Practical Management Issues for Idiopathic Generalized Epilepsies

Efficacy of highly purified cannabidiol (CBD) in typical absence seizures: A pilot study

OBJECTIVES

Clinical trials for typical absence seizures are notoriously difficult, because those seizures are clinically subtle and brief, so that seizure counts by caregivers are inaccurate. As a result, treatment options are limited. Currently, there are no published studies on the use of CBD in typical absence seizures. This pilot study aims to evaluate the efficacy of pharmaceutical grade CBD in typical absence seizures.

METHODS

We prospectively enrolled 14 patients aged 6 years and older, diagnosed with typical absence seizures. A baseline 24-hour ambulatory EEG was conducted, followed by a second 24-hour EEG after 90 days of treatment. The outcome was an objective measure of spike-wave complexes (SWC) burden change from pre- to post- treatment.

RESULTS

After taking CBD for 90 days, 9 (64.3%) patients had an increase in SWC (ranging from 8% to 2876.5%) and 5 (35.7%) had a decrease in SWC (ranging from 62.3% to 98.9%). Of the 5 patients who had a decrease, 3 (60%) were on concomitant ethosuximide (with or without other ASMs). All 3 patients on CBD and ethosuximide improved.

CONCLUSIONS

Although based on a small subset of patients, our results suggest that CBD may not be effective for typical absence seizures. However, patients on concomitant ethosuximide or on CBD monotherapy were more likely to improve.

Combined effect of stimulation and electromagnetic induction on absence seizure inhibition in coupled thalamocortical circuits

Deep brain stimulation (DBS) and electromagnetic induction are new techniques that are increasingly used in modern epilepsy treatments; however, the mechanism of action remains unclear. In this study, we constructed a bidirectional-coupled cortico-thalamic model, based on which we proposed three regulation schemes: isolated regulation of DBS, isolated regulation of electromagnetic induction and combined regulation of the previous two. In particular, we introduced DBS with a lower amplitude and considered the influence of electromagnetic induction caused by the transmembrane current on the membrane potential. The most striking finding of this study is that the three therapeutic schemes could effectively control abnormal discharge, and combined regulation could reduce the occurrence of epileptic seizures more effectively. The present study bridges the gap between the bidirectional coupling model and combined control. In this way, the damage induced by electrical stimulation of the patient's brain tissue could be reduced, and the abnormal physiological discharge pattern of the cerebral cortex was simultaneously regulated by different techniques. This work opens new avenues for improving brain dysfunction in patients with epilepsy, expands ideas for promoting the development of neuroscience and is meaningful for improving the health of modern society and developing the field of science.

Eslicarbazepine Acetate as Adjunctive Therapy for Primary Generalized Tonic-Clonic Seizures in Adults: A Prospective Observational Study

BACKGROUND

Eslicarbazepine acetate (ESL), a novel sodium channel blocker, is approved for mono and adjunctive treatment of partial epileptic seizures with or without secondary generalization. Its efficacy in primary generalized seizures has not yet been evaluated.

OBJECTIVE

To evaluate the efficacy and safety of ESL in primary generalized tonic-clonic seizures (PGTCS) in an observational study.

METHODS

The data were collected from a prospective population-based register. Effectiveness was measured as relative reduction in standardized seizure frequency (SSF), responder rate (≥ 50% reduction in SSF), and seizure freedom rate at 6 and 12 months after initiation of ESL. Safety and tolerability were evaluated using patients' diaries.

RESULTS

Fifty-six adult patients with PGTCS were treated with ESL as adjunctive therapy. Of these, 30.4% (n = 17) had myoclonic seizures in addition to PGTCS. The retention rate after 12 months was 80.4% (n = 45). After initiating ESL therapy, reduction in SSF for PGTCS on ESL was 56.0% after 6 months and 56.9% after 12 months (p < 0.01), whereas myoclonic seizures did not show any significant improvement in frequency. The responder rate for PGTCS was 64.3% after 6 months and 66.1% after 12 months, and seizure freedom was achieved in 32.1% and 35.7%, respectively. Forty-three patients (73.2%) reported no side effects. Among the reported side effects of ESL therapy, headache (7.1%), dizziness (8.9%), tiredness (7.1%), nausea (5.4%), and hyponatremia (5.4%) were the most prevalent.

CONCLUSIONS

Our data suggest that ESL may provide additional benefits in the treatment of patients with PGTCS and motivate randomized controlled trials in this indication.

An Insight into Molecular Mechanisms and Novel Therapeutic Approaches in Epileptogenesis

