuronidation only becomes fully effective by the age of 3-4 years. In children aged 2-10 years receiving valproate, plasma clearances are 50% higher than those in adults. Over the age of 10 years, pharmacokinetic parameters approximate those of adults. Valproate can increase plasma concentrations of concomitant drugs, such as phenobarbital and lamotrigine, by inhibiting their metabolism. As a result of its broad spectrum of efficacy in a wide range of seizure types and epilepsy syndromes, valproate is a drug of choice for children with newly diagnosed epilepsy (focal or generalized), idiopathic generalized epilepsy, epilepsies with prominent myoclonic seizures or with multiple seizure types, and photosensitive epilepsies. In the group of cognitive epilepsies, in which severe spike and wave discharges are accompanied by cognitive deterioration, valproate, ethosuximide, or both should be tested before using corticosteroids. In comparative trials with carbamazepine, phenytoin, and phenobarbital in focal epilepsy and with ethosuximide in absence epilepsy, valproate was as effective and showed a favorable tolerability profile, with minimal adverse cognitive and CNS effects. The low potential for paradoxical seizure aggravation and the long-term efficacy of the drug are additional important factors that contribute to its excellent profile. Intravenous valproate may be effective for the treatment of convulsive and non-convulsive status epilepticus that is refractory to conventional drugs. In infants, potential benefits should be carefully weighed against the risk of liver toxicity. Gastrointestinal intolerance is a relatively frequent, dose-related adverse effect of the drug in children. Bodyweight increase and tremor may be observed in older children and adolescents. Despite the challenge of newer drugs, valproate remains a gold standard antiepileptic drug for the treatment of children.

Effectiveness of clobazam as add-on therapy in children with refractory focal epilepsy

The objective of this study was to evaluate the safety and efficacy of clobazam in children with refractory focal epilepsy. We investigated 100 consecutive patients concerning etiology of epilepsy, previously used antiepileptic drugs, seizure frequency and adverse events. Clobazam was introduced as add-on therapy in patients with previous failure of at least two monotherapies. Mean age was eight years-old and 39 patients were girls. Clobazam mean dosage was 23.6 mg/day. Mean use of clobazam was 18.6 months. Twenty-two patients had adverse events. Twenty-six patients became seizure-free, 11 had an improvement of >75% and in 58 there was no modification in seizure frequency. Five patients had an increase in seizure frequency. Clobazam efficacy lasted for more than one year in 42% of the seizure-free patients. Clobazam seems to be safe and effective in the treatment of focal epilepsy in childhood and should be considered in patients with refractory seizures.

[Therapies for Lennox-Gastaut syndrome]

The treatment of Lennox-Gastaut Syndrome (LGS) has been improved with the introduction of the new anti-epileptic drugs: lamotrigine and topiramate, the employment of a ketogenic diet, and the availability of vagal nerve stimulation. It is difficult to provide recommendations for the treatment of LGS, in the absence of comparative trials. However, suggestions can be made on the basis of the best evidence available. Treatment should commence with valproate and continue with lamotrigine or topiramate. If seizure control is not sufficient, felbamate, a ketogenic diet, and vagal nerve stimulation are recommended. A partial callosotomy may be performed for the treatment of frequent drop attacks. Other anti-epileptic drugs may be used after a risks-benefits evaluation.

Improving the lives of patients with medically refractory epilepsy by electrical stimulation of the nervous system

Vagal nerve stimulation proved effective in animal models of epilepsy, and in open and double-blinded trials, in over 450 patients. Seizure reduction improved for at least 2 years. Almost 50% of treated patients achieve at least a 50% reduction in seizure frequency. Other advantages include termination of a seizure and improved alertness. Benefits were demonstrated in children, partial and generalized epilepsies, and in specific neurologic syndromes.

Beneficial interaction between vigabatrin and valproate against seizures induced by pentylenetetrazole in mice

The anticonvulsant effects of adding a non-protective dose of vigabatrin (VGB) to increasing single doses of sodium valproate (VPA) against seizures induced by 110 mgkg(-1) of pentylenetetrazole (PTZ) or by 4.5 mgkg(-1) of picrotoxin (PIC) were compared in CD1 mice with those of VPA alone and vice versa. Neurotoxicity was evaluated by the rotarod test. The study also assessed changes in concentrations of anticonvulsants, gamma-aminobutyric acid (GABA) and glutamate in the whole brain. VGB increased the potency ratio of VPA against PTZ (1.62, P < 0.05) but not against PIC (1.08, n.s.). VGB slightly decreased the neurotoxicity of VPA (0.93, n.s.) and the protective index of VPA was, therefore, increased from 1.93 to 3.34 for the PTZ model and from 1.40 to 1.61 for the PIC model. VGB did not modify brain concentrations of VPA, and increased brain GABA in relation to VPA alone. On the other hand, VGB did not achieve a complete protection neither against seizures induced by PTZ nor against seizures induced by PIC and a non-protective dose of VPA did not significantly modify the effects of increasing doses of VGB. In conclusion, the addition of a non-protective dose of VGB increased the anticonvulsants effects and the protective index of VPA in the PTZ model. A more than expected brain GABA increase together with the lack of a pharmacokinetic interaction support a pharmacodynamic basis for this interaction.

