The landscape of epilepsy-related GATOR1 variants.

PURPOSE: To define the phenotypic and mutational spectrum of epilepsies related to DEPDC5, NPRL2 and NPRL3 genes encoding the GATOR1 complex, a negative regulator of the mTORC1 pathway METHODS: We analyzed clinical and genetic data of 73 novel probands (familial and sporadic) with epilepsy-related variants in GATOR1-encoding genes and proposed new guidelines for clinical interpretation of GATOR1 variants. RESULTS: The GATOR1 seizure phenotype consisted mostly in focal seizures (e.g., hypermotor or frontal lobe seizures in 50%), with a mean age at onset of 4.4 years, often sleep-related and drug-resistant (54%), and associated with focal cortical dysplasia (20%). Infantile spasms were reported in 10% of the probands. Sudden unexpected death in epilepsy (SUDEP) occurred in 10% of the families. Novel classification framework of all 140 epilepsy-related GATOR1 variants (including the variants of this study) revealed that 68% are loss-of-function pathogenic, 14% are likely pathogenic, 15% are variants of uncertain significance and 3% are likely benign. CONCLUSION: Our data emphasize the increasingly important role of GATOR1 genes in the pathogenesis of focal epilepsies (>180 probands to date). The GATOR1 phenotypic spectrum ranges from sporadic early-onset epilepsies with cognitive impairment comorbidities to familial focal epilepsies, and SUDEP.

Correction to: The landscape of epilepsy-related GATOR1 variants.

The original version of this Article contained an error in the author list where the corresponding author Stéphanie Baulac was repeated twice. This has now been corrected in the HTML, the PDF was correct at the time of publication.

Correction: The landscape of epilepsy-related GATOR1 variants.

The original version of this article contained an error in the spelling of the author Erik H. Niks, which was incorrectly given as Erik Niks. This has now been corrected in both the PDF and HTML versions of the article.

Comparison of add-on valproate and primidone in carbamazepine-unresponsive patients with partial epilepsy.

PURPOSE: Evaluation of the efficacy of add-on valproate (VPA) or primidone (PRM) in patients with partial epilepsy unresponsive to carbamazepine (CBZ). METHODS: The trial was prospective and open. Patients, aged 8-58 years, with partial epilepsy who did not become seizure free on CBZ were randomized to either VPA add-on or PRM add-on. The baseline period and the evaluation period were both 3 months. Proportions of patients with different degrees of reduction in seizure frequency were determined. RESULTS: Significantly more patients on VPA (51% of 68 patients) achieved a greater than 50% seizure reduction than on PRM (34% of 68 patients). There was no significant difference in percentage seizure free (26% and 16%, respectively) or in percentage treatment withdrawals due to adverse effects. CONCLUSION: Our results indicated that the efficacy of the CBZ/VPA combination tends to be greater than the efficacy of the CBZ/PRM combination.

Place of polytherapy in the early treatment of epilepsy.

Polytherapy with antiepileptic drugs is not popular mainly because it is thought to be associated with more adverse effects and to contribute relatively little in terms of efficacy compared with monotherapy. However, there are two reasons to question this assumption: certain combinations are more effective than others and, therefore, generalisations about the poor effectiveness of polytherapy cannot be made; and the total drug load, i.e. the total amount of drug exposure for a certain indication, is usually higher in polytherapy, which may explain the higher toxicity seen during such treatment. In this article, the available literature on the effectiveness of first-line monotherapy, alternative monotherapy and second-line polytherapy is reviewed. There is no conclusive evidence in favour for choosing either alternative monotherapy or polytherapy when first-line monotherapy fails. Therefore, a pragmatic approach is recommended until an evidence-based choice can be made.

Selection criteria for the clinical use of the newer antiepileptic drugs.