Epilepsy is the second most common neurological disease with abnormal neural activity involving the activation of various intracellular signalling transduction mechanisms. The molecular and system biology mechanisms responsible for epileptogenesis are not well defined or understood. Neuroinflammation, neurodegeneration and Epigenetic modification elicit epileptogenesis. The excessive neuronal activities in the brain are associated with neurochemical changes underlying the deleterious consequences of excitotoxicity. The prolonged repetitive excessive neuronal activities extended to brain tissue injury by the activation of microglia regulating abnormal neuroglia remodelling and monocyte infiltration in response to brain lesions inducing axonal sprouting contributing to neurodegeneration. The alteration of various downstream transduction pathways resulted in intracellular stress responses associating endoplasmic reticulum, mitochondrial and lysosomal dysfunction, activation of nucleases, proteases mediated neuronal death. The recently novel pharmacological agents modulate various receptors like mTOR, COX-2, TRK, JAK-STAT, epigenetic modulators and neurosteroids are used for attenuation of epileptogenesis. Whereas the various molecular changes like the mutation of the cell surface, nuclear receptor and ion channels focusing on repetitive episodic seizures have been explored by preclinical and clinical studies. Despite effective pharmacotherapy for epilepsy, the inadequate understanding of precise mechanisms, drug resistance and therapeutic failure are the current fundamental problems in epilepsy. Therefore, the novel pharmacological approaches evaluated for efficacy on experimental models of epilepsy need to be identified and validated. In addition, we need to understand the downstream signalling pathways of new targets for the treatment of epilepsy. This review emphasizes on the current state of novel molecular targets as therapeutic approaches and future directions for the management of epileptogenesis. Novel pharmacological approaches and clinical exploration are essential to make new frontiers in curing epilepsy.

Late-onset idiopathic (genetic) generalized epilepsies: Clinical and EEG findings

PURPOSE

We investigated the occurrence and clinical characteristics of late-onset idiopathic generalized epilepsies (IGEs). We also provided a statistically meaningful definition for late-onset IGE in this large cohort of patients.

METHODS

In this cross-sectional retrospective chart review study, all patients with a clinical diagnosis of IGE were recruited at the outpatient epilepsy clinic at Shiraz University of Medical Sciences from 2008 until 2019. We defined "late-onset IGE" according to the following equation: those with an age at onset of their seizures above X years [X = mean age at the seizure onset of all patients + 2 × (standard deviation)].

RESULTS

During the study period, 601 patients with IGE were registered at our epilepsy clinic. Late-onset IGE was defined as having an age at onset of above 26 years. Fifteen patients (2.5%) had late-onset IGE. The syndromic diagnosis of these patients included: IGE with absences [6 patients (40%)], generalized tonic-clonic only (GTC-only) [5 patients (33.3%)], and juvenile myoclonic epilepsy (JME) [4 patients (26.7%)].

CONCLUSION

While late-onset IGE (IGE with an age at onset of above 26 years) is not common, one should consider the possibility of its occurrence in adults with new-onset seizures. This condition shares many of the clinical and electroencephalograic features of classical IGEs, which supports the hypothesis that IGE syndromes in different age groups share common biological determinants.

Expert opinion: use of valproate in girls and women of childbearing potential with epilepsy: recommendations and alternatives based on a review of the literature and clinical experience-a European perspective

Valproate is a broad-spectrum antiepileptic drug (AED) of particular interest in pediatric epilepsy syndromes and idiopathic generalized epilepsy, as it is relatively more effective in these syndromes than other AEDs. In 2018, the European Medicines Agency introduced new restrictions on the use of valproate in girls and women of childbearing potential to avoid exposure during pregnancy. The strengthening of existing restrictions sparked controversy and debate among patients and the medical community. The high prevalence of epilepsy syndromes amenable to valproate treatment in women of childbearing age and the little information available on the teratogenic potential of alternative treatments have created uncertainty on how to manage these patients. In this consensus statement, based on a review of the literature and the clinical experience of a panel of European epilepsy experts, we present general recommendations for the optimal clinical management of AED treatment in girls, women of childbearing potential, and pregnant women across the different epilepsy syndromes.

The Role of EEG in the Erroneous Diagnosis of Epilepsy

Errors in diagnosis are relatively common in medicine and occur in all specialties. The consequences can be serious for both patients and physicians. Errors in neurology are often because of the overemphasis on 'tests' over the clinical picture. The diagnosis of epilepsy in general is a clinical one and is typically based on history. Epilepsy is more commonly overdiagnosed than underdiagnosed. An erroneous diagnosis of epilepsy is often the result of weak history and an 'abnormal' EEG. Twenty-five to 30% of patients previously diagnosed with epilepsy who did not respond to initial antiepileptic drug treatment do not have epilepsy. Most patients misdiagnosed with epilepsy turn out to have either psychogenic nonepileptic attacks or syncope. Reasons for reading a normal EEG as an abnormal one include over-reading normal variants or simple fluctuations of background rhythms. Reversing the diagnosis of epilepsy is challenging and requires reviewing the 'abnormal' EEG, which can be difficult. The lack of mandatory training in neurology residency programs is one of the main reasons for normal EEGs being over-read as abnormal. Tests (including EEG) should not be overemphasized over clinical judgment. The diagnosis of epilepsy can be challenging, and some seizure types may be underdiagnosed. Frontal lobe hypermotor seizures may be misdiagnosed as psychogenic events. Focal unaware cognitive seizures in elderly maybe be blamed on dementia, and ictal or interictal psychosis in frontal and temporal lobe epilepsies may be mistaken for a primary psychiatric disorder.

Community-informed connectomics of the thalamocortical system in generalized epilepsy

OBJECTIVE

To study the intrinsic organization of the thalamocortical circuitry in patients with generalized epilepsy with tonic-clonic seizures (GTCS) via resting-state fMRI (rs-fMRI) connectome analysis and to evaluate its relation to drug response.

