Therapeutic Options for Childhood Absence Epilepsy

Childhood absence epilepsy (CAE) is a common pediatric generalized epileptic syndrome. Although it is traditionally considered as a benign self-limited condition, the apparent benign nature of this syndrome has been revaluated in recent years. This is mainly due to the increasing evidence that children with CAE can present invalidating neuropsychological comorbidities that will affect them up to adulthood. Moreover, a percentage of affected children can develop drug-resistant forms of CAE. The purpose of this review is to summarize the most recent studies and new concepts concerning CAE treatment, in particular concerning drug-resistant forms of CAE. A Pubmed search was undertaken to identify all articles concerning management and treatment of CAE, including articles written between 1979 and 2021. Traditional anticonvulsant therapy of CAE that is still in use is based on three antiepileptic drugs: ethosuximide which is the drug of choice, followed by valproic acid and lamotrigine. In the case of first line treatment failure, after two monotherapies it is usual to start a bi-therapy. In the case of absence seizures that are refractory to traditional treatment, other antiepileptic drugs may be introduced such as levetiracetam, topiramate and zonisamide.

Epileptic phenotype in late-onset hyperinsulinemic hypoglycemia successfully treated by diazoxide

OBJECTIVES

Serious hyperinsulinemic hypoglycemia (HH) is generally the main initial symptom of hyperinsulinism. Epilepsy, without any overt feature of hypoglycemia, might be a very rare initial presentation of late-onset isolated hyperinsulinism.

CASE PRESENTATION

We describe a case of late-onset HH in a 15-year-old boy with a history of idiopathic generalized epilepsy, now named genetic generalized epilepsy (IGE/GGE), beginning with a tonic-clonic seizure at the age of 11 years. Subsequently, absences with rare eyelid myoclonia were recorded on electroencephalogram (EEG), followed by episodes of impaired consciousness with facial myoclonia. Neurological status was normal except attention-deficit hyperactivity disorder (ADHD). At the age of 15 years, an episode of slight alteration of consciousness with neurovegetative signs could be recorded, which did not correspond to an absence status. Hypoglycemia due to hyperinsulinism was documented (clinically, biologically, and genetically). Diazoxide treatment resolved the glycopenic symptoms, the non-hypoglycemic seizures and normalized brain electrical activity allowing complete withdrawal of antiepileptic medication.

CONCLUSIONS

Epilepsy can be a very rare initial feature of HH starting in childhood. The occurrence of atypical features in the context of GGE as "absence statuses" with unusual vegetative symptoms and facial myoclonia might be suggestive for HH. Careful assessment and specific treatment are necessary to prevent hyperinsulinism related brain damage. Our case showed that diazoxide might also resolve seizures and normalize EEG.

Diagnostic and therapeutic approach to drug-resistant juvenile myoclonic epilepsy

INTRODUCTION

Juvenile myoclonic epilepsy (JME), also known as Janz syndrome, is a common form of generalized epilepsy of presumed genetic origin representing up to 10% of all epilepsy cases. Despite adequate anti-seizure medication (ASM) treatment, seizures persist in one-third of JME patients.

AREAS COVERED

A literature search was conducted using Pubmed search on the topics of drug-resistant JME.

EXPERT OPINION

About 30% of JME patients are drug-resistant. Valproate (VPA) is considered the first-choice drug. In women of childbearing potential, levetiracetam (LEV) should represent the first-choice treatment. Alternative monotherapy or add-on therapy should be considered in subjects with resistant seizures after the exclusion of pseudo-drug resistance. The choice of the add-on ASM depends on the predominant seizure type. In subjects with persistent bilateral tonic-clonic seizures, LEV or lamotrigine should be firstly considered. In patients with difficult-to-treat myoclonic seizures, clonazepam or LEV are recommended. In case of persistent absences, ethosuximide should be considered. With appropriate selection and safeguards in place, VPA should remain available as an option in women of childbearing potential whose seizures are resistant to other treatments.