In recent years, several new antiepileptic drugs (AEDs) have been licensed: felbamate, gabapentin, lamotrigine, levetiracetam, oxcarbazepine, tiagabine, topiramate, vigabatrin and zonisamide. These drugs have proven efficacy as add-on therapy in patients with difficult-to-treat partial epilepsy, as 20-50% of patients treated in add-on trials experienced a seizure reduction of >or=50%. Relatively few trials have been conducted to evaluate these drugs as monotherapy for patients with newly diagnosed epilepsy. In the monotherapy trials that have been conducted, the newer drugs were often as efficacious as conventional drugs, and their tolerability was often better. However, the methodology of these trials can be criticised. Because of the relative lack of robust data for the newer agents, the conventional drugs have thus far maintained their status as first-line monotherapy. However, when first-line monotherapy fails, an alternative drug has to be chosen from the available conventional and newer drugs. This article aims to give detailed background information on the newer AEDs in order to enable physicians to make a rational choice from the available drugs for individual patients. Data are provided for the different newer AEDs on mechanisms of action; efficacy in refractory partial epilepsy, newly diagnosed epilepsy in adults and generalised seizure types; adverse effects; pharmacokinetics; and use in special patient categories.

Overtreatment in adults with epilepsy.

Overtreatment of epilepsy patients is traditionally associated with the use of polytherapy, i.e. use of more than one antiepileptic drug (AED). Although monotherapy is now being used in 70% of patients with epilepsy, these patients are also at risk at being overtreated. Ten to 20% of patients withdraw from their first drug because of adverse effects. This is partly related to high starting dosages and fast titration rates. The conventional AEDs are still first choice monotherapy drugs, although they potentially have more adverse effects, especially in the elderly. Other problems are the random selection of second or third choice drugs and the uncertainty about when to switch to polytherapy. Several authors have suggested that patients with progressive forms of epilepsy, such as patients with mesiotemporal sclerosis, should be treated adequately as soon as possible and that epilepsy surgery should be considered for them in a much earlier stage. Overtreatment in polytherapy is still a large threat, due to several reasons: drug loads are much higher, and thus more adverse effects are likely to develop; drug combinations are selected randomly, as evidence about effective combinations has been scarce; the constant choice between continuing the existing treatment (which is suboptimal) and trying new drugs (which may disturb a patient's equilibrium); the long-term use of benzodiazepines.

Effects of the combination of valproate and ethosuximide on spike wave discharges in WAG/Rij rats.

OBJECTIVE: We studied the interaction between valproate (VPA) and ethosuximide (ESM) in diminishing the incidence of absence-like spike-wave discharges (SWDs) in the EEG of WAG/Rij rats. METHODS: VPA, ESM, their combination and saline were evaluated in 16 rats. The doses of VPA ranged from 0 to 280 mg/kg and the doses of ESM ranged from 0 to 40 mg/kg. For the drug combination, a fixed weight ratio of 7/1 VPA/ESM was used. The incidence of SWDs in the EEG was determined for the period of 15-75 min after injection and compared to the incidence of SWDs prior to injection. The sigmoid-E(max) equation was fitted to the data. Isobolic analysis, on 50% effect, was used to assess the character of the drug interaction. RESULTS: The parameters for diminishing the incidence of the SWDs were: VPA: ED(50): 121mg/kg; ESM: ED(50): 21.5mg/kg; VPA/ESM: ED(50): 112/16 mg/kg. Isobolic analysis showed that a higher drug load was needed of the combination than of the individual drugs to achieve a 50% reduction of SWDs: factor 1.67; P = 0.012. CONCLUSION: The interaction between valproate and ethosuximide was shown to be infra-additive in diminishing the incidence of SWDs in WAG/Rij rats.

[Recognition of temporal lobe epilepsy in adults]. / Herkennen van temporaalkwabepilepsie bij volwassenen.

Temporal lobe epilepsy has a subtle and diverse symptomatology, and therefore temporal lobe seizures can initially be misdiagnosed. Here we discuss 3 patients with this type of epilepsy, but with completely different presentations. The first, a 67-year-old woman suffered from episodes of confusion, and later she developed tonic-clonic seizures. The second patient, a 58-year-old man, had auras followed by impaired consciousness and oral automatisms and also developed a type of seizure resembling panic attacks. The third patient, a 65-year-old man, presented with isolated auras. A few years later he developed tonic-clonic seizures, and the diagnosis 'temporal lobe epilepsy' was made. This article discusses differences in presentation between limbic and neocortical temporal lobe epilepsy, as well as the results of EEG and MRI investigations.