METHODS

In a prospectively followed-up sample of 41 patients and 27 healthy controls, we obtained rs-fMRI and structural MRI. After 1 year of follow-up, 27 patients were classified as seizure-free and 14 as drug-resistant. We examined connectivity within and between resting-state communities in cortical and thalamic subregions. In addition to comparing patients to controls, we examined associations with seizure control. We assessed reproducibility in an independent cohort of 21 patients.

RESULTS

Compared to controls, patients showed a more constrained network embedding of the thalamus, while frontocentral neocortical regions expressed increased functional diversity. Findings remained significant after regressing out thalamic volume and cortical thickness, suggesting independence from structural alterations. We observed more marked network imbalances in drug-resistant compared to seizure-free patients. Findings were similar in the reproducibility dataset.

CONCLUSIONS

Our findings suggest a pathoconnectomic mechanism of generalized epilepsy centered on diverging changes in cortical and thalamic connectivity. More restricted thalamic connectivity could reflect the tendency to engage in recursive thalamocortical loops, which may contribute to hyperexcitability. Conversely, increased connectional diversity of frontocentral networks may relay abnormal activity to an extended bilateral territory. Network imbalances were observed shortly after diagnosis and related to future drug response, suggesting clinical utility.

Role of observational studies in supporting extrapolation of efficacy data from adults to children with epilepsy - A systematic review of the literature using lacosamide as an example

Extrapolation of efficacy data from adults to children is accepted for focal epilepsy - the antiepileptic drug, lacosamide, has been approved for the treatment of children ≥4 years of age on this basis. Since many small-scale, open-label studies are reported in the literature before approval, a systematic review was conducted to ascertain whether results of these could be used to support extrapolation in epilepsy in the future. In the absence of randomised trials, a second analysis was conducted for reports on lacosamide use in adults with generalized epilepsies. Twenty-seven articles were included in the paediatric qualitative synthesis, and 14 in the adult. Paediatric studies were analysed separately based on seizure type: focal, generalised and mixed. In focal epilepsy, safety and seizure-related findings mirrored those observed in the adult Phase II/III trials, supporting the feasibility of data extrapolation. Few studies reported outcomes in children with epilepsies associated with generalised seizures, and those that included children with different seizure types, mostly did not provide results separately. Lacosamide treatment appeared beneficial for children and adults experiencing tonic-clonic and myoclonic seizures. Reports of seizure aggravation were inconsistent and, in many cases, could not be clearly attributed to lacosamide. Given the absence of sufficient data, evidence for the feasibility of extrapolation was not as clear-cut as it was in focal epilepsy. These results highlight the complexities of conducting trials in the generalised epilepsy setting, and the importance of studies in the real-life setting and of analysing efficacy data per generalized seizure type and syndrome.

Computer modelling of connectivity change suggests epileptogenesis mechanisms in idiopathic generalised epilepsy

Patients with idiopathic generalised epilepsy (IGE) typically have normal conventional magnetic resonance imaging (MRI), hence diagnosis based on MRI is challenging. Anatomical abnormalities underlying brain dysfunctions in IGE are unclear and their relation to the pathomechanisms of epileptogenesis is poorly understood.

In this study, we applied connectometry, an advanced quantitative neuroimaging technique for investigating localised changes in white-matter tissues in vivo. Analysing white matter structures of 32 subjects we incorporated our in vivo findings in a computational model of seizure dynamics to suggest a plausible mechanism of epileptogenesis.

Patients with IGE have significant bilateral alterations in major white-matter fascicles. In the cingulum, fornix, and superior longitudinal fasciculus, tract integrity is compromised, whereas in specific parts of tracts between thalamus and the precentral gyrus, tract integrity is enhanced in patients. Combining these alterations in a logistic regression model, we computed the decision boundary that discriminated patients and controls. The computational model, informed with the findings on the tract abnormalities, specifically highlighted the importance of enhanced cortico-reticular connections along with impaired cortico-cortical connections in inducing pathological seizure-like dynamics.

We emphasise taking directionality of brain connectivity into consideration towards understanding the pathological mechanisms; this is possible by combining neuroimaging and computational modelling. Our imaging evidence of structural alterations suggest the loss of cortico-cortical and enhancement of cortico-thalamic fibre integrity in IGE. We further suggest that impaired connectivity from cortical regions to the thalamic reticular nucleus offers a therapeutic target for selectively modifying the brain circuit for reversing the mechanisms leading to epileptogenesis.

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Significant focal alterations along major white-matter fascicles in IGE patients are characterised.

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Increased white matter integrity found in thalamo-cortical connections.

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Decreased white matter integrity found in cortico-cortical connections.

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Disease mechanism is investigated by combining the neuroimaging findings with a dynamical model of seizure activity.

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Model implicates cortical projections to the thalamic reticular nucleus in IGE.

Lacosamide for uncontrolled primary generalized tonic-clonic seizures: An open-label pilot study with 59-week extension

OBJECTIVE

Assess the safety of adjunctive lacosamide for the treatment of uncontrolled primary generalized tonic-clonic seizures in patients (16-65 years) with primary generalized (genetic) epilepsy (PGE).