Pitfalls in the diagnosis of Jeavons syndrome: a study of 32 cases and review of the literature

Jeavons syndrome (JS) is mainly characterized by eyelid myoclonia with or without absences. It is thought to be underdiagnosed rather than have a rare prevalence. We aimed to investigate the electroclinical features of JS to determine possible factors influencing the diagnosis. We retrospectively identified the medical records of 32 cases (0.55%) from 5,796 patients with epilepsy. The inclusion criteria were: (1) eyelid myoclonia with or without absences; (2) generalized paroxysmal activity on EEG; and (3) discharges triggered by eyelid closure and/or intermittent photic stimulation. Eighteen (56.2%) of the patients were female. The mean age at seizure onset was 8.7±5.3 years and the mean age at admission to hospital was 17.8±10.7 years. A family history of epilepsy was present in 15 (46.8%) patients. Eyelid myoclonias were noticed in six (18.7%) patients by themselves. Based on the analysis of video-EEG recordings, 26 (81.2%) patients were sensitive to eye closure, 22 (68.7%) had photoparoxysmal responses, and 16 (50%) presented with absence seizures. Ten (31.2%) patients had focal epileptic discharges. Eight (25%) patients were on monotherapy. Seven (21.8%) patients achieved seizure freedom. Three patients underwent ketogenic diet therapy, which was effective in two patients. A vagus nerve stimulator was implanted into three patients, one of whom reported seizure reduction. Eyelid myoclonias are the main seizure type of JS but are usually overlooked. The time interval between seizure onset and clinical diagnosis suggests that this syndrome continues to be under-recognized. The genetic heterogeneity and phenotypic variability are likely to be more extensive than currently recognized, making the diagnosis more phalangine. [Published with video sequence].

Much Ado About Nothing: The Mental Representation of Omissive Relations

When the absence of an event causes some outcome, it is an instance of omissive causation. For instance, not eating lunch may cause you to be hungry. Recent psychological proposals concur that the mind represents causal relations, including omissive causal relations, through mental simulation, but they disagree on the form of that simulation. One theory states that people represent omissive causes as force vectors; another states that omissions are representations of contrasting counterfactual simulations; a third argues that people think about omissions by representing sets of iconic possibilities – mental models – in a piecemeal fashion. In this paper, we tease apart the empirical predictions of the three theories and describe experiments that run counter to two of them. Experiments 1 and 2 show that reasoners can infer temporal relations from omissive causes – a pattern that contravenes the force theory. Experiment 3 asked participants to list the possibilities consistent with an omissive cause – it found that they tended to list particular privileged possibilities first, most often, and faster than alternative possibilities. The pattern is consistent with the model theory, but inconsistent with the contrast hypothesis. We marshal the evidence and explain why it helps to solve a long-standing debate about how the mind represents omissions.

Misleading Focal Clinical, Neurophysiologic, and Imaging Features in 2 Children With Generalized Epilepsy Who Underwent Invasive Electroencephalographic (EEG) Monitoring

Children and adults with genetic generalized epilepsy may have focal clinical seizure symptoms as well as electroencephalographic (EEG) findings. This may pose a diagnostic challenge to clinicians, especially when concomitant focal neuroimaging findings exist and the epilepsy is medically refractory. We sought to highlight the challenges that clinicians may face through the description of 2 children with suspected genetic generalized epilepsy who had both focal seizure symptoms and EEG/neuroimaging findings and underwent invasive EEG monitoring. Ultimately, invasive monitoring failed to demonstrate a focal origin for the seizures in both cases, and instead confirmed the presence of genetic generalized epilepsy. We demonstrate that ≥3-Hz generalized monomorphic spike and waves are less likely to represent secondary bilateral synchrony, that focal neuroimaging findings may not always be causal and that repeated hyperventilation is an essential activation procedure for genetic generalized epilepsy.

