Natural history of absence epilepsy in children

Efficacy of vagus nerve stimulation in managing drug-resistant absence epilepsy syndromes

PURPOSE

Around 11% of patients with absence epilepsy develop drug-resistant absence epilepsy (DRAE), and are at increased risk for developing psychiatric and neurologic comorbidities. Current therapeutic options for DRAE are limited. The purpose of this study was to assess the efficacy of vagus nerve stimulation (VNS) in treating DRAE.

METHODS

Our institution maintains a database of patients who received VNS between 2010 and 2022. We identified DRAE patients who were <18 years of age at seizure onset, were electro-clinically diagnosed with an absence epilepsy syndrome (childhood absence, juvenile absence, or Jeavons Syndrome) by an epileptologist, and had normal brain imaging. The primary outcome measure was post-VNS absence seizure frequency.

RESULTS

Twenty-six patients (M/F:14/12) were identified. Median age at seizure onset was 7 years (IQR 4-10) and patients experienced seizures for 6 years (IQR 4.3-7.6) before VNS. After VNS, the median absence seizure frequency reduced to 1.5 days (IQR 0.1-3.5) per week from 7 days (IQR 7-7), a 66% reduction seizure frequency. VNS responder rate was 80%, and seven patients achieved seizure freedom. There was no significant effect on VNS efficacy between the time from DRAE diagnosis to VNS placement (p = 0.067) nor the time from first seizure onset to VNS implant (p = 0.80). The median follow-up duration was 4.1 years (IQR 2.4-6.7), without any significant association between follow-up duration and VNS efficacy (r2=0.023) CONCLUSIONS: VNS is effective in managing DRAE. The responder rate was 80%; seizure improvement was independent of age at both seizure onset and latency to VNS after meeting DRAE criteria.

Understanding Sunflower syndrome: Results of an online questionnaire

OBJECTIVE

To characterize the clinical phenotype, treatments, and impact on quality of life of Sunflower syndrome.

METHODS

A 138-question survey was created focusing on seizure description, disease course, treatment history, medical history, family history, and aspects of quality of life of individuals with Sunflower syndrome. The survey was administered to individuals with Sunflower syndrome who experience hand waving episodes (HWE) and/or their caregivers via Research Electronic Data Capture (REDCap).

RESULTS

Sixty-eight responses were included in analysis. Seventy-one% of respondents were female. The mean age of participants was 13.6 years, with 84% of respondents under the age of 18. The average age of onset of HWE was 6.7 years. HWE frequency varied from a few episodes per week to multiple episodes per hour. Sixty-two% of participants experienced other seizure types. Participants had been on an average of 1.9 anti-seizure medications with varying efficacy. Other methods to reduce HWE included wearing a hat or sunglasses, hand holding, using special tinted lenses, and avoiding the sun and bright lights. Sixty-nine% of participants reported anxiety or depression related to their epilepsy, and 65% said their HWE affected their social life.

SIGNIFICANCE

Sunflower syndrome is a highly stereotyped, refractory epilepsy which significantly impacts the lives of affected individuals. It remains underrecognized and poorly understood. These results characterize Sunflower syndrome in a large population of affected individuals and provides a basis for future research to better understand the epilepsy and improve clinical care.

Therapeutic Outcomes and Prognostic Factors in Childhood Absence Epilepsy

BACKGROUND AND PURPOSE

Childhood absence epilepsy (CAE) is one of the most common types of pediatric epilepsy. It is generally treated with ethosuximide (ESM), valproic acid (VPA), or lamotrigine (LTG), but the efficacy and adverse effects of these drugs remain controversial. This study compared initial therapy treatment outcomes, including VPA-LTG combination, and assessed clinical factors that may predict treatment response and prognosis.

METHODS

Sixty-seven patients with typical CAE were retrospectively enrolled at the Korea University Medical Center. We reviewed patients' clinical characteristics, including age of seizure onset, seizure-free interval, duration of seizure-free period, freedom from treatment failure, breakthrough seizures frequency, and electroencephalogram (EEG) findings.