METHODS

An open-label pilot safety study (SP0961; NCT01118949), comprising 12 weeks' historical baseline, 4 weeks' prospective baseline, 3 weeks' titration (target: 400mg/day adjunctive lacosamide) and 6 weeks' maintenance. Patients who continued to the extension study (SP0962; NCT01118962) then received ≤59 weeks of flexible treatment (100-800mg/day lacosamide with flexible dosing of concomitant antiepileptic drugs). The primary outcomes for SP0961 were the mean change (±standard deviation) in absence seizure or myoclonic seizure days per 28days from prospective baseline to maintenance; for SP0962, the incidence of treatment-emergent adverse events (TEAEs) and withdrawals because of TEAEs.

RESULTS

Of the 49 patients who enrolled, 40 (82%) completed the pilot study and 9 discontinued (5 because of adverse events). Of the 39 patients who continued to the extension study, 10 discontinued (2 owing to TEAEs) and 29 (74%) completed the study. During the pilot study, patients reported a reduction in mean (±standard deviation) absence and myoclonic seizure days per 28days (-0.37±4.80, -2.19±5.80). Reductions were also observed during the extension study (-2.38±5.54, -2.78±6.43). Five patients in SP0961 and 2 patients in SP0962 experienced TEAEs of new or increased frequency of absence seizures or myoclonic seizures. The most common TEAEs during SP0961 were dizziness (39%) and nausea (27%), and during SP0962 were dizziness (26%) and upper respiratory tract infection (26%).

CONCLUSIONS

The safety profile of adjunctive lacosamide was similar to that previously published. Adjunctive lacosamide did not systematically worsen absence or myoclonic seizures, and appears to be well tolerated in patients with PGE.

Choice of Antiepileptic Drugs in Idiopathic Generalized Epilepsy: UAE Experience

We retrospectively reviewed the electroencephalogram (EEG) reports of patients at our EEG lab from the years 2005–2010 to identify patients referred from the epilepsy clinic, with a confirmed diagnosis of idiopathic generalized epilepsy (IGE) by EEG criteria. We sought to report our experience in UAE of how often patients with IGE are placed on nonspecific antiepileptic drugs (AEDs) before being evaluated at an epilepsy referral clinic. 109 patients with a confirmed diagnosis of IGE based on EEG criteria were identified. When initially seen, 32.11% were taking a broad-spectrum (specific) AED only, 25.69% were taking a narrow-spectrum (nonspecific) AED, and 15.59% were placed on various combinations. Of the total patients who were receiving nonspecific AEDs, 35.71% were seizure-free and 64.28% were poorly controlled accounting for “pseudointractability status.” When converted to broad-spectrum (specific) AEDs, 50% became well controlled. Furthermore, 26.6% of patients, who were previously on no AED prior to the clinic visit, became well controlled once placed on specific AED.

Retention rates of levetiraceram in Chinese children and adolescents with epilepsy

BACKGROUND

Levetiracetam (Lev) is a new antiepileptic drugs, proved to be effective and tolerance in regulatory trials, but these controlled trials do not always predict how useful a drug will be in day to day clinical practice, Retention rates can provide a better indication of efficacy and tolerability in everyday use.

METHODS

Totally 124 patients with more than 3 months disease course were enrolled in the study from June 2007 to December 2007. The LEV dose ranged from 10 to 60 mg/kg per day. Follow up visit were performed at 6 months, 12 months, 24 months and 36 months, and treatment effects, adverse effects were recorded.

RESULTS

The LEV retention rates at 6, 12, 24, and 36 months were 93.5% (116/124), 84.7% (105/124), 65.3% (81/124), and 58.9% (73/124), respectively. The predominant causes of withdrawal were lack of efficacy (62.7%) and serious adverse effects (17.6%). In addition, 48.6% (51/105), 60.5% (49/81) and 72.6% (53/73) patients were seizure-free for 12 months, 24 months and 36 months, respectively. In this study, 75 (60.5%) patients experienced at least one side effect. The most common side effects observed were irritability 38.7% (29/75), somnolence 17.3% (13/75), learning disability 16.0% (12/75), anorexia 17.3% (13/75), somnipathy 13.3% (10/75), and abnormal behavior 13.3% (10/75).

CONCLUSIONS

Our study revealed the high retention rate of LEV in Chinese children and adolescents with epilepsy.

Die differentielle Validität neuropsychologischer Testverfahren zum Nachweis nicht-authentischer Störungen

Ziel dieser Studie ist es, die Eignung unterschiedlicher neuropsychologischer Verfahren zur Diagnostik von nicht-authentischen Störungen zu ermitteln. Darüber hinaus soll untersucht werden, ob Beschwerdenvalidierungstests (BVT) eine höhere Validität gegenüber anderen neuropsychologischen Verfahren zum Nachweis von nicht authentischen Störungen aufweisen. Dazu wurden 59 Probanden untersucht, die zwischen 2003 bis 2013 forensisch-neuropsychologisch begutachtet wurden. Sie wurden hinsichtlich ihrer Authentizität ihrer neuropsychologischen Beschwerden beurteilt. Neben neuropsychologischen Tests wurden auch BVT eingesetzt. Es zeigte sich, dass die BVT hoch signifikant mit der gutachterlichen Gesamtbeurteilung korrelieren. Zwischen den neuropsychologischen Standardverfahren und der gutachterlichen Gesamtbeurteilung konnten keine signifikanten Zusammenhänge nachgewiesen werden. Es sind demnach nur diejenigen Verfahren, die speziell für den Nachweis von nicht-authentischen Störungen entwickelt worden, dazu geeignet, die Authentizität der Beschwerdenschilderung zu messen.