Interaction between lamotrigine and felbamate in the maximal electroshock-induced seizures in mice: an isobolographic analysis

Isobolographic profile of interactions between lamotrigine (LTG) and felbamate (FBM), two second-generation antiepileptic drugs, against maximal electroshock (MES)-induced seizures, and neurotoxic adverse effects in the chimney test in mice were determined. LTG combined with FBM at the fixed ratios of 1:3, 1:1, and 3:1 exerted merely additive interactions against MES-induced seizures. In the chimney test, isobolography revealed that LTG coadministered with FBM at the fixed ratio of 1:1 displayed subadditivity (antagonism), whereas the remaining combinations tested (1:3 and 3:1) exerted additivity in terms of their neurotoxic side effects. LTG (at the dose of 2.3 mg/kg) coadministered with FBM (25.7 mg/kg) at the fixed ratio of 1:1 from the MES test did not impair long-term memory of mice challenged with the passive avoidance task. Furthermore, FBM (25.7 mg/kg) altered neither the free plasma nor brain concentration of LTG, hence pharmacokinetic events, which might affect the observed interactions in the MES test, are unlikely. Considering benefit indices for the respective fixed ratio combinations, it may be concluded that the combination of LTG with FBM at the fixed ratio of 1:1 is advantageous from a preclinical point of view, offering the highest benefit index reaching the value of 1.46. Likewise, the two-drug combination of 1:3 was also beneficial and is worth recommendation with benefit index amounting to 1.36. Only the combination of 3:1 was neutral with a benefit index of 1.08. Protection offered by LTG in combination with FBM against maximal electroconvulsions and its favorable neurotoxic side effect profile might provide the patients with intractable seizures with an efficacious treatment, as the rational polytherapy however, it requires to be clinically confirmed and verified.

Nonpharmacologic Treatment of the Catastrophic Epilepsies of Childhood

The catastrophic epilepsy syndromes of childhood are initially treated with a pharmacologic intervention in most cases. However, due to the poor response patients often have to pharmacologic interventions, nonpharmacologic treatment options are an important part of a comprehensive treatment plan for this group of children. Additionally, nonpharmacologic therapy may offer a method to minimize associated morbidity and mortality. This article discusses the use of epilepsy surgery, the ketogenic diet, and vagus nerve stimulation in the treatment of patients with infantile spasms, Lennox-Gastaut syndrome, and progressive myoclonic epilepsy. Efficacy of the nonpharmacologic treatment options, as measured by reduction in seizure frequency, as well as by developmental progress or behavioral improvement, varies according to the specific catastrophic epilepsy disorder and the treatment option.

Is the interaction between felbamate and valproate against seizures induced by 4-aminopyridine and pentylenetetrazole in mice beneficial?

We compared the effects of adding a non-protective dose of valproate (VPA) to increasing single doses of felbamate (FBM) with those of monotherapy and vice versa in CD1 mice. Anticonvulsant effects were evaluated against seizures induced by 14 mg kg(-1) of 4-aminopyridine (4-AP) and by 110 mg kg(-1) of pentylenetetrazole (PTZ), and neurotoxicity by the rotarod test. The study also assessed changes in concentrations of anticonvulsants, gamma-aminobutyric acid (GABA) and glutamate in the whole brain. VPA increased the potency ratio of FBM against 4-AP (1.94, P<0.05) but not against PTZ. VPA increased the neurotoxicity of FBM (3.30, P<0.05) and the protective index of FBM was, therefore, reduced from 12.0 to 7.0 for the 4-AP model and from 11.8 to 5.2 for the PTZ model; VPA reduced brain FBM, and increased brain GABA in relation to FBM monotherapy. On the other hand, FBM increased the potency ratio of VPA against 4-AP (1.60, P<0.05) but not against the PTZ, and had no effect on the rotarod model. Therefore, the protective index increased from 1.1 to 1.6 for the 4-AP model and decreased from 1.9 to 1.7 for the PTZ model. FBM did not change brain VPA, and changes in brain GABA and glutamate were not clearly related to anticonvulsant effects. In conclusion, although the addition of a low dose of FBM to VPA was beneficial in the 4-AP model, the addition of a low dose of VPA to FBM was not; both combinations were disadvantageous in the PTZ model. This interaction appears to be pharmacodynamic because a pharmacokinetic mechanism was discarded.

Prednisone therapy in pediatric epilepsy

Steroids are often an effective treatment for the West's syndrome. There have been few reports of steroid use in children with epilepsy outside the first year of life. I report my experience with prednisone for the treatment of older children with intractable epilepsy. Twenty-eight children (17 boys, 11 girls) aged 18 months to 10 years with intractable epilepsy were studied. Prednisone 1 mg/kg/day for 12 weeks (6 weeks daily and 6 weeks alternate therapy) was prescribed in addition to their regular antiepileptic medications. The parents kept seizure diaries, and the patients were regularly assessed for seizure frequency and side effects. The follow-up period was for 1 to 5 years. Thirteen patients (46%) became seizure free on prednisone and another 18 (40%) had a significant decrease in seizure frequency. Five patients (19%) had no change in seizure frequency. The best outcomes were seen in the absence group in which six out of seven patients became seizure free and in the Lennox-Gastaut syndrome group in which seven out of 10 became seizure free. Side effects were uncommon and included weight gain in five patients and aggression in four patients. Prednisone therapy is a safe and effective adjunctive treatment for epilepsy. It should be considered as an alternative treatment for older children with intractable generalized epilepsy who have failed conventional antiepileptic therapy.