RESULTS

The age at seizure onset was 7.9±2.7 years (mean±SD), and follow-up duration was 4.4±3.7 years. Initially, 22 children were treated with ESM (32.8%), 23 with VPA (34.3%), 14 with LTG (20.9%), and 8 with VPA-LTG combination (11.9%). After 48 months of therapy, the rate of freedom from treatment failure was significantly higher for the VPA-LTG combination therapy than in the three monotherapy groups (p=0.012). The treatment dose administrated in the VPA-LTG combination group was less than that in the VPA and LTG monotherapy groups. The shorter interval to loss of 3-Hz spike-and-wave complexes and the presence of occipital intermittent rhythmic delta activity on EEG were significant factors predicting good treatment response.

CONCLUSIONS

This study showed that low-dose VPA-LTG combination therapy has a good efficacy and fewer side effects than other treatments, and it should thus be considered as a firstline therapy in absence epilepsy.

Are there really "epileptogenic" mechanisms or only corruptions of "normal" plasticity?

Plasticity in the nervous system, whether for establishing connections and networks during development, repairing networks after injury, or modifying connections based on experience, relies primarily on highly coordinated patterns of neural activity. Rhythmic, synchronized bursting of neuronal ensembles is a fundamental component of the activity-dependent plasticity responsible for the wiring and rewiring of neural circuits in the CNS. It is therefore not surprising that the architecture of the CNS supports the generation of highly synchronized bursts of neuronal activity in non-pathological conditions, even though the activity resembles the ictal and interictal events that are the hallmark symptoms of epilepsy. To prevent such natural epileptiform events from becoming pathological, multiple layers of homeostatic control operate on cellular and network levels. Many data on plastic changes that occur in different brain structures during the processes by which the epileptogenic aggregate is constituted have been accumulated but their role in counteracting or promoting such processes is still controversial. In this chapter we will review experimental and clinical evidence on the role of neural plasticity in the development of epilepsy. We will address questions such as: is epilepsy a progressive disorder? What do we know about mechanism(s) accounting for progression? Have we reliable biomarkers of epilepsy-related plastic processes? Do seizure-associated plastic changes protect against injury and aid in recovery? As a necessary premise we will consider the value of seizure-like activity in the context of normal neural development.

The prognosis of idiopathic generalized epilepsy

Prognosis describes the trajectory and long-term outcome of a condition. Most studies indicate a better prognosis in idiopathic generalized epilepsy (IGE) in comparison with other epilepsy syndromes. Studies looking at the long-term outcome of different IGE syndromes are relatively scant. Childhood absence epilepsy appears to have a higher rate of remission compared to juvenile absence epilepsy. In absence epilepsies, development of myoclonus and generalized tonic-clonic seizures predicts lower likelihood of remission. Although most patients with juvenile myoclonic epilepsy (JME) achieve remission on antiepileptic drug therapy, <20% appear to remain in remission without treatment. Data on the prognosis of other IGE syndromes are scarce. There are contradictory findings reported on the value of electroencephalography as a predictor of prognosis. Comparisons are made difficult by study heterogeneity, particularly in methodology and diagnostic criteria.

Antiepileptic drugs withdrawal in patients with idiopathic generalized epilepsy

OBJECTIVES

To estimate the risk of seizure recurrence after antiepileptic drugs (AED) withdrawal and to identify related predictive features in patients with idiopathic generalized epilepsy (IGE) commencing at developing age (up to 16 year).

METHODS

Medical records of consecutive patients with IGE from two refferal hospitals were evaluated between 2001 and 2009. Inclusion criteria were clinical and EEG diagnosis of IGE and follow up for at least 2years after the AED withdrawal. The cohort consisted of 59 patients (38 females, 21 males). Follow up after withdrawal lasted 2-10years (median 3) Time to seizure relapse and predictive factors were analyzed by survival methods.