Age of onset in idiopathic (genetic) generalized epilepsies: clinical and EEG findings in various age groups

PURPOSE

The prevalence and differences of idiopathic (genetic) generalized epilepsies (IGEs) with atypical age of onset compared to classical IGEs is a matter of debate. We tried to determine the clinical and EEG characteristics of IGEs in various age groups.

METHODS

All patients with a clinical diagnosis of IGE were recruited at the outpatient epilepsy clinic at Shiraz University of Medical Sciences from 2008 through 2011. We subdivided the patients into four different age groups: 4 years of age and under, 5-11 years, 12-17 years, and finally, 18 years and above, at the time of their epilepsy onset. Syndromic diagnosis, sex ratio, seizure types and EEG findings were compared. Statistical analyses were performed using Pearson Chi square test.

RESULTS

2190 patients with epilepsy were registered. 442 patients (20.2%) were diagnosed as having IGEs. Age of seizure onset was 12.4±6.9 years. The peak age of onset had a bimodal appearance. Sixty-seven patients (15.2%) were four years and under at the time of the onset of their disease, 112 persons (25.3%) were 5-11 years, 197 people (44.6%) were 12-17 years of age, and 66 patients (14.9%) had 18 years and above at the onset of their epilepsy. The sex ratio was significantly different between patients in group one compared to groups three and four. All expected seizure types (i.e., generalized tonic-clonic, absence or myoclonic seizures) and all expected EEG abnormalities were observed among all age groups, despite some differences in their prevalence.

CONCLUSION

Although IGE syndromes are often age dependent and most of them appear within the first two decades of life, adult-onset IGE is not rare. Presentation of IGEs could be different in various age groups, but these differences do not offer pathognomonic or characteristic features at any age.

The adolescent or adult with generalized tonic-clonic seizures

Primary and secondary generalized tonic-clonic seizures (GTCs) together constitute up to 50% of adolescent and adult patients with epilepsy as diagnosed by history and EEG. Syncope and psychogenic nonepileptic seizures are major differential diagnoses and must be carefully excluded in therapy-resistant cases. Individual episodes can have up to seven phases in secondarily generalized GTCs. The distinction between primary and secondary GTCs depends mainly on history and EEG, and yield can be improved with sleep deprivation or overnight recording. Epilepsies with primary or unclassified GTCs can respond to any one of the five broad-spectrum antiepileptic drugs (AEDs): valproate, lamotrigine, levetiracetam, topiramate and zonisamide. Unless a focal onset is clearly confirmed, a sodium-channel blocking AED should not be used in the initial treatment of these conditions.

Genetic variations and associated pathophysiology in the management of epilepsy

The genomic era has enabled the application of molecular tools to the solution of many of the genetic epilepsies, with and without comorbidities. Massively parallel sequencing has recently reinvigorated gene discovery for the monogenic epilepsies. Recurrent and novel copy number variants have given much-needed impetus to the advancement of our understanding of epilepsies with complex inheritance. Superimposed upon that is the phenotypic blurring by presumed genetic modifiers scattering the effects of the primary mutation. The genotype-first approach has uncovered associated syndrome constellations, of which epilepsy is only one of the syndromes. As the molecular genetic basis for the epilepsies unravels, it will increasingly influence the classification and diagnosis of the epilepsies. The ultimate goal of the molecular revolution has to be the design of treatment protocols based on genetic profiles, and cracking the 30% of epilepsies refractory to current medications, but that still lies well into the future. The current focus is on the scientific basis for epilepsy. Understanding its genetic causes and biophysical mechanisms is where we are currently positioned: prizing the causes of epilepsy "out of the shadows" and exposing its underlying mechanisms beyond even the ion-channels.

Voxel-based morphometry and epilepsy

Voxel-based morphometry is an automated technique for MRI analyses, developed to study differences in brain morphology and frequently used to study patients with diverse disorders. In epilepsy, it has been used to investigate areas with reduction or increase of gray and white matter, in different syndromes (i.e., temporal lobe epilepsy, focal cortical dysplasia and generalized epilepsies). In temporal lobe epilepsy, voxel-based morphometry showed gray/white matter atrophy extending beyond the atrophic hippocampus. These widespread abnormalities have been associated with seizure frequency, epilepsy duration, incidence of precipitating factors, cognitive dysfunction and surgical outcome. In generalized epilepsies, gray matter abnormalities were identified mainly in the thalamus and frontal cortex, reinforcing the role of the thalamocortical network in the mechanisms of generalized seizures.