A cost-effectiveness decision model for antiepileptic drug treatment in newly diagnosed epilepsy patients.

OBJECTIVE: To establish cost-effectiveness of antiepileptic drug (AED) treatment strategies of newly diagnosed patients with epilepsy. METHODS: A decision analysis was carried out comparing effectiveness and treatment cost of six treatment strategies comprising carbamazepine (CBZ), lamotrigine (LTG), and valproate (VPA) as first-line and second-line drugs. Three outcome groups were defined: complete success, partial success, and failure. Data on seizure control and failure due to adverse effects were derived from the literature. Data on resource use and costs were collected for each outcome group by means of a patient survey. RESULTS: Cost data were obtained from 71 patients. Cost increased from complete success to failure outcome groups. The probability of obtaining complete success varied from 64% (VPA-CBZ strategy) to 74% (LTG-VPA strategy). The strategy LTG-VPA was more effective than the least expensive strategy CBZ-VPA, but at higher costs per additional effectively treated patient. Probabilistic sensitivity analysis confirmed these findings to be robust. Subsequent analysis showed that changing inclusion criteria used in the selection of the studies from the literature had a major effect on cost-effectiveness ratios of the various strategies. The probability that LTG first-line therapy is the most cost-effective option remains small, even defining a high cost-effectiveness threshold. Nevertheless, LTG second-line strategies can be cost-effective depending on the willingness to pay for patient improvement. CONCLUSIONS: Only a few studies satisfied our inclusion criteria for employment in our decision model. Our model supports the use of conventional AEDs as first-line options for patients with newly diagnosed epilepsy. LTG second-line therapy is likely to be the most cost-effective option in case society is willing to pay more than Euro 6000 for an additional successfully treated patient. This study also illustrates that, with the data presently available, the outcome of decision analysis for AED treatment choice depends on the inclusion criteria used to select trials. Prospective real-life studies are needed in which first- and second-line treatment strategies are compared with respect to both effectiveness and costs.

Volume and market share of anti-epileptic drugs in The Netherlands: impact of new drugs.

OBJECTIVE: In the past decade, several new anti-epileptic drugs (AEDs) were introduced in The Netherlands. These new drugs, one of which is lamotrigine, are 6 to 10 times more expensive than conventional anti-convulsants. In 1997, the high cost of lamotrigine, together with a lack of clinical data supporting its superiority over conventional drugs, prompted the Dutch Health Insurance Board to release a guideline in which the use of lamotrigine was restricted to difficult-to-treat patients. Other new drugs that were marketed after 1997 also became subject to this guideline. The utilisation of new AEDs and the cost consequences are the subject of this paper. METHODS: Data from extramurally prescribed AEDs was obtained from the Dutch Drug Information Project, which is a database containing prescriptions for about 5.5 million inhabitants of the Netherlands. This data was used to study the impact of new AEDs on volume and market share of AEDs in the period from 1995 to 2001 in The Netherlands. RESULTS: Between 1995 and 2001, the total volume of AEDs increased by 130%, 60% of which consisted of new AEDs. Gabapentin, lamotrigine and oxcarbazepine were the most frequently prescribed new compounds. The volume share of new AEDs increased from 5% in 1995 to 18% in 2001. The market share amounted to 21.5 million euros in 1995 and rose to 47 million euros in 2001; 80% of this increase was due to the introduction of new AEDs. DISCUSSION: Although in 2001 the volume share of new AEDs was still modest, their introduction has led to a strong increase in the cost. New data is emerging on the effectiveness and cost-benefit sum of the new AEDs; this may change the place in therapy of these drugs. Because of their strong potential to force up cost, the positioning of new AEDs requires further attention.