Rasmussen syndrome: absence seizures may be induced by oxcarbazepine

A female patient with electroclinical and neuroradiological features compatible with Rasmussen syndrome developed a particular clinical and EEG pattern. As the seizures were refractory to valproate at 750 mg/kg/day, oxcarbazepine (OXC) at 30 mg/kg/day was added. Seizures became more frequent and on neurological examination, no hemiparesis was detected. The interictal EEG showed focal spikes and diffuse paroxysms in the right fronto-temporal regions. Brain MRI revealed right hemiatrophy, mainly at the Sylvian fissure. After initiating OXC daily, brief absence seizures, lasting less than 20 seconds and associated with bilateral and synchronous 2.5-3-Hz spike-and-waves compatible with typical absences, were observed. OXC was discontinued and the typical absences disappeared. Treatment with intravenous gammaglobulin was started. At the last control visit, at nine years of age, no absence seizures were observed either by the parents or on the EEG recording. Our patient who met the diagnostic criteria for Rasmussen syndrome presented with absence seizures that may have been induced by OXC. The absence seizures disappeared after OXC was discontinued.

Agenesis of the Corpus Callosum and Generalized Epilepsy

The corpus callosum is the main band of interhemispheric axonal fibers in the human brain. Corpus callosum agenesis has widely varying symptoms, mainly associated with epilepsy, cognitive failure, and different neuropsychiatric disorders. Our case of corpus callosum agenesis includes eyelid myoclonia with absences. In the literature, there is no reported case of this combination. We report this case because it is rare, and relevant for the understanding of interhemispheric communications, based on our electrophysiological findings.

Low-dose sodium valproate in the treatment of idiopathic generalized epilepsies

OBJECTIVE

Most patients with idiopathic generalized epilepsies (IGEs) have good seizure control when on antiepileptic drugs. To analyze prospectively the response to low-dose sodium valproate (VPA) treatment (<1000 mg/day) together with plasma VPA levels in a cohort of patients with IGE.

METHODS

Patients with IGE were selected and followed for almost 2 years. In patients on VPA with no seizures in the last year, VPA dose was lowered to <1000 mg/day. Newly diagnosed patients with IGE started treatment on VPA directly on this low dose.

RESULTS

Fifty-four patients were included, with juvenile myoclonic epilepsy (JME) in 23 (42.6%), juvenile absence epilepsy (JAE) in 17 (31.5%), and generalized tonic-clonic seizures only (GTCS only) in 14 (25.9%). VPA at low dose was administered to 38 (70%) patients. Mean plasma VPA level was 44.21 mg/l (18-78; SD 15.18). Seizure relapse during the 2-year follow-up was observed in 8 (21%). A reduction in adverse events was observed (P < 0.048). The only factor related to efficacy of VPA at low dose was syndromic diagnosis. Low-dose VPA controlled 92.9% (13) of patients with GTCS only, 78.3% (18) of those with JME, and 29.5% (5) of those with JAE.

CONCLUSIONS

Low-dose VPA was a highly effective treatment for the majority of those with JME and GTCS only. The seizures in JAE tended to be more resistant to treatment, usually requiring higher doses of VPA or polytherapy.

Epilepsy and phenylketonuria: a case description and EEG-fMRI findings

Phenylketonuria (PKU) is characterized by phenylalanine accumulation due to phenylalanine hydroxylase deficiency. Up to 50% of PKU patients experience seizures. We evaluated an adult PKU patient who suffered from absences and primarily generalized tonicclonic seizures, associated with generalized spikeand-wave discharges (GSWs) on EEG. An analysis of blood oxygenation level-dependent (BOLD) signal changes during interictal epileptiform discharges showed early activation of the left perirolandic cortex followed by a BOLD signal decrease within cortical regions belonging to the default mode network and left frontoparietal cortex. Moreover, deactivation of the head of the right caudate nucleus and the left thalamus was observed. The fMRI pattern observed in our patient during GSWs is similar but not identical to that observed in idiopathic generalized epilepsy, suggesting different neurophysiological mechanisms. This is the first description of BOLD-fMRI patterns in a PKU patient with epilepsy. Similar studies in more patients might help to uncover the pathophysiology of seizures in this disease.