Seizure aggravation by antiepileptic drugs

Seizure aggravation by antiepileptic drugs (AEDs) is an overestimated phenomenon. While it undoubtedly occurs, the quality of evidence in most published reports is poor. Although seizure aggravation can be examined in clinical trials in the same way as seizure improvement, this is rarely done. Before concluding that an increase in seizures after the introduction of a new drug represents pharmacodynamic aggravation, alternative explanations should be explored. These include spontaneous fluctuation of seizure frequency, the presence of known seizure aggravators (such as sleep deprivation, alcohol, and psychotropic medications), progression of epilepsy, the development of drug resistance, and replacement of a partially effective drug with a less effective drug. The risk of incorrectly blaming a drug for a deterioration in seizures can be minimized by establishing baseline seizure frequency over a period long enough to encompass the extremes of seizure fluctuation and by educating the patient that a temporal relationship may not be a causal relationship. When feasible, the patient should continue the drug long enough to establish if the deterioration is transient. If the drug is stopped, rechallenge should be considered. The risk of seizure aggravation can be minimized by accurate diagnosis of the epilepsy syndrome and appropriate choice of AED.

Vagus nerve stimulation

Vagus nerve stimulation (VNS) is a key tool in the treatment of patients with medically refractory epilepsy. Although the mechanism of action of VNS remains poorly understood, this modality is now the most widely used nonpharmacological treatment for drug-resistant epilepsy. The goal of this work is to review the history of VNS and provide information on recent advances and applications of this technology.

Levetiracetam as add-on therapy for idiopathic generalized epilepsy syndromes with onset during adolescence: analysis of two randomized, double-blind, placebo-controlled studies

PURPOSE

To assess the efficacy and tolerability of adjunctive levetiracetam in idiopathic generalized epilepsy (IGE) syndromes with onset during adolescence: juvenile absence epilepsy (JAE), juvenile myoclonic epilepsy (JME), and generalized tonic-clonic seizures on awakening (GTCSA).

METHODS

Supplementary analysis of two double-blind, placebo-controlled trials. Patients received levetiracetam (target dose: adults 3000 mg/day; children 60 mg/kg/day; n=15 JAE, 78 JME, and 22 GTCSA) or placebo (n=12 JAE, 89 JME, and 27 GTCSA) for 16-24 weeks (including 4-week uptitration) in addition to 1-2 antiepileptic drugs.

RESULTS

Responder rates (> or =50%) were significantly higher for levetiracetam versus placebo for JAE (53.3% vs. 25.0%; p=0.004), JME (61.0% vs. 24.7%; p<0.001), and GTCSA (61.9% vs. 29.6%; p=0.024). Seizure freedom rates were significantly higher for levetiracetam versus placebo for JME (20.8% vs. 3.4%; p=0.002); differences between treatment groups for JAE (33.3% vs. 8.3%; p=0.15) and GTCSA (23.8% vs. 11.1%; p=0.45) appeared to be clinically relevant, but did not reach statistical significance. The most frequent adverse events on levetiracetam were headache (levetiracetam 16.8% and placebo 14.8%) and somnolence (levetiracetam 9.7% and placebo 3.9%).

CONCLUSIONS

Adjunctive levetiracetam was well tolerated and provided effective seizure control over 16-24 weeks in patients with insufficiently controlled IGE syndromes with onset during adolescence (JAE, JME, and GTCSA), supporting levetiracetam's broad spectrum of efficacy.

Characteristics of generalised epileptiform activity

OBJECTIVE

To study the age-related occurrence of specific features of generalised epileptiform activity (GEA), their correlation with EEG background activity (BA), and their internal correlation.

METHODS

17,723 consecutive routine EEGs from 12,511 patients were annotated and categorised into a database. The first EEG containing GEA from all 325 patients with such activity were selected and categorised for GEA features. The BA was studied in multivariable fractional polynomial regression models including intervening variables. The GEA features were studied in similar models for age-dependency and internal correlation.

RESULTS

High GEA-amplitude and low GEA-frequency correlated with BA slowing. The occurrence of 'irregular spike/sharp slow wave' pattern increased with age (p=0.003). Hyperventilation sensitivity was not age-related. There was no correlation between hyperventilation sensitivity and photoparoxysmal response. The age-related probability for specific GEA-types was established.

CONCLUSIONS

High GEA-amplitude and low GEA-frequency correlate with BA slowing, indicating cerebral cortical dysfunction. Hyperventilation sensitivity and photoparoxysmal response independently increase the yield of EEG. There is no age-dependency for hyperventilation sensitivity showing that an upper age threshold for hyperventilation provocation is inappropriate.

SIGNIFICANCE

The results extend our understanding of GEA and help the electroencephalographer in weighing the various GEA components.

Tratamento das epilepsias generalizadas idiopáticas

As epilepsias generalizadas idiopáticas (EGIs) correspondem a um-terço de todas as epilepsias. Apesar desta elevada freqüência, as EGIs permanecem pouco reconhecidas. As características clínicas são fundamentais para o diagnóstico. Neste grupo de epilepsias, todos os tipos de crises generalizadas podem ocorrer especialmente as crises tônico-clônicas generalizadas, as crises mioclônicas e as crises de ausência. O eletroencefograma é bastante sugestivo do diagnóstico quando evidencia os típicos complexos espículas ou poliespículas-onda lenta, generalizados, simétricos e com atividade de base normal. De acordo com o tipo de crise predominante e com a idade de início das crises, as EGIs são divididas em subsíndromes. A importância do diagnóstico preciso está relacionada com a elevada porcentagem de indivíduos livre de crises quando tratados com a medicação antiepiléptica apropriada. Por outro lado, o uso de algumas medicações antiepilépticas como carbamazepina e fenitoína pode exacerbar as crises ou até mesmo induzir estado de mal epiléptico em determinadas subsíndromes. Neste artigo, revisamos as principais medicações antiepilépticas utilizadas no tratamento das EGIs bem como alguns aspectos práticos no tratamento das subsíndromes mais freqüentes.