RESULTS

There were 21 (35.6%) patients with childhood absence epilepsy (CAE), 11 (18.6%) with juvenile absence epilepsy (JAE), 10 (16.9%) with isolated primary GTC seizures, and 17 (28.8%) with juvenile myoclonic epilepsy (JME). The relapses occured in 23 (52.2%) patients: one (6.2%) with CAE, 4 (50%) with JAE, 8 (80%) with IGE with GTC seizures and all with JME. During the first 6 months 54.5% patients relapsed (20% during withdrawal), 63.6% within 12 months, 81.8% within18 months and 95.4% within 24 months after withdrawal. Female gender, age at onset of seizures, seizure types, EEG worsening during/after AED withdrawal and age at withdrawal were significantly associated with relapse risk according to univariate analysis. In multivariate analysis, retained significant factors were: seizure types and EEG worsening.

CONCLUSION

Diagnosis of the specific IGE syndrome strongly affects relapse rate: the lowest was in CAE, the highest in JME. Independent risk factors for seizure relapse were: seizure type and EEG worsening during and/or after withdrawal.

Lamotrigine monotherapy for newly diagnosed typical absence seizures in children

Purpose

To evaluate the efficacy, tolerability, and effects on behavior and psychosocial functioning of lamotrigine monotherapy in children with newly diagnosed typical absence seizures.

Patients and methods

Children meeting enrollment criteria (n = 54) received a confirmatory 24-h ambulatory electroencephalogram (EEG) and then entered a Escalation Phase of up to 20-weeks during which lamotrigine was titrated until seizures were controlled or maximum dose (10.2 mg/kg) was reached. Seizure freedom was assessed by diary review and clinic hyperventilation (clinic HV) and then confirmed by EEG with hyperventilation (HV/EEG). Patients who maintained seizure freedom for two consecutive weekly visits were entered into the Maintenance Phase (n = 30). Diary, clinic HV, and HV/EEG data were supplemented with 24-h ambulatory EEG at baseline and the ends of the Escalation and Maintenance Phases. Health outcome assessments were completed at screening and at the end of the Maintenance Phase.

Results

By the end of the Escalation Phase, seizure-free rates (responders) were 59% by seizure diary (n = 51), 56% by HV/EEG (n = 54) (primary endpoint), and 49% by 24-h ambulatory EEG (n = 49). During the Maintenance Phase, 89% (week 24) and 86% (week 32) remained seizure free by diary (n = 28), 78% by clinic HV (n = 27), and 81% by 24-h ambulatory EEG (n = 26). Seizure freedom was first observed beginning at the fifth week of the Escalation Phase. The most frequent adverse events were headache and cough. Health outcome scores were either improved or unchanged at the end of the Maintenance Phase.

Conclusions

Lamotrigine monotherapy results in complete seizure freedom in a substantial number of children with typical absence seizures. Lamotrigine was well tolerated in this study.

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.

Absence epilepsy in childhood: electroencephalography (EEG) does not predict outcome

Absence epilepsy is a form of generalized epilepsy commonly seen in children. The clinician is often presented with a patient whose electroencephalogram does not fit the typical absence pattern. The purpose of this study is to more closely examine both typical and atypical absence variants and their outcome. A retrospective chart review was performed on children diagnosed with absence epilepsy over the past 5 years at the University of Alberta. A total of 119 patients were reviewed. Patients were classified with typical or atypical absence seizures following International League Against Epilepsy criteria and electroencephalography (EEG) characteristics. Clinical seizure characteristics, magnetic resonance imaging (MRI), initial response to treatment, and outcome were examined. Seizure characteristics were similar in both the typical and atypical absence groups. Aura, complex automatisms, changes in tone, and incontinence were seen in both groups, although status epilepticus was found only in the atypical group. Associated comorbid conditions such as attention-deficit hyperactivity disorder (ADHD), learning disorders, and enuresis were found equally in both groups. Developmental delay was found more often in the atypical group. Of the typical group, 83% responded to an initial antiepileptic drug (either valproic acid or ethosuximide), whereas only 51% of the atypical group came under control. Remission at 2 years however, was similar between groups, with 76% of the typical group and 71% of the atypical group completely seizure free. Absence seizures in childhood, both typical and atypical, share similar clinical and electroencephalographic features and appear to be part of a continuum. Associated comorbid features such as ADHD, learning disorders, and developmental delay are also seen in both groups. The outcome for both types is excellent, although the atypical variants may be initially more difficult to control.