Basic pharmacology of valproate: a review after 35 years of clinical use for the treatment of epilepsy

Since its first marketing as an antiepileptic drug (AED) 35 years ago in France, valproate has become established worldwide as one of the most widely used AEDs in the treatment of both generalised and partial seizures in adults and children. The broad spectrum of antiepileptic efficacy of valproate is reflected in preclinical in vivo and in vitro models, including a variety of animal models of seizures or epilepsy. There is no single mechanism of action of valproate that can completely account for the numerous effects of the drug on neuronal tissue and its broad clinical activity in epilepsy and other brain diseases. In view of the diverse molecular and cellular events that underlie different seizure types, the combination of several neurochemical and neurophysiological mechanisms in a single drug molecule might explain the broad antiepileptic efficacy of valproate. Furthermore, by acting on diverse regional targets thought to be involved in the generation and propagation of seizures, valproate may antagonise epileptic activity at several steps of its organisation. There is now ample experimental evidence that valproate increases turnover of gamma-aminobutyric acid (GABA) and thereby potentiates GABAergic functions in some specific brain regions thought to be involved in the control of seizure generation and propagation. Furthermore, the effect of valproate on neuronal excitation mediated by the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors might be important for its anticonvulsant effects. Acting to alter the balance of inhibition and excitation through multiple mechanisms is clearly an advantage for valproate and probably contributes to its broad spectrum of clinical effects. Although the GABAergic potentiation and glutamate/NMDA inhibition could be a likely explanation for the anticonvulsant action on focal and generalised convulsive seizures, they do not explain the effect of valproate on nonconvulsive seizures, such as absences. In this respect, the reduction of gamma-hydroxybutyrate (GHB) release reported for valproate could be of interest, because GHB has been suggested to play a critical role in the modulation of absence seizures. Although it is often proposed that blockade of voltage-dependent sodium currents is an important mechanism of antiepileptic action of valproate, the exact role played by this mechanism of action at therapeutically relevant concentrations in the mammalian brain is not clearly elucidated. By the experimental observations summarised in this review, most clinical effects of valproate can be explained, although much remains to be learned at a number of different levels about the mechanisms of action of valproate. In view of the advances in molecular neurobiology and neuroscience, future studies will undoubtedly further our understanding of the mechanisms of action of valproate.

Topiramate as add-on drug in children, adolescents and young adults with Lennox-Gastaut syndrome: an Italian multicentric study

The purpose of the study was to evaluate the efficacy and safety of topiramate (TPM) as adjunctive therapy in children, adolescents and young adults with Lennox-Gastaut syndrome (LGS). We performed a prospective open label add-on study in 45 patients (age 4-34 years, mean 15.9 years) with LGS and refractory seizures. TPM was added to one or two other baseline drugs and the efficacy was rated according to seizure type and frequency. TPM was initiated at the daily dose of 0.5-1 mg/kg, followed by a 2-week titration at increments of 1-3 mg/kg/24 h, up to a maximum daily dose of 12 mg/kg. After a mean period of 15.8 months of treatment (range 3-98 months), at a mean dose of 4.1 mg/kg/24 h (range 1.4-12 mg/kg), 18 patients (40%) had a seizure reduction more than 50%. TPM appeared to be effective mainly in major seizures (drop attacks, tonic and tonic-clonic seizures). Mild to moderate adverse events were present in 24 patients (53.3%), mostly represented by drowsiness, nervousness, hyporexia with or without weight loss and cognitive dulling. In conclusion, TPM adjunctive therapy reduced the number of drop attacks and major motor seizures in 40% of patients with LGS and produced only mild or moderate adverse events.

The clinical impact of new antiepileptic drugs after a decade of use in epilepsy

The introduction of numerous effective, well tolerated and safe new antiepileptic drugs (AEDs) in the last decade of the 20th century has widened the choice of treatment options in epilepsy and improved the tolerability and the ease of use of treating patients with epilepsy. Nevertheless, significant safety and efficacy deficits continue to exist. Severe idiosyncratic reactions and organ toxicity have hampered the wide use of some of the newer AEDs. As a decade before, about one third of patients with chronic epilepsy is resistant to current pharmacotherapy. Even in patients in whom pharmacotherapy is efficacious, current AED do not seem to affect the progression or the underlying natural history of epilepsy. In addition, there is currently no drug available which prevents the development of epilepsy, e.g. after head trauma. Thus, there is an unmet need for safer and more effective drugs, especially for chronic, drug-resistant epilepsy. To stimulate the development of even better compounds, the demonstrated benefits and risks of current new AEDs are reviewed.