Trends in the use of vagus nerve stimulation for epilepsy: analysis of a nationwide database

Object

Vagus nerve stimulation (VNS) plays a significant role in the treatment of intractable epilepsy. The goal of this study was to analyze trends in the use of VNS for epilepsy in the US by using a nationwide database.

Methods

Data for patients undergoing VNS were obtained from the nationwide inpatient sample for the years 1998–2005. Trends regarding number of procedures, length of stay (LOS), hospital charges, patient sex, and payer information were retrieved and analyzed.

Results

The number of VNS procedures for epilepsy increased between 1998 and 2003 but decreased in the subsequent 2 years. The LOS and hospital charges showed yearly increases. Female patients underwent VNS implantation more than males did, and most procedures were performed in the 18- to 64-year-old age group. The combination of Medicare and Medicaid provided most of the funding for VNS from 2002 through 2005. The VNS procedures were performed mostly in teaching hospitals.

Conclusions

Trends from a national database reveal consistent use of VNS for intractable epilepsy. Greater use of the procedure appears to be reflected in the female population, and the procedure has been performed most often at tertiary care teaching hospitals, where a comprehensive evaluation for all forms of therapy is arguably best able to target appropriate patients for appropriate therapies. With the recent application of VNS to target populations without epilepsy, such as patients with refractory depression, the trend of continued use of this treatment for epilepsy appears likely.

Focal EEG findings in juvenile absence syndrome and the effect of antiepileptic drugs

The presence of focal EEG abnormalities in juvenile absence syndrome (JAS) may cause it to be misdiagnosed as focal epilepsy. The purpose of our study was to determine the presence of focal EEG abnormalities in patients with JAS and to ascertain whether some clinical features or antiepileptic drugs (AEDs) have an effect on focality. Serial EEGs of 52 consecutive patients with JAS were retrospectively analyzed. The patients were divided into two groups according to whether they were treated with valproic acid and/or lamotrigine (VA-LTG) or not during the times of these EEG recordings. The relationship between the presence of EEG focality and the use of AEDs in addition to other risk factors was examined. Two or three consecutive EEGs (total 100) of the 52 patients were evaluated. Among these, the rates of focal EEG abnormalities were 18%, 36%, and 25% during the follow-up EEGs without AEDs (5/27) and first (16/45) and second EEGs (7/28) with AEDs, respectively. The last two EEGs showed a tendency towards a higher proportion of EEG focality in patients who received other AEDs (47%-45%) compared with those that received VA-LTG (13%-12%). The proportion of JAS patients with focal EEG findings in serial EEGs tended to decrease with an increasing rate of VA-LTG use. As a hypothetical explanation, changes in EEG focality may reflect the effect of AEDs other than VA and/or LTG, in addition to a developing hyperexcitable cortical area.

Neuropsychological deficits in childhood epilepsy syndromes

Seizure disorders are relatively common in childhood, and the International League Against Epilepsy (ILAE) provides a hierarchical classification system to define seizure types. At the final level of classification, specific epilepsy syndromes are defined that represent a complex of signs and symptoms unique to an epilepsy condition. The present review discusses the issues related to several of these epilepsy syndromes in childhood, including those classified as generalized idiopathic epilepsies (e.g., childhood absence epilepsy, juvenile absence epilepsy, juvenile myoclonic epilepsy), focal epilepsies (benign rolandic epilepsy, occipital epilepsy, temporal lobe epilepsy, frontal lobe epilepsy) and the "epileptic encephalopathies," including Dravet's Syndrome, West Syndrome, Lennox-Gastaut Syndrome, Myoclonic Astatic Epilepsy, and Landau-Kleffner Syndrome. For each syndrome, the epidemiology, clinical manifestations, treatments, and neuropsychological findings are discussed.

Neuropsychological deficits in childhood epilepsy syndromes

Seizure disorders are relatively common in childhood, and the International League Against Epilepsy (ILAE) provides a hierarchical classification system to define seizure types. At the final level of classification, specific epilepsy syndromes are defined that represent a complex of signs and symptoms unique to an epilepsy condition. The present review discusses the issues related to several of these epilepsy syndromes in childhood, including those classified as generalized idiopathic epilepsies (e.g., childhood absence epilepsy, juvenile absence epilepsy, juvenile myoclonic epilepsy), focal epilepsies (benign rolandic epilepsy, occipital epilepsy, temporal lobe epilepsy, frontal lobe epilepsy) and the "epileptic encephalopathies," including Dravet's Syndrome, West Syndrome, Lennox-Gastaut Syndrome, Myoclonic Astatic Epilepsy, and Landau-Kleffner Syndrome. For each syndrome, the epidemiology, clinical manifestations, treatments, and neuropsychological findings are discussed.