Thought disorder: A developmental disability in pediatric epilepsy

This study compared thought disorder (i.e., impaired use of language to formulate and organize thoughts) in 93 children with complex partial seizures (CPSs) and 56 children with primary generalized epilepsy with absence (PGE) and its relationship to age, seizure, cognitive, and linguistic variables. By the use of psychopathology, social competence, academic achievement, and school problem measures, the functional implications of thought disorder in these two groups were compared. When demographic variables were controlled for, there were no significant differences in thought disorder scores between the CPS and PGE groups. However, the profile of age, gender, seizure, and cognitive variables related to thought disorder differed in the CPS and PGE groups. Within each group, different aspects of thought disorder were associated with different seizure variables. Thought disorder was related to psychopathology, school problems, decreased academic achievement, and poor peer interaction in the CPS group, but with school problems in the PGE group. These findings suggest that CPS and PGE affect the normal maturation of children's discourse skills, albeit through different mechanisms. The relationship of thought disorder to behavioral, academic, and social problems implies that these discourse deficits are one component of the developmental disabilities or comorbidities associated with pediatric CPS and PGE.

Epilepsy Case Studies

Epilepsy is a common disorder affecting all age groups. Diagnosis depends on accurate eyewitness description and electroencephalography. Many genetic, metabolic, and structural perturbations of cortical function can cause seizures. MRI is the most important test for etiology. Medication selection is based on classification of seizure type and epilepsy syndrome, with consideration of patient age, gender, and comorbidities. Surgery is a good treatment for some patients who have medically refractory partial-onset seizures.

Seizures of idiopathic generalized epilepsies

Idiopathic generalized epilepsies (IGEs) comprise at least 40% of epilepsies in the United States, 20% in Mexico, and 8% in Central America. Here, we review seizure phenotypes across IGE syndromes, their response to treatment and advances in molecular genetics that influence nosology. Our review included the Medline database from 1945 to 2005 and our prospectively collected Genetic Epilepsy Studies (GENESS) Consortium database. Generalized seizures occur with different and similar semiologies, frequencies, and patterns, ages at onset, and outcomes in different IGEs, suggesting common neuroanatomical pathways for seizure phenotypes. However, the same seizure phenotypes respond differently to the same treatments in different IGEs, suggesting different molecular defects across syndromes. De novo mutations in SCN1A in sporadic Dravet syndrome and germline mutations in SCN1A, SCN1B, and SCN2A in generalized epilepsies with febrile seizures plus have unraveled the heterogenous myoclonic epilepsies of infancy and early childhood. Mutations in GABRA1, GABRG2, and GABRB3 are associated with absence seizures, while mutations in CLCN2 and myoclonin/EFHC1 substantiate juvenile myoclonic epilepsy as a clinical entity. Refined understanding of seizure phenotypes, their semiology, frequencies, and patterns together with the identification of molecular lesions in IGEs continue to accelerate the development of molecular epileptology.

Childhood Absence Epilepsy: Evolution and Prognostic Factors

PURPOSE

To evaluate how diagnostic criteria influence remission rates for patients with childhood absence epilepsy (CAE) and to assess clinical and EEG parameters as predictors of outcome.

METHODS

One hundred nineteen patients were diagnosed with CAE, according to International League Against Epilepsy (ILAE) classification criteria. They were subsequently evaluated according to stricter diagnostic criteria. Sixty-two subjects fulfilled these criteria as group 2; 57 did not and constituted group 1. Diagnostic parameters that prevented patients of group 1 from entering group 2, and variables such as sex, familial history of generalized epilepsy, and personal history of febrile convulsions also were tested as prognostic factors for terminal remission.

RESULTS

Compared with those in group 1, patients of group 2 had significantly higher rates of seizure control (95% vs. 77%), higher rates of terminal remission (82% vs. 51%), fewer generalized tonic-clonic seizures (8% vs. 30%), and shorter mean periods of treatment (2.2 vs. 3.8 years). Significantly fewer patients were receiving polytherapy in group 2 than in group 1 (11% vs. 47%), and fewer patients had seizure relapses at antiepileptic drug discontinuation (0 vs. 22%).