Management of breakthrough seizures in the emergency department: continuity of patient care

BACKGROUND

Epilepsy is a chronic disorder requiring long-term management. Communication between emergency physicians, neurologists, and primary care physicians (PCPs) is especially critical for the continuity of care for patients who present in an emergency department (ED) with a breakthrough seizure. Therefore, maximizing communication between the emergency physician and the PCP is of the utmost importance. The emergency physician, who is on the front line, must gather the information necessary to identify the underlying cause of the seizure and decide whether the pharmaceutical management must be changed.

SCOPE

This paper provides a clinical commentary on issues to consider when managing breakthrough seizures in the ED, to inform and facilitate communication between emergency physicians, consulting neurologists, and PCPs.

CONCLUSIONS

Clinical management decisions, especially when considering adjustment in an antiepileptic drug (AED) regimen, are often best made in coordination with a consulting neurologist. Increasing emergency physicians' comfort level regarding the use of newer-generation AEDs can improve the dialogue between the emergency physician and neurologist and the dialogue with the patient. Understanding the risks and benefits of the newer AEDs will assist the emergency physician in clinical decision making and, it is hoped, improve clinical outcomes. To preserve continuity of patient care, a patient's treating physician should be notified of all the particulars of the ED visit, and an appointment should be scheduled at the time of discharge for follow-up evaluation.

Is vagus nerve stimulation a treatment option for patients with drug-resistant idiopathic generalized epilepsy?

BACKGROUND

The value of vagus nerve stimulation (VNS) for treating patients with drug-resistant idiopathic generalized epilepsy (IGE) is not well documented.

PATIENTS AND METHODS

Twelve patients (2 males, 10 females) with a mean age of 31 years (11-48 years) and with drug-resistant IGE had VNS implanted in the period 1995-2006. All had generalized seizures documented by video-electroencephalogram. Mean follow-up period was 23 months (9-54 months).

RESULTS

There was a total seizure reduction of 61% (P = 0.0002). There was 62% reduction of generalized tonic-clonic seizures (P = 0.0020), 58% of absences (P = 0.0003) and 40% of myoclonic seizures (P = 0.0156). Eight patients were considered responders (>50% seizure reduction); two of these patients became seizure-free. Five out of seven patients with juvenile myoclonic epilepsy were responders. At the last follow-up visit, the patients had reduced the anti-epileptic drug (AED) usage from an average of 2.3 to 1.7 AED per patient (P = 0.0625). Two patients are currently being treated with VNS therapy only. Nine patients reported side effects, which were mostly mild and tended to diminish over time.

CONCLUSION

Our results indicate that adjunctive VNS therapy is a favourable treatment option for patients with drug-resistant IGE. Rapid cycling seems worth trying in some of the non-responders.

Channelopathies in idiopathic epilepsy

Approximately 70% of all patients with epilepsy lack an obvious extraneous cause and are presumed to have a predominantly genetic basis. Both familial and de novo mutations in neuronal voltage-gated and ligand-gated ion channel subunit genes have been identified in autosomal dominant epilepsies. However, patients with dominant familial mutations are rare and the majority of idiopathic epilepsy is likely to be the result of polygenic susceptibility alleles (complex epilepsy). Data on the identity of the genes involved in complex epilepsy is currently sparse but again points to neuronal ion channels. The number of genes and gene families associated with epilepsy is rapidly increasing and this increase is likely to escalate over the coming years with advances in mutation detection technologies. The genetic heterogeneity underlying idiopathic epilepsy presents challenges for the rational selection of therapies targeting particular ion channels. Too little is currently known about the genetic architecture of the epilepsies, and genetic testing for the known epilepsy genes remains costly. Pharmacogenetic studies have yet to explain why 30% of patients do not respond to the usual antiepileptic drugs. Despite this, the recognition that the idiopathic epilepsies are a group of channelopathies has, to a limited extent, explained the therapeutic action of the common antiepileptic drugs and has assisted clinical diagnosis of some epilepsy syndromes.

Repeated Intracarotid Amobarbital Tests

RATIONALE

Our goal was to determine the frequency of repeated intracarotid amobarbital test (IAT) at our center and to estimate the retest reliability of the IAT for both language and memory lateralization.

METHODS

A total of 1,249 consecutive IATs on 1,190 patients were retrospectively reviewed for repeat tests.

RESULTS

In 4% of patients the IAT was repeated in order to deliver satisfactory information on either language or memory lateralization. Reasons for repetition included obtundation and inability to test for memory lateralization, inability to test for language lateralization, no hemiparesis during first test, no aphasia during first test, atypical vessel filling, and bleeding complications from the catheter insertion site. Language lateralization was reproduced in all but one patient. Repeated memory test results were less consistent across tests, and memory lateralization was unreliable in 63% of the patients.

DISCUSSION

In spite of test limitations by a varying dose of amobarbital, crossover of amobarbital from one side to the other, testing of both hemispheres on the same day, practice effects, unblinded observers, fluctuating cooperation of the patients, and a biased sample of patients language lateralization was reproduced in all but one patient. In contrast, repeated memory test results were frequently contradictory. Memory results on IAT therefore seem much less robust than the results of language testing. Gain of reliable information versus the risks of complications and failed tests has to be considered when a patient is subjected to an IAT.