CONCLUSIONS

Remission rates of patients with CAE are greatly influenced by the classification criteria used for selection. Stricter diagnostic criteria allow the definition of a homogeneous group of patients with excellent prognosis. Factors predicting unfavorable prognosis were generalized tonic-clonic seizures in the active stage of absences, myoclonic jerks, eyelid myoclonia or perioral myoclonia, and EEG features atypical for CAE.

Absence seizures in succinic semialdehyde dehydrogenase deficient mice: a model of juvenile absence epilepsy

The succinic semialdehyde dehydrogenase (SSADH) null mouse represents a viable animal model for human SSADH deficiency and is characterized by markedly elevated levels of both gamma-hydroxybutyric acid (GHB) and gamma-aminobutyric acid (GABA) in brain, blood, and urine. GHB is known to induce absence-like seizures and absence seizures have been reported to occur in children with SSADH deficiency. We tested the hypothesis that the phenotype of the SSADH(-/-) mouse shows absence-like seizures because of the inordinately high levels of GHB in the brain of this mutant animal. Sequential electrocorticographic (ECoG) and prolonged video ECoG recordings from chronically implanted electrodes were done on SSADH(-/-), SSADH(+/-), and SSADH(+/+) mice from postnatal day (P) 10 to (P) 21. Spontaneous, recurrent absence-like seizures appeared in the SSADH(-/-) during the second week of life and evolved into generalized convulsive seizures late in the third week of life that were associated with an explosive onset of status epilepticus which was lethal. The seizures in SSADH null mice were consistent with typical absence seizures in rodent with 7 Hz spike-and-wave discharge (SWD) recorded from thalamocortical circuitry, the onset/offset of which was time-locked with ictal behavior characterized by facial myoclonus, vibrissal twitching and frozen immobility. The absence seizures became progressively more severe from P14 to 18 at which time they evolved into myoclonic and generalized convulsive seizures that progressed into a lethal status epilepticus. The absence seizures in SSADH(-/-) were abolished by ethosuximide (ETX) and the GABA(B)R antagonist CGP 35348. The seizure phenotype in the SSADH(-/-) recapitulates that observed in human SSADH deficiency. Hence, SSADH(-/-) may be used to investigate the molecular mechanisms that underpin the pathogenesis of absence and generalized tonic-clonic seizures associated with SSADH deficiency. As well, the SSADH(-/-) may represent a unique animal model of the transition from absence to myoclonic and generalized convulsive seizures that is observed in up to 80% of patients with juvenile absence epilepsy.

Gamma-hydroxybutyric acid: neurobiology and toxicology of a recreational drug

gamma-Hydroxybutyric acid (GHB) is a short-chain fatty acid that occurs naturally in mammalian brain where it is derived metabolically from gamma-aminobutyric acid (GABA), the primary inhibitory neurotransmitter in the brain. GHB was synthesised over 40 years ago and its presence in the brain and a number of aspects of its biological, pharmacological and toxicological properties have been elucidated over the last 20-30 years. However, widespread interest in this compound has arisen only in the past 5-10 years, primarily as a result of the emergence of GHB as a major recreational drug and public health problem in the US. There is considerable evidence that GHB may be a neuromodulator in the brain. GHB has multiple neuronal mechanisms including activation of both the gamma-aminobutyric acid type B (GABA(B)) receptor, and a separate GHB-specific receptor. This complex GHB-GABA(B) receptor interaction is probably responsible for the protean pharmacological, electroencephalographic, behavioural and toxicological effects of GHB, as well as the perturbations of learning and memory associated with supra-physiological concentrations of GHB in the brain that result from the exogenous administration of this drug in the clinical context of GHB abuse, addiction and withdrawal. Investigation of the inborn error of metabolism succinic semialdehyde deficiency (SSADH) and the murine model of this disorder (SSADH knockout mice), in which GHB plays a major role, may help dissect out GHB- and GABA(B) receptor-mediated mechanisms. In particular, the mechanisms that are operative in the molecular pathogenesis of GHB addiction and withdrawal as well as the absence seizures observed in the GHB-treated animals.